A major argument for making immediate and significant reductions in greenhouse gas emissions is that human-induced climate change--on top of other environmental problems--may overwhelm human and natural systems by increasing the prevalence of climate-sensitive diseases, reducing agricultural productivity in developing countries, raising sea levels, and altering ecosystems, forests, and biodiversity worldwide. But even assuming that human-induced climate change might prove to be the proverbial last straw, there are other, more-efficient approaches to saving the camel's back.
Instead of lightening or eliminating the last straw--analogous to reducing or halting climate change--we could save the camel's back by reducing its cumulative burden, by strengthening its back so that it can better withstand the total burden, or by sharing its burden with other camels. These alternative concepts can be used to devise policies to address the issue of climate change and would, in effect, lighten the cumulative environmental and public health burden on the globe, reducing vulnerability and increasing adaptability to climate change while, incidentally, also decreasing greenhouse gas emissions. We can, for example, reduce the cumulative ecological or public health burden by reducing existing threats so the Earth can bear a heavier load from any new or increased threats that might be generated by future global warming. Similarly, since climate change could create regional winners and losers, we could spread the burden more evenly through trade. As we shall see, these alternative approaches are in many respects superior to the single-minded pursuit of reductions in climate change.
The Present: The Bad News
Over the last century or more, the globe has warmed 0.4 to 0.8 degrees Celsius (0.7 to 1.4 degrees Fahrenheit), according to the Intergovernmental Panel on Climate Change (IPCC), an international panel established to examine the science and impacts of climate change. This change, perhaps, is due to man's influence. (1) Over this period, some climate-sensitive environmental indicators or sectors of the economy have worsened, but so far anthropogenic warming has had little to do with these declines.
Consider, for instance, that while sea level has risen a modest 8 inches in the past century, it's not clear what portion of that rise, if any, is due to global warming. Regardless, its current impacts on coasts and coastal resources are small compared with those arising from other human activities such as development; extraction of oil, gas, and water resources; over-fishing; agricultural runoff; and damming of rivers upstream of estuaries. (2)
Meanwhile, forested area declined by 190 million hectares (470 million acres) in developing nations between 1980 and 1995. This decline, which occurred largely because increases in food demand outstripped increases in agricultural yield, is unrelated to global warming. During the same period, forest cover in developed nations expanded by 20 million hectares (50 million acres) mainly because of technology-based, high-yield agriculture. (3) Conversion of forests and other habitat to agricultural uses is the greatest current and future threat to global biodiversity as well as to carbon stores and sinks. (4)
The Present: The Good News
For other critical climate-sensitive sectors and indicators, matters have actually improved. Global agricultural productivity has never been higher, for instance. An acre of cropland sustains about twice as many people today as it did in 1900. People have never been fed better or more cheaply. Between 1961 and 1998, food supplies per person increased 24 percent, although the population almost doubled; and between 1969-71 and 1995-97, the number of people in developing countries suffering from chronic hunger declined from 35 percent to 19 percent. (5)
In the richer countries, deaths due to climate-sensitive infectious and parasitic diseases are now the exception rather than the rule and are declining in most developing countries thanks to better nutrition and public-health measures. …