As part of the decision to adopt the Paris Agreement, the IPCC was invited to produce a Special Report on global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways. Finalized last week, a key message is that we are already seeing the consequences of 1°C of global warming through more extreme weather, rising sea levels and diminishing Arctic sea ice, among other changes. The report states that limiting global warming to 1.5°C would require rapid, far-reaching and unprecedented changes in all aspects of society.
Allowing the global temperature to temporarily exceed or ‘overshoot’ 1.5°C would mean a greater reliance on techniques that remove CO2 from the air to return global temperature to below 1.5°C by 2100. The effectiveness of such techniques are unproven at large scale and some may carry significant risks for sustainable development.