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Updated 15 November 2004

Consequences Vol. 3, No. 2, 1997








Editor's Summary of Articles

Climate, Ecology, and Human Health


In what ways do climatic and other environmental changes affect the prevalence and spread of infectious diseases? What signs are there that human health has suffered, this year or last, as a result of changes in the weather or climate, or our own disturbance of the natural world? What diseases are now on the rise, in our own or any nation; what has caused their resurgence, and who is most affected? Does the prospect of global warming bode well, or ill, in the battle to contain the spread of epidemic disease; and why should warmer temperatures pose any more a threat than cooler ones? What can we do, in terms of social and environmental measures, collectively or individually, to reduce vulnerabilities and improve the prospects for human health?

An Assessment

Environmental conditions, coupled with biological factors that include the evolution of pathogens and the prevalence of the insects and rodents that carry disease, can exert profound effects on human health and well-being. Ecosystems that are sufficiently stable and biologically diverse tend to keep pathogens and their carriers in check. When these natural safeguards are eroded by human activity, or disrupted by drought or floods, the opportunistic organisms that directly or indirectly prey on human health inevitably gain ground. Thirty diseases new to medicine, like toxic E. coli, hantavirus, and HIV, have emerged in the last twenty years, and in the same period, age-old scourges such as cholera, plague, yellow and dengue fever, and tuberculosis, have resurged in many parts of the world. Malaria is far more prevalent today than twenty years ago and each year strikes up to 500 million people. Mosquitoes that carry the disease have developed resistance to some insecticides, and the geographic range in which they can survive has been expanded to higher altitudes and geographic latitudes with the global warming of the twentieth century. Enhanced greenhouse warming, combined with biodiversity loss and other environmental stresses, will almost certainly aid the prevalence and spread of infectious disease, largely through effects on the prevalence and distribution of pests and pathogens.


Human health can be a casualty of environmental disturbance and change, and in the past two decades it has come under heavy siege, through natural connections that transcend simple concerns of air or water pollution. The spread of infectious disease depends very much on social conditions and enlightened public health measures, but also on ecological stability to keep opportunistic disease carriers and pathogens under control, and on climate itself. Nor is any nation an island in the interconnected world of today, for insofar as resurgent and pandemic diseases are concerned, we are all at risk. We already know many of the impacts on the human condition that will follow this year's El Niño, and we have a good idea, and early evidence, of what to expect from enhanced greenhouse warming. If we are wise, we need consider the penalties to human health in what we take from the natural world, and include these factors, as well, in the economists' calculations of the impacts of controlling carbon emissions.

Go to: Climate, Ecology, and Human Health

Keeping Watch on the Earth: An Integrated Global Observing Strategy


How well are we monitoring global trends in stratospheric ozone or other important environmental indicators? What progress has been made in practical weather and climate prediction, and how far can forecasts be extended in the future? What determines the course of global and regional climate, and what stands in the way of more reliable and useful forecasts, months or perhaps years in advance? What are the obstacles to designing and implementing a truly international global observing system that would allow a better understanding of important changes in all parts of the environment?

An Assessment

The story of how weather forecasts were incrementally extended from one day, in the 1950s, to the five-day projections that are broadcast today, is largely a tale of more and more comprehensive observations of the atmosphere, more openly shared around the world, augmented, most recently, by computers and orbiting sensors. There is hope of extending the range of usable forecasts to time scales of seasons to years, and eventually decades, but it will require monitoring far more than the air itself. The oceans, for example, play a major role in determining the course of seasonal to interannual climate. Our emerging capability to anticipate the onset and severity of El Niño events-- like that of 1997-1998--up to half a year in advance, rests chiefly on a newly-installed system of instrumented buoys that continually monitor the near-surface temperatures of the Pacific. Extending forecasts to longer spans of time requires a knowledge of changes in a much longer list of environmental variables that include vegetation, soil moisture, ice and snow, and solar radiation. This cannot be accomplished without a well-coordinated system of worldwide observations of the many interlocking parts of the total climate system.


The pressures of global population growth and economic development can only increase the demands that a crowded and interconnected world now place on the natural environment. This certainty, coupled with our capacity to inadvertently alter the course of climate, calls for a more dedicated, international effort to understand the Earth as a system, and to monitor the planet's vital signs. The capacity to do that is now within our technical capabilities, through coordinated land, sea, and spaceborne observations. Many of the needed elements are now in place, through the efforts of our own and other countries. A more integrated global observing system, prudently designed and sufficiently flexible, could provide answers to most of the questions that now limit our understanding of the global climate system. It would provide invaluable information regarding not only weather and climate but almost every significant aspect of the global environment. A permanent archive of what is changing where, and by how much, would help our own and future generations in sorting human-induced perturbations from natural changes, and in separating urgent concerns from false alarms.

Go to: Keeping Watch on the Earth: An Integrated Global Observing System
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