Global warming could result in northern
A study, based on analysis of changing climate patterns at the end of the last ice age, confounds the widely-held view that global warming will be uniform across the world. It also suggests that ice age conditions could return to the northern hemisphere sooner than was previously thought.
The research, which claims that the north
The study is significant because it suggests that major shifts in global climate are influenced not just by atmospheric conditions, but also by fluctuations in ocean currents. The researchers say that a complex climatic ‘seesaw’ effect – last triggered when the post-Ice Age earth heated thousands of years ago – could be set off again in our present warming world.
The research team spent 14 years analysing radiocarbon and isotope samples from
When they compared their results with existing data which mapped north Atlantic glacier changes over the same time period, the scientists reached a striking conclusion. They found that during times of major climate change, glaciers in
The idea of such a bipolar seesaw effect has been mooted before, but this study is the first to present firm dating evidence from a southern land mass to support it. The data shows that the seesaw occurred only during the transition from a full Ice Age climate 17,500 years ago to our present non-Ice Age climate, which began 11,400 years ago. Significantly, there was no evidence of the effect taking place in more stable Ice Age and non-Ice Age periods.
With the Earth now appearing to move out of a settled climate period, the findings seem significant.
The past 11,400 years of climatic stability have resulted in a warm Europe and cold southern ocean, because the Gulf Stream takes warm water north across the equator. However, the study suggests that global warming could prompt a significant cooling of the north
“Our discoveries raise interesting questions for our present warming world,” explains Project leader Professor David Sugden, of the
“This evidence, which shows north and south acting ‘out of phase’ during periods of great change, but acting ‘in phase’ during more stable periods presents an interesting puzzle. Perhaps it means that the world’s climatic system is stable and all-pervasive when it is in its Ice Age mode or non-Ice Age mode. Under such circumstances, changes in the atmosphere dominate the world’s climates. It is during the transition from one mode to the other that the climate may become more sensitive to the effects of the seesaw.”
Scientists from the Universities of Durham and
The research programme was funded by the UK Natural Environment Research Council with additional support from the Royal Society, Royal Society of Edinburgh, and the Carnegie Trust for the Universities of Scotland.