Interesting use of lacustrine microfossils to look at climate change.

Twentieth-century warming revives the world’s northernmost lake

Bianca B. Perren, Alexander P. Wolfe, Colin A. Cooke, Kurt H. Kjær, David Mazzucchi and Eric J. Steig

Abstract

Geology, November 2012, v. 40, p. 1003-1006, doi:10.1130/G33621.1

Although recent ecological changes are widespread in Arctic lakes, it remains unclear whether they are more strongly associated with climate warming or the deposition of reactive nitrogen (Nr) from anthropogenic sources.

We developed a 3500-yr paleolimnological record from the world’s northernmost lake to explore this question. Microfossils indicate that siliceous diatoms and chrysophytes were abundant initially, but disappeared 2400 yr ago in concert with Neoglacial cooling.

Microfossils reappear in 20th-century sediments and reach unprecedented concentrations in sediments deposited after ca. A.D. 1980, tracking increasing summer temperatures in the absence of evidence for atmospheric nutrient subsidies. These results indicate that current warming in northern Greenland is unprecedented in the context of the past 2400 yr, and that climate change alone is responsible for the marked biological changes observed.

Interesting

While the warming may be unprecedented, which particular part of the microfossil record indicates the cause of the warming?

Michael V said:

We developed a 3500-yr paleolimnological record from the world’s northernmost lake to explore this question. Microfossils indicate that siliceous diatoms and chrysophytes were abundant initially, but disappeared 2400 yr ago in concert with Neoglacial cooling.

Huh? What Neoglacial cooling? I was under the impression that there was a negligible amount of climate change in about 390 BC … unless of course they’re talking about purely local effects, which if so would cast doubt on the reliability of the method for studying global climate change.

Reports from Herodotus 430 BC suggest that the northern areas of Europe were exceptionally cold then, but was getting warmer, as shown by the fact that northern tribes had not too long before moved into areas that were previously too cold to inhabit.

Michael V said:

We developed a 3500-yr paleolimnological record from the world’s northernmost lake to explore this question. Microfossils indicate that siliceous diatoms and chrysophytes were abundant initially, but disappeared 2400 yr ago in concert with Neoglacial cooling.

Where is the lake?

OCDC said:

Michael V said:

We developed a 3500-yr paleolimnological record from the world’s northernmost lake to explore this question. Microfossils indicate that siliceous diatoms and chrysophytes were abundant initially, but disappeared 2400 yr ago in concert with Neoglacial cooling.

Where is the lake?

The world’s northernmost lake, situated near the coast of Greenland

roughbarked said:

OCDC said:

Michael V said:

We developed a 3500-yr paleolimnological record from the world’s northernmost lake to explore this question. Microfossils indicate that siliceous diatoms and chrysophytes were abundant initially, but disappeared 2400 yr ago in concert with Neoglacial cooling.

Where is the lake?

The world’s northernmost lake, situated near the coast of Greenland

http://news.nationalgeographic.com.au/news/2012/10/121017-northernmost-lake-greenland-global-warming-science-environment/

Thanks.