The synthesis reports of the Millennium Ecosystem Assessment, initiated by United Nations Secretary-General Kofi Annan in 2000 and sponsored by the United Nations Environmental Program were released in the summer and fall of 2005.

   They offer an evaluation of the state of the world's ecosystems and their effects on human well-being, but impressive as these documents are, none of them provide much flavor of the technical studies on which they are based. The purpose of this new book is to provide that flavor from current technical papers, mostly published in the last year.

   The effects of increased human population size and global warming on ecosystem services are clearly in the minds of scientists, if not yet the general public. The papers reviewed here are but a small fraction of ones published in the past year or so that examine these issues, but they are broadly representative of how scientists are proceeding and what they now know.

   There is no question whatever that the increasing human population and its levels of natural resource consumption are putting a severe strain on the environment: we are converting more land to agriculture, buildings and roads; we are increasing the levels of air pollution in cities all over the globe; and we now know that this pollution reaches every nook and cranny of the planet. Very few natural populations of plants and animals—including ourselves—are unaffected, and many already have been locally extirpated.

   Some have been globally extirpated and for many others the possibility of extinction becomes more likely daily. We are depopulating the oceans of their fishes and corals, destroying freshwater and wetland habitat, and fragmenting terrestrial and river habitat to the extent that many species can no longer successfully make the migrations that are crucial to their life cycles. And the migrations themselves are becoming causes for alarm when our intensification of poultry production transfers avian flue to wild birds, and potentially to us.

   For some reason, the concept of global warming has become in many people's minds a political rather than a scientific issue. I hear countless arguments in the media that a "fair and balanced" look would reveal that scientists are extremely uncertain about whether global warming is occurring, and whether human activities have anything to do with it if it is. The truth is that virtually all scientists who know anything about it think we are changing the earth’s temperature alarmingly rapidly, that it is going to get considerably warmer before we see any reversal, and that there will be severe consequences. We do not yet know for sure what they are, but we can surely expect rising sea levels, declining glaciers and ice fields, reductions in freshwater supply in many places, probably more intense hurricanes and if we are extremely unlucky, a change in the circulation of ocean currents that among other things will rapidly and more or less permanently make Europe considerably colder while making most everywhere else much warmer.

   Furthermore it is crystal clear that even if something were to offset the warming effects of carbon dioxide and the other greenhouse gasses we are pumping into the air, carbon dioxide itself has the potential for profound physiological effects on plant communities globally, with extremely uncertain outcomes both for the plants and for the animals that depend on them. Besides that, the fine particulates, ozone and heavy metals that accompany the carbon dioxide production from the burning of fossil fuels are all toxic, not only to us, but to all other organisms as well. We now know that many of these substances are transported globally, so controlling them has become a global problem.

    You will learn from this book that the ecological processes that provide ecosystem services are extremely complex. The more closely we look at them the more we understand that the services are extremely valuable to us in economic terms, but we are far from certain about the specific effects of most of the environmental changes humans are causing, and this uncertainty is likely to continue into the foreseeable future because this kind of science proceeds one small step at a time. Because of the complexities of ecology—each species interacting with other species and the physical environment in its own way—we are unlikely to project or detect some sort of environmental tipping point that would then galvanize us into action. But if we do not act, we will see a continuing and accelerating degradation of our air and water quality and of our natural lands, and we will end up paying much more than we need to for services nature has always provided for free.

   Even though we do not know all the details of our environment's decline, we do know the general direction and its causes, and hence, we know what to do to reverse it. If our offspring (and our political leaders) cannot understand the science behind this knowledge, they too will think environmental degradation is just a political issue. It would be good for all of us if there were many more leaders who could understand the science. It is particularly valuable when economics and government majors—the students most likely to become economists, financial analysts, business executives and politicians—understand these issues at a technical level. As the economic consequences of environmental degradation become clearer it is they, rather than scientists, who will be in a position to make the economic and political decisions to reverse the problems.

About the Roberts Environmental Center

 The Roberts Environmental Center, a research institute at Claremont McKenna College, is the leading analyst of corporate environmental and sustainability reporting, with free on-line analysis of more than 600 corporate reports. Students from all five of the Claremont Colleges study and work in the Center and this research is a joint effort among the center's faculty, research associates and students. All analyses are available online with more added weekly.

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