Past warming shows gaps in climate knowledge

SINGAPORE (Reuters) - A dramatic warming of the planet 55 million years ago cannot be solely explained by a surge in carbon dioxide levels, a study shows, highlighting gaps in scientists' understanding of
impacts from rapid climate change.

During an event called the Palaeocene-Eocene Thermal Maximum, global temperatures rose between 5 and 9 degrees Celsius within several thousand years. The world at that time was already warmer than now with no surface ice.

"We now believe that the CO2 did not cause all the warming, that there were additional factors," said Richard Zeebe, an oceanographer with the University of Hawaii at Manoa.

"There may have been an initial trigger," he told Reuters on Wednesday from Hawaii. This could be a deep ocean warming that caused a catastrophic release of methane from hydrate deposits under the seabed.

Methane is a potent greenhouse gas but much of it is oxidised into CO2 when it is released from hydrate deposits. Zeebe and his colleagues estimated the amount of CO2 released during the Palaeocene-Eocene event by studying sediment cores from seabeds around the globe. Their study is published in the latest issue of Nature Geoscience.

They estimated about 3 trillion tonnes of carbon (11 trillion tonnes of CO2) was released over several thousand years from the methane deposits, leading to a 70 percent rise in atmospheric CO2 levels from pre-event levels.

But Zeebe said this could only explain a 1 to 3.5 degree Celsius rise in temperatures, adding that a commonly accepted scientific range for a doubling of CO2 is between 1.5 and 4.5 degrees Celsius.

This meant other factors must have been at work to drive up temperatures between 5 and 9 degrees Celsius.

So what does this mean? It means that scientists do not fully understand what influences the weather. It means they do not understand all the factors behind global warming and cooling. It means there are variables at play that can and will dramatically alter their predictions and estimates, or null them entirely. That means that global warming predictions cannot be accurate because there are too many variables; they can't possibly know, or take everything into account.

Furthermore, this admission of unknown causes, raises the issue of whether or not CO2 is the cause of current (supposed) global warming, man made or otherwise. If the temperature rose by more than the speculated amount attributed to CO2 in the aforementioned example, that means there were other factors at play, and where is the proof that those same factors aren't the cause of any recent (supposed) temperature shifts? Where is the proof that man made C02 is the culprit? There is plenty of proof that C02 is on the rise, and even research suggesting a direct correlation. But, if there are admitted variables outside our realm of knowledge, then that means that no current research can prove beyond doubt that man made C02 is the cause. That also means that there is no solid evidence that government regulations to reduce CO2 will prevent any sort of rise in temperature. No amount of tax payer money spent will solve this alleged disaster. No amount of money can solve a problem we can not yet explain, or understand.