Geoscience Reference
In-Depth Information
trend. The grey line shows northern hemisphere temperature anomalies for the same
periods. Note that between 1951 and 1975, temperature anomalies were declining, whilst
half of the apparent increase in rainfall occurred. A more appropriate conclusion of the
paper could have been that (i) rainfall intensities are highly variable in time, and (ii)
temperature appears not to significantly influence the risk of intense rainfalls. The paper
would not have been published in
Nature
, nor would it have received any of the attention
that it got (and still gets).
The reality is that climate is hugely complicated and highly variable and that it is
actually meaningless to attempt to identify anthropogenic climate change through climate
events like floods or droughts. So if this is the case—how does one test climate change?
Figure 1: Rainfall (black) and temperature (grey) anomalies 1952-2000
Source: S-K Min, X. Zhang, F.W. Zwiers and G.C. Hegerl, “Human contribution to more intense precipitation
extremes,”
Nature
, Vol. 470 (2011), 378-381
The key to testing claims of catastrophic anthropogenic climate change lies in the
simplicity of the mechanism itself—atmospheric carbon dioxide concentrations are rising,
carbon dioxide is a greenhouse gas, and it absorbs and re-radiates longwave radiation
downwards. The radiation is trapped (or at least delayed) meaning that there is more of
it around and hence temperatures go up. So the simplest way to test the hypothesis is to
measure the planet's energy balance, in particular downward longwave radiation.
