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".
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.
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?