We show that stricter, shorter COVID lockdowns reduce overall losses relative to weaker but longer ones. But even a lengthy period of moderate restrictions is economically preferable to lifting all restrictions if it can avoid the need for another round of strict lockdowns. Regardless, losses propagate via global supply chains; best case responses are globally coordinated.
We show that ambitious climate mitigation scenarios entail drastic, and perhaps un-appreciated, changes in the operating and/or retirement schedules of power infrastructure. For example, in 1.5 or 2°C scenarios, the median age of global coal plants at retirement is <10 years.
Future changes in the fraction of precipitation falling as snow and the timing of snowmelt jeopardize food production in basins where irrigated agriculture relies heavily on snowmelt runoff. We assess the most at-risk basins and crops worldwide, where adaptation of water management and agricultural systems may be especially critical in a changing climate.
By analyzing 35 years of temperature, ozone levels, and crop yield data, we estimate the impacts of warming and ozone pollution on perennial fruits and nuts in California. These crops, which represent ~38% of the state's agriculture by value, suffer damages of about $1 billion per year due to ozone in recent years. With 2°C of warming, almond yields will drop by ~10%.
If operated as historically, existing fossil energy infrastructure will emit >650 Gt of CO2, well over the most recent 1.5°C carbon budgets and 2/3 of the remaining 2°C budget. There is thus little or no room for new fossil infrastructure under the targets; rather existing infrastructure must be retired early.
Although there are many options for reducing energy-related CO2 emissions, some energy services entail emissions that are much more difficult to eliminate. We review technological opportunities and barriers for eliminating and/or managing difficult-to-decarbonize services, and critical areas for further research, development, demonstration and deployment.