Most scenarios that avoid 2°C of global warming require large-scale deployment of negative emissions technologies. We review the impacts and resource demands of such deployment, and conclude that it's cheaper, easier and less risky to tackle global warming before fossil CO2 is in the atmosphere.
China's coal-based energy system and emissions-intensive manufacturing technologies produce drastically more CO2 emissions the same sectors in developed countries. We identify specific industries and provinces where improvements are most needed to reduce the CO2-penalty of trade with China.
Using a simple model that includes infrastructural carbon lock-in, we show that avoiding 2 °C of warming with continued economic growth will require extremely low carbon intensity of new infrastructure--even with immediate action, relatively short infrastructure lifetimes, and the possibility of large negative emissions after 2050.
Peak warming will be proportional to cumulative CO2 emissions, but the rate and velocity of climate change may be very different under different emissions pathways, even when cumulative emissions are equal. Thus, the ability of ecosystems to adapt or migrate is sensitive to the pathway of emissions.
US CO2 emissions dropped 11% between 2007-2013; a trend has been widely attributed to the increased use of natural gas over coal. We decompose the drivers of the decline and show that the recent economic downturn and not the gas boom deserves most of the credit for the decrease in emissions.