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Scientists Question That Global Warming Is Shrinking Sheep

Scientists have questioned claims that global warming is causing sheep to change size and colour in the latest row to engulf climate change science.

The theory first emerged a year ago when scientists noticed that wild sheep on the island of St Kilda north of Scotland were getting smaller – despite the fact that according to evolutionary law larger sheep should be more successful. It was also noticed that the Soay sheep were getting lighter as the climate warmed.

The idea captured the imagination of the public at a time when people were becoming increasingly concerned about the effects of climate change.

But scientists are now saying there is no evidence sheep shrink in a warming climate and are questioning the use of such theories to explain the impacts of global warming.

The row comes after a series of scandals rocked the world of climate science. Sceptics claim emails stolen from the University of East Anglia show scientists were willing to manipulate data in a row known as “climategate”. United Nations scientists have also been criticised for wrongly claiming the Himalayan glaciers would melt by 2035 in a scandal known as ‘glaciergate”.

In the latest row, which could become known as ‘sheepgate’, scientists in the Royal Society journal Biology Letters are questioning the theory that climate change causes sheep to change size and colour.

Dr Jake Gratten at the University of Sheffield said the darker, larger sheep have a different genetic make up that is more likely to be causing numbers to decrease than any environmental factor.

“Given the scrutiny that climate change science is currently under, attributing biological changes to global warming should surely require the highest standards of proof. In this case, there is no evidence that warming climate is responsible for the decline in frequency of dark Soay sheep on St Kilda,” he said.

But the original author of the theory, Dr Shane Maloney at the University of Western Australia, insisted that dark sheep survive better in the cold because they absorb sunlight, therefore numbers are falling as the temperature warms and they lose their advantage. At the same time smaller sheep are better able to breed and increase in numbers in warmer climes.

He said the genetic make up could be an explanation for the change in numbers, but climate change was just as plausible an answer.

“The field of climate change science being under close scrutiny should not hinder the free exchange of ideas. We have presented a plausible hypothesis alternative to that of Gratten et al and their recent comments do not persuade us to retract that hypothesis. What we have presented is not a proof. It is an idea, just as a co-assorted QTL of unknown function [genetic make-up] is an idea,” he said.

“Climate change is plausible as an explanation, but that does not make genetic linkage wrong. And likewise, a genetic linkage is plausible, but that does not make climate change wrong as an explanation.”

The Daily Telegraph, 7 April 2010