Search for: All records

Anthropogenic aerosols are hazardous to human health but have helped offset warming from greenhouse gases (GHGs), creating a potential regulatory tradeoff. As countries implement their GHG reduction targets under the Paris climate agreement, the co‐emissions of aerosols and their precursors will also change. Since these co‐emissions vary by country and by economic sector, each country will face different tradeoffs between aerosol‐driven health or temperature co‐benefits. We combine simple parameterizations of physical processes and health outcomes to examine three idealized climate policy approaches that are consistent with the Paris Agreement targets, which (i) optimize for local air quality, (ii) reduce global temperature change, or (iii) reduce emissions equally from all domestic economic sectors. We evaluate aerosol impacts on premature mortality and global mean temperature change under these three policy approaches and find that by 2030 the three policies yield differences of over 1 million annual premature deaths and global temperature differences of the same magnitude as those from GHG reductions. We also show that implementing equal reductions between all economic sectors can actually result in less beneficial health and temperature outcomes than either of the other options, especially in less industrialized regions. We therefore conclude that aerosol‐related co‐benefits and aerosol accounting guidelines should be explicitly considered in setting international climate policy.

 

The distribution of anthropogenic aerosols’ climate effects depends on the geographic distribution of the aerosols themselves. Yet many scientific and policy discussions ignore the role of emission location when evaluating aerosols’ climate impacts. Here, we present new climate model results demonstrating divergent climate responses to a fixed amount and composition of aerosol—emulating China’s present-day emissions—emitted from 8 key geopolitical regions. The aerosols’ global-mean cooling effect is fourteen times greater when emitted from the highest impact emitting region (Western Europe) than from the lowest (India). Further, radiative forcing, a widely used climate response proxy, fails as an effective predictor of global-mean cooling for national-scale aerosol emissions in our simulations; global-mean forcing-to-cooling efficacy differs fivefold depending on emitting region. This suggests that climate accounting should differentiate between aerosols emitted from different countries and that aerosol emissions’ evolving geographic distribution will impact the global-scale magnitude and spatial distribution of climate change.

 

Aerosols markedly modify the social cost of anthropogenic emissions depending on where they are emitted. 

Satellites reveal crop yield losses from nitrogen dioxide around the world. 

Recent dramatic and deadly increases in global wildfire activity have increased attention on the causes of wildfires, their consequences, and how risk from wildfire might be mitigated. Here we bring together data on the changing risk and societal burden of wildfire in the United States. We estimate that nearly 50 million homes are currently in the wildland–urban interface in the United States, a number increasing by 1 million houses every 3 y. To illustrate how changes in wildfire activity might affect air pollution and related health outcomes, and how these linkages might guide future science and policy, we develop a statistical model that relates satellite-based fire and smoke data to information from pollution monitoring stations. Using the model, we estimate that wildfires have accounted for up to 25% of PM 2.5 (particulate matter with diameter <2.5 μm) in recent years across the United States, and up to half in some Western regions, with spatial patterns in ambient smoke exposure that do not follow traditional socioeconomic pollution exposure gradients. We combine the model with stylized scenarios to show that fuel management interventions could have large health benefits and that future health impacts from climate-change–induced wildfire smoke could approach projected overall increases in temperature-related mortality from climate change—but that both estimates remain uncertain. We use model results to highlight important areas for future research and to draw lessons for policy.