|Abstracts on Global Climate Change|
Multi-scale analysis of global temperature changes and trend of a drop in temperature in the next 20 years
Zhen-Shan, L Xian, S
METEOROLOGY AND ATMOSPHERIC PHYSICS 95:1-2 115-121
A novel multi-timescale analysis method, Empirical Mode Decomposition (EMD), is used to diagnose the variation of the annual mean temperature data of the global, Northern Hemisphere (NH) and China from 1881 to 2002. The results show that: (1) Temperature can be completely decomposed into four timescales quasi-periodic oscillations including an ENSO-like mode, a 6-8-year signal, a 20-year signal and a 60-year signal, as well as a trend. With each contributing ration of the quasi-periodicity discussed, the trend and the 60-year timescale oscillation of temperature variation are the most prominent. (2) It has been noticed that whether on century-scale or 60-year scales, the global temperature tends to descend in the coming 20 years. (3) On quasi 60-year timescale, temperature abrupt changes in China precede those in the global and NH, which provides a denotation for global climate changes. Signs also show a drop in temperature in China on century scale in the next 20 years. (4) The dominant contribution of CO2 concentration to global temperature variation is the trend. However, its influence weight on global temperature variation accounts for no more than 40.19%, smaller than those of the natural climate changes on the rest four timescales. Despite the increasing trend in atmospheric CO2 concentration, the patterns of 20-year and 60-year oscillation of global temperature are all in falling. Therefore, if CO2 concentration remains constant at present, the CO2 greenhouse effect will be deficient in counterchecking the natural cooling of global climate in the following 20 years. Even though the CO2 greenhouse effect on global climate change is unsuspicious, it could have been excessively exaggerated. It is high time to re-consider the trend of global climate changes.
On climate response to changes in the cosmic ray flux and radiative budget
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 110:A8 -
We examine the results linking cosmic ray flux ( CRF) variations to global climate change. We then proceed to study various periods over which there are estimates for the radiative forcing, temperature change and CRF variations relative to today. These include the Phanerozoic as a whole, the Cretaceous, the Eocene, the Last Glacial Maximum, the 20th century, as well as the 11- yr solar cycle. This enables us to place quantitative limits on climate sensitivity to both changes in the CRF, and the radiative budget, F, under equilibrium. Under the assumption that the CRF is indeed a climate driver, the sensitivity to variations in the globally averaged relative change in the tropospheric ionization I is consistently fitted with mu &3bond; ( dT(global)/ dI) approximate to 7.5 +/- 2 degrees K. Additionally, the sensitivity to radiative forcing changes is lambda &3bond; dT(global)/ dF = 0.35 +/- 0.09 degrees KW(-1)m(2), at the current temperature, while its temperature derivative is undetectable with (d lambda/ dT)(0) = - 0.01 +/- 0.04 m(2)W(-1). If the observed CRF/ climate link is ignored, the best sensitivity obtained is lambda = 0.54 +/- 0.12 degrees KW-1 m(2) and ( d lambda/ dT)(0) = - 0.02 +/- 0.05 m(2) W-1. Note that this analysis assumes that different climate conditions can be described with at most a linear function of T; however, the exact sensitivity probably depends on various additional factors. Moreover, l was mostly obtained through comparison of climate states notably different from each other, and thus only describes an average sensitivity. Subject to the above caveats and those described in the text, the CRF/ climate link therefore implies that the increased solar luminosity and reduced CRF over the previous century should have contributed a warming of 0.47 +/- 0.19 degrees K, while the rest should be mainly attributed to anthropogenic causes. Without any effect of cosmic rays, the increase in solar luminosity would correspond to an increased temperature of 0.16 +/- 0.04 degrees K.
Climate change: Conflict of observational science, theory, and politics
AAPG BULLETIN 88:9 1211-1220
Debate over whether human activity causes Earth climate change obscures the immensity of the dynamic systems that create and maintain climate on the planet. Anthropocentric debate leads people to believe that they can alter these planetary dynamic systems to prevent what they perceive as negative climate impacts on human civilization. Although politicians offer simplistic remedies, such as the Kyoto Protocol, global climate continues to change naturally. Better planning for the inevitable dislocations that have followed natural global climate changes throughout human history requires us to accept the fact that climate will change, and that human society must adapt to the changes. Over the last decade, the scientific literature reported a shift in emphasis from attempting to build theoretical models of putative human impacts on climate to understanding the planetwide dynamic processes that are the natural climate drivers. The current scientific literature is-beginning to report the history of past climate change, the extent of natural climate variability, natural system drivers, and the episodicity of many climate changes. The scientific arguments have broadened from focus upon human effects on climate to include the array of natural phenomena that have driven global climate change for eons. However, significant political issues with long-term social consequences continue their advance. This paper summarizes recent scientific progress in climate science and arguments about human influence on climate.