6.5

3 5 - ~ - - - Mean 1931-1995 I _ loyearmean I

References

Barber, K. E. (1981) Peat stratigraphy and climate change. A. A. Balkema, Rotterdam

Howard, P. J. A., Loveland, P. J., Bradley, R. I., Dry, F. T., Howard, D. M. and Howard, D. C. (1995) The carbon content of soil and its geographical distribu- tion in Great Britain. Soil Use Manage., 11, pp. 9-15

IPCC (1995) Climate change 1994. Cambridge University Press

~ (1996) Climate change 1995. Cambridge University Press

Manley, G. (1932) Meteorological records from the northern Pennines. Meteorol. Mag., 67, pp. 206-208 - (1941) The Durham meteorological record, 1847-

1940. Q. J. R. Meteorol. SOC., 67, pp. 363-380 ~ (1980) The northern Pennines revisited: Moor

Morecroft, M. D., Adamson, J. K. and Lane, A. M. (1997) The Environmental Change Network Inte- grating climate and ecological monitoring. Weather,

Pepin, N. C. (1995) The use of GCM scenario output to model effects of future climatic change on the ther- mal climate of marginal maritime uplands. Geogr. Ann., 77, pp. 167-185

RatclBe, D. (Ed.) (1977) A Nature Conservation review. Cambridge University Press

Tallis, J. H. (1995) Climate and erosion signals in British blanket peats: the significance of Racorninium lanuginosum remains. J. Ecol., 83, pp. 1021-1030

52, pp. 7-12

Correspondence to: Mark Garnett, Institute of Terrestrial Ecology, Merlewood Research Station, Windermere Road, Grange-over-Sands, Cumbria LA11 6w.

Hurricanes hardly happen.. .

normal number of intense hurricanes. There were 13 tropical storms, 9 of which became hurricanes. Six of these reached category 3 or higher on the Saffir-Simpson hurricane scale. The 1996 season tied with 1955 and 1980 as the eighth most active season on record. It was also the first year that every tropical depression turned into a named

H. R. James Serco Aviation Services Inc., Bermuda

In the Atlantic/Caribbean/Gulf of Mexico, 1996 was a busy year for hurricanes. It featured above normal hurricane activity, and a much above

storm. Bermuda, at 32.3"N, 64.7"W, is in a very

isolated position, 1300km north of the Caribbean

351

itself, and 950km from the next nearest land (Cape Hatteras). It is only 351un long and is no more than 74m at its highest point. The land itself is protected by a large coral reef which all but surrounds the island. There was no human habitation until 1609 when a convoy, heading from England to Virginia, was caught in a hur- ricane and was wrecked on Bermuda’s reefs. Shakespeare’s play “The Tempest” was based, in part, on this event.

For the meteorologst, Bermuda presents a unique challenge. In the summer it is well within the hurricane belt. In winter cold fronts and polar air, moving off the North American continent, bring storms of their own. There are no met. stations immediately upwind to gve the fore-

caster much warning or any detail of what sys- tems may be approaching and, being far from the major shipping lanes, ship reports are not very frequent. Satellite imagery and the airfield’s weather radar are thus crucial to any forecasting decisions. Within the last ten years there have been two direct hits from hurricanes - Emib on 25 September 1987 and Felix on 14115 August 1995. Unlike the USA, where communities are evacuated if they are in the direct path of a hurricane, the 60000 residents of Bermuda have nowhere else to go, and are left to sit out the storm for better or for worse. Bermudians tend to be quite stoical about the weather, but much attention is paid to utterances from the airport met. office, particularly when hurricanes are

1 CLOSEST POINT O F APPROACH (CPA) ] m r E :TIME , I O O O 1 - r su hlbflV 20oc-i DISTANCE , ’ l ~ l l ~ E C ’ ~ I ~ l ~ , 3 4 h i M S E A A b f ?

I 3 0 0 L T ~

IO ‘ IV : o o w / > o w / l a P M NEXT UPDATE WILL BE AT:

U S E THE FOLLOWING SECTION ONLY AFTER THE SETTING OF H U W C A N E ’TROPICAL STORM WATCH OR WARNING.

ONSET OF 35 KT W N D b ONSET OF 50 tiT WINDS ONSET OF 65 KT WINDS

LASTING I‘NTIL LASTING LNTIL LASTING LNTIL

Fig. l(a) Huiricane Lli advisory number 13 issued at 0600 local time on 18 October 1996

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around. The office has a staff of 12, six observers and six forecasters, and is open 24 hours per day, 7 days per week. Normally one observer and one forecaster are on duty at any one time, but during a hurricane alert it is necessary to bring in more staff just to cope with the increased volume of telephone enquiries.

In 1996 attention was focused on Hurricane Edouard which passed 440km to the west of the island on 31 August, Hurricane H o m e passing 384km west-north-west on 13/14 September, and Hurricane Lili passing 224km south-east on 20 October. LiZi gave us the biggest scare because on 18 October the National Hurricane Center (NHC) in Miami was predicting the storm centre to pass within 54km of Bermuda - see Fig. l(a). The forecaster was left with a dilemma - to issue warnings accordingly, and thus cause an enor- mous amount of disruption to island life, or to wait and see ifthe hurricane altered course. In the event we were a little circumspect with our predictions, Lili did change track (see Fig. 2) and life went on much as normal. The NHC were still saying that “residents on Bermuda should be ready to take quick action if Lili moves to the left of forecast track.”

From the weather record for 20 October 1996 it is estimated that the closest the centre of Lili came to Bermuda was 224 km to the south-east at 1410 local time (1710 GMT), when a gust of 42kn in the easterly winds was recorded. There were showers in the vicinity, and the sky was overcast with some remarkable cloud formations. Prior to this there had been eight hours of more or less continuous rain with low stratus. The infamous hurricane swell beyond the reef was estimated to be at 5 to 5.5m, period 10 seconds, with the sea surface temperature measured at 25.4”C. The hurricane sunset photographs were taken about four hours later looking west fi-om Bailey’s Bay towards Royal Naval Dockyard. The fi-ont cover photograph shows patchy cumulus with a thin line of fast-moving stratocumulus above it, show- ing signs of turbulence within a narrow vertical band. Overhead there is a veil of rapidly changing altocumulus with some altostratus. Twenty min- utes later (Fig. 3, p. 348) there was still some patchy cumulus, there was a line of altocumulus castellanus, and the veil had become more al- tostratus than altocumulus. Sunset was officially at 1840 local time.

To keep matters within perspective, the maxi-

Hurricane Lili track and forecart movement, issued with a d k q number 13 (21062=0600 GMT on the 21st, e t . )

353

Readers' Forum

The UK drought and climate change

Several sources suggest climate change as a reason for the recent prolonged drought. What is thc evidence, if any, for such a cause, bearing in mind that, by definition, climatc change is a long-term process, i.c. of at least 30 years?

Dover, Kent F. G. Thomas

Terry Marsh* replies: The climate of the UI< is inherently variable and any linkage between a single drought event and climate change must be speculative. Similarly, any apparent climatic trend over a period of '1

relatively feu years needs to be treated with

considerablc caution. However, the climatic conditions experienced in the recent past have been sufficiently unusual for them to be legitimately interpreted as a possible signal of climate change.

Interestingly, UI< rainfall over the last ten years, taken together, has been very close to the long- term average. But the spatial and temporal distribution of that rainfall has been far from typical many regions, in southern Britain especially, have experienced very protracted departures from the seasonal average with extended rainfall deficiencies punctuated by notably wet interludes. For England and Wales the two-year period ending in April 1997 was the driest 24-month sequence in a record from 1767; rainfall during the 1988-92 drought was also exceptionally low in the 24-48 month time- frames. Generally, the period between these two notable droughts produced exceptionally high rainfall totals. Of course, climatological records are being broken all the time and by linking

354