I'm optimistic: Current terrain is vastly underutilized for food: consider ethanol made out of corn etc. Unless it gets seriously extreme, all the terrain that gets too hot to farm should be replaced by more land that becomes warm enough to farm. And increased wetness in the world(from melting ice caps) should increase fertility over areas like deserts.
You can be more optimistic. Increased carbon dioxide and longer growing seasons increases plant yield, and this is seen in increased plant biomass in the world.
I heard (though I'm not entirely sure how to cite or quantify, so salt as necessary) that the weather patterns that will be inspired by climate change will tend towards extremes: either drier deserts or more damaging monsoons/hurricanes/flooding rains, not "bringing more rain to places that don't get rained on much today".
Historically, warming leads to shrinking deserts, and cold earth eras were also the driest. Some researchers have found that the Sahara is shrinking as the Sahel spreads north (though the Sahel itself is threatened by desertification caused by bad agricultural practices).
In particular, I've heard that too much ice melting, leading to too low seawater salinity, could stop the Gulf Stream, making the climate in Europe much colder.
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?