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Climate Change and the United Kingdom (UK)
There are two scenarios for the UK as a result of global warming. It could get warmer or the climate could even become cooler.
A Warmer Climate for the UK
Bird Migration Patterns
Studies by the British Trust for Ornithology (BTO) and the Wildfowl and Wetlands Trust between 2001 and 2004 indicate that the British winter climate is warming.
Ducks, geese and waders are attracted by the relatively warmer winter conditions in the British Isles but, claims the BTO, global warming could be persuading migrating birds to stay in cooler northern and eastern waters. The British Isles benefits from the warn Gulf Stream which keeps the British Isles warmer in winter than would be expected for land at such a northerly latitude.
It is thought that global warming is keeping the birds breeding grounds warm enough in winter to negate the necessity for the birds to migrate to warmer climates.
Predictions by the Climate Research Unit (University of East Anglia) in 2000
In 2000 the Climate Research Unit predicted that by 2050 average temperatures in the south east of the British Isles would increase by 1.5°C to 2°C with the west and north of Ireland and Scotland rising by 1.5°C to 2°C. By 2080 the predicted temperature rises are:
Winter precipitation (rainfall and snow) is also expected to increase. The increased precipitation will not be even over the British Isles. By 2080 it is expected that the south east corner of England will see a 5%-10% increase in precipitation; all of Wales and England below Manchester and Leeds will see a 10%-20% increase in precipitation; Ireland, Scotland and the north of England will see over 20% increase in precipitation. Although winter precipitation is expected to increase, summer precipitation is expected to be reduced in many areas with a predictions of 18% less summer rainfall for central and southern UK by 2080. On the other hand, northern England and Scotland are expected to have both wetter summers and wetter winters.
Report by the Scotish Executive in 2006
The Scotish Executive issued a report in March 2006 called Changing Our Ways: Scotland's Climate Change Programme which includes predictions for the climate of the UK due to global warming. Much of its conclusions are broadly in line with the predictions by the Climate Research Unit in 2000. However the Scotish Executive reports does indicate that precipitation in the south and east of the UK could deline by up to 50% in the summer by 2080.
A Cooler Climate for the UK
The reason why global warming is likelier to cause localised cooling of the UK is to do with the Gulf Stream.
At present, there is a warm current that starts in the Gulf of Mexico that transports warm tropical water from the Gulf of Mexico into the North Atlantic. Technically, at this point the current changes its name from the Gulf Stream to the North Atlantic Drift. The North Atlantic Drift continues to transport this warm water to the shores of Ireland, South West England, Scotland and a small part of Wales. The air above this warm current takes some of the heat from the water and takes this warm air across the British Isles. In winter, this keeps the British Isles warmer than would be expected for it northerly latitude.
As global warming continues, it is expected that Arctic ice will melt releasing huge quantities of fresh water into the North Atlantic. Not only will this ice melt increase sea level, it will have a dramatic effect on the North Atlantic Drift.
Salt water is more dense than fresh water. This is the key to the effect of the ice melt will have on the North Atlantic Drift.
As more fresh water is released in the North Atlantic, it will flow south to meet the North Atlantic Drift. Where they meet, the heavier salt water of the North Atlantic Drift will start to descend beneath the lighter fresh water from the Arctic. As soon as the warm salt water sinks beneath the cooler fresh water, the warming effect of the North Atlantic Drift will cease. As the air will also cool, the beneficial effect of the North Atlantic Drift will end. This will result in winters in the British Isles being about 9°C cooler then present. Winter temperatures in the British Isles will be more akin to those found in Labrador.
Although global warming will see much of the Earth with higher temperatures, for some place, especially the British Isles, the average temperature could fall. Thus, it is more appropriate to talk about climate change rather then global warming.
Will the Gulf Stream collapse?
A key question in climate research concerns the stability of the thermohaline circulation, a system of large-scale currents including the Gulf Stream in the North Atlantic Ocean, which carries heat from the tropics to higher latitudes as cold salty water sinks near the pole, drawing warm water north-eastwards. The arm of the Gulf Stream which flows up the west coast of Scotland (the North Atlantic Drift) is responsible for keeping our climate temperate.
Recent observations have shown a reduction in the amount of salt in the sea water deep in the north-west Atlantic, and this has been interpreted by some as an early sign of a weakening thermohaline circulation.
The climate model run by the Hadley Centre - part of the Met Office - shows that the observations are, in fact, consistent with a slight strengthening of the thermohaline circulation since the 1960s. Nevertheless, the model predicts that in future it will weaken somewhat as a result of global warming.
Hadley Centre models suggest a reduction in the strength of the Gulf Stream by as much as a quarter, but not a collapse. However, even with this reduction in the Gulf Stream, the net result of climate change is expected to be a warmer Europe.