The governments of more than 190 nations gather in Paris in late November to discuss a global agreement on climate change.
Scientists have warned that unless greenhouse gas emissions start to fall, we will exceed a temperature rise of 2 degrees C above pre-industrial levels. Above this rise, global warming will become catastrophic and irreversible.
However, the UK and other nations with the biggest greenhouse gas emissions are likely to make commitments in Paris that will not be enough to keep the temperature rise within 2 degrees.
At 2 degrees of warming (i.e. a global average of 2 degrees above pre-industrial levels), we face severe global water shortages, an increase in extreme weather events, and massively increased migration, as people flee drought, floods and other disasters. 2 degrees is a politically-chosen limit. Scientists have said 1-1.5 was the maximum we should envisage if we are to avoid millions of deaths in vulnerable regions (the regions least responsible for emissions.) In November 2015, we already hit 1 degree, and at current rates will have used up the carbon required to reach 2 degrees in less than 20 years.
The CO2 already in the atmosphere - which takes 40+ years to translate to actual temperature changes - guarantees further warming, so 3-4 degrees is currently more likely than 2 degrees, unless the offers made prior to the Paris talks are improved on, significantly, during the negotiations. Those people and countries with high levels of emissions need to take rapid action to reduce these to have the required short-term impact.Elected governments find this very hard to suggest to their populations as there will undoubtedly be some difficult choices, but many of the measures such as insulated houses, more efficient machines and reliable renewable energy would actually make us more comfortable and better off.
However, a 4 degrees rise is incompatible with an 'organised global community': it is beyond adaptation, devastating to eco-systems & very unstable, with various 'tipping points' each precipitating sudden, rather than gradual, environmental changes. Once the world is on this path, 6+ degrees of warming may be unstoppable, and those temperatures would be barely survivable.
What say you?