Comment to “ Recent Climate Observations Compared to Projections ” by Rahmstorf et al . Gerhard Kramm University of Alaska Fairbanks , Geophysical Institute 903

With great interest I read this article of Rahmstorf et al. [1]. It is surprising to me that the authors only consider a period from the beginning of the seventies to recent years. I think that this is, clearly, a source of misinterpretation. The Mauna Loa observation of the atmospheric carbon dioxide (CO2) concentration (probably the best CO2 data we have) started in 1958. Therefore, one should consider the whole period of these observations. As illustrated in Figures 1 and 2, the correlations for the period 1958 to 2004 show a somewhat different picture as presented by Rahmstorf et al. [1] in their Figure 1. The results of my figures are based on the Mauna Loa CO2 data (monthly and annual averages) and the mean near surface temperature anomalies of the Hadley Centre for Climate Prediction and Research, MetOffice, UK, for the northern hemisphere (also monthly and annual averages), too. If we do not consider the whole period of available data, then we might run in the wrong direction. Figures 3 and 4, for instance, illustrate results from correlation calculations for the period ranging from 1958 to 1988. Remember that in 1988 the Intergovernmental Panel of Climate Change (IPCC) of the United Nations and the World Meteorological Organization (WMO) was established. As shown in the figures attached, during 1988 there was certainly no correlation between CO2 and the temperature anomalies, neither on the annual time scale (Figure 3) nor on the monthly time scale (Figure 4). Consequently, I wonder why the IPCC was established during that time.