Stephen Day calls the evidence for manmade climate change "somewhat doubtful" (9 September). That is not the case: there is clear, direct evidence that increasing CO2 levels are caused by us and are warming the planet. Other commonly suggested causes (the sun, volcanoes, cosmic rays) have all been rejected by sound scientific evidence.
He then claims that the world isn't warming at all, yet the only evidence he can cite is two papers that do not, on close inspection, support his assertion. Climate is defined as a trend over decades (look at any long- term graph), so Mr Day's argument that 2005 was slightly cooler than 2008 is akin to saying "late September was warm, therefore winter isn't coming".
I stand by my assertion that deniers are not interested in truth. There is a clear distinction between deniers and sceptics: it is one of approach. A sceptic forms opinions based on evidence; a denier forms them based on worldview (look at Rick Perry or James Delingpole).
It worries me that anyone is teaching in our schools who does not get this distinction. The point about being "naturally sceptical" is disingenuous: all scientists are naturally sceptical about everything. I, like the vast majority of scientists, accept the theory of manmade climate change because the evidence demands it. Worldview has nothing to do with it.
The correct approach is to present the evidence to pupils in a balanced and accurate manner. How is it dogmatic or arrogant to teach what the evidence indicates?
Children should be taught this distinction between sceptics and deniers - it's part of critical thinking. The term "denier" should apply to those who deliberately invent and disseminate misinformation for personal, financial or political gain. We should distinguish these from members of the public who doubt climate change simply because they're taken in by all this misinformation, andor because they understandably don't want it to be true.
Scientists need to engage with the latter and change their minds by clear presentation of the evidence. That is what my presentation at the Scottish Learning Festival was about, and it is a great shame that Mr Day did not attend.
Richard Milne, Institute of Molecular Plant Sciences, Edinburgh University.