Analysing ancient air trapped in ice cores for signatures of the natural carbon sinks of the past. This will show how the earth has responded to natural climate change in the past, and help predict the climate change feedback processes in the future, which may be caused by today’s carbon sinks as they respond to a warming planet.

The Problem

Over the last 200 years human activity has increased greenhouse gases (GHGs) to well beyond the natural range for the last 800,000 years. In the past, many drastic climate changes have occurred and ice cores provide evidence of the close correlation between temperatures and the concentrations of carbon dioxide [CO2], methane [CH4] and nitrous oxide [N2O]. Man-made climate change is occurring much faster than, and in addition to, natural climate variability. The changes to environmental conditions brought on by this climate change will, in turn, alter the natural release and absorption of greenhouse gases. It is vital to understand these relationship between GHG concentrations and global temperatures to better predict the future climate. Fundamental questions remain:

• How sensitive is the climate to GHG variations on human time scales?
• What magnitude of climate change will be caused by anthropogenic GHGs?
• What is the response and reservoir time of major GHG sources and sinks?
• What feedbacks will trigger further greenhouse gas emissions in a warming world?

The goal of this study is to understand short term, i.e. on time scales of decades, the sensitivity of the climate in the past to GHG variations. We want to characterise GHG sources and sinks in order to improve climate models and provide much needed information to policymakers. We need to know more about the effect an increase of these gases will have on our immediate future climate in order to show how important it is to make changes now - or plan to adapt to them in the future.

The Solution

Ice cores provide the only way to analyse the atmosphere prior to direct concentration measurements (i.e. the last 50 years). They provide a record of atmospheric composition changes over the recent centuries and are therefore indispensable for studying connections between climate and GHG concentrations. So far, ice core programmes have focused on long term records (e.g. EPICA 820.000 years, Vostok 450.000 years) which resolve changes in climate and atmospheric composition on long time scales. Man made climate change takes place on a shorter, decadal time scale. Our project will therefore concentrate on these periods and determine accurately the associated GHG concentration changes.

We will analyse ice cores from two coastal sites in Antarctica with extremely high annual ice accumulation. These cores yield large air volumes per year of accumulation, enabling us to simultaneously analyse a greater number of GHG species from a single ice core with high temporal resolution. These large volumes of gas will allow us to employ a new ice-core gas extraction technique, to not only analyse the concentrations of carbon dioxide, methane and nitrous oxide, but also track down minute quantities of carbon13 and carbon14. This will identify the sources of the methane and carbon in the atmosphere from their isotopic composition, and therefore help determine how carbon sinks have responded to climate change in the past.

The additional information gained from our unique multiple-species approach will provide additional constraints on past climate change interpretations, specifically the role of the ocean, atmosphere, and the terrestrial biosphere in GHG variations. This will help to identify how sensitive our climate really is to such changes. This knowledge will be critical in evaluating the response of Earth’s future climate to increasing GHG concentrations.

The Result

The new technique for collecting high volume ice-core air samples is currently being perfected. Preliminary results are expected soon.