The first picture of climate change in the northern hemisphere using data from stalagmite growth has been created by researchers at the University of Birmingham’s School of Geography, Earth and Environmental Sciences.
By using this new method, they have discovered that there has been a global temperature rise of 0.65 degrees centigrade over the last 500 years. The stalagmite records suggest a more gradual increase in temperatures during this time period, in addition to the rapid rise during the 20th century.
Data from tree rings has previously been the main data source used by scientists to collect information about past climate change, but trees grow for short periods – usually decades or centuries – and provide better evidence of short term climate variability. Stalagmites grow for tens of thousands of years and their layers provide a better picture of long term climate variability.
Stalagmites grow in caves and are linked to the weather as they form from rain water which has passed through soil and limestone forming calcite deposits. As the chemistry of this water and the climate of the cave change through the year, different types of calcite is deposited, creating layers or rings that are formed annually. The width of a ring, or how fast a stalagmite has grown in any one year can be linked directly to climate change.
Claire Smith, postgraduate student in the School of Geography, Earth and Environmental Sciences, says, ‘This is the first time that ring width series from many stalagmites from across the northern hemisphere have been used in a climate change study. Because stalagmites grow for long periods of time we are confident that the information we have gained gives a clearer picture of long term climate variability than the studies that have previously used tree ring data.’
Dr Andy Baker continues, ‘It is very important to get accurate measurements of climate change in the recent past, as this data is essential to calibrate computer models that predict future climate change. Also data from the past helps us understand the importance of the many natural factors that can affect climate change, and help us understand the relative importance of today’s greenhouse gas induced global warming.’
Stalagmite data from China, Italy and Scotland were used in this study.
Notes to Editors
The study is published by the International Journal of Climatology and appears online at http://www3.interscience.wiley.com/cgi-bin/jissue/77004368
For further information
Kate Chapple, Press Officer, University of Birmingham, tel 0121 414 2772 or 07789 921164.