Right. There is a pretty simple argument against climate change alarmism that goes as follows. Let F(T) be some function of the global average temperature T - food production is a good one because it's concrete, but you could also talk about some kind of "global human wellbeing" function. Let's assume we are currently at the optimum Tmax. By basic calculus, the first derivative of F(.) at Tmax is zero. So a small increase in the global average temperature, say from Tmax to Tmax+2C, won't have much affect on net food production. This is just a mathematical way of saying that there will be benefits as well as costs associated with global warming, but the costs will probably only exceed the benefits by a small amount.
Someone could counterargue that we are actually above Tmax already, so that the world is suboptimally warm and the derivative of F(T) is already substantially negative. But I think that claim would require some good evidence, and a serious investigation of the issue might actually reveal the opposite - the world is actually suboptimally cool and so we should welcome global warming.
The actual T at any given time doesnt necessarily matter as much as the rate of change...
A Guardian article on the impact of climate change on food security. This is worrying (albeit perhaps not a global catastrophic (or existential) risk). It has the potential to wipe out the gains made against extreme poverty in the last few decades.
Should we be so pessimistic? Climate change might be averted through government action or a technological fix; or the poorest might get rich enough to be protected from this insecurity; or we could see a second 'Green Revolution' with GM, etc. I've also seen some discussion that climate change could in fact increase food cultivation - in Russia and Canada for example.
How do people feel about this - optimistic or pessimistic?