The Undeniable Facts of GHGs

The Stern Review, although not the first economic report on climate change, is one of the most significant, largest and most widely known and discussed reports of its kind. It was put together by economist Nicholas Stern and published for the British Government in 2006. It is one of the most comprehensive reviews to date and helped establish the 2 degree global warming goal adopted at the UNFCCC sessions. Was looking through it recently and found an excellent quote (page 5), that sets out the fundamental truth of climate change and why we can't ignore it:

"The key conclusion, that the build-up of greenhouse gases in the atmosphere will lead to several degrees of warming, rests on the laws of physics and chemistry and a broad range of evidence beyond one particular graph."

In its context, p. 5 of the Stern Review 2006 (http://mudancasclimaticas.cptec.inpe.br/~rmclima/pdfs/destaques/sternreview_report_complete.pdf):

"Much discussion has focused on whether the current trend in rising global temperatures is
unprecedented or within the range expected from natural variations. This is commonly referred to as
the “Hockey Stick” debate as it discusses the validity of figures that show sustained temperatures for
around 1000 years and then a sharp increase since around 1800 (for example, Mann et al. 1999,
shown as a purple line in the figure below).

Some have interpreted the “Hockey Stick” as definitive proof of the human influence on climate.
However, others have suggested that the data and methodologies used to produce this type of figure
are questionable (e.g. von Storch et al. 2004), because widespread, accurate temperature records are
only available for the past 150 years. Much of the temperature record is recreated from a range of
‘proxy’ sources such as tree rings, historical records, ice cores, lake sediments and corals.

Climate change arguments do not rest on “proving” that the warming trend is unprecedented over the
past Millennium. Whether or not this debate is now settled, this is only one in a number of lines of
evidence for human induced climate change. The key conclusion, that the build-up of greenhouse
gases in the atmosphere will lead to several degrees of warming, rests on the laws of physics and
chemistry and a broad range of evidence beyond one particular graph."