We now face an unprecedented crisis that threatens the lives of billions of people. The severity of this crisis will largely depend on our collective ability to constrain global warming. For many years, it was widely accepted that by limiting warming to within 2ºC of pre-industrial levels, we could avoid ‘dangerous’ level of climate impacts (beyond the estimated 300,000 deaths annually, loss of species, and billions of dollars of extreme weather-related damage currently being caused by the crisis).
However, due to protracted inaction, the chance of limiting warming to 2ºC is now looking increasingly remote.
We are already in a situation where only [by] the most dramatic of all climate protections can we hold the 2-degrees line.
Professor John Schellnhuber (Director of German’s Potsdam Institute for Climate Impact Research and arguably Europe’s top climate scientist)
Furthermore, due to revised understandings of climate sensitivity, it appears that between 1-2ºC now represents ‘dangerous’ climate change, which will precipitate events such as the permanent loss of Arctic sea ice.
Sounds pretty bad right? Actually, 2°C of warming starts to look positively peachy when we examine where our current emissions trajectory is taking us.
If the world fails to meet it’s obligations to a global carbon budget we could then be on track for up to 4°C of warming by the end of this century, and potentially as early as 2060.
…the implications of 4C of warming shows that the impacts are so significant that the only real adaptation strategy is to avoid that at all cost because of the pain and suffering that is going to cost… There is no science on how we are going to adapt to 4C warming. It is actually pretty alarming.
Professor Neil Adger (A Tyndall Centre climate change adaptation expert)
For humanity it’s a matter of life or death, I think it’s extremely unlikely that we wouldn’t have mass death at 4C. If you have got a population of nine billion by 2050 and you hit 4C, 5C or 6C, you might have half a billion people surviving.
Professor Kevin Anderson (Director of the UK’s Tyndall Centre for Climate Change)
… [at 4°C of warming] carrying capacity estimates [for population are] below 1 billion people.
Professor John Schellnhuber