New study shows no simultaneous warming of northern and southern hemispheres…for 20 000 years

[OKIsItJustMe]

http://www.lunduniversity.lu.se/o.o.i.s?id=24890&news_item=5714

New study shows no simultaneous warming of northern and southern hemispheres as a result of climate change for 20 000 years

21 October 2011

A common argument against global warming is that the climate has always varied. Temperatures rise sometimes and this is perfectly natural is the usual line.

However, Svante Björck, a climate researcher at Lund University in Sweden, has now shown that global warming, i.e. simultaneous warming events in the northern and southern hemispheres, have not occurred in the past 20 000 years, which is as far back as it is possible to analyse with sufficient precision to compare with modern developments. Svante Björck’s study thus goes 14 000 years further back in time than previous studies have done. “What is happening today is unique from a historical geological perspective”, he says

Svante Björck has gone through the global climate archives, which are presented in a large number of research publications, and looked for evidence that any of the climate events that have occurred since the end of the last Ice Age 20 000 years ago could have generated similar effects on both the northern and southern hemispheres simultaneously. It has not, however, been possible to verify this. Instead, he has found that when, for example, the temperature rises in one hemisphere, it falls or remains unchanged in the other.

“My study shows that, apart from the larger-scale developments, such as the general change into warm periods and ice ages, climate change has previously only produced similar effects on local or regional level”, says Svante Björck.

…

http://dx.doi.org/10.3354/cr00873

[customerserviceguy]

1. Ok, so someone help me out here

If man-made global warming has been a factor for, say, the last 5,000 years of recorded human history, then why is this uneven warming for the 10-15 thousand years before that significant?

[OKIsItJustMe]

2. Generally speaking we’re looking at the last 130 years or so…

The reason why it is significant is that “global warming skeptics” like to point out that warming and cooling happens all of the time, so, the reasoning goes, the observed warming is not unusual.

This study says the current warming is unusual, because both the Northern and Southern hemispheres are warming simultaneously, which they haven’t done in 20,000 years. (Clearly, something different is happening.)