Because the (Apocalyptic) Anthropogenic Global Warming ((A)AGW) debate covers way too much topics, I would like to propose a discussion of some selected parts. These will not on their own prove or disprove AGW (assuming we reach a consensus on any one point of course), but they will help to get the discussion focused and the current data and arguments from both sides collected.
I would like to use this thread to discuss if there is for the moment Global Warming (GW), without looking at the causes at first (perhaps this will follow automatically). So no discussion of CO2, solar cycles, 800 year gaps... if possible. I would also like to start this thread as if we have said nothing about GW yet on this board, so we can start afresh.
Example questions are: for what periods do we have reliable data, globally and/or locally, and for what periods do we have useful but perhaps less reliable or complete data? Are these data filtered to exclude local features and give a more global view? Are there regions which clearly differ from the trend (like Antarctica or so, or oceans versus land masses)? Discussion of the evidence used for making these statistics is welcome as well, so we can better judge their value.
This discussion will of course talk about the Hockeystick Graph, but I would like it to be not exclusively about it. I would like if possible a comparison of short-time temperatures (the last 15 decades or so), mid-range (the last ten or twenty centuries), and long range (the last few million years or so), if at all possible.
A good summary of global temperature research in the last 100 years can be found
here, from the American Institute of Physics. I don't claim that it's perfectly neutral (no text on global warming is, it seems), but I think it can be used as a starting point, and it offers a lot of references and links.
Conclusions from it (if I am allowed some conclusions in the very first post of the debate
) seem to be that we are having currently a very warm period if we look at the last 150 years (since 1861), with the five warmest years of this period occurring in the last 7 years; that the hockeystick, while not necessarily incorrect, was certainly misleading in the emphasis it laid on the average temperature of the last 1000 years, while just giving the range (and the uncertainty) would have been better and more honest; and that in the hockeystick and in other, more recent studies of the global average temperature of the last thousand years, the last decade is as warm or warmer than any period in the millennium.
I guess that especially the last ones will be debated, but that's the purpose.