Tiny fossils hold answers to big questions on climate change

Jan 22, 2013
Tiny fossils hold answers to big questions on climate change
Glacial melting leads to icebergs, brash ice and slush in the Antarctic coastal ocean.

(Phys.org)—The western Antarctic Peninsula is one of the fastest warming regions on the planet, and the fastest warming part of the Southern Hemisphere.

Scientists have debated the causes of this warming, particularly in light of recent instrumental records of both atmospheric and oceanic warming from the region. As the atmosphere and ocean warm, so the ice sheet (holding an equivalent of 5 metres of rise, locked up in ice) becomes vulnerable to collapse.

Now research led by Cardiff University published in Nature Geoscience (Jan 20, 2013) has used a unique 12,000 year long record from microscopic marine algae fossils to trace entering the ocean along the western .

The study has found that the atmosphere had a more significant impact on warming along the western Antarctic Peninsula than oceanic circulation in the late Holocene (from 3500-250 years ago).

This was not the case prior to 3500 years ago, and is not the case in the modern environment. The study has also shown that this late Holocene atmospheric warming was cyclic (400-500 year long cycles) and linked to the increasing strength of the El Niño – phenomenon (a centred in the low latitude Pacific Ocean) demonstrating an equatorial influence on high latitude climate.

Dr Jennifer Pike, School of Earth and Ocean Sciences said: "Our research is helping to understand the past dynamic behaviour of the Antarctic Peninsula Ice Sheet.  The implications of our findings are that the modern observations of ocean-driven warming along the western Antarctic Peninsula need to be considered as part of a natural centennial timescale cycle of , and that in order to understand along the Antarctic Peninsula, we need to understand the broader climate connections with the rest of the planet."

Ice derived from land has a very distinctive ratio of . This research is the highest resolution application in coastal Antarctic marine sediments of a technique to measure the oxygen isotope ratios of microscopic marine algae fossils (diatom silica).  When a large amount of glacial ice is discharged into the coastal ocean, this alters the oxygen isotope ratio of the sea water that the are living in.  This creates a clear imprint in the fossils that reveals the environmental conditions of the time.  The scientists used the oxygen isotope ratio of the fossils to reconstruct the amount of glacial ice entering the coastal ocean in the past 12,000 years, and to determine whether the variations in the amount of ice being discharged were the result of changes in the ocean or atmospheric environment.

Professor Melanie Leng, from the British Geological Survey and Chair of Isotope Geosciences in the Department of Geology, University of Leicester,  said: "Technologically the analysis of the oxygen isotope composition of diatom silica is extremely difficult, the British Geological Survey is one of a very few research organisations in the world that can undertake this type of analysis. For this research project the methodology has been developed over the last five years with the specific aim of investigating the different amounts of melting in the polar regions. It's fair to say we are world leading pioneers in this technique."

Explore further: Global warming 'pause' since 1998 reflects natural fluctuation, study concludes

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2.3 / 5 (12) Jan 22, 2013
Referencing "fastest warming" region is not accurate and honest to readers when in fact the highly volcanically active peninsula is the *only* Antarctic area that is warming at all instead if steadily cooling and also growing in ice area instead of falling as is also dishonestly implied. Ice sheets do not "collapse" due to melting anyway, but due to *growth*, as continental ice mass expands out onto to sea. Antarctica is will remain vastly below the melting T of ice for many hundreds if not thousands of years if the hundred year old trend carries on cycling between some warming and some cooling on a century time scale. Basic peer reviewed facts about Antarctica are out there for all to see, if they reject the blatant lies of your headlines. Author Steig tried to color all of Antarctics red instead of cooling blue and made the cover of Nature doing so. Skeptical debunking of his blatantly bad math that very much was "lying with statistics" was also peer reviewed.
2.5 / 5 (13) Jan 22, 2013
Sea surface T in the Southern Hemisphere as been steadily *cooling* for 15+ years according to standard peer reviewed data archives to the great discomfort of climate modelers who cannot say "we told you so" since their predictions were for the globe to warm not cool over decadal time scales, 30 of which are defined as climate instead of just weather, forced by CO2 which China has vastly outpaced assumptions of output. Rapid warming predictions add massive water vapor amplification of the basic physics of a greenhouse effect, and the laugh test had already caught up with this hypothesis.

4 / 5 (4) Jan 22, 2013
Ice sheets do not "collapse" due to melting anyway, but due to *growth*, as continental ice mass expands out onto to sea.

That would be convenient if this were the only mechanism. I, however, highly doubt your assertions especially since there seems to be no room in your view for any other mechanism.
2.5 / 5 (11) Jan 22, 2013
The Penninsula was naturally warmer than today in the past according to ice cores. Attribution of Penninsula warming to CO2 is logically ridiculous when the bulk of the continent that does not suffer from a hot spot of the Earth's crust has been cooling throughout the period in which the tiny Penninsula was shown warming.

3.8 / 5 (4) Jan 23, 2013
Only one denialist? I'm disappointed.