Every now and again, the myth that “we shouldn’t believe global warming predictions now, because in the 1970′s they were predicting an ice age and/or cooling” surfaces. Recently, George Will mentioned it in his column (see Will-full ignorance) and the egregious Crichton manages to say “in the 1970′s all the climate scientists believed an ice age was coming” (see Michael Crichton’s State of Confusion ). You can find it in various other places too [here, mildly here, etc]. But its not an argument used by respectable and knowledgeable skeptics, because it crumbles under analysis. That doesn’t stop it repeatedly cropping up in newsgroups though.
Technical Note: We have changed the contact email for the blog to reduce the amount of unsolicited email. If you want to contact us at the blog, please use contact-at-realclimate.org.
We’ve used the term “consensus” here a bit recently (see our earlier post on the subject), without ever really defining what we mean by it. In normal practice, there is no great need to define it – no science depends on it. But it’s useful to record the core that most scientists agree on, for public presentation. The consensus that exists is that of the IPCC reports, in particular the working group I report (there are three WG’s. By “IPCC”, people tend to mean WG I). Fortunately that report is available online for all to read at http://www.grida.no/climate/ipcc_tar/wg1/. It’s a good idea to realise that though the IPCC report contains the consensus, it didn’t form it. The IPCC process was supposed to be – and is – a summary of the science (as available at the time). Because they did their job well, it really is a good review/summary/synthesis.
A collection of airborne solid or liquid particles, with a typical size between 0.01 and 10 µm and residing in the atmosphere for at least several hours. Aerosols may be of either natural or anthropogenic origin. Aerosols may influence climate in two ways: directly through scattering and absorbing radiation, and indirectly through acting as condensation nuclei for cloud formation or modifying the optical properties and lifetime of clouds (from the always useful IPCC glossary).
There are quite a few reasons to believe that the surface temperature record – which shows a warming of approximately 0.6°-0.8°C over the last century (depending on precisely how the warming trend is defined) – is essentially uncontaminated by the effects of urban growth and the Urban Heat Island (UHI) effect. These include that the land, borehole and marine records substantially agree; and the fact that there is little difference between the long-term (1880 to 1998) rural (0.70°C/century) and full set of station temperature trends (actually less at 0.65°C/century). This and other information lead the IPCC to conclude that the UHI effect makes at most a contribution of 0.05°C to the warming observed over the past century.
When I joined RC, I was a climate modeller with the British Antarctic Survey. Now I’m a software engineer for CSR. I’m still interested in communicating the science of climate change, but can no longer do so at a professional level.
One of the people in the picture is me. Guess which.
ps: all my contributions online are released under the GFDL, unless I explicitly note otherwise.
All posts by william.