More than a number

If you want to know what’s happening on a stockmarket, the first place to look is at the relevant index — the Footsie (FTSE) for the London Stock Exchange, or the Dow Jones for Wall Street. Those indices aggregate all the price movements over a day into one handy number, to give a quick overview of how the market’s behaving. Now a group of scientists working for the International Geosphere-Biosphere Programme (IGBP) have compiled a Climate Change Index (CCI) to provide the same service for the evidence of climate change. The CCI was launched in Copenhagen yesterday. The video above describes the approach they’ve used, and the “ladder” graphic below shows how the CCI has moved over the last 30 years:


The CCI tracks changes in global temperature, atmospheric CO2, Arctic sea ice, and sea level. An increase in the CCI shows a move away from a stable climate. Over the last 30 years the cumulative shift has been 574 points — in the wrong direction. The IGBP team point out that the CCI responds to global cooling events such as the Pinatubo and El Chichon eruptions, but they are also looking at adding other indicators to the index including land-use, fisheries exploitation, population, fire and extreme events. They are planning to update the index every year, and to backdate it to periods before 1980.

[The Drifters]

6 thoughts on “More than a number”

  1. It would be good to include antarctic sea ice although the net increase has been small and should not effect the overall results of this index.

    However, this type of index despite its faults (all indices have aggregation problems) does have the advantage of taking a global prespective on a global problem, helping to ovecome what I call the small minded problem.

    To paraphrase ‘it was cool where I live yesterday so climate change isn’t happening’ or ‘I will ignore global trends and focus on one glacier, one temperature record, or one region to the exclusion of the everything else’.

  2. More likely the situation in the Antarctic is a tad more complicated. Increased sea ice extent was a prediction of the climate models deniers hate so much (deniers believing wild guesswork is preferable). Only a transitional stage though, the continued warming will mean eventual decreases in Antarctic sea ice.

    A recent (ish) paper on the topic:

    “Estimates of sea ice extent based on satellite observations show an increasing Antarctic sea ice cover from 1979 to 2004 even though in situ observations show a prevailing warming trend in both the atmosphere and the ocean. This riddle is explored here using a global multicategory thickness and enthalpy distribution sea ice model coupled to an ocean model. ”

    ” The model shows that an increase in surface air temperature and downward longwave radiation results in an increase in the upper-ocean temperature and a decrease in sea ice growth, leading to a decrease in salt rejection from ice, in the upper-ocean salinity, and in the upper-ocean density. The reduced salt rejection and upper-ocean density and the enhanced thermohaline stratification tend to suppress convective overturning, leading to a decrease in the upward ocean heat transport and the ocean heat flux available to melt sea ice. The ice melting from ocean heat flux decreases faster than the ice growth does in the weakly stratified Southern Ocean, leading to an increase in the net ice production and hence an increase in ice mass. This mechanism is the main reason why the Antarctic sea ice has increased in spite of warming conditions both above and below during the period
    1979–2004 and the extended period 1948–2004.”

    Don’t worry R2, additionally the Ozone Hole over Antarctica will eventually close and then things will really warm up down there. Should be able to add Antarctic sea ice to the Climate Change Index eventually.

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