Friday, March 23, 2012

Paper: Antarctica did experience both MWP and LIA

The Medieval Warm Period was apparently global

Before "the cause" started to contaminate climatology about two decades ago, climate scientists realized that around the years 950-1250 AD or so, the Earth experienced warmer temperatures than in some later centuries, e.g. 1550-1850 AD. They called the first period the Medieval Warm Period (MWP) and the second period was the Little Ice Age (LIA).

This fact was inconvenient for "the cause" because it is one of the ways to show that there is nothing unusual about the temperature changes in the 20th century so its champions tried to erase the fact. All of us know the notorious quotes that we have to get rid of the MWP etc.

However, the extensive data showing MWP couldn't be erased and were coming from numerous places of the North Hemisphere. So the champions of "the cause" at least decided that the Medieval Warm Period affected just the Northern Hemisphere, and because the Northern Hemisphere is a tiny, negligible portion of the Earth's surface, we may consider the 300-year Medieval Warm Period to be a regional, provincial fluctuation of the weather that can't compare with the holy greatness of the recent Anthropogenic Global Warming. ;-)

However, a new paper shows that the Medieval Warm Period and the Little Ice Age probably occurred in another region that may even lie outside the Northern Hemisphere, if the IPCC allows me to say that, namely in the Antarctica Peninsula. If true, that implies that the MWP and the LIA were at least as global as the recent "global warming".

Here are the sources:
An ikaite record of late Holocene climate at the Antarctic Peninsula (by Zunli Lu and eight co-authors, Earth and Planetary Science Letters, April 2012)

Medieval warming WAS global – new science contradicts IPCC (a review in The Register)

Democratic Underground (that's where I saw it for the first time)
The overwhelming global consensus between Phil Jones – whose papers start to be withdrawn from journals as people begin to appreciate that they're wrong – and Michael Mann – who may soon be forced to release his probably horribly dirty e-mails to the ATI – seems to be collapsing.

The authors, Lu et al., looked at $$\delta^{18}O$$ contained in ikaite in the Antarctic Peninsula and presented reasons why it is a good temperature proxy. Just to be sure, ikaite is the hexahydrate of calcium carbonate, $$CaCO_3\cdot 6H_2O$$. Read the paper above to learn why those things should be interpreted as the temperature. The result is that the Antarctic temperatures qualitatively agree with those reconstructed in the Northern Hemisphere.

Ikaite

After a few years, the temperature in the Antarctic Peninsula is changing in a similar way as the temperature in the Northern Hemisphere. This is what we have observed recently as well. I would add that I can imagine that the rest of Antarctica may be "protected" against certain climate variations. There are reasons related to ocean circulation why it could be so; there are also recent temperature data saying the same thing. And it could have been true many centuries ago, too.

At any rate, the idea that the global temperature between 900 AD and 1900 AD looked like a shaft of a hockey stick seems increasingly indefensible. That didn't prevent various advocates of the "cause" from codifying it as the "consensus in the IPCC" just a few years ago. Of course, they could easily do so because they have no integrity and they have never built on the accuracy of their results – just on the attractiveness of their wrong results for the environmental activists and warriors for a Big or World Government.

It's time for these people, if you allow me one euphemism per blog entry, to hide in holes and never show up to the public again.