Thursday, December 10, 2009

'Unequivocal, global, and in one direction'

IGSP Climate-Change Index

IGSP: At the United Nations climate negotiations in Copenhagen, the International Geosphere-Biosphere programme launches the IGBP Climate-Change Index...

It brings together key indicators of global change: carbon dioxide, temperature, sea level and sea ice. The index gives an annual snapshot of how the planet's complex systems -- the ice, the oceans, the land surface and the atmosphere -- are responding to the changing climate. The index rises steadily from 1980 -- the earliest date the index has been calculated. The change is unequivocal, it is global, and, significantly, it is in one direction. The reason for concern becomes clear: in just 30 years we are witnessing major planetary-scale changes.

The index dips in just three years, 1982, 1992 and 1996 and looks effective at capturing major natural events that affect climate, and their knock-on effect on the planet. The dip in the curve in 1992 may have been caused by the massive Mount Pinatubo volcanic eruption in the Philippines in 1991. The eruption was large enough to affect temperature and sea level on a planetary scale. The other falls coincide with the El Chichon volcanic eruption in Mexico in 1982 and the volcanic eruption on the Caribbean island of Montserrat in 1996. If this link proves robust, the index is an excellent visual tool to show how external events can have rapid planetary-scale effects. Of course, the overall direction of change -- a climbing cumulative index -- highlights the extent human activities are having on the planet's climate system.