Westerly winds and CO2 levels

Aug 07, 2013
Platform for sediment coring on the Patagonian lake Laguna Potrok Aike during strong Westerlies. Credit: B. Zolitschka

The end of the last Ice Age was preceded by a gradual rise in atmospheric CO2. A new study supports the idea that a shift in the position, and increase in the intensity, of zonal westerly winds in the Southern hemisphere promoted this rise.

The end of the last Ice Age, which occurred around 11,700 years ago, was heralded by a progressive increase in the concentration of carbon dioxide in the atmosphere. "The reasons for the rise in the level of this prior to the end of the last Ice Age have been the subject of intense scientific debate," says LMU geobiologist Dr. Christoph Mayr. A team led by Mayr and his colleague Dr. Andreas Lücke (Forschungszentrum Jülich) has now used data obtained from sediment cores recovered from the floor of Potrok Aike Lake in Argentina to test the hypothesis that the increase resulted from the release of CO2 from reservoirs in the deep sea, which was in turn stimulated by a shift in the position and strength of zonal westerly winds in the Southern hemisphere.

Laguna Potrok Aike is 100 m deep and lies in southern Patagonia, placing it right in the middle of the zone in which are now dominated by the so-called Southern Hemisphere Westerlies. The team studied oxygen isotope ratios in the cellulose of freshwater mosses preserved at various levels in sediment cores taken from the . The data allowed them to deduce the rate of evaporation in the lake and plot its course over the period recorded by the core. Evaporation rates serve as an indicator of the strength of the prevailing winds at any given time. Higher surface wind velocities imply higher rates of evaporation from the lake surface.

Careful investigation of the and sensitive analysis of the of the remains of mosses contained within it led the researchers to conclude that, in Late Glacial times, the climate in the Argentinian section of Patagonia was as dry as it is today. "We infer from this that, during the Late Glacial, the zone of shifted southwards, and the winds strengthened," says Mayr.

This shift occurred at a time that coincides with the period in which the concentration of atmospheric CO2 reached the level that characterized the whole of the present warm period, the Holocene, until the onset of industrialization. "The intensification of the westerlies ultimately augmented the release of CO2 from the Southern Ocean," Mayr explains. The greenhouse effect of the gas in the atmosphere then provoked a rise in temperature and brought the last Glacial Period to an end. The new findings strongly suggest that the position and strength of the Southern Hemisphere Westerlies are factors that have a significant effect on the carbon cycle and are therefore likely to have a substantial impact on the world's climate. (Geology 2013)

Explore further: Arson to blame for Argentine forest fires

More information: geology.gsapubs.org/content/41/8/831.abstract

add to favorites email to friend print save as pdf

Related Stories

Dwindling buffer effect?

Mar 28, 2013

(Phys.org) —The Southern Ocean could absorb relatively less carbon dioxide in future if the global temperatures continue to rise as a result of human activities, as climate researchers from ETH Zurich demonstrate ...

Wind shifts may stir CO2 from Antarctic depths

Mar 12, 2009

Natural releases of carbon dioxide from the Southern Ocean due to shifting wind patterns could have amplified global warming at the end of the last ice age--and could be repeated as manmade warming proceeds, ...

How the ice ages ended

May 01, 2013

A study of sediment cores collected from the deep ocean supports a new explanation for how glacier melting at the end of the ice ages led to the release of carbon dioxide from the ocean.

Recommended for you

Is iron rain the reason why Earth and the moon are so different?

26 minutes ago

New experiments show that the asteroids that slammed into Earth and the moon more than 4 billion years ago were vaporised into a mist of iron. The findings, published in Nature Geoscience, suggest that the iron mist thrown up from the high ve ...

What's beneath Hawaii's most active volcano?

2 hours ago

Step away from the villages and idyllic beaches of Hawaii, and you may think you've been transported to the moon. Walking along the lava flows of the Kilauea volcano, the landscape changes from a lush tropical ...

Arson to blame for Argentine forest fires

16 hours ago

Fires that have ravaged some 20,000 hectares of forest in Argentina's remote Patagonia region were deliberately set, according to Argentine officials on Monday.

Water in smog may reveal pollution sources

17 hours ago

The chemical signature of water vapor emitted by combustion sources such as vehicles and furnaces has been found in the smoggy winter inversions that often choke Salt Lake City. The discovery may give researchers ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

2 / 5 (12) Aug 07, 2013
So, the increase in CO2 was really caused by the warming, as also suggested by all of the ice core data from around the globe.
With no evidence, this BS: "The greenhouse effect of the gas in the atmosphere then provoked a rise in temperature and brought the last Glacial Period to an end." had to be included by Mayr et al if they ever wanted to receive more funding and future publication in "Geology".

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.