Climate Change Data: Ice Core Samples

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Climate Change Data: Ice Core Samples

Climate Change Data: Ice Core Sampling

According to the University of Maine, An ice core is

a cylinder-shaped sample of ice drilled from a glacier. Ice core records provide the most direct and detailed way to investigate past climate and atmospheric conditions. Snowfall that collects on glaciers each year captures atmospheric concentrations of dust, sea-salts, ash, gas bubbles and human pollutants. Analysis of the physical and chemical properties of an ice core can reveal past variations in climate ranging from seasons to hundreds of thousands of years. Ice core records can be used to reconstruct temperature, atmospheric circulation strength, precipitation, ocean volume, atmospheric dust, volcanic eruptions, solar variability, marine biological productivity, sea ice and desert extent, and forest fires..

As we look at a graph of the data from ice core samples, at left, we can see trends.

According to CDIAC (These records are maintained by the World Data Center for Paleoclimatology, National Oceanic and Atmospheric Administration (NOAA),)

Over the last 800,000 years atmospheric CO2 levels as indicated by the ice-core data have fluctuated between 170 and 300 parts per million by volume (ppmv), corresponding with conditions of glacial and interglacial periods. The Vostok core indicates very similar trends. Prior to about 450,000 years before present time (BP) atmospheric CO2 levels were always at or below 260 ppmv and reached lowest values, approaching 170 ppmv, between 660,000 and 670,000 years ago. The highest pre-industrial value recorded in 800,000 years of ice-core record was 298.6 ppmv, in the Vostok core, around 330,000 years ago. Atmospheric CO2 levels have increased markedly in industrial times; measurements in year 2010 at Cape Grim Tasmania and the South Pole both indicated values of 386 ppmv, and are currently increasing at about 2 ppmv/year.

What does this mean?

It tells us that over very large periods of time, atmospheric CO2 levels are cycling, and are currently increasing. It does not tell us why.

The government of Scotland says:

"Ice core data shows a complex picture, but there are some very obvious features.

• The climate has been very variable over the last 650,000 years.
• Greenhouse gas concentrations change in step with temperature, though in a complicated way.
• Greenhouse gas concentrations in the atmosphere are now at a higher level than they have ever been in the last 650,000 years.
• Temperature levels are relatively high at present."

References:

1. Ice Core Data Help Solve a Global Warming Mystery - Why do some ice core samples seem to indicate CO2 spikes trailed increases in global temperature? It's all about the way bubbles move in ice, Scientific American
   "The wide margin of error in the EPICA core data is due to the way air gets trapped in layers of ice. Snowpack becomes progressively denser from the surface down to around 100 meters, where it forms solid ice. Scientists use air trapped in the ice to determine the CO2 levels of past climates, whereas they use the ice itself to determine temperature. But because air diffuses rapidly through the ice pack, those air bubbles are younger than the ice surrounding them. This means that in places with little snowfall-like the Dome C ice core-the age difference between gas and ice can be thousands of years."