geoffjenkins , new climate change scenarios

8/14/2019 GeoffJenkins , New Climate Change Scenarios

1/21

Sense about Science

St Johns College Oxford, 17 March 2007

New climate change scenarios for the UK

Geoff Jenkins, Hadley Centre, Met Office, Exeter

and

Royal Meteorological Society, Reading.


2/21

2Met Office Hadley Centre

Global temperatures 1850-2006 (+ 2007 forecast)

Hadley Centre/UEA


3/21


Natural factors which can change climate

Variations in the Earth's orbit

(Milankovic effect)

Stratosphericaerosol from

energetic

volcanoes

Variations in the energy

received from the sun

Chaotic interactions in

the Earth's climate

(for example, El Nino, NAO)


4/21


Emissions of CO2 from fossil-fuel burning;rapid rise since 1950

Source: CDIAC, ORNL


5/21


Atmospheric concentration of carbon dioxide

1800 1900 2000

375

350

325

300

275

Carbon dioxide

concentration in

parts per million


6/21

6Met Office Hadley CentreSource: Intergovernmental Panel on Climate Change (IPCC)

1.0

0.5

0

1900 1950 2000

Temp

eraturechange

CObservations

Model

simulations withnatural variability

plus mans

activities

Model

simulations

with only

natural

variability

Models can only simulate recent change whenhuman factor are included

Source: IPCC AR4


7/21


Central England Temperature 1772-2006

2006 was easily the warmest year in England.The warming of nearly 1degC since 1980 cannot be explained by natural factors

and is consistent with the expected response to human factors.


8/218Met Office Hadley Centre

Emissions to 2000, and IPCC projections to 2100

1850 1900 1950 2000 2050 2100

30

20

10

0

Fossil-fuelemissio

ns

GtC/y

High (SRES A1FI)

Medium-High (A2)

Medium-Low (B2)

Low (SRES B1)

Source: CDIAC and IPCC

Problem: we do not know

the relative likelihood of

each emission scenario



Global average temperature rise UK model

Globaltemperatureri

se,

degreesC High emissions

Medium-high emissions

Medium-low emissions

Low emissions

Start to diverge

from 2040s

Red bar =

likely range

from all

climate

models

Blackbar =

best

estimate



Planning adaptation to climate change in the UK

Adaptation planners, eg: Transport (road, rail) Environment Agency Utilities (water, energy)

Insurance Local Government Government Regulators Many others

UK

Climate

Impacts

Programme,

Oxford

other

adaptationtools& advice

ClimateChange

Scenarios

Met OfficeHadley Centre



2002 Climate change scenarios (UKCIP02)

50km resolution from Hadley

Centre GCM and RCM

4 future emissions scenarios Starting to be used by

private and public-sector to

plan adaptation (eg EA 20%

uplift of winter river flow)



winter summer

C

Change in UK temperature by the 2080sMedium High emissions scenario



winter summer

%

Change in UK precipitation by the 2080sMedium High emissions scenario



UK snowfall will be greatly reduced

% reduction in snowfall by 2080sSnowman

February 2007



Modelling uncertainties IPCC 4AR (2007)

Problem: we do not know the relative likelihood of each prediction



Next scenarios: Moving from uncertainty to probability

current situation future situation

2080s SE England summer rainfall

-50% -40% -30% -20% -10% 0% +10%

Probability

-50% -40% -30% -20% -10% 0% +10%

2080s SE England summer rainfall

Probability



UK climate is warmed by the Gulf Stream Ocean currents can be affected by climate change

Rapid cooling 11 000 years ago due to Gulf Stream shutdown

Could this happen again due to human activity?

Could the Gulf Stream switch off?



How the Gulf stream is maintained

Warm surface current

Cold deep current

Convection areas



Gulf Stream collapse would mean a cold UK

UK: 3-5C cooling



Gulf Stream: predicted to decline but not switch off

Circulationstr

ength(Sv)

High emissions

Medium-HighMedium LowLow Emissions



Summary

Very likely that human activities, mainly fossil fuel burning,are to blame for most of the last 50yr warming

Cannot explain Central England warming by natural factors

Even with strong mitigation policies, climate will change, so

scenarios are needed by planners to prepare for adaptation. Scenarios generated for UK Climate Impacts programme in

2002 have been widely used to explore possible responses.

But climate models give very different predictions for local

regions and for extremes; difficult for planners. Next set of scenarios will handle this uncertainty by being

probabilistic in nature.

geoffjenkins , new climate change scenarios

Documents