The climate index – one number to define the change

Scientists attending the COP15 conference in Copenhagen last night unveiled a Dow Jones-style “climate-change index” which aims to assign an index number illustrating year to year changes in the climate.

The index is the work of the International Geosphere-Biosphere Programme and takes a basket of factors – carbon dioxide (CO2), temperature change, sea level and sea ice,  distilling them into a single figure.

The index is listed below.

Date Climate-change index Cumulative change
1980 24 24
1981 37 61
1982 -19 42
1983 39 81
1984 9 90
1985 8 98
1986 5 103
1987 31 134
1988 33 167
1989 18 185
1990 34 218
1991 10 228
1992 -25 203
1993 14 217
1994 21 237
1995 47 284
1996 -6 278
1997 35 313
1998 37 349
1999 15 365
2000 7 372
2001 19 391
2002 34 425
2003 28 454
2004 15 468
2005 43 512
2006 29 541
2007 33 574

The Science Media Centre in London wrapped up reaction from scientists.

Dr Norman Cheung, Senior Lecturer in the School of Geography, Geology and the Environment at Kingston University, said:

“Climate is changing continuously throughout history.  It can be due to natural variability or exacerbated by human activity.  Though there is abundant scientific evidence to show the global temperature is rising, there are still some fundamental problems we have to solve before a universal consensus can be made on the subject.  There is still uncertainty in trends determined over short-time periods and the possibility of unrecognised biases remaining in the data.

“The IGBP Climate change index can give a simple composite representation of the interrelationships between atmospheric CO2, global average temperature, arctic sea-ice cover and sea level.  It is a user-friendly index for the general public but my reservation is that it may be too simple.

“Politically, I believe the Copenhagen summit can set the platform for enhancing the communication between the political leaders on the global climate issues. Even if the natural variability of climate reverses our picture of climate change in the future, it is where we can come to discuss our problems.”

Dr Chris Huntingford, Climate Modeller at the Centre for Ecology and Hydrology, said:

“The IGBP have provided an excellent summary.  The development of more general indices of climate change, beyond just the temperature record, is very important.  Formal confirmation of the expected alterations to other aspects of our climate system provides support to the argument that the burning of fossil fuels is causing global warming, which in turn alters a broad range of environmental factors.  Aside from increased risk of heat-related stress for some regions of the world, it is the impact of global warming on entities such as the hydrological cycle that will be of most concern.

“Characterising climate change impacts in this way will help significantly in developing adaptation strategies.  It also reconfirms the need for future emissions reductions to stabilise or even change the direction of some of these indices, which otherwise could ultimately become associated with catastrophic climate change.”

Professor Robert Spicer, Professor of Earth Sciences at the Open University, said:

“Measuring the average global surface temperature is difficult because measurements are not evenly distributed over land (for example there are far more weather stations across the USA than in Antarctica), and there are very few over the oceans.  To combine the temperature data with other measures that integrate climate over the whole planet, like sea level rise, and condense them to a single value is therefore a very good idea.  These data show, without a shadow of doubt, that climate is moving, inexorably, in a direction that will cause humanity huge problems in the near future.”

Dr Simon Carr, Senior Lecturer in Physical Geography at Queen Mary, University of London, said:

“This index is probably the clearest illustration of the pattern and significance of recent climate trends for wide public consumption: for the first time key data on temperature, carbon dioxide, sea level and sea ice extent are brought together in a single measure of the rate and impact of climate change.

“Whilst any such index is by nature a simplification of the complex processes and interactions, the fact that we are seeing a consistent picture of increasing instability in global climate should be of immense concern to us all.

“This is the clearest indication we have yet seen that whatever the underlying climate change factors, humans are operating in an environment which is becoming progressively more hostile to our survival and prosperity. It would be good to see how this index has varied over longer timescales to place the recent changes in context.”