Old ice provides insights into major climate change

March 23, 2006
New climate data from old ice
The single segments of the ice core are labeled and stored until final analysis in laboratory. Foto: Sepp Kipfstuhl, Alfred Wegener Institute.

All cold periods throughout the past 740,000 years were associated with a significantly larger sea ice cover around the Antarctic than warm periods. At the same time, South America’s south was significantly drier and windier than nowadays, leading to a much higher dust deposition in the Antarctic.

These are some of the results published this week in the scientific journal Nature as part of a study on aerosols retrieved from an ice core 3 kilometres long, carried out by a European team of scientists with participation of the Alfred Wegener Institute for Polar and Marine Research.

Change of Antarctic sea ice cover

The ice core obtained in December 2004 as part of EPICA (European Project for Ice Coring in Antarctica) from Dome C in the eastern Antarctic (75° 06’S, 123° 21’E) covered more than eight consecutive alternations of ice ages and warm periods (glacial cycles). Thus, the core represents the longest continuous ice core archive ever retrieved. For their investigation, the EPICA scientists measured concentrations of aerosols within the ice, tracing the minute particles which had originated at the ocean surface or on continents far away and had been transported by wind to the Antarctic. The concentration of sea salt aerosol, for instance, formed in the process of seawater freezing, indicates a large scale expansion of sea ice cover around the Antarctic during all cold periods.

No increase in biological activity

Rising concentrations of small mineral dust particles during cold periods suggest a drier climate in the neighbouring continents, especially South America. The dust carried into the Southern Ocean by wind, provides additional nutrients for plankton in the surface ocean. However, analyses of sulphate aerosols from the ice core, produced after algal blooms, do not point towards an increase in biological activity in the Southern Ocean. “Our results require a revision of previous perspectives on the biological response to climate change in the Southern Ocean. At least for southern parts of that ocean, our perception about increased biological productivity during ice ages needs to be reconsidered”, suggests Hubertus Fischer, head of the chemical investigations at the Alfred Wegener Institute.

Predicting the future from viewing the past

After the analysis of temperature changes throughout the past eight climate cycles, the recent investigation of dissolved chemical components from the ice core represents another important step towards the evaluation of historical changes in climate. “Our research results reveal a similar succession of identical changes, whenever warm climate conditions alternated with cold ones over the past 740,000 years”, explains Eric Wolff of the British Antarctic Survey, primary author of the current publication. “This leads us to conclude that the Earth follows certain rules in the process of changing climates. If we can understand these rules, we will be able to improve our climate models and hence our predictions of the future.”

Source: Alfred Wegener Institute for Polar and Marine Research

Explore further: Wind, warm water revved up melting Antarctic glaciers

Related Stories

Wind, warm water revved up melting Antarctic glaciers

September 20, 2017

A NASA study has located the Antarctic glaciers that accelerated the fastest between 2008 and 2014 and finds that the most likely cause of their speedup is an observed influx of warm water into the bay where they're located.

How openings in Antarctic sea ice affect worldwide climate

September 11, 2017

In 1974, images acquired from NOAA satellites revealed a puzzling phenomenon: a 250,000 square kilometer opening in the winter sea ice in the Weddell Sea, south of South America. The opening, known as a polynya, persisted ...

Recommended for you

New technique spots warning signs of extreme events

September 22, 2017

Many extreme events—from a rogue wave that rises up from calm waters, to an instability inside a gas turbine, to the sudden extinction of a previously hardy wildlife species—seem to occur without warning. It's often impossible ...

0 comments

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.