About the role of GHGs on slowdown in GMST trends

Climate Models Radiative Forcing Greenhouse Gases


Overview of a paper about the recent slowdown in global mean surface temperatures. It is based in an estimation of radiative forcing of several greenhouse gases and a mapping of their contributions to temperature trends.

New results from our research at the University of Reading has been publicated recently on Environmental Research Letters. In this case with the use of a Energy Balanced Model we are able to assess on the contribution of each greenhouse gases to the recent slowdown in globa-mean temperatures trends.

Abstract: The recent slowdown in the rate of increase in global-mean surface temperature (GMST) has generated extensive discussion, but little attention has been given to the contribution of time-varying trends in greenhouse gas concentrations. We use a simple model approach to quantify this contribution. Between 1985 and 2003, greenhouse gases (including well-mixed greenhouse gases, tropospheric and stratospheric ozone, and stratospheric water vapour from methane oxidation) caused a reduction in GMST trend of around 0.03–0.05 K decade−1 which is around 18%–25% of the observed trend over that period. The main contributors to this reduction are the rapid change in the growth rates of ozone-depleting gases (with this contribution slightly opposed by stratospheric ozone depletion itself) and the weakening in growth rates of methane and tropospheric ozone radiative forcing. Although CO2 is the dominant greenhouse gas contributor to GMST trends, the continued increase in CO2 concentrations offsets only about 30% of the simulated trend reduction due to these other contributors. These results emphasize that trends in non-CO2 greenhouse gas concentrations can make significant positive and negative contributions to changes in the rate of warming, and that they need to be considered more closely in analyses of the causes of such variations.

Any interested reader can have more information about the paper on the following links:

The following figure, published online with the paper shows the global mean surface temperature trends estimated in the article.

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