Humanity has emitted over 1 trillion tonnes of CO2 into the atmosphere since the industrial revolution, raising atmospheric concentrations of CO2 from 280 to 417ppm. Every year, we add another 50 billion tonnes of CO2 equivalent, meaning that in 20 years we will double our total emissions. 

There are signs that global emissions are plateauing, and many governments around the world have penned ambitious commitments to reach net zero. However, talk is cheap, and many plans hinge on dubious assumptions around the role of bioenergy with CCS for example. 

There has been a shift in the climate debate with by and large an abandonment of the “denier” position and a growth in the lukewarmist camp, which acknowledges the reality of anthropogenic climate change but minimizes its consequences.

In a previous episode with Mark Lynas, we explored what 1-6 degrees of warming looks like in terms of its impacts on humanity and the environment. Today, we do our best to understand the probabilities of reaching 3+ degrees of warming. How has climate modeling held up over the years? How likely are phenomena like methane clathrates to act as a significant positive feedback mechanism? Will the climate stabilize if and when we reach zero emissions? 

Zeke Hausfather is a climate scientist and energy systems analyst whose research focuses on observational temperature records, climate models, and mitigation technologies. He was the senior climate analyst at Project Drawdown, and the US analyst for Carbon Brief. He has master's degrees in environmental science from Yale University and Vrije Universiteit Amsterdam and a Ph.D. in climate science from the University of California, Berkeley.