Global warming and agriculture

Fannou Jean Louis Comlan^{* *}Correspondence: Fannou Jean Louis Comlan, School of Basic Sciences, Career Point University, India, Email: Fannou Jean Louis Comlan, School of Basic Sciences, Career Point University, India, Email:

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Introduction

Global warming is a phrase that refers to the effect on the climate of human activities, in particular the burning of fossil fuels (coal, oil and gas) and large scale deforestation, which cause emi s- sions to the atmosph ere of large amounts of 'gree n- house gases', of which the most important is carbon dioxide. Such gases absorb infrared radiation emitted by the Earth's surface and act as blankets over the surface keeping it warmer than it would otherwise be. Associated wit h this warming are changes of climate. The basic science of the 'greenhouse effect' that leads to the warming is well understood. More detailed understanding relies on numerical models of the cl i- mate that integrate the basic dynamical and physical equation s describing the complete climate system. Many of the likely characteristics of the resulting changes in climate (such as more frequent heat waves, increases in rainfall, increase in frequency and intens i- ty of many extreme climate events) can be identified . Substantial uncertainties remain in knowledge of some of the feedbacks within the climate system (that affect the overall magnitude of change) and in much of the detail of likely regional change. Because of its negative impacts on human communities (incl uding for instance substantial sea level rise) and on ecosy s- tems, global warming is the most important enviro n- mental problem the world faces. Adaptation to the inevitable impacts and mitigation to reduce their ma g- nitude are both necessary. International ac tion is being taken by the world's scientific and political commun i- ties. Because of the need for urgent action, the greatest challenge is to move rapidly to much increased energy efficiency and to non fossil fuel energy sources. Global Warming: The Hard Sc ience presents a co m- prehensive, qualitatively rigorous, and critical discu s- sion of the science underlying the global warming issue. The major processes in the climate system needed to understand projected human induced cl i- matic change are presented in deta il. Observational systems used to monitor changes in the climate system and the ways in which the raw data are analyzed in order to produce estimates of current trends are also critically reviewed. The author discusses the hierarchy of computer models used to project changes in the carbon cycle, in climate, and in sea level and exa m- ines the physical principles underlying the greenhouse effect and projected warming. The text also presents a detailed discussion of the carbon cycle, of climate sensitivity, and of projected patterns of climatic change through time. Sea level rise and issues of risk and potential surprises are also critically assessed. Emphasis is placed throughout on developing an intu i- tive understanding of those results that do not depend on th e details of any one computer simulation model. A series of boxes illustrate the key points through step by step calculations. Anthropogenic climate change has the potential for slightly increasing the intensity of tropical cyclones through warming of sea surface temperatures. Emanuel has shown a striking and surprising association between sea surface te m- peratures and destru c tiveness by tropical cyclones in the Atlantic and western North Pacific basins. Howe v- er, I question his analysis on the following grou nds: it does not properly represent the observations d e- scribed; the use of his Atlantic bias removal scheme may not be warranted; and further investigation of a substantially longer time series for tropical cyclones affecting the continental United States does not show a tendency for increasing destructiveness. These fa c- tors indicate that instead of “unprecedented” tropical cyclone activity having occurred in recent years, hu r- ricane intensity was equal or even greater during the last active period in the mi d twentieth century.