Home » climate
Category Archives: climate
Posted on 8 July 2013
A laboratory study by researchers from the Universities of Reading and York has demonstrated that balls of calcium carbonate (small lumps of chalk-like material) excreted by the earthwormLumbricus terrestris – commonly known as lobworms or nightcrawlers – maintain a memory of the temperature at which they were formed.
This, say the researchers, in an article in the journal Geochimica et Cosmochimica Acta, means that calcite granules, commonly recorded at sites of archaeological interest, have the potential to reveal important information about past climates which could be used to enhance and benchmark climate change models.
The study, which also involved English Heritage’s Centre for Archaeology, was funded by the Natural Environment Research Council (NERC).
Lead author Dr Emma Versteegh from the Department of Geography and Environmental Science at the University of Reading, said: “These chalk balls will allow us to reconstruct temperatures for specific time intervals in which they were formed. Reconstructions like this are interesting for archaeologists, because they give a climatic context to their finds. More importantly, climate proxies are the only means we have to study climate beyond the instrumental record, which only goes back about 150 years.
“This knowledge about past climates is of vital importance for developing and benchmarking climate models that make predictions for the future. Many different proxies already exist, but no proxy is perfect, or is available in every location, so it is good to have many different ones.”
The proof of concept study involved keeping modern-day Lumbricus terrestris at different temperatures, then carrying out isotopic testing on the calcite granules excreted. This successfully demonstrated that the granules remembered the temperature at which they were formed.
Principal Investigator Professor Mark Hodson from the University of York’s Environment Department, and formerly of the University of Reading, said: “There are many conflicting theories about why earthworms produce calcite granules, but until now, the small lumps of chalk-like material found in earthworm poo have been seen as little more than a biological curiosity. However, our research shows they may well have an important role to play, offering a window into past climates.”
The researchers are now gathering samples from archaeological sites dating back thousands of years in preparation for isotopic testing.
Dr Stuart Black, from the University of Reading’s Department of Archaeology, added: “We believe this new method of delving into past climates has distinct advantages over other biological proxies. For example, we believe it will work for the full seasonal range of temperatures, whereas methods such as tree rings, do not ‘record’ during winter. In addition, because the chalk balls are found in direct context with archaeological finds, they will reveal temperatures at the same location. At present, links are often attempted with climate proxies many hundreds or even thousands of miles away.”
Release Date 18 December 2012
Ocean mussels could be key to helping scientists predict more accurately the rise in sea levels caused by the melting of the Greenland Ice Sheet.
A University of Reading study has shown that mussel shells accurately record the amount of meltwater running off the ice sheet during the summer. The researchers believe analysing shells hundreds to thousands of years old will reveal how much Greenland meltwater, caused by the natural climate variability of the Earth, contributed to previous sea level fluctuations.
This information can then be fed into climate models allowing scientists to better predict the behaviour of the Ice Sheet during future variations in climate. Crucially this will also tell us how much melting is due to human influence.
Due to global warming the sheet melted at an unprecedented rate during 2012 with the thawed ice area jumping from 40% to 97% in just four days during July. Melting is predicted to raise global sea levels during the 21st century by up to 10 cm and if the sheet was to completely melt, which would take centuries, sea levels would rise by about seven metres. This could threaten low-lying countries like the Netherlands and less developed countries such as Bangladesh.
Dr Emma Versteegh, from the University of Reading’s Department of Geography and Environmental Sciences, who conducted the research with co-workers from Greenland and Denmark, said: “The Earth’s climate naturally varies over long timescales and there have been warm intervals before during which the amount the Greenland Ice Sheet melted might have varied considerably. Examples include the Holocene Climatic Optimum (roughly 9000 to 5000 years BC) and the Medieval Warm Period (~ AD 950 to 1250).
“Very little is known about the dynamics of Greenland Ice Sheet melting. In order to understand its behaviour and predict future melting, information on meltwater amounts during different climatic regimes is hugely important. However instrumental data only cover the last few decades, so other methods are needed to look further into the past.”
Using blue mussels found in different areas off the coast of West Greenland, Dr Versteegh found that the shells revealed the amount of meltwater running off the ice sheet during the summer. Mussels and other shells have been used before to reconstruct past climate, but this is the first time they have been used to indicate past meltwater amounts.
Dr Versteegh continued: “Over several years we collected shells at different locations in Godthåbsfjord and also measured water composition and temperature. Meltwater is characterised by a very different oxygen isotopes composition than seawater. By analysing these isotopes in the mussels’ annual growth bands we will be able to reconstruct the melting of the Greenland Ice Sheet during several warm periods over the past 10,000 years. This will give climate scientists vital information on how the Earth’s natural variations in climate affect the Ice Sheet, and in turn sea levels, which they can use to further improve predictions of sea level rises stemming from climate change.”
Oxygen isotope ratios in the shell of Mytilus edulis: archives of glacier meltwater in Greenland is published on the Biogeosciences websites http://www.biogeosciences.net/
For all media enquiries please contact James Barr, University of Reading Press Officer on 0118 378 7115 or by email on firstname.lastname@example.org
Notes for Editors
The University of Reading is ranked among the top 1% of universities in the world (THE World University Rankings 2012) and is one of the UK’s top research-intensive universities.
The University of Reading’s Department of Geography and Environmental Science has a strong research environment which focuses on key issues at home and abroad, from the social and economic impact of developments in the UK, to studies of Brazilian rainforests, Caribbean towns and livelihoods in Africa. The Department works with business and industry, charities and non-governmental organisations, and has links with other departments whose expertise provide a diverse and stimulating research environment.
Greenland Climate Research Centre
Danish Ministry of the Environment (Dancea);
Commission for Scientific Research in Greenland, Ministry of Education;
Research and Nordic cooperation (IIN);
Aage V Jensen Charity Foundation;
Canada Excellence Research Chair Program (University of Manitoba, Canada)