How the tropics affect global warming....

It seems like everyday there is a new study on global warmings that adds to our knowledge - and shows just how little we know about climate. Here's an article about how the tropics affect global warming....the opposite of what we have believed.

Dr Erin McClymont, who lead the study from Bristol University’s Chemistry Department, said: “Our data challenge the idea that tropical climate change is simply a response to high-latitude changes, such as the waxing and waning of ice-sheets.

“We show that in fact it is the other way round, and that the development of the modern tropical Pacific circulation system about a million years ago caused the expansion of the ice sheets.”

In an article, published in GEOLOGY, Dr McClymont shows that about a million years ago the sea-surface temperature gradient and the strength of the trade winds in the tropical Pacific began to increase, eventually reaching values found at the present day.

This altered the transfer of heat and moisture from low to high latitudes, resulting in more precipitation and cooler temperatures over the ice-sheet source regions, and an expansion of the ice sheets.

Such changes in the ice-sheets were previously thought to be controlled only by the ice-sheets themselves, by ocean and atmospheric circulation in the northern hemisphere, or possibly by atmospheric CO2.