Global warming secret may lie at bottom of ocean
Posted on 30. Jun, 2010 by admin in Earth Sciences, Science
A scientist is hoping to provide answers to questions about catastrophic climate change by looking back in time.
Dr Craig Storey, of the University of Portsmouth, aims to unlock the secrets in tiny grains of rock deep under the Atlantic Ocean and paint a picture of the last time the earth had a similar climate to that predicted for the end of this century.
He will study how much of Greenland was covered with ice the last time Earth was as warm as sophisticated computer models predict for the end of the 21st century.
Dr Storey is funded by a £30,000 grant from the National Environment Research Council (NERC) and hopes his research will help inform the Intergovernmental Panel on Climate Change’s next report.
Dr Storey will use laser technology to examine tiny particles of rock that were carried off Greenland by the ice sheet 3.3-3 million years ago. Each fragment of rock carries the fingerprint of where it came from on land. This, in turn, will reveal much more precisely than ever before how much ice there was on Greenland the last time the earth had similar temperatures and levels of CO2 as predicted for the end of this century.
Dr Storey, of the School of Earth and Environmental Sciences, will pass on the results of his research to the expert modellers who are attempting to model what will happen to the ice sheet informed by its state in the past.
Dr Storey said: “The predicted rise in earth’s temperatures, rising sea levels and CO2 emissions have all had a dramatic impact on science and on policy.
“If it transpires that the General Circulation and Ice Sheet Models successfully reproduce large-scale climate changes that occurred in the past, this will give us more confidence in their prediction for the future.
“The models simulate the effects of greenhouse gas emissions on global climate and their affect on the polar ice caps and are very complex, but though they are used to inform government policies on global warming and the state of the ice on Greenland in particular they have rarely been tested by direct observations.”
The Greenland ice sheet has melted before – as part of the natural cycle of Earth – but Dr Storey is examining how much of the ice sheet was present three million years ago.
He said: “We don’t know if Greenland had more or less ice 3.3-3m years ago. How much of the continental ice sheets of Greenland and Antarctica melt is a key question because that determines how much sea levels will rise by. For example, if all the ice on Greenland were to melt, the global sea level would be about seven metres higher.
The sand-sized grains of rock Dr Storey will study were originally incorporated into the ice sheet by glacial erosion, then transported to the ice margin and incorporated into icebergs before being deposited on the sea floor as the iceberg melted in the open ocean.
He will test whether the chemical and isotopic composition and age of grains accurately reflect the region of Greenland from which they were eroded to estimate which areas were covered in ice 3.3-3m years ago.
This reconstruction can then be compared to existing model results to examine their performance.
He said: “Over the last 150 years or so burning fossil fuels, deforestation and cement making have caused the planet’s climate to change. As a result the continental ice sheets and valley glaciers are beginning to melt, contributing to 15cm rise in sea level. Up to now these changes have been relatively minor. What is of more concern is the magnitude of the warming to come and the climate changes that will accompany it due to our continued and previous greenhouse gas emissions.
