Tropospheric ozone and aerosols in climate agreements: scientific and political challenges

Rypdal, Kristin; Berntsen, Terje; Fuglestvedt, Jan S.; Aunan, Kristin; Torvanger, Asbjørn; Stordal, Frøde; Pacyna, Józef M.; Nygaard, Lynn P.

doi:10.1016/j.envsci.2004.09.003

Cited by 61 publications

(43 citation statements)

References 46 publications

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“…Both of these studies show that there are significant benefits to pursuing coordinated policies for air quality and climate, and not only for the improvement of O 3 -related air quality. Rypdal et al (2005) commented on the challenges for putting tropospheric ozone in climate agreements.…”

Section: The Future -Air Quality and Climatementioning

confidence: 99%

Tropospheric ozone and its precursors from the urban to the global scale from air quality to short-lived climate forcer

et al. 2015

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Abstract. Ozone holds a certain fascination in atmospheric science. It is ubiquitous in the atmosphere, central to tropospheric oxidation chemistry, yet harmful to human and ecosystem health as well as being an important greenhouse gas. It is not emitted into the atmosphere but is a byproduct of the very oxidation chemistry it largely initiates. Much effort is focused on the reduction of surface levels of ozone owing to its health and vegetation impacts, but recent efforts to achieve reductions in exposure at a country scale have proved difficult to achieve owing to increases in background ozone at the zonal hemispheric scale. There is also a growing realisation that the role of ozone as a short-lived climate pollutant could be important in integrated air quality climate change mitigation. This review examines current understanding of the processes regulating tropospheric ozone at global to local scales from both measurements and models. It takes the view that knowledge across the scales is important for dealing with air quality and climate change in a synergistic manner. The review shows that there remain a number of clear challenges for ozone such as explaining surface trends, incorporating new chemical understanding, ozone-climate coupling, and a better assessment of impacts. There is a clear and present need to treat ozone across the range of scales, a transboundary issue, but with an emphasis on the hemispheric scales. New observational opportunities are offered both by satellites and small sensors that bridge the scales.

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Section: The Future -Air Quality and Climatementioning

confidence: 99%

Tropospheric ozone and its precursors from the urban to the global scale from air quality to short-lived climate forcer

et al. 2015

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“…Methane reductions also pose huge challenges. About 33-45% of the annual CH 4 emission of 230-300 Mt is caused by livestock and the agriculture sector, 30% is caused by the energy sector, and 25% is caused by waste treatment and disposal (13,27,28). The required actions include reduced pipeline leakage in the gas sector, productivity improvements in livestock management and rice cultivation, and reduction of CH 4 emissions from landfills and coal extraction with subsequent recovery for energy purposes.…”

Section: Constraintsmentioning

confidence: 99%

The Copenhagen Accord for limiting global warming: Criteria, constraints, and available avenues

Ramanathan

Xu²

2010

Proc. Natl. Acad. Sci. U.S.A.

161

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At last, all the major emitters of greenhouse gases (GHGs) have agreed under the Copenhagen Accord that global average temperature increase should be kept below 2°C. This study develops the criteria for limiting the warming below 2°C, identifies the constraints imposed on policy makers, and explores available mitigation avenues. One important criterion is that the radiant energy added by human activities should not exceed 2.5 (range: 1.7-4) watts per square meter (Wm −2 ) of the Earth's surface. The blanket of man-made GHGs has already added 3 (range: 2.6-3.5) Wm −2 . Even if GHG emissions peak in 2015, the radiant energy barrier will be exceeded by 100%, requiring simultaneous pursuit of three avenues: (i) reduce the rate of thickening of the blanket by stabilizing CO 2 concentration below 441 ppm during this century (a massive decarbonization of the energy sector is necessary to accomplish this Herculean task), (ii) ensure that air pollution laws that reduce the masking effect of cooling aerosols be made radiant energy-neutral by reductions in black carbon and ozone, and (iii) thin the blanket by reducing emissions of short-lived GHGs. Methane and hydrofluorocarbons emerge as the prime targets. These actions, even if we are restricted to available technologies for avenues ii and iii, can reduce the probability of exceeding the 2°C barrier before 2050 to less than 10%, and before 2100 to less than 50%. With such actions, the four decades we have until 2050 should be exploited to develop and scale-up revolutionary technologies to restrict the warming to less than 1.5°C. December 7-19, 2009, in Copenhagen to arrive at an international agreement for mitigating climate change. An agreement could not be reached; instead, the COP-15 arrived at the so-called "Copenhagen Accord" (CHA). Of the 193 nations that attended, including the leaders of major developed and developing nations, all but a few nations (Bolivia, Cuba, Nicaragua, Sudan, and Venezuela) supported the accord. The most significant part of the succinct three-page 12-paragraph CHA (1) is the following: "We underline that climate change is one of the greatest challenges of our time" in its opening paragraph, followed by the second paragraph, which begins with "We agree that deep cuts in global emissions are required according to science, and as documented by the IPCC Fourth Assessment Report with a view to reduce global emissions so as to hold the increase in global temperature below 2 degrees Celsius, and take action to meet this objective consistent with science and on the basis of equity." Targets for greenhouse gas (GHG) emission reductions as required by Appendix 1 of the CHA have already been provided by over 100 countries, including most if not all of the major emitters. The initial response to the CHA was one of disappointment (2), particularly because it did not include binding targets for reductions in CO 2 emissions. As such, the CHA is considered to be just a political document (2).The present article, on the other hand, argues that an agreement...

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“…Most greenhouse gases, including CO 2 and CH 4 , have a sufficient atmospheric lifetime to become well mixed throughout the atmosphere. The climate forcing potential (forcing per unit emission) of greenhouse gas emissions is therefore insensitive to the location of the source, aiding the formulation of international climate policies such as the Kyoto Protocol Rypdal et al, 2005;Shine et al, 2005;Unger et al, 2008). In contrast, aerosols have an atmospheric lifetime of days to weeks, resulting in a patchy distribution driven by the location of emissions, regional differences in transport and removal processes, and, in the case of secondary aerosol components like sulfate, by variable chemical and photochemical factors.…”

Section: Introductionmentioning

confidence: 99%

Variable CCN formation potential of regional sulfur emissions

et al. 2009

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Abstract. Aerosols are short lived so their geographical distribution and impact on climate depends on where they are emitted. Previous model studies have shown that the mass of sulfate aerosol produced per unit sulfur emission (the sulfate burden potential) and the associated direct radiative forcing vary regionally because of differences in meteorology and photochemistry. Using a global model of aerosol microphysics, we show that the total number of aerosol particles produced per unit sulfur emission (the aerosol number potential) has a different regional variation to that of sulfate mass. The aerosol number potential of N. American and Asian emissions is calculated to be a factor of 3 to 4 times greater than that of European emissions, even though Europe has a higher sulfate burden potential. Pollution from N. America and Asia tends to reach higher altitudes than European pollution so forms more new particles through nucleation. Regional differences in particle production and growth mean that sulfur emissions from N. America and E. Asia produce 50 nm diameter cloud condensation nuclei up to 70% more efficiently than Europe. For 80 nm diameter CCN, N. America and Europe produce CCN 2.5 times more efficiently than E. Asia. The impact of regional sulfur emissions on particle concentrations is also much more widely spread than the impact on sulfate mass, due to efficient particle production in the free troposphere during long range transport. These results imply that regional sulfur emissions will have different climate forcing potentials through changes in cloud drop number.

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Tropospheric ozone and aerosols in climate agreements: scientific and political challenges

Cited by 61 publications

References 46 publications

Tropospheric ozone and its precursors from the urban to the global scale from air quality to short-lived climate forcer

Tropospheric ozone and its precursors from the urban to the global scale from air quality to short-lived climate forcer

The Copenhagen Accord for limiting global warming: Criteria, constraints, and available avenues

Variable CCN formation potential of regional sulfur emissions

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