SYSTEMS thinking is vital to understanding how our planet functions, not least to understanding and tackling the causes and consequences of climate change.

Yet the drive to reduce greenhouse gas emissions appears devoid of such thinking in Scotland and the UK.

Scottish Renewables' PR about carbon dioxide emissions "displaced" by renewable electricity production ("Record level of carbon emissions displaced by renewable", The Herald, December 12) is just the latest example.

To assess the real CO2 reduction achieved thus far by renewables one must consider the entire electricity generation system and its actual emissions, not just take the renewables part of the system and multiply its output by average emissions of the fossil fuel part, and then claim that theoretical calculation as the amount saved.

The Government makes system-wide assessment more difficult by publishing renewables statistics for Scotland quarterly but whole-system statistics much less frequently and about a year in arrears. Scotland is, of course, only part of the integrated Great Britain electricity system and there are international flows as well. However, since the Scottish Government pretends Scotland is a separate system I shall follow their lead.

What does looking at the whole system tell us about Scottish CO2 reductions? Comparing 2001 and 2012, when electricity generation levels were very similar but renewables generated 10% and 40%, respectively, of electricity production, greenhouse gas emissions from public electricity and heat production fell from 18.9 to 12.7 Mt CO2e. This was a total-system reduction of 6.2Mt. Yet the claimed "displacement" by renewables for 2012 is 10.4Mt. So theoretical displacement figures overstate very substantially the true CO2 reduction in the electricity system achieved by renewables.

This matters enormously because the repetitive optimistic spin from government, industry and organisations such as WWF sends out the subliminal message that climate change in Scotland is being solved and we can just carry on consuming as usual. It lets both government and population remain in denial about the true scale of the challenge of global environmental degradation, of which climate change is just one manifestation, and the pathetic progress made thus far in tackling it.

(Dr) Dave Gordon,

60 Bonhard Road, Scone, Perthshire.