GLOBAL: A Dow Jones Index for climate change
Photo: NASA  |
| Distilling the complexity of the Earth's climate down to one number |
COPENHAGEN, 9 December 2009 (IRIN) - Confused by the various datasets on sea level rise, global temperature, Arctic sea ice melt and the level of carbon dioxide in the atmosphere? Help is at hand.
The International Geosphere-Biosphere Programme (IGBP), a research network of 10,000 scientists, has taken these four key indicators to develop the world's first climate change index as a useful tool for policy-makers, launched at the UN climate change talks in Copenhagen.
The index, which will be updated each year, uses data starting from 1980 to provide an annual snapshot of how the planet's systems – ice, oceans, land surface and atmosphere - have been reacting to a changing climate. The index rises steadily from 1980, showing that the planet is warming, said Sybil Seitzinger, executive director of IGBP.
The decision to develop the index was prompted by asking: "What if the complexity of the Earth's climate were distilled down to one number, in the same way that the Dow Jones Index [which tracks targeted stock market activity] condenses volumes of data into a single figure? What then would be the general trend?"
Seitzinger said the index not only silenced climate change science dissidents, but also provided an accessible overview of how each variable has been responding to climate change.
"We felt people outside global-change research were not clear about the scale of changes scientists are witnessing," she said. "The index is a response to these concerns."
The scientists have calculated the average change for each indicator every year, taking into account climate variability, and the index is accompanied by graphs illustrating the impact of climate change on each indicator; one can see at a glance, for instance, that sea-level is rising by more 2mm annually.
"The earth's systems are very complex, so you don't know how a variable might have responded to other factors in a certain year," said Seitzinger. So you have peaks and dips in the graphs, but the overall trend for each indicator shows that carbon dioxide concentration in the atmosphere, global average temperatures, and the sea level, are rising.
She said the network was looking at taking into account a longer time period - such as paleodata - going beyond recorded climate data, which is only about 140 years old. Paleodata is derived from coral cores, ice cores, tree rings, pollen, sediment from oceans and lake beds, and other sources.
The climate change index was the first step, Seitzinger told IRIN. The IGBP intends including more variables, such as precipitation. "Maybe we could do a separate index on each variable, or even regional or country-specific indices – we are exploring these options and taking feedback."
The index can provide useful information to fill the gap in time between the authoritative Intergovernmental Panel on Climate Change (IPCC) reports, which provide background for most policy-makers at present; the last IPCC reports were released in 2007, and the next assessment reports are only due in 2014.
"Data since then has shown that the sea level is rising faster than the IPCC projections," Seitzinger noted. The IPCC's 2007 reports projected the average sea-level rise for the 20th century at 0.17mm.
Watch a film on the index here: Climate change index
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