The broader view

The published mainstream science provides a coherent story that is supported by established science

First, let me reassure Andrew Goodman (PE on-line letters 10 Feb) that he can stop worrying about the earth moving out of orbit or stopping spinning, neither event is likely to happen in the foreseeable future (where the foreseeable future is at least hundreds of millions of years).  

Fortunately, the earth’s orbit and spin are the under the control of Newtonian mechanics and this area of science is well understood. Of course, if an enormous asteroid or rogue planet hits us all bets are off!  But don’t worry, it’s not likely to happen as none have been identified so far!

More seriously, dealing with Goodman’s second point, the earth’s surface temperature has varied greatly over geological time, but the real question is whether these temperature fluctuations were associated with changes in the atmospheric concentration of CO2 and other greenhouse gases. Ice cores provide reliable measurements of atmospheric CO2 and temperature over the last few hundred thousand years, but charting global temperature and atmospheric CO2 concentrations over geological time is difficult. This has not stopped some geologists, geophysicists and climate scientists from trying! There are two conclusions, one that atmospheric CO2 concentrations and global average temperature are linked (and have been for more than 500 million years), and the other concludes that there is no linkage.

If variations in CO2 concentrations can be shown to have caused some of the climate changes in the very distant past this will add further support to the present mainstream view (as stated by the IPCC) regarding global warming. What is not in doubt is that doubling the atmospheric CO2 concentration will result in an additional greenhouse warming effect of about 4 W/m2. Where the debate in serious science lies with to regard global warming is whether associated feedbacks will amplify or attenuate this increase. Mainstream science suggests that amplification will occur; the sceptics suggest that attenuation will occur.

As far as I can judge, the published mainstream science provides a coherent story that is supported by established science and relies on peer review to filter out poor science. The sceptics claim that their science is kept out of peer reviewed publications by a conspiracy; of course, it could be that it is of poor quality and does not merit publication.

Robin Trow, Kent