CLIMATE VARIATIONS ANALYZED FIVE MILLION YEARS BACK IN TIME

When we talk about climate change today, we have to look at what the climate was previously like in order to recognize the natural variations and to be able to distinguish them from the human-induced changes. Researchers from the Niels Bohr Institute have analyzed the natural climate variations over the last 12,000 years, during which we have had a warm interglacial period and they have looked back 5 million years to see the major features of the Earth's climate. The research shows that not only is the weather chaotic, but the Earth's climate is chaotic and can be difficult to predict.

The Earth's climate system is characterized by complex interactions between the atmosphere, oceans, ice sheets, landmasses and the biosphere. Astronomical factors also play a role in relation to the great changes like the shift between ice ages, which typically lasts about 100,000 years and interglacial periods, which typically last about 10-12,000 years.

The researchers studied temperature measurements over the last 150 years, ice core data from Greenland from the interglacial period 12,000 years ago, for the ice age 120,000 years ago, ice core data from Antarctica, which goes back 800,000 years, as well as data from ocean sediment cores going back 5 million years.

The research shows that the natural variations over a given period of time depends on the length of this period in the very particular way that is characteristic for fractals. This knowledge tells us something about how big we should expect the 1000-year storm to be in relation to the 100-year storm and how big the 100-year storm is expected to be in relation to the 10-year storm. They have further discovered that there is a difference in the fractal behavior in the ice age climate and in the current warm interglacial climate.

"We can see that the climate during an ice age has much greater fluctuations than the climate during an interglacial period. There has been speculation that the reason could be astronomical variations, but we can now rule this out as the large fluctuation during the ice age behaves in the same 'fractal' way as the other natural fluctuations across the globe," said the author.

Thanks to: sciencedaily.com