“As present world temperatures are already 0.7C above the pre-industrial level, the process is well under way…
when the temperature moves up to 2C above the pre-industrial level, expected in the middle of this century – within the lifetime of many people alive today – that serious effects start to come thick and fast…
when the temperature moves up to the 3C level, expected in the early part of the second half of the century, these effects will become critical. There is likely to be irreversible damage to the Amazon rainforest, leading to its collapse…
There will be a rapid increase in populations exposed to hunger, with up to 5.5 billion people living in regions with large losses in crop production, while another 3 billion people will have increased risk of water shortages…
Above the 3C raised level, which may be after 2070, the effects will be catastrophic: the Arctic sea ice will disappear.”