The combustion of fossil fuels produces emissions of the long-lived greenhouse gas carbon dioxide and of short-lived pollutants, including sulfur dioxide, that contribute to the formation of ...atmospheric aerosols
. Atmospheric aerosols can cool the climate, masking some of the warming effect that results from the emission of greenhouse gases
. However, aerosol particulates are highly toxic when inhaled, leading to millions of premature deaths per year
. The phasing out of unabated fossil-fuel combustion will therefore provide health benefits, but will also reduce the extent to which the warming induced by greenhouse gases is masked by aerosols. Because aerosol levels respond much more rapidly to changes in emissions relative to carbon dioxide, large near-term increases in the magnitude and rate of climate warming are predicted in many idealized studies that typically assume an instantaneous removal of all anthropogenic or fossil-fuel-related emissions
. Here we show that more realistic modelling scenarios do not produce a substantial near-term increase in either the magnitude or the rate of warming, and in fact can lead to a decrease in warming rates within two decades of the start of the fossil-fuel phase-out. Accounting for the time required to transform power generation, industry and transportation leads to gradually increasing and largely offsetting climate impacts of carbon dioxide and sulfur dioxide, with the rate of warming further slowed by reductions in fossil-methane emissions. Our results indicate that even the most aggressive plausible transition to a clean-energy society provides benefits for climate change mitigation and air quality at essentially all decadal to centennial timescales.
I present a multi-impact economic valuation framework called the Social Cost of Atmospheric Release (SCAR) that extends the Social Cost of Carbon (SCC) used previously for carbon dioxide (CO
2
) to a ...broader range of pollutants and impacts. Values consistently incorporate health impacts of air quality along with climate damages. The latter include damages associated with aerosol-induced hydrologic cycle changes that lead to net climate benefits when reducing cooling aerosols. Evaluating a 1 % reduction in current global emissions, benefits with a high discount rate are greatest for reductions of co-emitted products of incomplete combustion (PIC), followed by sulfur dioxide (SO
2
), nitrogen oxides (NO
x
) and then CO
2
, ammonia and methane. With a low discount rate, benefits are greatest for PIC, with CO
2
and SO
2
next, followed by NO
x
and methane. These results suggest that efforts to mitigate atmosphere-related environmental damages should target a broad set of emissions including CO
2
, methane and aerosol/ozone precursors. Illustrative calculations indicate environmental damages are $330-970 billion yr
−1
for current US electricity generation (~14–34¢ per kWh for coal, ~4–18¢ for gas) and $3.80 (−1.80/+2.10) per gallon of gasoline ($4.80 (−3.10/+3.50) per gallon for diesel). These results suggest that total atmosphere-related environmental damages plus generation costs are much greater for coal-fired power than other types of electricity generation, and that damages associated with gasoline vehicles substantially exceed those for electric vehicles.
Extreme heat is already occurring more frequently and with greater intensity, with this trend predicted to continue. Exposure to extreme heat causes labor supply declines, but studies to quantify the ...economic effects from future climate changes are limited. In this study, we adopt two different exposure-response functions relating extreme heat to the loss of labor working minutes or labor productivity. We estimate that temperature differences between 2006 and 2016 relative to 1980–1990 led to labor losses of ~$1.7 billion annually in the USA. Under the high emissions RCP8.5 scenario, approximately 1–1.8 billion workforce hours will be lost annually in the 2050s, and 1.5–4.4 billion hours will be lost by the 2100s, depending on the exposure-response function used. The lost hours lead to an estimated $51–119 billion in losses by the 2100s, without considering future climate adaptation, demographic, employment, wage structure, or economic changes. Whereas 2006–2016 losses correspond to 0.07% of the 2016 GDP, the 2100s losses rise roughly fourfold to 0.3%, which are mainly caused by the increases of extreme heat conditions with population growth a secondary factor. With the climate change mitigation strategies of the RCP4.5 scenario, 600–2600 million hours of lost labor per year could be avoided in the 2100s, saving $20–78 billion depending on the chosen exposure-response function. We also evaluated the effect of decarbonizing the energy sector in a manner consistent with the 1.5 °C target of the Paris Agreement, finding that these lead to ~77 million avoided lost work hours worth ~$2.5 billion annually by the 2050s with global collaboration but insignificant impacts with US action alone. Though uncertainties and limitations exist in the study, we find that extreme heat will cause large economic losses to US businesses, especially in southern states (from California to Florida), though widespread climate change mitigation has the potential to substantially reduce these losses. We find that uncertainties among the exposure-response functions used to derive the economic effects of extreme heat on labor are much larger than those from the climate models. Previous studies using only one exposure-response function may exhibit substantial biases and likely underestimate uncertainties associated with the effect of climate changes on labor.
SignificanceThis study clarifies the need for comprehensive CO
and non-CO
mitigation approaches to address both near-term and long-term warming. Non-CO
greenhouse gases (GHGs) are responsible for ...nearly half of all climate forcing from GHG. However, the importance of non-CO
pollutants, in particular short-lived climate pollutants, in climate mitigation has been underrepresented. When historical emissions are partitioned into fossil fuel (FF)- and non-FF-related sources, we find that nearly half of the positive forcing from FF and land-use change sources of CO
emissions has been masked by coemission of cooling aerosols. Pairing decarbonization with mitigation measures targeting non-CO
pollutants is essential for limiting not only the near-term (next 25 y) warming but also the 2100 warming below 2 °C.
Working in hot and potentially humid conditions creates health and well-being risks that will increase as the planet warms. It has been proposed that workers could adapt to increasing temperatures by ...moving labor from midday to cooler hours. Here, we use reanalysis data to show that in the current climate approximately 30% of global heavy labor losses in the workday could be recovered by moving labor from the hottest hours of the day. However, we show that this particular workshift adaptation potential is lost at a rate of about 2% per degree of global warming as early morning heat exposure rises to unsafe levels for continuous work, with worker productivity losses accelerating under higher warming levels. These findings emphasize the importance of finding alternative adaptation mechanisms to keep workers safe, as well as the importance of limiting global warming.
Increased concentrations of ozone and fine particulate matter (PM2.5) since preindustrial times reflect increased emissions, but also contributions of past climate change. Here we use modeled ...concentrations from an ensemble of chemistry-climate models to estimate the global burden of anthropogenic outdoor air pollution on present-day premature human mortality, and the component of that burden attributable to past climate change. Using simulated concentrations for 2000 and 1850 and concentration-response functions (CRFs), we estimate that, at present, 470 000 (95% confidence interval, 140 000 to 900 000) premature respiratory deaths are associated globally and annually with anthropogenic ozone, and 2.1 (1.3 to 3.0) million deaths with anthropogenic PM2.5-related cardiopulmonary diseases (93%) and lung cancer (7%). These estimates are smaller than ones from previous studies because we use modeled 1850 air pollution rather than a counterfactual low concentration, and because of different emissions. Uncertainty in CRFs contributes more to overall uncertainty than the spread of model results. Mortality attributed to the effects of past climate change on air quality is considerably smaller than the global burden: 1500 (−20 000 to 27 000) deaths yr−1 due to ozone and 2200 (−350 000 to 140 000) due to PM2.5. The small multi-model means are coincidental, as there are larger ranges of results for individual models, reflected in the large uncertainties, with some models suggesting that past climate change has reduced air pollution mortality.
The profound changes in global SOsubscript 2 emissions over the last decades have affected atmospheric composition on a regional and global scale with large impact on air quality, atmospheric ...deposition and the radiative forcing of sulfate aerosols. Reproduction of historical atmospheric pollution levels based on global aerosol models and emission changes is crucial to prove that such models are able to predict future scenarios. Here, we analyze consistency of trends in observations of sulfur components in air and precipitation from major regional networks and estimates from six different global aerosol models from 1990 until 2015. There are large interregional differences in the sulfur trends consistently captured by the models and observations, especially for North America and europe. europe had the largest reductions in sulfur emissions in the first part of the period while the highest reduction came later in North America and east Asia. the uncertainties in both the emissions and the representativity of the observations are larger in Asia. However, emissions from East Asia clearly increased from 2000 to 2005 followed by a decrease, while in India a steady increase over the whole period has been observed and modelled. the agreement between a bottom-up approach, which uses emissions and process-based chemical transport models, with independent observations gives an improved confidence in the understanding of the atmospheric sulfur budget.
PDF
