Abstracts on Global Climate Change

Nov 2006

An atmosphere-ocean time series model of global climate change

Stern, DI


Time series models of global climate change tend to estimate a low climate-sensitivity (equilibrium effect on global temperature of doubling carbon dioxide concentrations) and a fast adjustment rate to equilibrium. These results may be biased by omission of a key variable-heat stored in the ocean. A time series model of the atmosphere-ocean climate system is developed, in which surface temperature (atmospheric temperature over land and sea surface temperature) moves towards a long-run equilibrium with both radiative forcing and ocean heat content, while ocean heat content accumulates the deviations from atmospheric equilibrium. This model is closely related to Granger and Lee’s multicointegration model. As there are only 55 years of observations on ocean heat content, the Kalman filter is used to estimate heat content as a latent state variable, which is constrained by the available observations. This method could be applied to other climate change problems where there are only limited observations on key variables. The final model adopted relates surface temperature to the heat content of the upper 300m of the ocean. The resulting parameter estimates are closer to theoretically expected values than those of previous time series models and the estimated climate sensitivity to a doubling of carbon dioxide is 4.4 K. (c) 2005 Published by Elsevier B.V.

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The influence of the possible global climate change on the properties of Mexican soils

Nikol’skii, YN Castillo-Alvarez, M Bakhlaeva, OS Roma-Calleros, XA Maslov, BS


To estimate the changes in the integral fertility index of virgin soils in Mexico upon the expected global climate changes, we applied a method based on revealing the quantitative relationship between the Budyko radiation index of dryness and the modal values of the regional agrochemical properties of soils located on a nearly horizontal surface (with slope of less than 0.001) at elevations ranging from 0 to 2500 m a.s.l. The results of existing forecasts of the alteration of the global air temperature, radiation, and precipitation were also used. In the case that the carbon dioxide content is doubled in the atmosphere by the end of the 21st century, a medium and weak decrease in the soil fertility will be observed in the central (cereal) regions of Mexico; furthermore, a significant (over 20%) decrease in fertility will be observed in the tropical regions, where sugar cane is cultivated.

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Study on the trace species in the stratosphere and their impact on climate

Chen, YJ Zhou, RJ Shi, CH Bi, Y


The trace gases (O-3, HCl, CH4, H2O, NO, NO2) in the stratosphere play an important role, not only in the photochemical processes in which the ozone layer destroyed, but also in the radiative processes. In this paper, we review the works on the distribution and variation of the trace gases in the stratosphere and their impact on climate, which have been carried out at the University of Science and Technology of China in the recent 20 years. The Halogen Occultation Experiment (HALOE) data were used to analyse the distribution and variation of the mixing ratio of these trace gases and the temperature trends in the stratosphere in the most recent decade. And the reanalyzed National Centers of Environmental Prediction (NCEP)/NCAR data were also used to give the temperature trends and compared with the results from HALOE data. Numerical simulations were also carried out to study the impact of ozone depletion on the global climate. In this review, the distributions of the trace gases, especially those over the Qinghai-Xizang Plateau, are discussed, and the variations and trends for the trace gases in various levels in the stratosphere have been given for the most recent decade. The temperature variation and the cooling trend obtained from HALOE data in the middle and lower stratosphere for the last 13 years are significant, which agree well with the results from NCEP/NCAR data. While the temperature trend in the upper stratosphere in this period do not seem to have much cooling. The numerical simulations show that either the Antarctic ozone hole or the ozone valley over Qinghai-Xizang Plateau affect not only the temperature and circulation in the stratosphere, but also the temperature, pressure and wind fields in the troposphere, then lead to the global climate change.

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Oceanic implications for climate change policy

McNeil, BI


Under the United Nations convention on the law of the sea (1982), each participating country maintains exclusive economic and environmental rights within the oceanic region extending 200 nm from its territorial sea, known as the exclusive economic zone (EEZ). Although the ocean within each EEZ is undoubtedly an anthropogenic CO2 sink, it has been overlooked within international climate policy. In this paper I use an area-weighted scaling argument to show that the inclusion of the EEZ CO2 sink within national carbon accounts would have significant implications in tracking national greenhouse commitments to any future climate change policy initiative. The advantages and disadvantages for inclusion of the EEZ CO2 sink into global climate change policy are also explored. The most compelling argument for including the EEZ CO2 sink is that it would enhance the equity and resources among coastal nations to combat and adapt against future climate change that will inherently impact coastal nations more so than land locked nations. If included, the funds raised could be used for either monitoring or adaptive coastal infrastructure among the most vulnerable nations. On the other hand, the EEZ anthropogenic CO2 sink cannot be directly controlled by human activities and could be used as a disincentive for some developed nations to reduce fossil-fuel related greenhouse gas emissions. This may therefore dampen efforts to ultimately reduce atmospheric greenhouse gas concentrations. In consideration of these arguments it is therefore suggested that an “EEZ clause” be added to Kyoto and any future international climate policy that explicitly excludes its use within national carbon accounts under these international climate frameworks. (c) 2006 Elsevier Ltd. All rights reserved.

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Evidence for carbon dioxide and moisture interactions from the leaf cell up to global scales: Perspective on human-caused climate change

Alpert, P Niyogi, D Pielke, RA Eastman, JL Xue, YK Raman, S


It is of utmost interest to further understand the mechanisms behind the potential interactions or synergies between the greenhouse gases (GHG) forcing(s), particularly as represented by CO2, and water processes and through different climatic scales down to the leaf scale. Toward this goal, the factor separation methodology introduced by Stein and Alpert [Stein U. and Alpert, P. 1993. Factor separation in numerical simulations, J. Atmos. Sci., 50, 2107-2115.] that allows an explicit separation of atmospheric synergies among different factors, is employed. Three independent experiments carried out recently by the present authors, are reported here, all strongly suggest the existence of a significant CO2-water synergy in all the involved scales. The experiments employed a very wide range of up-to-date atmospheric models that complement the physics currently introduced in most Global Circulation Models (GCMs) for global climate change prediction. Three modeling experiments that go from the small/micro scale (leaf scale and soil moisture) to mesoscale (land-use change and CO2 effects) and to global scale (greenhouse gases and cloudiness) all show that synergies between water and CO2 are essential in predicting carbon assimilation, minimum daily temperature and the global Earth temperature, respectively. The study also highlights the importance of including the physics associated with carbon-water synergy which is mostly unresolved in global climate models suggesting that significant carbon-water interactions are not incorporated or at least well parameterized in current climate models. Hence, there is a need for integrative climate models. As shown in earlier studies, the climate involves physical, chemical and biological processes. To only include a subset of these processes limits the skill of local, regional and global models to simulate the real climate system. In addition, our results provide explicit determination of the direct and the interactive effect of the CO2 response on the terrestrial biosphere response. There is also an implicit scale interactive effect that can be deduced from the multiscale effects discussed in the three examples. Processes at each scale-leaf, regional and global will all synergistically contribute to increase the feedbacks-which can decrease or increase the overall system’s uncertainty depending on specific case/setup and needs to be examined in future coupled, multiscale studies. (C) 2006 Elsevier B.V. All rights reserved.

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