AT THREE DEGREES

Climate change will be complicated, and forecasting the impacts of climate change is by no means easy. But there are lots of forecasts out there, and we’ve pulled some of them together here. They are organized on this page for easy reference, but without references. Many are drawn from 2020 Lynas_Our Final Warning Six Degrees of Climate Emergency.

Note that 3^o C is likely, but could arguably still be avoided.

• 3^o C - 1/3 of the global land area will exceed “deadly heat thresholds” 20 days a year

• 3^o C - 2/3 of North American bird species are at risk of extinction

• 3^o C - 136 UNESCO World Heritage Sites put at risk

• 3^o C - 200 million people could be affected by flooding annually, with a quadrupuling of deaths to 20,000 people per year

• 3^o C - 20-year return period heat waves will be happening every years in many regions including the U.S.

• 3^o C - African generally faces a 20-50 fold increase in exposure to dangerous heat

• 3^o C - Amazon fires smoke could be the global equivalent of a volcanic eruption

• 3^o C - Arctic permafrost emissions could add .3 to .4 oC of warming to existing estimates

• 3^o C - by 2050, the frequency of 100-year floods will have doubled across 40% of the globe, affecting 450 million people

• 3^o C - by 2100, sea levels will be rising by more than they have risen during any point in human history

• 3^o C - countries like Canada that were projected to benefit agriculturally in a 2^o C world, experience yield losses

• 3^o C - enough to melt the entire WAIS over the next 500 years

• 3^o C - extreme heat waves currently expected 4 times a century in SE Asia will occur every other year

• 3^o C - flood damage in the U.S. more than doubles

• 3^o C - flooding damages rise by 1000% to more than a trillion dollars

• 3^o C - food shortages are the highest probability cause of a societal collapse

• 3^o C - global food production could be cut by half

• 3^o C - hundreds of thousands of square kms in the Amazon become subject to wildfire

• 3^o C - in CA, SLR could cost $150 billion and affect 600,000 people

• 3^o C - invasive species like the tropical rabbitfish will do large-scale damage to kelp forests as they move North

• 3^o C - IPCC assesses a 50% chance of a meter of SLR by 2100, and a 5% chance of 1.77 meters

• 3^o C - large parts of the world see a 500% increase in drought risk

• 3^o C - major crops become unviable in Africa

• 3^o C - more than 10 million people are exposed to “extreme risk” of heat stroke if working outside

• 3^o C - more than half of insects, 44% of plants, and 20% of birds will lose more than half their climatic range

• 3^o C - NYC could see 3 Hurricane Sandy flood events annually, which flooded 50 square miles of the city

• 3^o C - over a billion people exceed the “workability” heat threshold

• 3^o C - permafrost thawing could release 100 billion tons of carbon by 2100

• 3^o C - rainfed agriculture will cease to exist in many parts of the world

• 3^o C - subsistence farming becomes impossible in most of Africa and South Asia, affecting 1 billion people

• 3^o C - takes us back in time about 3 million years

• 3^o C - the average Mediterranean drought will last a decade or more

• 3^o C - the fraction of the world population exposed to “deadly heat” will rise from 30% in a 1oC world to 53%

• 3^o C - the massive East Antarctic ice sheet to melt over several thousand years

• 3^o C - the water resources of a billion people are threatened

• 3^o C - West African cities experience 145 dangerous heat days per year by the 2090’s

• 3^o C - will generate 2-4 meters of SLR from Greenland over the next 1000 years

• 3^o C - would cause the loss of 80% of glacier mass in many parts of the world, and 50% in Alaska