A study on a Chinese policy providing free coal heating north of the Huai River, but not south, created a natural experiment. This revealed that the resulting increase in particulate pollution caused residents in the north to live, on average, five years less than their southern counterparts.
A randomized trial in Surat, India established a pollution market for industrial plants. Contrary to assumptions that such systems are too complex for developing countries, the program reduced emissions by 20-30% while also lowering compliance costs for firms, providing a successful proof of concept.
Standard metrics like the Air Quality Index (AQI) are abstract and fail to motivate change. Economist Michael Greenstone created the Air Quality Life Index (AQLI), which translates pollution into a tangible, personal metric—years of life expectancy lost—making the data hard to ignore and spurring action.
Economist Michael Greenstone recounts how his academic communication style, efficient among peers, was perceived as abrasive and exclusionary in government, nearly getting him fired. To have real-world impact, experts must translate specialized jargon into accessible ideas, a skill academia doesn't teach or reward.
The Tropical Forest Forever Facility (TFFF) uses a clever economic design. It offers a small payment ($4/hectare) for existing forests but imposes a massive penalty ($400/hectare) for any destroyed. This focuses financial incentives on the margin, where deforestation actually occurs, making the program more cost-effective.
While controversial, the boom in inexpensive natural gas from fracking has been a key driver of US emissions reduction. Natural gas has half the carbon content of coal, and its price advantage has systematically pushed coal out of the electricity generation market, yielding significant climate benefits.
After holding a consensus view for 30 years, climate scientists revised the "equilibrium climate sensitivity parameter." This change reduced the probability of extreme temperature increases (e.g., 4-5°C) for a given amount of CO2, recalibrating end-of-century projections towards a less catastrophic, though still severe, path.
Setting rigid global warming limits (e.g., 2°C) creates a finite carbon budget. Since most future emissions will come from developing countries, these caps effectively tell poorer nations they must cut projected emissions by up to 90%, forcing them to choose between development and global climate goals.