Climate Change

Climate System

A climate system is defined as a highly complex system consisting of five major components: the atmosphere, the hydrosphere, the cryosphere, the land surface, and the biosphere, with high dynamics interactions between them. The climate system evolves in time under the influence of its own internal dynamics and because of external and human forcings.

Effects of Climate Change

Climate change, as well climate variability, can exert multiple and different effects on human population and, generally, on life or on the biosphere. These phenomena may affect [Page 112]life direct or indirectly, usually in a dynamic interplay with multiple factors interacting between them as a consequence of the significant changes of environmental elements such as temperature, rainfall patterns, storm severity, frequency of flooding or droughts, and rising sea levels.

Such changes impact different elements of the biosphere, including the balances between health and disease. Most populations will see the effects of climate change on health in the next decades, as billions of people face a greater risk of illnesses and uncomfortable environments, which could put their lives and well-being in danger. Today and in the recent past, some studies and well-done scientific research have demonstrated that climate change and climate variability produced significant shifts in the incidence and prevalence of different diseases—both communicable and noncommunicable.

No matter what the degree of preparedness, projections suggest that future extreme weather events will be catastrophic because of their unexpected intensity, as seen during Hurricane Katrina in 2005. Here, a National Guard helicopter works to close the breach in the 17th Street Canal in New Orleans after that storm.

Status of Climate Change and Predictions

During this century, the Earth's average surface temperature increase is likely to exceed the safe threshold of two degrees Celsius per century, which is the maximum increment above preindustrial average temperature. Again, this increment may produce direct or indirect effects on human health. Rises will be greater at higher latitudes, with medium-risk scenarios predicting two to three degrees Celsius rises by 2090 and four to five degrees Celsius rises in northern Canada, Greenland, and Siberia. Currently, different academic groups are outlining the major threats—both direct and indirect—to global health from climate change through changing patterns of disease, water and food insecurity, vulnerable shelter and human settlements, extreme climatic events, and population growth and migration in order to improve the understanding of them, as well to propose strategies to reduce them and to develop plans to mitigate their potential effects.

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