Is 2ºC the "safe limit" to global warming?

No! Warming the earth anywhere close to +2ºC above pre-industrial (1750) levels would be highly catastrophic and immoral. It would likely cause a global food crisis, an extreme increase in international freshwater scarcity, and an 82-foot sea level rise over the next 2,000 years that would inundate many of the world’s core population centers. 

The truth is that humanity has already warmed the earth too much, and any further warming is insanely risky. We are experiencing the hottest global average temperatures in the history of human civilization. Dangerous climate change is already here:

  • In 2014, NASA glaciologist Eric Rignot warned that global warming has already set in motion the collapse of the West Antarctic Ice Sheet, which could ultimately raise sea levels by 13 feet.

  • A 2012 study commissioned by 20 vulnerable countries found that ~1ºC global warming kills, on average, 400,000 people every year - including 1,000 children every day - via increased hunger and the spread of communicable diseases. Since then, the planet has warmed to nearly +1.2ºC above 1750 levels, according to our advisor, the climate scientist Michael Mann.

  • Warming of +1.6ºC would likely melt the entirety of the Greenland Ice Sheet, leading to a long-term 23 foot sea-level rise, as well as the release of 8 percent of the world’s freshwater into the oceans, which could radically alter ocean circulation patterns. 

  • A 2013 study of Siberian caves led by the earth scientist Anton Vaks projected that global warming of +1.5ºC above pre-industrial levels will likely initiate a "continuous thaw" of the land-based permafrost, or frozen soils, in the Arctic regions — an event that could release hundreds of billions of tons of carbon in the coming decades and centuries and make it virtually impossible for us to restore a safe and stable climate on any time-scale relevant to humanity. The land-based permafrost contains approximately 1.7 trillion tons of carbon, which is more than three times the amount of carbon released into the atmosphere through fossil fuel burning since the industrial revolution. The carbon would be released in the form of carbon dioxide and methane — a short-lived, extremely potent greenhouse gas.

    Even worse, the Vaks study projected that a "continuous thaw" could occur at some point between a range of +1ºC and +2ºC of global warming above pre-industrial levels, with warming of +1.5ºC being the most "likely" to cause the continuous thaw. We are now in the low end of that range, and there is growing evidence that the boundaries of the permafrost are beginning to thaw and release methane. See the terrifying short film posted by Yale Climate Connections on the potential for a continuous thaw of the permafrost. The film features Vaks and former Energy Secretary Steven Chu, who warns: "We cannot go there." 

According to Mann, if the current rate of emissions continues, the earth will warm +2ºC by 2036 - just twenty years from now. A climate catastrophe for the poorest people in the world will almost certainly unfold before then, unless we act immediately and on an emergency basis. In a Feb. 24 interview with Veerabhadran Ramanathan, a renowned climate scientist at the Scripps Institution of Oceanography who advises Pope Francis and Governor Jerry Brown, described the extreme urgency of our situation: 

The worst consequences of climate change will be experienced by the poorest 3 billion (people), largely living in villages, who had nothing to do with this. Not 100 years from now. Not 50 years from now. Ten to 15 years from now, they’re going to see major disasters...The Paris agreement is a watershed, but it’s a toothless agreement. The actions we need to take are so drastic, no leader in the world has the support to take these actions.
The prevailing media narratives around +2ºC or even +1.5ºC of global warming being "guardrails" between climate safety and climate danger simply do not square with climate science or basic ethics. There is simply no "carbon budget" left for humanity to burn. This is a full-blown existential moral emergency, requiring emergency action right now.

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