I don’t believe that this graph is an improvement to the traditional hockey stick image. Even with access to the raw data or even processed data, I was not able to understand the information well enough to provide a critical reinterpretation. However this graph changes the aspect of the graph by showing simply the estimated surface temperatures by using data collected from lake cores from Lake Tanganika in East Africa. I chose this data set because in Mann et al. 1998 they acknowledged few if any data from the African continent. While I understand that Mann et al. were working with the data sets they had available, I thought it would be interesting to work with data that are from a drastically under-represented area.
Where these charts differ the greatest from the hockey stick projection, is that they do not show the departures of temperature from the 1961 to 1990 average but rather just display the estimated temperatures based on lake core analyses. In fact they do not show contemporary temperatures at all. I tried this same projection with other data sets and I came up with similar looking charts that seem not to have any consistent pattern. In this way we can see that perhaps one single study cannot add to current climate change debates, however, only aggregate compilations of these studies can give weight and force to the international, scholarly and secular, and very public debate on climate change.
The elementary graphs above were produced with excel based on data from
Tierney, J.E., J.M. Russell, Y. Huang, J.S. Sinninghe Damsté, E.C. Hopmans, and A.S. Cohen. 2008. "Northern Hemisphere Controls on Tropical Southeast African Climate During the Past 60,000 Years" Science, Vol. 322, No. 5899, pp. 252-255, 10 October 2008. available here.
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