scholarly journals Projections of atmospheric mercury levels and their effect on air quality in the United States

2014 ◽  
Vol 14 (2) ◽  
pp. 783-795 ◽  
Author(s):  
H. Lei ◽  
D. J. Wuebbles ◽  
X.-Z. Liang ◽  
Z. Tao ◽  
S. Olsen ◽  
...  
Keyword(s):  
Climate Change ◽  
United States ◽  
Climate Warming ◽  
Wet Deposition ◽  
Global Climate ◽  
The United States ◽  
Atmospheric Mercury ◽  
Western Us ◽  
Natural Emissions ◽  
Ipcc Sres

Abstract. The individual and combined effects of global climate change and emissions changes from 2000 to 2050 on atmospheric mercury levels in the United States are investigated by using the global climate-chemistry model, CAM-Chem, coupled with a mercury chemistry-physics mechanism (CAM-Chem/Hg). Three future pathways from the Intergovernmental Panel on Climate Change (IPCC) Special Report on Emissions Scenarios (SRES) are considered, with the A1FI, A1B and B1 scenarios representing the upper, middle and lower bounds of potential climate warming, respectively. The anthropogenic and biomass burning emissions of mercury are projected from the energy use assumptions in the IPCC SRES report. Natural emissions from both land and ocean sources are projected by using dynamic schemes. TGM concentration increases are greater in the low latitudes than they are in the high latitudes, indicative of a larger meridional gradient than in the present day. In the A1FI scenario, TGM concentrations in 2050 are projected to increase by 2.1–4.0 ng m−3 for the eastern US and 1.4–3.0 ng m−3 for the western US. This spatial difference corresponds to potential increases in wet deposition of 10–14 μg m−2 for the eastern US and 2–4 μg m−2 for the western US. The increase in Hg(II) emissions tends to enhance wet deposition and hence increase the risk of higher mercury entering the hydrological cycle and ecosystem. In the B1 scenario, mercury concentrations in 2050 are similar to present level concentrations; this finding indicates that the domestic reduction in mercury emissions is essentially counteracted by the effects of climate warming and emissions increases in other regions. The sensitivity analyses show that changes in anthropogenic emissions contribute 32–53% of projected changes in mercury air concentration, while the independent contribution by climate change and its induced natural emissions change accounts for 47–68%.

scholarly journals Projections of atmospheric mercury levels and their effect on air quality in the United States

2013 ◽  
Vol 13 (8) ◽  
pp. 20165-20194
Author(s):  
H. Lei ◽  
D. J. Wuebbles ◽  
X.-Z. Liang ◽  
Z. Tao ◽  
S. Olsen ◽  
...  
Keyword(s):  
Climate Change ◽  
Climate Warming ◽  
Global Climate Change ◽  
Wet Deposition ◽  
Global Climate ◽  
The United States ◽  
Atmospheric Mercury ◽  
Western Us ◽  
The Us ◽  
Ipcc Sres

Abstract. The individual and combined effects of global climate change and emissions changes from 2000 to 2050 on atmospheric mercury levels in the US are investigated by using the global climate-chemistry model, CAM-chem, coupled with a mercury chemistry-physics mechanism (CAM-Chem/Hg). Three future pathways from the Intergovernmental Panel on Climate Change (IPCC) Special Report on Emissions Scenarios (SRES) are considered, with the A1FI, A1B and B1 scenarios representing the upper, middle and lower bounds of potential climate warming, respectively. The anthropogenic and biomass burning emissions of mercury are projected from the energy use assumptions in the IPCC SRES report. Natural emissions from both land and ocean sources are projected using dynamic schemes. The zonal mean surface total gaseous mercury (TGM) concentrations in the tropics and mid-latitudes of the Southern Hemisphere are projected to increase by 0.5–1.2 ng m-3 in 2050. TGM concentration increases are greater in the low latitudes than they are in the high latitudes, indicative of a larger meridional gradient than in the present day. In the A1FI scenario, TGM concentrations in 2050 are projected to increase by 2.1–4.0 ng m-3 for the eastern US and 1.4–3.0 ng m-3 for the western US. This pattern corresponds to potential increases in wet deposition of 10–14 μg m-2 for the eastern US and 2–4 μg m-2 for the western US. The increase in Hg(II) emissions tends to enhance wet deposition and hence increase the risk of higher mercury entering the hydrological cycle and ecosystems. In the B1 scenario, mercury concentrations in 2050 are similar to present level concentrations; this indicates that the domestic reduction in mercury emissions is essentially counteracted by the effects of climate warming and emissions increases in other regions. The sensitivity analyses presented show that anthropogenic emissions changes contribute 32–53% of projected mercury air concentration changes, while the independent contribution by climate change accounts for 47–68%. In summary, global climate change could have a comparable effect on mercury pollution in the US to that caused by global emissions changes.

scholarly journals Assessing the influence of an extended hurricane season on inland flooding potential in the Southeast United States

2016 ◽  
Author(s):  
Monica H. Stone ◽  
Sagy Cohen
Keyword(s):  
United States ◽  
Tropical Cyclones ◽  
Climate Warming ◽  
Global Climate ◽  
River Basins ◽  
The United States ◽  
Southeast United States ◽  
Global Climate Warming ◽  
Hurricane Season ◽  
Near Future

Abstract. Recent tropical cyclones, like Hurricane Katrina, have been some of the worst the United States has experienced. Tropical cyclones are expected to intensify, bringing about 20 % more precipitation, in the near future in response to global climate warming. Further, global climate warming may extend the hurricane season. This study focuses on four major river basins (Neches, Pearl, Mobile, and Roanoke) in the Southeast United States that are frequently impacted by tropical cyclones. An analysis of the timing of tropical cyclones that impact these river basins found that most occur during the low discharge season, and thus rarely produce riverine flooding conditions. However, an extension of the current hurricane season of June–November, due to global climate warming, could encroach upon the high discharge seasons in these basins, increasing the susceptibility for riverine hurricane-induced flooding. This analysis shows that an extension of the hurricane season to May–December (just 2 months longer) increased the number of days that would be at risk to flooding were the average tropical cyclone to occur by 37–258 %, depending on the timing of the hurricane season in relation to the high discharge seasons on these rivers. Future research should aim to extend this analysis to all river basins in the United States that are impacted by tropical cyclones in order to provide a bigger picture of which areas are likely to experience the worst increases in flooding risk due to a probable extension of the hurricane season with expected global climate change in the near future.

scholarly journals Model analyses of atmospheric mercury: present air quality and effects of transpacific transport on the United States

2013 ◽  
Vol 13 (4) ◽  
pp. 9849-9893 ◽  
Author(s):  
H. Lei ◽  
X.-Z. Liang ◽  
D. J. Wuebbles ◽  
Z. Tao
Keyword(s):  
United States ◽  
Air Quality ◽  
Wet Deposition ◽  
Total Mercury ◽  
The United States ◽  
Atmospheric Mercury ◽  
Anthropogenic Sources ◽  
Mercury Deposition ◽  
Transpacific Transport ◽  
Mercury Cycle

Abstract. Atmospheric mercury is a toxic air and water pollutant that is of significant concern because of its effects on human health and ecosystems. A mechanistic representation of the atmospheric mercury cycle is developed for the state-of-the-art global climate-chemistry model, CAM-Chem (Community Atmospheric Model with Chemistry). The model simulates the emission, transport, transformation and deposition of atmospheric mercury (Hg) in three forms: elemental mercury (Hg(0)), reactive mercury (Hg(II)), and particulate mercury (PHg). Emissions of mercury include those from human, land, ocean, biomass burning and volcano related sources. Land emissions are calculated based on surface solar radiation flux and skin temperature. A simplified air–sea mercury exchange scheme is used to calculate emissions from the oceans. The chemistry mechanism includes the oxidation of Hg(0) in gaseous phase by ozone with temperature dependence, OH, H2O2 and chlorine. Aqueous chemistry includes both oxidation and reduction of Hg(0). Transport and deposition of mercury species are calculated through adapting the original formulations in CAM-Chem. The CAM-Chem model with mercury is driven by present meteorology to simulate the present mercury air quality during the 1999–2001 periods. The resulting surface concentrations of total gaseous mercury (TGM) are then compared with the observations from worldwide sites. Simulated wet depositions of mercury over the continental United States are compared to the observations from 26 Mercury Deposition Network stations to test the wet deposition simulations. The evaluations of gaseous concentrations and wet deposition confirm a strong capability for the CAM-Chem mercury mechanism to simulate the atmospheric mercury cycle. The results also indicate that mercury pollution in East Asia and Southern Africa is very significant with TGM concentrations above 3.0 ng m−3. The comparison to wet deposition indicates that wet deposition patterns of mercury are more affected by the spatial variability of precipitation. The sensitivity experiments show that 22% of total mercury deposition and 25% of TGM concentrations in the United States are resulted from domestic anthropogenic sources, but only 9% of total mercury deposition and 7% of TGM concentrations are contributed by transpacific transport. However, the contributions of domestic and transpacific sources on the western United States levels of mercury are of comparable magnitude.

The Contemporary US Energy System Overview Including A Comparison With China

2016 ◽  
Author(s):  
Michael B. McElroy
Keyword(s):  
Climate Change ◽  
United States ◽  
Global Climate ◽  
Energy System ◽  
The United States ◽  
Economic Benefits ◽  
Personal Consumption ◽  
Energy Economy ◽  
Near Term ◽  
Reduce Emissions

The discussion in chapter 2 addressed what might be described as a microview of the US energy economy— how we use energy as individuals, how we measure our personal consumption, and how we pay for it. We turn attention now to a more expansive perspective— the use of energy on a national scale, including a discussion of associated economic benefits and costs. We focus specifically on implications for emissions of the greenhouse gas CO2. If we are to take the issue of human- induced climate change seriously— and I do— we will be obliged to adjust our energy system markedly to reduce emissions of this gas, the most important agent for human- induced climate change. And we will need to do it sooner rather than later. This chapter will underscore the magnitude of the challenge we face if we are to successfully chart the course to a more sustainable climate- energy future. We turn later to strategies that might accelerate our progress toward this objective.We elected in this volume to focus on the present and potential future of the energy economy of the United States. It is important to recognize that the fate of the global climate system will depend not just on what happens in the United States but also to an increasing extent on what comes to pass in other large industrial economies. China surpassed the United States as the largest national emitter of CO2 in 2006. The United States and China together were responsible in 2012 for more than 42% of total global emissions. Add Russia, India, Japan, Germany, Canada, United Kingdom, South Korea, and Iran to the mix (the other members of the top 10 emitting countries ordered in terms of their relative contributions), and we can account for more than 60% of the global total. Given the importance of China to the global CO2 economy (more than 26% of the present global total and likely to increase significantly in the near term), I decided that it would be instructive to include here at least some discussion of the situation in China— to elaborate what the energy economies of China and the United States have in common, outlining at the same time the factors and challenges that set them apart.

China-US deal sets stage for new climate change regime

2015 ◽  
Keyword(s):  
Climate Change ◽  
United States ◽  
Developing Countries ◽  
Global Climate Change ◽  
Global Climate ◽  
The United States ◽  
Content Type ◽  
Bilateral Agreement ◽  
The Eu ◽  
Game Changer

Significance The United States has already committed, in an unprecedented deal with China in November 2014, to reducing its emissions to 26-28% below 2005 levels by 2025 (an improvement on its previous 17% goal). China in return pledged that its emissions would peak around 2030. This agreement is a game-changer for combating global climate change, since the two countries are the world's largest sources of carbon emissions, together accounting for 40% of the total, and were not covered under the now-expired Kyoto Protocol. Impacts Washington is poised to reclaim its place, lost after Kyoto, as a leader in global efforts against climate change. US-China climate cooperation initiatives could serve as templates for other developing countries. There are new opportunities for trilateral cooperation involving the EU. Fears that the bilateral agreement makes the UNFCCC obsolete are unwarranted, but it could preclude more ambitious efforts.

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