Greenland Ice Core Provides Dataon Snowfall Levels During The Past 11,000 Years New Music Festival A Multicultural Air

BUFFALO, N.Y. -- Cold climates generally are associated with large quantities of snow. But a paper published this week in Science indicates that during the Holocene period, the geological era covering the past 11,000 years, snowfall was lower in colder years than when temperatures were more moderate.

That conclusion confirms what had been assumed by geoscientists, but had not previously been demonstrated over an extended record.

"This is the most accurate accumulation record we have of the Holocene," said Michael Ram, Ph.D., a University at Buffalo geophysicist who is a co-author of the report.

The paper also demonstrates that to some extent, the climate of the Holocene period was not as stable as was commonly thought, and was characterized by short-term fluctuations, even during periods known as the medieval warming period and the little ice age.

Authored by scientists at the Cold Regions Research and Engineering Laboratory, UB and other institutions involved in the Greenland Ice Sheet Project 2 (GISP2), the paper is based on data obtained from the top 1,700 meters from a 3,040-meter-long ice core retrieved from Greenland.

The paper concludes that the GISP2 data do not support the perception that the little ice age was a period of sustained cold.

"The idea behind the paper is that as it gets colder, accumulation levels go down because there is less moisture in the air," said Ram.

"For example, even though temperatures are much colder in Minneapolis/St. Paul than they are in Buffalo, that city gets less snowfall than Buffalo because the air is drier in Minneapolis."

The first step in the research was to accurately date the ice, using several sources of information, including Ram's laser-light scattering studies.

These studies have produced the first continuous record of dust concentration measurements throughout the Holocene and Wisconsin periods, which go back more than 100,000 years.

"When you look at an ice core, you don't see the accumulations of snow from each year because they've been thinned down," Ram said. "What you see is the annual layer, which differentiates individual years."

When laser light is directed at an ice-core meltwater sample, the dust particles suspended in the water scatter the light, producing a pattern of peaks and valleys, which correspond to seasonal dust changes. The more dust there is in a sample, the more light it scatters.

According to Ram, the amount of dust changes throughout the ice core, with the highest levels of dust corresponding to the spring and summer.

"The largest influx of dust occurs in the spring, which is when dust storms are most likely," said Ram.

The distance between successive dust peaks corresponds to one annual layer.

Information on these dust concentrations must then be combined with results from other techniques to determine the annual layer thickness and to date the ice core.

Once this data is gathered, glacial-flow models are used to reconstruct the accumulation records, the meters of snow that fell at that time.

By measuring oxygen isotopes in the air, which are enclosed in air bubbles in the ice, the researchers then determine the atmospheric temperatures at the time the snow fell.

By studying the fluctuations in accumulation, they have developed a continuous and detailed climate history for central Greenland during the Holocene.