Ice core warning questioned
Prominent scientists have poked holes in a new set of climate change predictions.
The journal Nature has published the Evolution of Global Temperature over the Past Two Million Years, which attempted to reconstruct 2 million years of global average temperatures.
The report concluded that Earth's temperature could rise by between 3 and 7 degrees Celsius over the next thousand years.
But Dr Gavin Schmidt, a climate scientist and director of the NASA Goddard Institute for Space Studies, says the conclusion may not be correct.
“I'm pretty certain that is an incorrect calculation,” he told reporters.
“The ratio that gave that, which was the very high sensitivity that she calculates, comes from a correlation between temperature and the carbon dioxide and other greenhouse gases from the ice cores, but as we all know, correlation does not equal causation.
“And in this case, the causation is the orbital wobbles of the Earth's climate that are controlling both the temperature and the carbon dioxide at the same time and so that's giving you an exaggerated view of how carbon dioxide affects temperature directly.”
The study added about 2 million years of detail to the world’s temperature record using analyses of dozens of different sediment cores.
Dr Schmidt welcomed this new data.
“The meat of this study is really a synthesis of deep sea ocean sediment cores that come from all around the world but put together in a way that allows you to say something about the global temperatures at every point between recently and 2 million years ago,” he said.
“And so that's a really impressive synthesis.”
But, he said, the headline-making temperature prediction might outweigh that good work.
“I think it's unfortunate both for the journal which is going to be accused of hyping sensational results without being scientific rigorous,” he said.
“I think it's unfortunate for the author whose really good work is being overshadowed by this particular error, and it is unfortunate for the public because what you're seeing is a very confused message that people are going to take away all sorts of different messages from.”