Abstract
The health co-benefits of CO2 mitigation can provide a strong incentive for climate policy through reductions in air pollutant emissions that occur when targeting shared sources. However, reducing air pollutant emissions may also have an important co-harm, as the aerosols they form produce net cooling overall. Nevertheless, aerosol impacts have not been fully incorporated into cost-benefit modeling that estimates how much the world should optimally mitigate. Here we find that when both co-benefits and co-harms are taken fully into account, optimal climate policy results in immediate net benefits globally, overturning previous findings from cost-benefit models that omit these effects. The global health benefits from climate policy could reach trillions of dollars annually, but will importantly depend on the air quality policies that nations adopt independently of climate change. Depending on how society values better health, economically optimal levels of mitigation may be consistent with a target of 2 °C or lower.
Highlights
The health co-benefits of CO2 mitigation can provide a strong incentive for climate policy through reductions in air pollutant emissions that occur when targeting shared sources
We move this literature forward by developing a comprehensive cost-benefit integrated assessment model based on William Nordhaus’ Regionalized Integrated Climate Economy (RICE) model, where the new developments allow the model to weigh both the health co-benefits and the climate coharms of aerosol co-reductions; the latter in particular has been a largely neglected aspect of the co-benefits discussion. (We use the term co-harm to refer to the net climate harm of aerosol reductions, recognizing that reducing some species of emissions individually may produce different effects than the net of all species together; for example, reducing black carbon produces a climate benefit, that effect may be outweighed by the climate harm of reductions in other species.)
This includes determining: (1) the optimal climate policy across time and how it is affected by independent air quality control, (2) whether climate policy produces immediate net benefits, or if there are intergenerational tradeoffs, and (3) if specified climate targets are justifiable on cost-benefit grounds
Summary
The health co-benefits of CO2 mitigation can provide a strong incentive for climate policy through reductions in air pollutant emissions that occur when targeting shared sources. Prior studies on the topic have quantified the associated health co-benefits of pre-defined greenhouse gas reduction scenarios[1,2,3,4,5,6], or estimated the economic impacts from reducing specific pollutants[7,8,9], but these types of impacts have not been fully incorporated into costbenefit modeling that estimates how much the world should optimally mitigate We move this literature forward by developing a comprehensive cost-benefit integrated assessment model based on William Nordhaus’ Regionalized Integrated Climate Economy (RICE) model, where the new developments allow the model to weigh both the health co-benefits and the climate coharms of aerosol co-reductions (co-harms exist because aerosols produce net cooling overall10); the latter in particular has been a largely neglected aspect of the co-benefits discussion. Depending on how society values better health, we show that economically optimal levels of mitigation may be consistent with a target of 2 °C or lower
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
