International Atomic Energy Agency

United Nations Educational. Scientific and Cultural Organization

MIH!

lnternational Centre for Theoretical Phvsics

No. 44145March/April 1991

Contents

Round Table Conference onScientific Brain Drain in theThird World and in Centraland Eastern Europe 1

ICTP Dirac Medals 3

Dr. Khursheed AwardedSalam Prize 4

Symposium on Geometryand Physics, Edinburgh 4

International Prize"Primo Rovis" l99l 4

The Greenhouse Effect andGlobal Warming 5

IOI Training Programmeon the Managenent andConservation of MarineResources in theMediterranean 13

Post-doc Position atUniversity of Oklahoma t 4

NSERC Women's FacultyAwards in Physics atCarleton University andUniversity of Ottawa L4

Yisits to ICTP l 4

Conferences- and Lectures t 4

Activities at ICTP

in March/April 1991 t 4

Round Table Conferenceon Scientific Brain Drainin the Third World and in

Central and Eastern Europe

The Round Table Conference onScientific Brain Drain in the ThirdWorld and in Cennal and Eastem Europewas held on 25-26 March at theInternational Centre for TheoreticalPhysics in Trieste. Prof. Abdus Salam,Director of the ICTP, inaugurated thetwo-day Round Table Conference inwhich he had invited thirty personalitiesfrom the Third World, Central andEastern Europe and internationalorganizations to discuss the scientificbrain drain to the developed world. Thespeakers overviewed the problems ofbrain drain in Science & Technology andput fonvard some important recommend-ations on how to stop the brain drainfrom the developing countries to thedeveloped countries.

Prof. AMus Salam, in his introductoryspeech said, "People are the ultimatesource and beneficiary of all humanactivities. It has been estimated thathuman potential, capital, particularly inthe developed wodd, represent more thanhalf of the wealth of nations. This isintangible wealth, created throughinvestments in education, health,various social aims, as compared totangible wealth which includes means ofproduction like machines, tools, rawmaterials etc. Science & Technologyhas been the highest, most pronouncedachievement of human creation and thesource of all the wealth, including themost modern, angible ones, because themost efficient machines, tools etc.incorporate more and more Science &Technology (as a human creation). Thatis why all societies interested inprogress devote the utmost attention tohuman capital, scientists andtechnologists in particular.

Professor Abdus Salam Director, International Centre for Theoretical. Physics,inaugurated tle Routtd Table Conference on Scientifrc Brain Drain the the Third World ardCetural and Eastern Eruope on 25th March, 1991, in tlw Main Lecture Hall of tlv ICTP.Prof. D. Ekong is on the brt atd Prof. A. Hanpui on the riglx.

News from ICTP - No. 44145 - March/Aprll 1991

Increasing internationalization,globalization and interdependence havebeen the prominent features of the worldof today, quickly affecting all aspects ofhuman activities. This is demonstratedby increased trade in goods and services,movement of capital, Science &Technology (both directly or asincorporated in goods and services) andespecially in the circulation of people —migrations, temporary internationalcontacts, tourists and, unfortunately, asrefugees.

Checking the brain drain to the"reversed transfer of technology" fromthe poor nations to the more advancedones, the recent emigration waves fromMeditenanean and developing countriesas well as from Central and EasternEurope to the West has called for theattention of governments in the West.In particular, the re-organization ofscience academies and universities inEastern Europe after 1989 is such that alarge number of active scientists will nolonger be employed by their formerorganizations and forced 0o either leavetheir counry or leave their profession.

The brain drain is a serious problem,especially in the Third World countries,not merely because of befter attractionselsewhere, but also of bureaucratic andadministrative control, lack of high-quality facilities, absence of peerappraisal and of social respect. There isa small percentage of GNP allocated forScience & Technology and R&D in theThird World countries. and the amountallocated for R&D per scientists andengineers is much less than in the West.

The South Commission hasdemanded increases in the allocation ofGNP for R&D to lVo on average (muchmore in some countries) i.e., a littlemore than doubling the currenIallocation. In the case of scientists andengineers the request is higher. Bothcomponents of the recommendation areinlerconnected, meaning a substantialpush for S&T in the South. At thesame time, this may serve not only asan anti-brain-drain action but may alsocontribute in some cases !o the reversalof that trend, even to the return of somescientists from abroad.

Prof. Salam suggested a fewremedies that should be taken as anti-brain{rain.1. Like the one pioneered. by the

Associateship Scheme of the ICTPhere in Trieste.

2. TWAS has a number of schemesdesigned to encourage scientists fromthe South !o pursue research in their

A glimpse of the audience.

own countries.3. Another scheme is TOKTEN,

devised by UNDP.4. The privately-run Foundation for

Science, organised by expatriatescientists could greatly help theirhome countries. Even without theFoundation for Science, individualscientists could help their owncountries.

5. Finally, another instrument can bethe creation of a commonwealth ofscience on a regional or subregionalbasis.He sfongly pornted out that nobody

has the right, under the pretext ofnational- interest, !o keep scientists athome without giving them conditionsf c optimum scientific achievements.

Dr. D. Ekong (Secretary General,Association of African Universities) andDr. O. Moretto (President, Academy ofSciences, Argentina) stressed theproblem of brain drain in Science &Techirology in Latin America. l,atinAmerica is composed of 19 countries,including Cuba and Dominican Republicand excluding the Caribbean. Possiblyone could divide Latin Americancountries in two groups — one is moreadvanced in S&T like Argentin4 Braziland Mexico, and another is leastadvanced countries such as Bolivia,Paraguay and some Central Americancountries. The brain drain of LatinAmerica is as serious as in the ThirdWorld. Argentina devotes a little over4.57o of its GNP to research and&velopment

Prof. A. PapiC (former member ofthe South Commission), Prof. A.

Hamoui (Kuwait University, Kuwait)and Dr. V. Kuzminov (Director,LJNESCO-ROSTE, Venice) read out theoverview of the South, North, Centraland East European brain drain in Science& Technology.

In the morning session of March 26,the case studies of the Third WorldanalyzeA the situation of scientific braindrain in various selected countries likeBangladesh, Sri Lanka, Mor@co,focusing on the origin and amplinde ofthe phenomenon, and its effect on thescientific and economic impoverishmentof these countries. Prof. J.N. Islam(Bangladesh) and Prof. V.K.Samaranayake (Sri lanka) delivered theirpapers !o overview the spientific braindrain in S&T of these countries.

One session was dedicated to thepresentation of various modalities tocounteract the scientific brain drain.Prof. L. Bertocchi, (Deputy DirectorICTP), hof. M.H.A. Hassan @xecutiveSecretary, Third World Academy ofSciences) and Dr. B. Jerman Blazic(Institute Jozef Stefan, Yugoslavia) werethe speakers of this session andpresented their papers.

After each pr€sentation, there wasample time for open discussion. Ideasand proposals were debated in the lastsession which had been scheduled fordrawing the conclusions of theconference and setting up recommend-ations for the follow-np.

The recommendations are:a. Measures should be taken by the

govemments in the South to sopthe migration of highly-qualified

News from ICTP - No. 44145 - March/Aprlt 1991

scientists and lechnologists to thedeveloped world by improving theirworking conditions and involvingthem fully in national developmentprogrammes. Governments shouldhave full confidence in their ownscientists and technologists who inseveral cases have demonstratedbetter abilities than many of theforeign scientific and technicalexpertise hired as consultants.

b. To counteract this brain drain,building of appropriate institutionsin the South needs to be vigorouslypursued at all levels of scientificeducation, training and research.This will require rebuilding thescientific infrastructure in schoolsand universities and ensuring theavailability of equipment andscientific literature.

c. The establishment of world-classresearch and raining institutions inthe South in critical areas, such asfood security, energy sup'ply, tropicaldiseases, soil erosion, deforestationand desertification, are vital to thesurvival and credibility of thedeveloping nations.

& In addition, an international effort isneeded to establish high-levelresearch and training centres in keyareas of frontier science and hightechnology such as molecularbiology, biotechnology, informaticsand new mat€rials.

e. A major effort should be made tofully mobilize competent researchand training institutions within theSouth !o train scientists from othercountries with poorer facilities. Tofurther facilitate the development ofhuman resources, a massive regionalscholarship programme should besponsored by governments of theSouth and donor agencies to enablestudents to pursue training ininstitutions in the South withadequate facilities and infrasfucure.

f. There is an urgent need !o identifyand nurture young talented studentswith exceptional scientific ability.To faciliate this, institutes for talentsearching and development need to beestablished in the South. Suchinstitutes can organize regionalprogr:rmmes like school olympiadsto identify and encourage talentedstudents. It can also sponsor asystem of 61ite schools and collegesas well as specialized courses inbasic sciences to nurture gifteds0dene to develop their talent.

g. Measures should be taken by

governments to promote stronglinkages between researchinstitutions, industry and agriculturewith the aim of involving scientisBand technologists in the majorproduction sectors of the counfy.

ICTP Dirac Medals

The 1990 Dirac Medals of theInternational Centre for TheoreticalPhysics (ICTP), Trieste (Italy), havebeen awarded to Prof. LudwigDmitriyevich Faddeev (SteklovMathematical Institute, Leningrad,USSR) and Sidney Richard Coleman(Harvard University, Cambridge,Massachusetts, USA).

Ludwig Dmitriyevich Faddeev ishonoured for researches in the area ofquantum field theory and mathematicalphysics. His name is well known intheoretical physics in connection withthe Three Body System (Faddeev'sequation). He made decisivecontributions to the quantization of theYang-Mills and gravitational field. TheFaddeev-Popov covariant prescription ofquantization of non-Abelian gaugetheories discovered in l%6-67 has manyessential applications including quantumeffecs in the Glashow-Salam-Weinbergmodel of electroweak interactions and in$nntum chromodynamics. Faddeev is adisciple of Dirac's ideas in theoreticalphysics. His studies are related with theevolution of the Dirac Hamiltonianinterpretation in the inverse scatteringmethod (1971, and with exact integmblesystems, as well as with quantum theoryof solitons (1975). He also clarified ttregroup-theoretical origin of anomalies inthe context of cocycles (198a). Hisworks stimulated the wide-spreadapplication of solitons in relativisticquantum field theory. Faddeev'scontributions to the quantum inversescatlering method and 4-marix theoryinitiated the development of thisdirection which is now known as theQuantum Group Approach. Hisscientific work significantly conributedo the broad extent of geomefical and

algebraic ideas in modern theoretical andmathematical physics

*

Life of Prof. FaddeevProf. Ludwig Dmiriyevich Faddeev

was born in l*ningrad on March 23,193 . He graduted frrom I$ingrad SEteUniversity in 1956. He received hisPh.D. in 1956 and degree of docor ofsciences in 1963 at Steklov

Mathematical Institute of the USSRAcademy of Sciences. Prof. Faddeevpermanently works at LeningradDepartment of Steklov MathematicalInstitute. He started as a ResearchAssociate (1960), Senior ResearchAssociate (196/.r, then became leader ofthe Laboratory of Mathematical Methodsof Physics (1974) and Deputy Directorfor the Leningrad Department of SteklovInstitute in 1976. He was appointed asProfessor at the Department ofMathematical and Mathematical Physicsin 1967. Ludwig D. Faddeev is amember of the USSR Academy ofSciences (1976), Member of theAmerican Academy of Scierce and Art atBoston (1979), President of theInternational Union of Mathematics(1986), Honorary Member of theAcademy of Science of Poland (1987),Doclor Honoris Causa of Universities atNankai and Buenos Aires (1987 and1988), Foreign Member of the Academyof Science and Literature of Finland(1988). He has published more than150 scientific articles and five books.He is a member of the editorial board ofseveral international journals. Honoursbesoowed include: USSR State Prize(1971) and Danny Heinemann hize onMathematical Physics (1975).

Dirac Medal AwardCeremony

On Tuesday, 23rd April 1991,Professor Ludwig D. Faddeev (SteklovMathematical Institute, Leningrad,USSR) received the 1990 Dirac Medalwhich had been awarded to him las year.The other 1990 Dirac Medal will bepresented to Prof. Sidney RichardColeman (Harvard University,Cambridge, Massachrseus, USA) duringthe 1991 Summer School in HighEnergy Physics and Cosmology. Thesetwo Medals are awarded ev€ry year on8th August, birthday of P.A.M. Dirrc.

Professor AMus Salam, Director ofICfP, was not therc to preside over theceremony, as he was travelling abroadfor urgent work. Prof. Stig Lundqvist,Chairman of the Scientific Council ofthe ICTP, chaired the function He paida tribute to the memory of Dirac. As astudent he had found Dirac's book onquantum mechanics very difficult tourderstand" He discovered that dris bookcontained the seeds for topologicalmethods in quantum field thooiy, formagnetic monopoles and also for thequantum Hall effect — topic closer to

News from ICTP - No. 44145 - March/Aprll 1991

Professor Ludwig D. Faddeev receiving the Dirac Medal from Prof. L- Bertocchi,Deputy Director, ICTP.

his own research field. Early papers ofDirac were seminal to the path integralmethod. Prof. Lundqvist inroduced himas the man who has bridged mathematicsand theoretical physics in a most fruitfulway and also as a very helpful colleaguein the international work.

Prof. L. Bertocchi, Deputy Directorof the ICTP, had the pleasant occasionof presenting the golden medal and acheque of US$5,000, on behalf ofProfessor Abdus Salam, to Prof.Faddeev. Prof. Faddeev inroduced thesubject of his lecture "Dirac'sGeneralized Dynamics and Gauge FieldTheory". He felt himself as a disciple ofDirac. He decided to work on thequantization of gauge fields since hefinished his research on the quantumthree-body problem, the results of whichhad brought him in the limelight oftheoretical physics lowards the end ofthe fifties. Qrnntum field theory whichhad produced a successful theory ofquanturn electrodynamics, failed when itwas extended o particles other than theelectron.

Many theoreticians had abandoned itand turned o different approaches likethe S-matrix theory, encouraged by W.Heisenberg, or !o dispersion relations.Only a few obstinately persevered in thisdirection. These included Dirac himselfand Gell-Mann. Faddeev was notinfluenced by the Yang-Mills theorywhich was not related to physicalactivities; but he was struck by astatement of Hermann Weyl:"Electrodynamics is a geomerical theoryin the charged space". Another elementwhich errcouraged him !o work on gauge

field theory was a book by A.Lichnerowicz on the theory of globalconversion and holonomy discoveredeventually in a bookshop in Irningrad.His research with the geometricalapproach absorbed his energy for manyyears and it took twenty square metres ofa blackboard filled with I-agrangians andother formulas and fifty minutes tosummarize it o the audience.

The Dirac Medal lecture will bepublished in the next ICTP newsletter.

Dr. Khursheed AwardedSalam Prize

Courtesy ofHigher Education News,

Februry I99L

Dr. Khursheed Hassan, Professor ofPhysics, Quaid-i-Azam University,Islamabad, was awarded the Salam Prizefor the year 1990, for his research on"Magnetic Propenies of Superconductmsat High Temperatures". The award-giving ceremony which was organizedby the University Grant Commissionand Salam Prize Committ@, was held uIslamabad College for Girls, F-6f2, onDecember 23,1990.

Dr. Khursheed Hassan's researchcould help produce fast computers andfast railway trains with the use ofmagnetic properties. loss of elecficityin transmission could also be saved byutilisation of high research.

Dr. Khursheed Hassan is the fourthfrom Quaid-i-Azarfl Univenity to receivo

the Salam Prize which is given inrotation to people who make exceptionalcontribution in the field of Mathematics,Physics, Chemisry or BiologY.

Dr. Khursheed Hassan, who wasawarded a cash pize of $1000, oPinedthat one could work wonder even in badconditions, with determination and astrong sense of commitmenl

Symposium on Geometryand Physics' Edinburgh

A Symposium on Geometry andPhysics was held in Edinburgh, UK,from 19 to 28 March, 1991. Thisconference was the first scientificactivity of the International Centre forMathematical Sciences which was set upin Edinburgh with the co-operation ofthe ICTP, for the benefit ofmathematical scientists throughout theworld. The aims of ttris venture will bevery similar to those of the TriestecenEe.

International Prizet o r Rovis" 1991

On the occasion of its tenthanniversary, the Trieste lnternationalFoundation for Scientific Progress andFreedom has instituted a prize o beawarded to a candidate who has notablycontributed to the diffusion of scientificculture: a contribution according to theaims of the didactic activities andcultural services which the laboratoriodell'Immaginario Scientifico has beencarrying out according to the NationalProgramme for he diffusion of scientificculnre and information.

Over the last few years, the Problemof scientific communication has affrctedthe interest of the whole world, and inparticular Europe and ltaly. Nowadays,the need for the diffusion of science andhislory of science is deeply felt" notonly by the scientific cornmunity.

The Trieste International Foundationfor Scientific Progress and Freedom,presided over by the Nobel lalreateProfessor Abdus Salam, Directs of theInternational Centre for TheoreticalPhysics (ICTP), has inStituted anintenrational prize on ttre occasion of i stenth anniversary. The Prize is meantfor scientists who have effectivelyworked on this very important andbpical cultural activity, whether in ltaly

News from ICTP - No. 44145 - March/Aprll 1991

or abrcad-The Prize, instituted out of the

generosity of businessman Primo Rovisand worth US$ 20,000 per year, is atoken of the role which Trieste isplaying in Italy and Europe in the fieldof scientific culture.

The Prize Committee, presided overby Prof. Salam and composed ofrepresentatives of international reputefrom local universities and researchinstitutions, has awarded the Prize toProf. Richard Langton Gregory with thefollowing citation: "Foundcr of "TheExploratory" in Bristol (UK);international promoter of thedevelopment of interactive didactics inscientiftc museuns; First President ofthe European Consortium of ScienceIndustry and Technology Exhibitions;scientist, epistemological writer,promoter of new concepts in scientiJicmuseology".

The presentation ceremony tookplace on 19 March, 1991, at theLaboratorio dell'Immaginario Scienti-fico, within the framework of the"National Week of Scientific Culture".Many personalities from the political,economic, cultural and scientific sectorswere a[ending.

After this first edition, theFoundation intends to disseminate theannouncement of the Prize to allscientific instinrtions and museums bothin Italy and abroad, so as to receiveinformation on the work of scientistsand/or qualified managers in the selectedscientific field, and !o draw the a$entionof these institutions and museums onthe initiatives taken up by the City ofTrieste through the Primo Rovis Prize.

The Greenhouse Effectand Global Warming

Prof. Sir John Mason, guestscientist of ttre Third Wuld Academy ofSciences (TWAS) and Royal SocietyLectureship hogramme, presented apaper on the greenhouse effect andglobal wrming at the Adriatico LectureHall on Thursday 18 April, 1991. Thislecnrre described how increasing levelsof carbon dioxide and other 'greenhouse'gases, such as methane and CFCs, arelikely to affect the global climare overthe next 50-100 years. The estimatesare based on the predictions of thelargest compu&er models of the world'sclimate which are presently not insufficient agreement to providegovernments with firm scientific

guidance for remedial action.Research in the next ten years will

therefore concenmte on improving thecomplex physics of these models whichinvolve both the (rceans and theatmosphere. A pre-requisite will be agreatly improved supply of world-wideobservations to feed and validate themodels, and to detect any acnral climaticchanges that may be atributed to thegreenhouse effect

Sir John Mason was Professor ofcloud physics and a colleague ofhofessor Abdus Salam at ImperialCollege in the 1960's. In 1965 hebecame Director-General of the UKMeteorological Office and retired fromthere in 1983. During that period hewas also Senior vice-President andTreasurer of the Royal Society for tenyears.

Since retirement, he has been verybusy — he says has four half time jobs.He is Chancellor of the University ofManchester Institute of Science andTechnology, as well as Direclor of theAnglo-Scandinavian research progranmeon acid rain which involves some 300scientists from 30 research institutionsin a six-year major study, now almostcompleted. He is Chairman of the Co-ordinating Council for Marine Scienceand Technology charged with producinga national stralegy for all activities inthis field ranging from oceanography,fisheries, North Sea oil and gas, marinebiology. He was Chairman of theInternational Committee for planningthe World Climate Reserch Programmefor six years. His latest job is Scientific

Adviser to the new Global EnvironmentResearch Centre at Imperial College,Iondon'

The Greenhouse Effectand Global Warming

Sir lohn Mason

Lecture presented at tle Royal Societyon November Sth, 1990.

SunmaryAtmospheric concentrations of

greenhouse gases such as waler vapour,carbon dioxide and methane affect theradiative heat balance and surfacetemperature of the Earth. On presenttrends, increases in carbon dioxide andthe other greenhouse gases are togetherlikely to approximale to a doubling ofthe present concentration of carbondioxide by the year 2060. The effects ofsuch a perturbation on the globalclimate are estimated using large,complex computer models designed !osimulate the present climate and itsnatural variations, and !o predict futurechanges, whether natural or man-made.Current best estimatas, based on coupledatrnosphere-ocean models, indicate that adoubling of carbon dioxide wouldproduce an average global surfacetemperature rise of 2.5°C and a rise insea level of 50 cm.

However, the model predictions aresensitive Eo rather small changes in theproperties of clouds and their influenceon radiation, so that the treatment of

Sir Jotn Mason, gucst scientist of rwAS atd Royat socicry Lcctureship progrannu,presefted a paper at thc Adriatico Guest Hous Leawe Hall on ISth April, 1991.

News from ICTP - No. 44145 - March/Aprll 1991

these and other feedback mechanismswill have to be improved in order toreduce the uncertainties of currentpredictions and provide firmer scientificguidance for remedial action.

The oceans will almost certainlyreduce and delay any global warmingbecause of their large capacity to absorbheat and about half of the carbon dioxideemitted into the atmosphere. This maylargely explain why it is not yetpossible to detect a clear signal that canbe confidently ascribed to greenhousewarming rather than to natural climatefluctuations.

1 . IntroductionThe greenhouse gases, especially

water vapour and carbon dioxide, play acrucial role in regulating the temperatureof the Earth and its atmosphere. In theabsence of these gases, the averagesurface temperature would be -l9°Cinstead of the present value of +15°C,and the Earth would be a frozen, lifelessplanet. There is now concern thatatmospheric temperatures will risefurttter, due to the steadily increasingconcentration of carbon dioxide resultinglargely from the burning of fossil fuels.The concentration is now 27Vo higherthan that which prevailed before theindustrial revolution, and is increasing at0.5Vo p.a. It is expected to reach doublethe 1860 value during the second half ofthe next century. Recently we havebecome aware that other stronglyabsorbing gases, notably methane,ni t rous ox ide , ozone andchlorofluorocarbons (CFCs) are addingto the greenhouse warming and may, bythe middle of the next century,contribute about half as much again asthe increase in carbon dioxide.

Higher temperatures will beaccompanied by changes in other climateparameters such as precipitation,cloudiness, soil moisture and snowcover and may, eventually, result insignificant expansion of the oceans andmelting of the mountain glaciers, andhence a rise in sea level-

Although the climate changes andtheir economic and their social effectsare likely to vary seasonally, andgeographically from region to region,and even from country 0o country, theoverall problem of man-induced climaticchange is a global one, whose thoroughstudy is beyond the resources of any onecountry. It follows that nationalresearch prognmmes should be plannedlargely as contributions !o internationalprojects, such as the World Climate

Research Programme and the WorldOcean Circulation Experiment" describedby Mason etal. (1987).

2 . The global budget of carbondioxide

In order to estimate more accuratelythe future concentration of atmosphericcarbon dioxide, it will be necessary !ostudy and understand in more deail thecomplete carbon cycle. The problem isthat partition of the added man-madecarbon dioxide benpeen the atmosphere,oceans and biosphere, involves difficultestimates of small differences betweenlarge two-way fluxes between enormousreservoirs (...).

The total atrnospheric reservoir ofcarbon dioxide is equivalent to 743 GtC(gigatonnes of carbon: I gigatonne =109 = I billion tonnes) which is muchsmaller than 1760 GtC for the terrestrialbiosphere, of which about 560 GtC isstored in trees and plants, and is tinycompared with the 39,000 GtC in theoceans. The atrnospheric concentrationis therefore susceptible to rather smallchanges in the fluxes between thesereservoirs. The current rate of emissionof carbon dioxide from the burning offossil fuels is 5.4 GtCin, whilst the netemissions due to deforestation andchanges in land use are estimated at 1.6Gtciyr. These are small compared withthe fluxes exchanged between theatmosphere and the Earth's surface,which exceed 200 Gtclyr. Theatmosphere retains about 3.4 GtCly(almost 507o of the emissions) leaving 3Gtclyr to be taken up by the oc€ans.The net fixation of carbon dioxide byphotosynthesis, largely by phyto-plankton growing in the op 100 m orso of ocean is about 100 GtC/yr, aboutthe same as for the terrestrial biosphere.Most of this is released by respirationand retums to the aunosphere, but someis dissolved in the ocean and some isconverted into inorganic carbon in theskeletons and faeces of zooplankton andfalls to the ocean floor.

Models of the ocean uptake suggestthat it can accept about 1.8 GtC/yr, sothat there is an apparent imbalance ofabout 1.6 GtC/yr. This is a measure ofthe uncertainty in current understandingof the global budget of atmosphericcarbon dioxide. Either there are some asyet unidentified mechanisms forremoving carbon dioxide from theatmosphere, or the amount of carbondioxide released by ropical deforestationhas been greatly over-estimated, and/oro r quantitative lnowledge of the knorn

mechanisms is unsatisfactory.Nevertheless relatively minoradjustments in the world oceancirculation and chemistry are likely toaffect significantly the amount of carbondioxide added each year to theatmosphere, even if emissions arestabilized. In particular, ocean warmingis likely to decrease the net uptake ofcarbon dioxide by sea water. Until thisproblem is resolved, predictions of theproportion of future emissions of carbondioxide retained in the atmosphere willbe subject to considerable uncertainty.However, an even larger uncertainty liesin the future global ra&e of increase ofcombustion of fossil fuels and wood, forwhich estimates range from less than2Vo per annum to double this figure.

3 . Carbon dioxide in theatmosphere

Analysis of air bubbles trapped inthe deep interiors of glaciers reveals thatthe arnospheric concentration of carbondioxide in the last Ice Age was about210 ppmv. The value at the beginningof the industrial revolution is estimatedat 275 ppm and to have increased byl57o over the following 100 years toreach 316 ppm in 1960. Since accurateand continuous measurements werestarted in 1958, the concentration hasrisen at an ever-increasing rate which iscurrently very nearly 0.5Vo p.a. Thepresent concentration of 354 ppm is277o above the 1860 value. If theconcentration were to continue toincrease at the present r:le, (0.5% p.a-),it would double i s p're-indusrial valueby 2080, and double i s present value by2130 A.D. However, it is likely thatthe increase will continue to accelerate,particularly if the world's populationcontinues to increase at the current rate,and may reach double the present vdue,i.e.700 ppm, in 80-130 years, dependingon the future rate of burning fossil fuelsand wood and the extent to which carbondioxide is taken up and stored in theoceans and by trees and vegetationthrough phoosynthesis.

4 . The effect of carbon dioxideand water vapour on theradiation budget of theatmosphere

(...) Of the shst-wave solar radiationincident on the top of the atnbsptrcre (aglobal annual average of 340 Wtn2)about l7% is reflected back to ryacq byclouds, 8% is back-scattered by the air,and 6% reflected by the Earth's surfacgto give a planetary albedo d 3l%.

News from ICTP - No. 44145 - Merch/Aprtl 1991

About l97o is absorbed by watervapour, ozone and dust and about 4Vo byclouds as the radiation passes throughthe atmosphere, so only 46Vo isabsorbed at the surface. This istransfened to the aunosphere as infra-redradiation (a net 15 unis where 100 unitsrepresents the incoming solar radiation),as sensible heat (7 unis), leaving 24units to evaporate water which latercondenses to form clouds and a globalannual average rainfall of 104 cm.

Considering now the balance of thelong-wave radiation (...), of the l l 5units (390 Wm 2 ) emiued by the Earth'ssurface, only 9 are transmitted throughthe atmospheric window !o space, theother 106 being absorbed by theatmosphere, mainly by water vapour,carbon dioxide and ozone. Thisabsorption of the up-welling long-waveradiation, plus that from the incomingsolar radiation (19 units), plus thesensible heat flux (7 units), total 132units to which must be added a netcontribution of Q4 + 4 - 20 = 8) unitsfrom clouds. Of this lotal heat input of140 units, the atmosphere emits 40 tospace and 100 (340 W m 2 ) to thesurface, the net long-wave radiative fluxfrom the surface to the atrnosphere beingonly 15 units. The net absorption ofinfra-red radiation by the greenhousegases is the difference between the 115units of outgoing radiation from theEarth's surface and the 69 units emittedat the top of the atmosphere, i.e. 46unig or 154\'tlm2.

In the absence of absorbinggreenhouse gases (mainly water vapourand carbon dioxide), the equilibriumblack-body surface temperature, 7", ofthe planet, assuming it to have analbedo of c = 0.31, is given by theequation

or

where o is Stefan's constant, S the solarconstant and a the radius of the planel

The intensity of the emitted radiationwould be only 236 Wlm 2 comparedwith the actual value of 390 Wlm2,which again implies that the combinedcontribution of the greenhouse gases is154 'Wlmz

: About 100 W m 2 arecalculated !o come from water vapourand about 50 W m 2 from carbondioxfob.

Both water vaporn and cafton dioxide

absorb infra-red over a range ofwavelengths, and the relatively highconcentrations of the.se two gases ensurethat many of the spectral lines aresaturated, and any increase in abscptionfrom an increase in their concentration islimited to the wings of the absorptionlines. Thus, while the presentconcentration of carbon dioxide (354ppmv) produces a downward arnosphericflux of 50 W m / , a near doubling to600 ppmv would increase the flux byonly 3 Wlm2 and raise the surfacetemperature by only 0.9°K in theabsence of feedback effects due !o watervapour, clouds, ice, etc. Thequantitative impact of the various feed-back mechanisms in the global climatesystem can be estimated only from theresults of large, complex modelsdescribed in Section 7.

However, a simple calculation for aclimate system in thermal equilibriumindicates that the concomitant increasein water vapour would amplify thetemperatue rise due to carbon dioxide bya factor of 1.6 to l.4°K. On the samebasis, the enhancement of carbon dioxidesince 1860 should have produced awarming of about 0.5°K.

5 . The role of the othergreenhouse gases

Although water vapour and carbondioxide are the main cause of thegreenhouse effect, any gas that absorbsin the infra-red will help o reduce theloss of terrestrial radiation to outerspace. However, absorbtion by watervapour and carbon dioxide is so strongthat other gases will conributre littleunless they absorb at wavelengths,mainly from 8 microns to 12 microns(the atmospheric 'window'), whereabsorption by carbon dioxide and wateris weak.

The most important of the tracegases which conribute significantly sothe trapping of terrestrial radiation,despite their small concentrations, aremethane, nitrous oxide and thechlorofluorocarbons, especially CCI3F(Fl l ) and CCL2F2 Gl2) . Methane

concentrations are only about 0.5% ofthose of carbon dioxide, but are 2l timesas effective molecule for molecule ascarbon dioxide as an absorber ofterrestrial radiation. CFCs are only one-millionth as abundant as carbon dioxidebut 14,000 times more effective.

Methane, currently at 1750 ppbv, isincreasing at about 1% annually, and isexpected to double in about 70 years.Various sources of methane have beenidentified but not quantified. Theseinclude emissions from ruminants, ricepaddies, was&e disposal sites and oilrecovery operations. Doubling methanewould have about 15% of the warmingeffect of doubling carbon dioxide.

Ninous oxide, cunently at 300 ppbv,is increasing at 0.25% per annum forlargely unknown reasons. It is formedprimarily as a product of bacterialdenirification but also in combustionprocesses. It is likely to increase bya b u t 207o by 2060, conributing in themeantime about 47o to the totalgreenhouse warming.

Table I shows the presentconcentrations of cFCs in theatmosphere and their contributions toglobal warming to be about O.2 Wlm2

or l2%o. The trace gases combined nowcontribute about half as much again ascarbon dioxide to greenhouse warming.

Even if CFC emissions are reduced,the concenfiations may continue !o risebecause F l l and F12 have atmosphericlifetimes of 80 and 140 years,respectively. If tlre Montreal Agreernentto reduce emissions to 80% of 1986levels from 1993, and to 50% from1998, is fully implemented, CFCs arelikely to contribute almost l0% togreentrouse warming in 2Ci&.

A simple radiative calculation withno feedbacks would suggest that thosegreenhouse gases ogether, should haveproduced a global warming of 0.7°Krelative 0o 1765, but enhanced to l.l°Kby the concomitant increase in watervapour. A corresponding calculation ofthe present warming relative to 1900gives 0.85°K, very close to the bestestimate obtained from advanced models

TABLE 1. -GI.OBAL WARMING BY GREENHOUSE GASES IN I99O REI.ATTVE TO 1765.

COj cTI4 N p CFCrr CFC12 HCFC2

Concentrations (1765)Concentration (1990)

Increas€d heat flux2 = 2.30 'ff/m2

% conributions

279354

Ppm1.5

66

79O1720ppb

0,42

l8

285310Ppb

0.10

0280Ppt

0.06

0480PPt

0.14

0320pPt

0.08

t2

News from ICTP - No. 44145 - March/Aprll 1991

of 0.9"K. However, this agreement isprobably fortuitous as the simplecalculations ignore all feedbacks exceptthat due !o water vapour.

6 . Is greenhouse warmingapparent in the observations?

The above estimate that the climateshould have warmed by almost l°Ksince 1900 prompts one to examine theobserved average global temperaturerecord which (...) indicates a rise ofabout 0.5°K over the last 90 years.However, it is unlikely that this can beattributed to the greenhouse effect for thefollowing reasons:• 0.3°K of the 0.5°K rise occurredbetween 1900 and 1940 when carbondioxide was increasing at only O.IVo perannum, compared with the current rateof 0.5Vo.• there was a small fall in temperaturebetween 1940 and the mid 1960s, widelyclaimed by the media and somescientists in the 1970s to herald a newIce Age!• despite the rather sharp rise duringthe last decade in average global airtemperatures, this has not occurred inhigh latitudes, nor has there been anysignificant decrease in the ice cover,although all the models predict greatestgreenhouse warming in the Arctic.

The timing of the fluctuations in thetemperature record, and the fact thatgreenhouse warming is likely to bedelayed for some decades because of thethermal inertia of the oceans (...)strongly suggest that these are naturalclimatic fluctuations.

If we assume that this is indeed thecase, we may use a coupled arnosphere-ocean model to estimate how long itwill take for a greenhouse signal of, say,0.5°K to be detectable. The onlypublished account (Manabe et at. 1990)of a coupled atmosphere-deep oceanmodel, in which carbon dioxide isallowed to increase at L% p r annumcompound and so double in 70 years,predicts an average global temperaturerise of 2-3K, a rise of 0.5°K occurringafter 20 years.

7 . Model simulations andpr'edictions of climate change7.1 Introduction

Changes in global and regionalclirnates due to greenhouse gases will besmall, slow and difficult o detect abovenatural fluctuations during the next l0to 20 years. It will therefore benecessary to rely heavily on modelpredictions of changes in temperature

and rainfall, ice cover, etc. Indeed, inthe absence of any direct evidence,concern over the greenhouse effect isbased almost entirely on modelpredictions, which unforfirnately vary sowidely that they do not yet provide asufficiently firm basis for governmentaction.

Climate models, ranging fromsimple one-dimensional energy-balancemodels to enormously complex, three-dimensional global models requiringvast computing power, have beendeveloped during the last 20 years, themost advanced at three centres in theUSA, and at the UK Meteorological0ffice.

Until recently, effort wasconcentrated on developing models (thatevolved from weather prediction models)of the global atmosphere coupled to theoceans and cryosphere (sea and land ice)only through prescribing and up-datingsurface p:u:rmeters such as temperatureand albedo, from observations.However, realistic predictions of long-term changes in climate, natural or man-made, must involve the atmosphere,oceans, cryosphere and, eventually, thebiosphere, treated as a single, stronglycoupled and interactive system. Theoceans play a major, stabilizing role inglobal climate because of their inertiaand heat storage capacity. Moreover,they transport nearly as much heatbetween the equator and the poles asdoes the atrnosphere. The oceans absorbabout half of the carbon dioxide emittedby fossil fuels and will hence delaywarming of the atmosphere. The oceansalso absorb and ransport a good deal ofthe associated additional heat flux fromthe atmosphere.

The Meteorological Office hasdeveloped perhaps the most advancedmodel of the global atmosphere coupledto simple models of the ocean, land andsea ice, and has used these to study theeffects of nearly doubling the presentlevel of carbon dioxide !o 600 ppmv.

7.2 The atmospheric modelThe physicomathematical models of

the atmosphere are based on the physicaland dynamical laws that govern thebirth, growth, decay and movement ofthe main weather systems that can beresolved by the model. In other words,the models must properly represent therelevant or significant scales of motionand their non-linear reactions, butsmooth out all the smaller scalemotions that cannot be adequatelyobserved or represented individually;

while allowing for their overallconfibution to transport and energyconservation processes by representingtheir statistically averaged properties interms of larger-scale parameters that canbe measured. The pmr:alrlletenzcfion ofthese sub-grid scale processes is one ofthe most difficult and uncertain featuresof weather and climate models, andoccupies a good deal of the presentresearch effort

The models incorporate theprinciples of conservation of mass,momentum, energy and water in all itsphases, the Newlonian (Navier-Stokes)equations of motion applied to a parcelof air, the laws of thermodynamics andradiative transfer, and the equation ofstate of humid air. Parameters specif,redin advance include the size, rotation,geography and opography of the Earth,the incoming solar radiation and i sdiurnal and seasonal variations, theradiative and heat conductive propertiesof the land surface according to thenature of the soil, soil moisture,vegetation and snow or ice cover, all ofwhich are computed every 5 days.

The atmosphere is divided ino 1lconcentric shells ( l l levels) between hesurface and 20 mb (approx 30 km) with3 levels in the surface boundary layer(lowest km) !o allow calculation of thesurface fluxes of heat, moisture andmomentum. There are also 3 levels inthe soil to calculate the heat fluxthrough the soil and hence the landsurface lempemture. The variables arecalculated on a spherical grid with mesh2.5 degrees latitude x 3.75 degreeslongitude with some 30,000 points ateach level, or about 350,m0 points inall.

The main physical processesrepresented in the mo&l are:transfer of heat by:• - solar and terrestrial (infra-red)

radiation, including absorption bythe greenhouse gase.s wal€r Yapour,cafton dioxi&, ozone u d metturp;

- scattering and absorption byclouds;

- reflectiory'absorption at the Eartlt'ssurface by soil, vegetatiolt, stow,land and sea ice and by the oceang

- strallow ard doep cctvectim;- conduction at the Earth's surface;the hydrological cycle:- evaporation of moisture from land

and watef surfrces, condensation inthe atmosphere o fqm clouds, rainand snow (precipiation), calculationof nrnoff and soil moisture;

- transport of heat, moisture and

News from ICTP - No. 44145 - March/Aprll l99l

momentum in the lowestatmospheric layers (atmosphericboundary layer) by small-scaleturbulent motions;

- the frictional drag on the atmosphereexerted by mountains, the landsurface, breaking gravity waves inthe atmosphere, and by waves on theocean surface.Starting from initial values derived

from observations on a particular day,the governing finitedifference equationsare integrated in time-steps of 20minutes to give new values of thefollowing parameters at all the relevantgrid points, which are then averaged togive monthly mean values over totalintegration times of years m decades.

The most important computedvariables are:E-W and N-S components of the wind,Vertical motion,Air temperanue and humidity,Heights of the 1l specified pressuresurfaces,Short-and long-wave radiation fluxes,Cloud amount, height and liquid-watercontent,Precipitation - rairy'snow,Aunospheric pressure at Earth's surface,Land srface temperahre,Soil moisture content,Snow cover and depth,Sea-ice cover and depth,Ice-srfrce temperature,Sea-srrface temperanre.

The arnospheric model is coupled oa simple shallow well mixed ocean layeronly 50 m deep, which transports heathorizontally and vertically and allowscomputations of the fluxes of heat,moisture and momentum between theocean surface and the atmosphere. Anenergy-balance sea-ice model allows theareal cover, snowdepth and ice thicknesso be calculated every 5 days and the

albedo !o decrease gradually as the icemelts and recedes. The surfacetemperature of the sea-ice is calculatedfrom the heat balance equation at everymodel time step.

A 24 hour integration for the wholesystem involves about 1012 numericaloperations, so that a complete annualcycle takes about l0 hours on the mostpowerful supercomputer, the CRAYYMP.

Such models have been remarkablysuccessful in simulating the mainfeatures of the present global climate —the distribution of temperature, rainfall,winds, etc. — and their seasonal andregional variations. They do, however,conbin some systematic erron (different

in different models) and will requirecontinued development and improvementin order to provide accuratesimulations/predictions of thefractionally small but, nevertheless,potentially very important changes thatmay result from natural or man-madeperturbations.

7.3 Model simulations for thedoubling of carbon ilioxide

The changes in global temperaturesand precipitation to be expected from anear doubling of carbon dioxide !o 600ppm, rs predicted by the MeteorologicalOffice model before tle recent changesin the reatment of clouds are describedbelow (...). These changes, achievedwhen the climate system represented bythe model has come into equilibriumwith the enhanced atmospheric carbondioxide, are the highest predicted by anyof the advanced models. A detailed.lccount is given by Wilson and Mitchell(1987). Although recent modificationsto the cloud parameteri sation schemehave produced smaller changes, these'upper' estimates are presented herebecause they bring out more clearly ttregeographical and seasonal pauerns of thechanges which are not greatly altered inthe newer simulations.

The global average temperature isincreased by 5.2°K, accompanied by aI57o increase in both globalprecipitation and evaporation of waterfrom the surface. Comparable resultsfrom other advanced models are shown

in Table 2. The enhanced radiativeheating of the surface due !o increases incarbon dioxide and wator vapour causesincreased evapoation (which re,srics thetemperature rise), and produces a moreintense globally-averaged hydrologicalcycle. Enhanced carbon dioxide causesincreased emission of long-waveradiation from the op of ttn afrnosphereto space and, consequently, a cooling ofthe straosphere (...).

The zonally-averaged (along latiurdebands) warming is generally mostpronounced in high latitudes near thesurface in winter because of severalamplifying factors. Firstly, greenhousewarming reduces the highly reflectingsnow and ice cover and leads !o geaterabsorption of heat, which accelerates theretreat of the ice. Secondly, in highlatitudes in winter, there is a shallowlayer of cold, dense air near the surface(an inversion), which raps the increasedradiative heating, whereas in fte tropicsand sub-tropics this is mixed throughthe whole depth of the atmosphere bydeep convection, to produce a smallerwarming. Thirdly, the warmer, moisteratmosphere transports more latentenergy upwards and polewards from thetropics, releasing additional latent heatby condensation in the middle and uprpertroposphere on the way. These positivefeed-back effects, together, result inwinter polar surface temperatures beingincreased by 12"K, compared with only4°K in the tropics.

The simulated changes in

TABLE 2. - GL,OBAL MEAI.I CHANGES CAUSED BY DOLJBLING C q AS PREDICTED BYVARIOUS MODELS r.rNDER EQr.rrLrBRruM CONDmONS WTTI{ DIFFERENT CITLJDSCHEMES.All models consist of a global atmosphere with 9 to 11 levels and a shall<iw mixed-layerocean with prescribed heat transport.

Model Cloudrepresentation

Radiative properties Temperature Precipitationof clouds rie 'K ircreov %

Fixed

Fixed

IJKMO(3)

GFDL

UKMO (1) Empirical-linkedrelative humidity.All-water clouds.

LJKMO (2) Computed liquidwater and ice contenl

Variable-function ofwater and ice content.

EmpiricalJinked Fixedto relative humidity.

GISS " Fixedc c c " Variable

LIKMO: UK Met Offrce.GFDL: Geophysical Fluid Dyramics Laboratory, hinceton.GISS: Goddard hstinrte of Space Surdies.CCC: Canadian Climarc Centre, Toronto.

5.2 l5

3.2

1.9

4.O

4.83.5

8

3

8

134

News from ICTP - No. 44145 - March/Aprll 1991

temperature also vary considerably withlongitude and season. Greenhousewarming is greatest over sea-ice inwinter, smallest over sea-ice in summer.In summer, sea-ice in the Arctic ismaintained at constant temperature bymelting. Greenhouse warming eitherproduces more melting with no changeof temperature, or melts sea icecompletely to expose an oceanic mixedlayer which warms only slowly becauseof its large thermal inertia. Theadditional heat stored in the mixed layeris released in autumn and winter,delaying the onset of freezing andleading to thinner sea ice through whichheat from the ocean can diffuse morerapidly and enhance surface warming inwinter. There is also considerablevariation in the predicted greenhousewarming within individual continents.In regions where the soil becomes drier,evaporation may be restricted, leading toincreased warming, and vice-versa.

The increase in atmospheric moistureaccompanying the warming due toenhanced carbon dioxide would lead oneto expect increased precipitation,especially in regions where the low-levelwinds converge to produce risingmotions, notably in the extra-tropicaldepression belts and along the inter-tropical convergence zone. This isconfirmed (...) bV an increase in thesummer monsoon rains over SE Asia.There is also a general increase inprecipitation in high latitudes, especiallyin winter, consistent with increasedtransport of moisture from low latitudes.(There are) large areas of slightly

decreased rainfall, especially in the sub-tropics in DJF and over Eurasia in thenorthern summer. These large-scalelatitudinal and seasonal changes arebroadly reproduced in the variousmodels, but they show considerabledifferences in their predictions on theregional and small scales. Models ofhigher resolution and improved physicswill be required to resolve thesedifferences. This is important becauseglobal or zonal averages are of little usein assessing the effects of greenhousewarming on agriculture, forestry, energyconsumption, water supply etc.

7.4 Sensitivity of modelsIt is important to note that the model

results are quite sensitive to therepresentation of the many interactingphysical processes, in particular, !o thesimulation of clouds and their influenceon the incoming solar and outgoingtenestrial radiation, to the fluxes of heatand moisture between the oceans and theatmosphere, to the positive feedbackbetween changes in ice cover and oceanor atmosphere temperature, and tochanges between melting snow-coverand soil moisture.

This sensitivity of the modelsimulations, and the differences orinefficiencies of the various models intreating these physical processes, arelargely responsible for the rather widerange of predicted changes of climaticpanmeters due o prescribed increases ofcarbon dioxide shown in Table 2.

Climate models are particularlysensitive to the parameterization of

Sir loln Mason presented a papcr on thc "Greenlause efect and gloM warming" atthc Adriatbo Lecture HaIl on Tfursday 18th April, 1991.

clouds, which may affect the computedequilibrium greenhouse warming by afactor of more than two. Importantfactors are tle coverage, height and typeof cloud; their optical thickness,reflectivity, absorptivity and emissivity,which are determined by theooncentration and size of fte drqlets andice particles. Depending on thesefactors, clouds can generat€ a feedbackeffect that is either positive or negative.Thus a relative increase in high cloud,which has a relatively low albedo andemits less radiation, tends o warm theatmosphere, whereas a relative increasein low cloud, with its higher albedo andlarger emission of radiation !o space,will have a cooling effect. Overall,clouds have a net cooling effect on theplanet of about l 5 W m 2 so that; on asimplistic view, doubling of carbondioxide could be completely offset by a20Vo increase in the present clouddistribution, but by a smaller percentageincrease if this were mainly low cloud.

The recent introduction of a morerealistic representation of clouds andtheir radiative properties in theMeteorological Office model has led o amarked reduction in the predictedwarrning due to entranced carbon dioxi&.For the model simulations described inthe last section, the cloud coyer wascalculated from an empirical formula onthe basis of the prevailing relativehumidity, but the liquid-waler content ofthe cloud and its detailed radiativeproperties were not computed.

The new version of the modelcalculates the liquid water content of thecloud as the difference between thatformed by condensation E air cmled byvertical ascent and that released asprecipitation. Also ice crystals areintroduced above the -15°C level inconcentrations which increase withdecreasing lemperature. Furthermore,the different radiative properties of thewater droplets and ice crysals a e takeninto account. These changes result in anaunosphere with doubled carbon dioxideproducing an increase in low andmedium-level cloud cover at middlelatitudes, and a reduction in the globalaverage geenhouse warming from 5.29Kto only 1.9'K (Mitchell et al. 1989).The end result is to change theMeteorological Offrce predictions frombeing the highest o the lowes of $oseshown in Table 2.

Other important feedback effectsresult ftom the melting and rereat of deice and snow cover induced bygreenhouse warming. As the higtly

in

News fron ICTP - No. 44145 - March/Aprll l99l

reflecting sea ice retreats and is replacedby more strongly absorbing sea water,the latter is warmed, causes furthermelting of ice, and so enhances thegreenhouse warming. The greenhousewarming also accelerates the melting andretreat of the snow cover at middle andhigh latitudes in the Spring. The newlyexposed soil is then subject !o greaterwarming and evaporation and the soil

is is reduced.The model simulations suggest that

the combined effect of these variousfeedback mechanisms is !o enhance themagnitude of the warming that wouldarise from the purely radiative effects ofthe greenhouse gases, including watervalx)ur, by a factor of between 1.5 and3.5, depending on the particular modelused, and imply values for the globalaverage warming for nearly doublingcarbon dioxide to 600 ppmv of between2°K and 5"K. By the time carbondioxide reaches this concentration, theother greenhouse gases will haveincreased these figures by at least 50%,even if the Montreal Agreement iscarried out

Inespective of the acnral magnitudesof the climate changes predicted by thevarious models, it is important to realisethat they involve only very smallpercentage changes in the normalradiative fluxes — much smaller thanthe errors in either measurements orcalculations of these fluxes. Wetherefore have to rely on the assumptionthat systematic errors will be the samein the 'perturbed' and normal (connol)models, and so disappear in thedifferences which may be attributed tothe greenhouse effecL

Furthermore, these greenhouse'signals' are compirnrble in magnitudewith the inler-annual variations thatoccur both in the models and the realatmosphere, so it is necessary to assesswhether they are significant relative tothe nanrral noise. Such statistical tessare made as a routine in theMeteorological Office model, the resultsdescribed in Section 7 (...) beingsignificant at the 90% confidence level.

7.5 Limitations and fatwemodel development

We have already intimated thatcuirent models contain some importantdeficiercies leading to uncertainty in theprediction of greenhouse effects whichshould therefore be taken as only brcadindications of likely changes, givinglitde weight at this stage to the actualmagnitudes, and even less to their

significance on regional and smallerscales. The hope is that continueddevelopment of the different models willcause their predictions to converge,narrow the range of uncertainty, andthereby provide more reliable guidancefor remedial action.

Improvements are likely !o comemainly from better representation of thephysical pr@esses and greater spatialresolution. The former will requiremore intensive study of ttre processes inthe real atmosphere using highly-instrumented research aircraft, radars,lasers, etc. Higher resolution, doublingof which increases the amount ofcomputation at least 8-fold, requiresgreater computing power than iscurrently available. One therefore has tochoose, or effect a compromise, betweenthe need for high resolution and moredetailed physics leading to greateraccuracy on the one hand, and the needfor long model runs to study inter-annual and longer-term variations inclimate on the other.

These longer-term changes, on time-scales of decades to centuries, will belargely determined by the oceans, notonly in the surface layers, but at depth.It is therefue necessary to develop fully3-dimensional models of the globalocean circulation which are coupled to,and driven by, the winds of theatmospheric model. Such models arebeing developed in the USA and theMeteorological Office with encouragingsuccess and should be ready !o utilisedata on sea-surface temperature, surfacewinds and wind stress. and circulationsin the surface layers of the ocean, fromthe new oceanographic satellites in theearly 1990s and beyond. However, asyet very few long-term integrations havebeen made with these fully-coupledmodels, which will require even morecomputing power, especially if it provesnecessary tro resolve the ocean 'weather'systems such as gyres, eddies and frontsthat are an order of magnitude smaller inlinear dimension than their atmosphericcounterparts.

The improvement of climate modelswill also depend on an adequate supplyof observations from all pars of theclimatic system, not least theatrnosphere. These are requircd f a inputto, and initialization of, the models, fortheir validation, and for the detection andmonitoring of climdte changes in theclimate system itself. Provision ofthese observations is one of the mainfunctions of the World Climate Re,searchProgramme and the \Vorld Ocean

Circulation Experiment, which weredescribed by lvlason (1987).

8 . Time'dependent simulationsof greenhouse warming —delaying effects of the oceans

Virtually all the model calculationson greenhouse warming to date haveassumed thtit both the normal climatesystem (confol model), and the systemperturbed by enhanced levels ofgreenhouse gases, are in equilibrium atall stages. The carbon dioxide isdoubled in one step and the modelclimate system is allowed to come inloequilibrium with the new concenfration.In the real world this will never be thecase because the trace gases areincreasing gradually with time and theresponse of the total climate systemdepends upon a variety of physical andbio-geochemical processes acting onwidely different time scales. Theatmosphere, together with the sea ice,the upper layers of the ocean, and theland-surface hydrology, respond quiterapidly and reach a quasi-equilibrium inthe model after a few annual cycles. Ottthe other hand, the deep oceancirculation and the land-based ice sheetsrespond much more slowly on timescales of hundreds of years, and so willconstantly lag behind the response of thearnosphere.

The large thermal capacity of theoceans and their ability to store andtransport some of the additional heatflux from the race gases will delay thegreenhouse warming but also ensure thattemperatures will continue o rise longafter any reduction in emissions takesplace. This is probably the main reasonwhy there is, as yet, no convincingobservational evidence of temperaturerises due to the gases rccumulated so far.

The delaying effect of the ocearu willbe determined by the net additional heatflux at the ocean surface poduced by thegreenhouse gases, and the effective heatcapacity of the ocean, which isdetermined by tlrc peneration of the tpatbelow the surface. Initially tlrc warmingwill involve only the well-mixed, sablystratified, 'warm water shell' down !o amean depth of 100 m or so and, evenafter 20 years, may involve only the op500 m, as indicated by the observedpenetration of tritium ejected into theatmosphere during the 1950s series oftlrcrmo-nuclear explosians.

The actual changes in climaticparameters for a given increase ingreenhouse gas concentrations aretherefore likely !o be smaller than those

11

News from ICTP - No. 44145 - March/ Aprtl 1991

predicled by the 'equilibrium' models,and to be delayed. More realisticestimates of the magnitude and timingof ttre greenhouse effects will require theconcentrations of the gases to increasegmdually at current or predicted rates, ina model which couples the atmosphereto a global deep ocean. Only a very fewmodel simulations of this type havebeen published. The results of oneexperiment by Manabe et al. (1990), inwhich the carbon dioxide was increasedat 1% per annum compound to double in70 years, (...) plotting the increase insurface air temperatures over the globe,averaged over one annual cycle. Theglobally averaged value of 2.3°K ismuch lower than that obtained by allother advanced models, except the latestMeteorological Office venion mentionedin Section 7. The reduced warming isespecially marked in the SouthernHemisphere, which shows littleenhanced warming in the Antarcticcompared with that in the Arctic. Thisis explained by the vertical oceancirculation in the southern oceans,which produces a deep down-welling ofwater around 65 deg South that carriesmuch of the additional greenhouse fluxof heat from the surface to great depths(...) where it is stored for many decades.This very interesting result should betreated with caution, because ttris is onlythe first experiment with a model that,like all coupled ocean-atmospheremodels, has considerable difficulty inreproducing the correct fluxes of heat andmoisture at the inlerface. However, itpoints !o the moderating and delayingeffect of the oceans on greenhousewarming of the atmosphere. Accordingto this simulation, a temperature rise of0.S°K would occur after 2O years.

When, during the next century, thegreenhouse gases will reachconcentrations at which they willproduce significant climate changes, willdepend also on the rates of exchange ofthe gases between the atmosphere andthe oceans, the fraction retained in theatmosphere, the take-up, storage andrelease of carbon dioxide byphytoplankton, forests and othervegetation, all involving biologicalprocesses that will have to beincorporated into global climate modelsat a. suitable stage. The first requirementis to obtain trign-quality observationaldata, which is one of the objectives ofthe lnternational Geosphere BiosphereProgramme. The National

Biogeochemical Ocean Fluxes Study,which is part of the International Joint

Global Ocean Fluxes Study, and whichwill form a strong inlerface with theWorld Climate Research Programme, isan important frst step along this road.However, by far the most importantfacor in determining the futwe levels ofatmospheric carbon dioxide and othergreenhouse gases, and hence the timingof significant climale' changes, will bethe future rates of emissions, scenariosfor which differ so widely that estimatesof the time likely !o elapse before thecarbon dioxide reaches double the presentday concentration range from 80 to 130years.

Predicted rises in average globattemperature for a number of emissionscenarios published in the IPCC Report,Houghton et al. (1990) are shown inTable 3. These are computed from asimplified atmosphere-ocean modelcalibrated against the GDFL globalcirculation model described above, [ogive a 2.5"K rise when in equilibriumwith a doubled carbon dioxideconcentration.

9. Sea-level riseA potentially important consequence

of greenhouse warming is the melting ofsea-ice and ice sheets on land, only thelatter resulting in a rise in sea level.The sea-level will also rise as the oceanwaters expand in response to theadditional warming. Estimates of these

consequences involve large unceraintiesbecause of lack of observations and ofunderscanding of the mass balance anddynamics of glaciers and ice sheets.Moreover, there is considerableuncertainty in the predicted increases insurface temperature due to gteenhousewarming.

Glaciers and small ice caps are verysmall in volume compared with themajor ice sheels, but are liable o meltmuch more rapidly. Their melting iscalculated to have confibuted about 40%to the total sea-level rise of some l0 cmover the last hundred yean (see Table 4).

The mass balance of the greatAntarctic ice sheet, ard of the Greenlandice sheet with only one-tenth thevolume, are determined by the differencebetween accumulated snowfall on theone hand, and melting and calving onthe other. In Antarctica, observationssuggest that accumulation is very nearlybalanced by calving of slabs of ice onthe ice shelves with little melting takingplace because of the very low airtemperature. In Greenland,accumulation is balanced about equdlyby melting and calving. In neither caseis there any direct evidence that the icesheets are far from equilibrium, so thattogether they are unlikely to havecontributed more than 20% to sea-levelrise over the last cennrry.

The remaining 40% of this rise is

TABLE 3. - FUTURE PREDICTIONS OF C q CONCENTRATIONS, RISES IN GITOBALTEMPERATURE AIID SEA LEYEL FOR VARIOUS EMISSION SCENARIOS

(A) BUSINESS-AS-USUAI. HIGH EMISSION SCENARIOCO2 emissions continue to increase linearly with time adidng 27o of 1990 values eachyear. Montreal Agreement 754o implemorrted CHa and N2O continue to increase at 1990raresAD 1990 2030 2060 2100

CO2 concentration 354ATfK) 0Sea-level rise (cm)

47O1.1

IE

(B) ALL EMISSIONS KEPT CCINSTAI.IT AT l99O Rl|ifESCO2 concentration 354 42OATCK) 0 0.72Sea-level rise (cm) 0 15

5902.0

38

4651.1

27

(C) 2% PA. (COMFOLJND) REDUCTION IN ALL EMISSIONS FROM I 9 0CO2 concentration 354 3E8 395AffK) 0 0.4 0.4Sea-level rise (cm) 0 1I 18

8503.25

65

5201.6

42

3900.3

2l

(D) 2% PA. INCREASE IN ALL GAS EMISSIONS 1990-2010, 'IUEREAFTER A * P"A..DECREASECO2 concentration 354 436 458 164ATfK) 0 0.93 1.10 1.0Sea-level rise (cm) 0 l7 28 34

12

News from ICTP - No. 44145 - March/Aprtl l99l

attributed to thermal expansion of seawater. Since this is very sensitive totemperature, being six times greater at25°C than at O°C, the rise in sea-leveldepends very much on the depth towhich the warming penetrates andtherefore the mass of water whichexpands. This can, in principle, bedetermined from a fully coupledatmosphere-ocean model, but no suchlong-period calculations have yet beenmade. Calculations based on a simpleone-dimensional model and quoted in theIPCC Report (1990), indicate thatthermal expansion has connibuted 2-6cm, with a best estimate of 4 cm, to atotal estimated rise of 10.5 cm Clable4).

If atmospheric and surfacetemperahrres increase due to greenhousewarming, thermal expansion of theoceans and melting glaciers are likely tocontinue to make the largestconributions to sea-level rise, as shownin Table 5, where the best estimates ofcontributions for a temperature rise ofl.l"K by 2030 are 10 and 7 cm,respectively, to a total rise of 18 cm. Ifby 2060 AD the global warmingincreases to 2.0°K, the correspondingsea-level rise is estimated to be 38 cm;by 2 1 S AD it may rise by 65 cm inresponse 0o a temperature increase of3.25"K. Estimates for lower emissionscenarios leading to slower temperatureincreases are given in Table 3.

All these estimales of sea-level rise,which are probably uncertain by a factorof two, are much less than exaggeratedclirims based on the assumption that thelvestern Antarctic ice sheet will largelydisintegrate and melt. Mostglaciologists discount such a scenario,rendered even more unlikely by therecent model climate simulations whichare described in Section 8, whichproduce very little greenhouse warmingin Antarctica.

TABLE 4. ESTIMATED CONTRIBUNONST0 SEA-LEVEL RISE (IN CM) OVER lj,STlOO YEARS.

Thermal expansionMeirrntain glaciersGrgenlurd Ice SheetAntarctic lce: SheetTotalObserved

low

21.5|

-5-0.510

Bestestimate

442.50

10.515

High

6745

2220

Iow

6.82.30.5

-0.88.8

Bestestimate

10.17.01.8

-0.618.3

High

14.910.33.70

28.9

Frorn IPCC Report, p. n 4 .

TABLE 5. ESTIMATES OF CONTRIBUT-IONS TO SEA-LEVEL RTSE (IN CM) FROM1990-2030 ACCORDING TO BUSINESS-AS-USUAL SCENARIO IN TABLE 3.

Thermal expansionMountain glaciersGreenlandAntarcticaTotal

From IPCC Repor! p. 276.

10 . In conclusionIt is virtually certain that the

troposphere is warming very slowly inresponse !o the continually increasingconcentrations of carbon dioxide andother greenhouse' gases, but the signalis as yet too small to detect above thelarge natural climate variations, partlybecause it is being delayed by thethermal inertia of the oceans.Predictions of the magnitude and timingof the greenhouse warming, and of theconcomitant changes in rain-fall andother climate parameters come entirelyfrom physico-mathematical models ofthe global cl imate sy$tem.Unfortunately, the differences betweenthe various model predictions, which arevery sensitive to how clouds and theirinteraction with the radiation fields arerepresented, are too large o provide firmguidance for major policy decisions.Continued improvement in modelresolution and model physics shouldcause the predictions to converge andthereby harrow ttre range of uncertainty.This will require several years of modeldevelopment, especially in respect of theoceans; much faster computers; and,above all, an adequate supply of globalobsenrations from both the atmosphereand the oceans, !o feed and validate themodels, and to monitor the actualchanges in climate that may eventuallybecome evidenr

In the meantime, although thecurent best estimates of global warmingare not so alarming as to warrant majorsrategic changes in energy, agf,iculture,etc., industrialized counries should takeall reasonable and practical steps torestrain or reduce energy consumption,utilize all fuels morg efficiently, andexplore economically promisingalternatives to fossil fuels. The decisionof the government to restrict UKemissions of carbon dioxide by 2005 tocurrent levels, and o reduce emissions

of CFCs in line with the MonrealAgreement, are realistic first steps.

In addition, we should develop,without delay, adaptive strategies inagriculture, forestry, coastal defences,\ilater supplies and so on, o make theeconomy less vulnerable to climatechanges when they occur. It wouldappear that we have a breathing space ofsome 50 years but this may prove toooptimistic; in any case, it is none toolong.

IOI Training Programme onthe Management

and Conservationof Marine Resourcesin the Mediterranean

The International Ocean Institute(IOI) is convening an internationaltraining progxamme on the Managementand Conservation of Marine Resourcesin the Mediterranean for officials fromgovernments and universities in theMediterranean Region at the Third WuldAcademy of Sciences and theInternational Centre for TheoreticalPhysics in Trieste, Italy, between 29April and 2/l May, 1991.

The training programme will beconducted in cooperation with theTrieste-based Third World Academy ofSciences, International Centre forTheoretical Physics and lnternationalCentre for Earth and EnvironmentalSciences, the Italian Ministry of ForeignAffairs and the Italian Commission forNuclear and Alternative Energy (EI'{EA).Also cooperating with the IOI in thisprogramme are the LINEP CoordinatingUnit for the Meditenanean Action Plan(Athena) and the UNESCO Commissionfon Qatar.

The training programme is thesecond in a series of three such courses.The first was convened in Mala in theautumn of 1989. The 1991 programmeis highly interdisciplinary and addressescmperation and susainable developmentof Mediterranean marine resources. Thecourse aims at expcing decisim-rukento the broad range of marine uses ard theimpact on the environment, the role ofscience and technologl, the legal andpolicy framewqk of ocean developmentand management, regional cooperationand major socio-economic issues facingthe region today.

The course will be attended by up totwenty participants from Algeria,Cyprus, Egypt, Italy, Libya, Malta,Morocco, Spain, Tunisia, Turkey and

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News lrom ICTP - No. 44145 - March/Aprll 1991

Yugoslavia. The course director is Dr.Anton Vratusa, Honorary hesident ofthe International Centre for PublicEnterprises in Developing Countries,Ljubljana, Yugoslavia. The coursefaculty is also international and drawnmainly from the region.

The IOI is an international non-govemmental organisation registered inthe Netherlands and with headquarters inMalta since 1972. It has beenorganising global and regional trainingprogrammes in marine resourcesmanagement for government officialsfrom developing countries in NorthAmerica, Europe, the Caribbean, IndianOcean, South Pacific and Mediterraneansince 1980. The Class C trainingprogramme in Trieste is the thirty-second such course.

Post-Doc Position atUniversity of Oklahoma

A postdoctoral position in HEPtheory is expected to be availableSeptember 1, 1991 in the HEP goup atOU. In addition to carrying outinteractive research with other groupmembers, this position carries theadminisrative responsibility of planningand running TV-satellite communi-cations, e.g. seminars, between groupsinvolved in SSC related research anddevelopment. The initial appointrnentwill be for one year with possiblecontinuations for up to a total of three.

Applicans are requested to send avita and the names (with e-mailaddresses) of three refererrces promptly toR. Kantowski, Department of Physicsand Astronomy, 440 \Mest Brooks,University of Oklahoma, Norman, OK73019. Fax or e-mail is prefened,Fax (405\325-7557,e-mail kantowski@uokniels,

@ phyasrnhn.uoknor.edu,orUOKHEP::

NSERC Women's FacultyAwards in Physics at

Carleton University andUniversity of Ottawa

The Ottarva-Carleton Institute forPhysics invites applications fromwomen who wish !o be nominated forthe NSERC women's faculty awards inPhysics, to be held either at CarletonUniversity or the University of Ottawa.

Research at the Univenity of Ottawa isprincipally in theoretical andexperimental aspects of condensed matterphysics, including surface physics,polymer physics , magnetism,sqperlanices and superconductms. Thereis also interest in nuclear physics, neuralnetworks and nonlinear systems. AtCarleton the medical physics programincludes work in radiation dosimetry, X-ray and ultrasound imaging, andhyperthermia. Work in experimen0alhigh energy physics concentrates on theOPAL detector, at LEP, and the SudburyNeutrino Observatory (SNO). Thetheoretical program is mainly concernedwith phenomenological aspects of theStandard model and extensions to iL

The NSERC awards will besupplemented by the university toprovide a salary equal to that of aconventional faculty position.Assistance towards travel expenses willbe offered. Appointment will beinitially for three years, with renewal fora further two providing satisfactoryprogress is made. It is possible that theposition will become a tenure track oneat an early stage. The teaching load willbe kept small in order !o maximise thetime for research.

Applications should include acurriculum vitae, a list of publicationsand the names of three referees.Applications should be received byAugust 30th, 1991 for appointment inIuly 1992, although the latter date isflexible. This position is restricted toCanadian citizens or permanent residentsof Canada

Applicants should contact theappropriite person below:Dr. Richard HodgsonDeparunent of Physics,University of Ouawa,Ouawa, Ont. KlN 6N5(613-564-3356)trDr. Peter WasonDepartment of PhysicsCarleton University,Ottawa, Onr KIS 586(613-7884326)

Visits to ICTP

Japanese Ministryof Forcign Affairs

Mr. H. Kato and Mr. Watanabe fromthe Nuclear Energy Division of theJapanese Ministry of Foreign Affairs,responsible for budget preparations intheir Division, had a meeting with the

Deputy Director of ICTP on 12 April,to discuss matters of administration,research related to technical cooperationand official development assistance.

High-School StudentsStudents from the Scientific High

School "Gdileo Galilei", Trento (Italy)and from the Vocational TrainingInstitute from Tirano (Sondrio, Italy),were shown ttre ICTP facilities on 18and 2i April, respectively.

Conferences and Lectures

• Dr. Bonaventure Loo, VisitingMathematician, was invited to give atalk at the University of Durham onMonday, 18 March 1991. The title ofhis paper was "Superminimal surfaces ins4" .

• Prof. M.P. Tosi, in charge of theCondensed Matter Research Group, wasinvited to the l l th General Conferenceof the Condensed Mauer Division of theEuropean Physical Society o deliver thepaper "Stability of local structure forpolyvalent metal ions in molten salts".The Conference was held from 8 o 1lApril in Exeter, UK.

• Dr. M.-S. Lubuma, post-docloralstudent at the Mathematics Section,prcsented the talk "Eror Estima0es inthe Projective Solution of Radon'sEquation" at the conference"Approximation Theory, SplineFunctions and Applications" organizedby the NATO-Advanced Sudy Instiuein Maratea, Italy, from 29 April to 9May 1991.

Activities at ICTPMarch-April 1991

T i t l e : WORKSHOP ONMATHEMATICAL PHYSICS ANDGEOMETRY, 4 - 15 March.

Organizers: Professors X. GomezMont (Centro de Investigaci6n enMatemdticas, Guanajuato, Mexico, andUniversidad Nacional Aut6noma deMexico) and M.S. Narasimhan (TataInstitute of Fundamental Research,Bombay, India).

Lectures: Topology of compactsimply connected smooth 4-manifolds.Moduli space of connections. Linearsuperalgebra and supermanifolds. 4-manifolds and gauge theory.

14

News from ICTP - No. 44145 - March/Aprll 1991

Supergravity. A local index theorem forfamilies of D-operators on puncturedRiemann surfaces and a new Klhlermetric on their moduli space. Jones-Witten invariant for flows on 3-manifolds. Symmetry wider thansupersymmetry. Gravitational instantonsand monopoles in a Kaluza-Klein modelwith scalar fields. The geometry ofspaces of conformal structures.Compactifications of the space of stablebundles. Geometric superalgebra and theDirac equation. Eigenvalues andEigenspaces of Dirac and Casimiroperators over noncompact symmetricspaces. Connections and curvatures oncomplex Riemannian manifolds. Morsetheory, classifying spaces and Floerhomology. Variations of Hodgestructure and Higgs bundles. Algebraicgeometry of instantons. On thetopology of 4-manifolds. Conformalfield theory and vector bundles onvariable Riemann surfaces. Algebraicgeometry, Fay's identity and correlationfunctions. Differential equations onsupermanifolds and R1/l-actions.Determinant line bundles and theholomorphic factorization in 2dimensional field theory. Does aspherically symmetric space time admitfive isometries? 2+I dimensionaltopological field theory and algebraicgeometry. Some problems in linear andnonlinear analysis on noncompactmanifolds. Monads, connections andcompactifications. Consistent approachto supennanifolds modelled over finitedimensional exterior algebras. A remarkon the quantization of electric chargefrom Dirac monopoles. Geometricquantization of the momentum mappingassociated with coupled harmonicoscillators.

The Workshop was attended by 101lecturers and participants (77 fromdeveloping countries).

T i t l e : ICS-ICTP-WMOINTERNATIONAL TECHNICALCONI]ERENCE ON LONG.RANGEWEATHER FORECASTINGRESEARCH, S-12 April.

O r g a n i z e r s : Professors K.Miyakoda (Chairman of the InternationalOrganizing Committee; PrincetonUniversity, USA) and G. Furlan(University of Trieste and ICTP), in co-operation with the International centrefor Science and High Technology flCS,Trieste, Italy) and the WorldMeteorological Organization (WMO,Genev4 Switzerland).

Lectures: Climatological variationof 30-60 day oscillation around EastAsia during Northern Summer. A studyon climate predictability: theoreticalaspects. Transient Eddies and forecastskill in low frequencies. Sensitivity ofmesoscale predictions to standard errorsin upper air data. The droughts ofNortheast Brazil: from diagnostics toprediction. Issue of tropical long-rangeforecasu status and development of newforecasts. Regularities in the chaoticatmospheric dynamics. Predictability ofEl Niflo onset, Kenyan droughts andfloods. Numerical study for formationmechanism of short anomalous climatechange. The WMO sponsoredi nterc ompari son of sea surfacetemperature data sets for long-rangeforecasting. Stratospheric oscillationsand long-range prediction of Indianweatler. One month forecast of wet anddry spell of the monsoon. Energeticinteractions between El Niflo andAfrican droughts. The choice of anobserved climatology to verify extendedrange forecasts. The influence of ElNif,o/Southern Oscillation (ENSO) onthe Ethiopian seasonal rainfall.Techniques of operational long-rangeforecasts at the UK MeteorologicalOffice. Practical extended-rangedynamical forecasting at UKMO. Linearinsability analysis and its application toensemble forecasting. Improvement oflong-range predictions by combinationof model forecasts. Prediction of ropicalPacific SST with coupled ocean-atmosphere models. Desigp ofexperimental seasonal forecasts using anair-sea model. Monitoring andprobabilistic forecasting of short-termclimate variations. hedictability andphysical factors influencing Sahelrainfall variation. Variability andtemporal prediction of summer monsoonrainfall over India, China, and SriIanka. Seasonal mesoscale circulationsand LRF in East Africa. Seasonalpredictions with the COLA GCM.Seasonal simulations with ECMWFNWP model. The feasibility of seasonalNWP from decadal simulations.Prediction of forecast skill. On rhe useof the sufficiency relation to evaluateclimate forecasl Seasonal predictabilityof East African rainfall from SSTanomalies and Southern oscillationsignal. Long-range forecasting of theonset and cessation of rainfall in theNigerian Sahel. The onset of the1982183 Summer monsoon overSouthern Africa: a diagnostic study. Anumerical study of the imprct of SST in

the warm pool of Western Pacific on theEast Asia Winter monsoon. Temporalvariability of the structure and phasepropagation of the Madden-Julianoscillation in tropical convection.Nature of Madden-Julian oscillationsover Indian monsoon regions. Variationsof 30-60 day oscillation during l982 BlNiflo. Empirical prediction of NE Brazil(North Nordeste). Tropical cycloneactivity over the Western North Pacificfrom El Nino !o La Nif,a. Status andprospects of long-range forecasting atthe Hungarian meteorological service.Detailing of the monthly forecasting bythe statistical orientation of adeterministic model. Establishment ofthe method of long-range forecast for Brefirst severe cold period in Winler in theNorth of Viet Nam. Typifying theevolution in the meteorologicalparameter by using the analogy method.Skill characteristics of US long-rangeforecasts. Economic loss byprecipitation. Value of long-rangeforecasts to commercial users in ttre UK.Relating climatological information tothe value of long-range weatherforecasts.

The Conference was attended by 97lecturers and participants (43 fromdeveloping countries).

Title: SPRING SCHOOL ANDWORKSHOP ON STRING TTIEORYAND QUANTUM GRAVTTY, L5-26April.

Organ ize r s : Professors J.A.Harvey (Enrico Fermi Institute,Univenity of Chicago, USA), R. Iengo(International School for AdvancedStudies, SISSA, Trieste, Italy), H.Verlinde (Princetoh University, USA)and Drs. K.S. Narain and S. Randjbar-Daemi (ICTP).

Lectures: (School) Introduction otopological and conformal field theory.Introduction to matrix model andLiouville theory. Some properties ofnon-critical strings. Instantons andsolitons in heterotic string theory.Introduction to W algebras. Stringtheory in 2-dimensions. Integrablemodels. Liouville theory and is recentdevelopments

(Workshop) Target space dualitysymmetries and effective actions ofstring theory. Geometric stnrctues ineffective superstring Lagrangians.Duality invariant effective action forsupersymmetries. Equivarianttopological Sigma models andtopological open strings. New

News from ICTP - No. 44145 - March/Aprll l99l

parafennion SU(2) coset and N=2su percon formal field theory. Transitionfrom critical to non-critical string athigh temperanres. Correlation functionsin compactified C=l quantum gravity.On a multiorbit geometrical action forthe integrable system. The quantumgroup symmetry of conformal fieldtheories. I-arge gauge transformation andspecial Virasoro orbits. The origin ofthe string equation. Quantization ofSL(2,R) Chern-Simons topologicaltheory. String propagation in a blackhole geometry. Classical 3-d gravitywith N particles. Currents and anomaliesin the topological Yang-Mills theory.Dorible scaling limit in the O(N) vectormodel. Multicritical complex matdxmodels and nonperturbative 2-d quantumgravity. O(N) vector model andnonperturbative particle theory. l-dconformal field theories .Nonperturbative super-symmetryanomaly in supersymmetric QCD.Singular vectors in Virasororepresentations. Schwinger-Dyson eqs.for 2-matrix model and W3 algebra.Quantum Hamiltonian reduction andN=2 coset model. Nonlinear realizationsof classical W3 symmery. O(|0 vectormodel in the double scaling limir

The Spring School and Workshopwere attended by 161 lecturers andparticipants (57 from developingcounfies).

T i t l e : COURSE ON"OCEANOGRAPHY OF SEMI-ENCLOSED SEAS", 15 April - 4May.

O r g a n i z e r s : Dr. L. Cavaleri(Istituto Dinamica Grandi Masse,Venice, Italy), Sir Alan Cook (SelwynCollege, Cambridge, UK), Dr. M. Gacic

(Institute of Oceanography andFisheries, Split, Yugoslavia), Dr. F.Sravisi (University of Trieste, Italy) andDr. E. Accerboni (OsservatorioGeofisico Sperimentale, Trieste, Italy,in collaboration with the InternationalCentre for Science (ICS, Trieste, Italy)and with the co-sponsorship of theDirezione Generale per la Cooperaziornallo Sviluppo (Ministry of ForeignAffairs, Rome, Italy).

Lectures : Geophysical fluiddynamics. Tides. Long waves alongcoasts and over continental shelves.Long waves in the Gulf of California.The general circulation in the Gulf ofCalifornia. hessure and wind forcing.The use of satellite data. Analysis ofoceanographic time series. Marinechemistry. Thermohaline forcing andheat fluxes. Oceanographic instruments.Shallow sea modelling. Chaos inoceanography. Surface gravity waves.Oceanography from space. Marinebiology. Historical oceanography.Marine geology. Ecological models.

Poster Sessions: Frequencydependence of the reflection coefficientfor compressional plane waves at theseabed. Acoustic measurements inArgentinian continental shelf andcontinental slope. Surface mixed layertempedure and layer depth in water offthe Argentinian coast. Shallow-waterwaves on a rotating ocean due tooscillatory surface stresses. Hydro-dynamics and sediment flux in the Gulfof Guinea. Dynamical studies on theYellow Sea. Windows techniques forcl imate trend ana lys i s .Paleoenvironment of the continen0almargin of Egypt: interstitial waterstudy. Typifying the evolution in themeteorological

parameters by using the analogymethod. Light attenuation in theAdriatic Sea-

Presentations by Participants:The index of refraction forcompressional plane waves in oceanbottoms of the Voigt's type andcausality. F,nvironmental processes andbeach changes: observation on the Westcoast of Cross River estuary. Oceandynamics and the stability of theNigerian coastline: a case, study ofVictoria Island. Wind wave modelling inthe N. Aegean Sea. Summerstratification effecs on the wind-cunentsin the Northern Adriatic. Damping ofthe Adriatic seiches. Time seriesanalysis of Adriatic daa: package and afew examples. Numerical modelling inthe environmental research of XiamenBay. Circulation and hydrography of theSea of Marmara. Subinertial variationsalong the coast of the Gulf of Mexico.Sea level variations along the coast ofthe Gulf of Mexico. Sea level variationsalong the Bulgarian Black Sea coast:analysis and modelling of sorm surges.Winter circulation in the Northpatagonicgulfs: COX/CIMA model. Large-scalecirculation in the bay of Bengal duringthe Southwest monsoon. Dilutioncharacteristics of the water of the Bay ofBengal. Weather and climate of theocean: the Atlantic and Indian oceans.Intrathermocline lenses in the AtlanticOcean originated from intermediateMediterranean Sea waier.

Round Tables: The Adriatic Sea.The Meditenanean Sea. The Gulf ofCalifmnia-

The Course was attended by 97lecturers and participants (63 fromdeveloping counrias).

Intemational Centre for Theoretical Phvsicsof IAEA and UNESCOStrada Costiera l lP.O. Box 58634136 TriesteItaly

Telephone: (40) 22,401Cable: CENTRATOM

Telex: 460392 ICTP ITelefar (40) 2U163

E-mait FOSTOHCE@ICTP.TRIESTEJTBitneu FOSTOFF@ITSICTP

Decneu V)CCPI::POSTOFFICEor4012{::POSTOffiCEPPSDN: 0222241L0125

EDITORHL NOTE - News lrom ICTP is not an official document of the Intemational Centre for Theoretical Physics. Its purpose is tokeep scientists informed on past and funue activities at the Ce,nte and initiatives in their home countries. Suggestions and criticismsshould bc addressed to Dr. M. Farooque, Scientific Information Officer.

l6