Couplings Between Changes in the Climate System and Biogeochemistry Coordinating Lead Authors: Kenneth L. Denman (Canada), Guy Brasseur (USA, Germany) Lead Authors: Amnat Chidthaisong (Thailand), Philippe Ciais (France), Peter M. Cox (UK), Robert E. Dickinson (USA), Didier Hauglustaine (France), Christoph Heinze (Norway, Germany), Elisabeth Holland (USA), Daniel Jacob (USA, France), Ulrike Lohmann (Switzerland), Srikanthan Ramachandran (India), Pedro Leite da Silva Dias (Brazil), Steven C. Wofsy (USA), Xiaoye Zhang (China) Contributing Authors: D. Archer (USA), V. Arora (Canada), J. Austin (USA), D. Baker (USA), J.A. Berry (USA), R. Betts (UK), G. Bonan (USA), P. Bousquet (France), J. Canadell (Australia), J. Christian (Canada), D.A. Clark (USA), M. Dameris (Germany), F. Dentener (EU), D. Easterling (USA), V. Eyring (Germany), J. Feichter (Germany), P. Friedlingstein (France, Belgium), I. Fung (USA), S. Fuzzi (Italy), S. Gong (Canada), N. Gruber (USA, Switzerland), A. Guenther (USA), K. Gurney (USA), A. Henderson-Sellers (Switzerland), J. House (UK), A. Jones (UK), C. Jones (UK), B. Karcher (Germany), M. Kawamiya (Japan), K. Lassey (New Zealand), C. Le Quere (UK, France, Canada), C. Leck (Sweden), J. Lee-Taylor (USA, UK), Y. Malhi (UK), K. Masarie (USA), G. McFiggans (UK), S. Menon (USA), J.B. Miller (USA), P. Peylin (France), A. Pitman (Australia), J. Quaas (Germany), M. Raupach (Australia), P. Rayner (France), G. Rehder (Germany), U. Riebesell (Germany), C. Rodenbeck (Germany), L. Rotstayn (Australia), N. Roulet (Canada), C. Sabine (USA), M.G. Schultz (Germany), M. Schulz (France, Germany), S.E. Schwartz (USA), W. Steffen (Australia), D. Stevenson (UK), Y. Tian (USA, China), K.E. Trenberth (USA), T. Van Noije (Netherlands), O. Wild (Japan, UK), T. Zhang (USA, China), L. Zhou (USA, China) Review Editors: Kansri Boonpragob (Thailand), Martin Heimann (Germany, Switzerland), Mario Molina (USA, Mexico) This chapter should be cited as: Denman, K.L., G. Brasseur, A. Chidthaisong, P. Ciais, P.M. Cox, R.E. Dickinson, D. Hauglustaine, C. Heinze, E. Holland, D. Jacob, U. Lohmann, S Ramachandran, P.L. da Silva Dias, S.C. Wofsy and X. Zhang, 2007: Couplings Between Changes in the Climate System and Biogeochemistry. In: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M.Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.

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Couplings between changes in the climate system and biogeochemistry

A review of surface ozone background levels and trends

A common view is that the current global warming rate will continue or accelerate. But we argue that rapid warming in recent decades has been driven mainly by non-CO2 greenhouse gases (GHGs), such as chlorofluorocarbons, CH4, and N2O, not by the products of fossil fuel burning, CO2 and aerosols, the positive and negative climate forcings of which are partially offsetting. The growth rate of non-CO2 GHGs has declined in the past decade. If sources of CH4 and O3 precursors were reduced in the future, the change in climate forcing by non-CO2 GHGs in the next 50 years could be near zero. Combined with a reduction of black carbon emissions and plausible success in slowing CO2 emissions, this reduction of non-CO2 GHGs could lead to a decline in the rate of global warming, reducing the danger of dramatic climate change. Such a focus on air pollution has practical benefits that unite the interests of developed and developing countries. However, assessment of ongoing and future climate change requires composition specific long-term global monitoring of aerosol properties.

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Global warming in the twenty-first century: An alternative scenario

The impact of global air pollution on climate and the environment is a new focus in atmospheric science. Intercontinental transport and hemispheric air pollution by ozone jeopardize agricultural and natural ecosystems worldwide and have a strong effect on climate. Aerosols, which are spread globally but have a strong regional imbalance, change global climate through their direct and indirect effects on radiative forcing. In the 1990s, nitrogen oxide emissions from Asia surpassed those from North America and Europe and should continue to exceed them for decades. International initiatives to mitigate global air pollution require participation from both developed and developing countries.

https://science.sciencemag.org/content/sci/302/5651/1716.full.pdf

Global air quality and pollution.

Global review and synthesis of trends in observed terrestrial near-surface wind speeds; implications for evaporation

Using observations from the Cheeka Peak Observatory in northwestern Washington State during March-April, 1997, we show that Asian anthropogenic emissions significantly impact the concentrations of a large number of atmospheric species in the air arriving to North America during spring. Isentropic back-trajectories can be used to identify possible times when this impact will be felt, however trajectories alone are not sufficient to indicate the presence of Asian pollutants. Detailed chemical and meteorological data from one of these periods (March 29th, 1997) indicates that the surface emissions were lifted into the free troposphere over Asia and then transported to North America in ∼6 days.

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Transport of Asian air pollution to North America

A global 3-D CTM has been used to study the impact of current and future emissions from Asia on CO, PAN and O3 across the North Pacific. Recent measurements from Washington State have been used to verify the model results with respect to average concentrations as well as amplitude of perturbations during episodic events of strong Asian influence. By performing CTM experiments with and without anthropogenic emissions from Asia, we find that there is a significant contribution from Asian sources in the air arriving to the North Western United States, especially during spring. The mean contribution, which can not easily be inferred from the available measurements, during spring are 34 ppbv, 26 pptv and 4 ppbv for CO, PAN and O3, respectively. The maximum enhancements caused by Asian sources during episodes are 42 ppbv, 75 pptv, and 7.5 ppbv, respectively. The amplitude of the perturbations during short term (2–5 days) episodes of strong Asian influence are quite similar to springtime Asian pollution events which have recently been observed on the west coast of Washington state. A doubling of the current Asian emissions in the model yields significant enhancements in all species, though not necessarily in a linear manner.

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/1999GL900477

Influence of Asian emissions on the composition of air reaching the north western United States

We present a 3-D model study, where the focus is on CH4 lifetime and variations related to changes in the global distribution of OH. The observed CH4 concentration and estimates of the anthropogenic emissions of CO, NOx and NMHC's, for the period 1980–96 is used to calculate changes in OH and in CH4 lifetime. The model suggests that CH4 lifetime has decreased by 0.49%/yr, while the annual global average OH concentration has increased by 0.43%/yr. Combining the calculated change in CH4 lifetime and the observed CH4 concentration the yearly average CH4 emission from 1980–96 is calculated to increase by 0.67%/yr. A moderate decrease in CH4 emissions is obtained towards the end of the period, 0.53%/yr from 1993–96 compared to 0.69%/yr from 1980–90. The key to the changing oxidation of CH4 is the increasing anthropogenic emissions in SE-Asia, which more than compensate for the declining emissions seen over Europe and N-America.

https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/1999GL010860

Changing methane lifetime: Possible cause for reduced growth

During the last 20–30 years, noticeable changes have occurred in emissions related to anthropogenic activity over the globe. In this study a three-dimensional chemical transport model for the troposphere (the 3-D Oslo CTM1 model) is used to investigate how changes in the concentration of carbon monoxide (CO) and ozone (O3) in the period 1980–1996 can be related to changes in emission rates and patterns. The results indicate that changes in both species reflect the emission changes well, especially CO because it is to a large degree driven by CO emissions. The most pronounced effect of the changes in emissions for CO and O3 is seen in eastern Europe and Southeast Asia. The annual trend in CO and O3 concentrations in the planetary boundary layer during the period 1980–1996 in eastern Europe is −1.94±0.42 ppbv/yr and −0.01±0.02 ppbv/yr, respectively. In Southeast Asia a positive trend is seen, with 2.29±0.13 ppbv/yr in the CO concentration and 0.6 ± 0.03 ppbv/yr in the O3 concentration. The agreement between the modeled CO and O3 concentrations and observations is good. For O3 an improvement is gained in the modeled results compared with observations, by including changes in emissions from aircraft, and two effects of reduced stratospheric O3 level (altered photolysis rates and stratospheric-tropospheric exchange) during the period of study.

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2000JD900374

Trend analysis of O3 and CO in the period 1980–1996: A three‐dimensional model study

Materials can be subjected to severe wear and corrosion due to high temperature, high pressure and mechanical loads when used in components for the production of geothermal power. In an effort to increase the lifetime of these components and thus decrease cost due to maintenance High-Entropy Alloy Coatings (HEACs) were developed with different coating techniques for anti-wear properties. The microstructure, mechanical and tribological properties of CoCrFeNiMox (at% x = 20, 27) HEACs deposited by three different technologies—high-velocity oxygen fuel (HVOF), laser cladding (LC) and electro-spark deposition (ESD)—are presented in this study. The relationship between surface morphology and microstructural properties of the as-deposited coatings and their friction and wear behavior is assessed to evaluate their candidacy as coatings for the geothermal environment. The wear rates were lower for the HVOF coatings compared to LC and ESD-produced coatings. Similarly, a higher hardness (445 ± 51 HV) was observed for the HVOF HEACs. The mixed FCC, BCC structure and the extent of σ + µ nano precipitates are considered responsible for the increased hardness and improved tribological performance of the HEACs. The findings from the study are valuable for the development of wear-resistant HEAC for geothermal energy industry applications where high wear is encountered.

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Sigrún Karlsdóttir

Papers

Transport of Asian air pollution to North America

Influence of Asian emissions on the composition of air reaching the north western United States

Changing methane lifetime: Possible cause for reduced growth

Trend analysis of O3 and CO in the period 1980–1996: A three‐dimensional model study

Microstructural Properties and Wear Resistance of Fe-Cr-Co-Ni-Mo-Based High Entropy Alloy Coatings Deposited with Different Coating Techniques