Of all our environmental debts the production of carbon dioxide through automobile exhaust and industrial emissions looms as our presiding usurer. Despite fifty years of warnings from the scientific community about the effects of greenhouse gases and global warming, concentrations of carbon dioxide in the atmosphere climb annually at alarming rates. While sulfur and nitrogen emissions have started to level off, while chloroflourocarbons and other ozone depleting emissions have been significantly reduced, we can not seem to curb our production of carbon dioxide. Sadly, the United States is one of the worst abusers, alone generating a quarter of the world's carbon emissions.
To make matters worse, the world economy is hooked on fossil fuels. Getting off oil, decarbonizing for the sake of the climate, involves a complete economic makeover, and really, a complete change in the way we live, particularly in the United States, where suburban America is laid out with sprawling networks of roads and shopping malls. Cars, vast systems of highways, and gasoline were built into America's social design. Now as petroleum nears a peak in production, it is clear this embedded design is unsustainable. Any effort we make to decarbonize and minimize global warming will equally necessitate a change in our socio-economic expectations.
According to current evidence, we are looking at atmospheric temperature increases in the range of 3 to 5 degrees Fahrenheit in the continental United States during our lifetimes. Even using one of the most conservative of climate models and quoting the United States' Environmental Protection Agency's evaluation of it as a source, the anticipated changes are staggering. Should we somehow stop burning fossil fuels today, because of the "long lifetimes of greenhouse gases already in the atmosphere, the momentum of the climate system would continue to cause climate to change for more than a century." In that period, temperatures "in the contiguous United States would rise 5 to 9 degrees Fahrenheit." "The central tier of states would experience climate conditions roughly equivalent to those now experienced in the southern tier, and the northern tier would experience conditions much like the central tier." Soil moisture content across the grain belt would decrease by a third or more. Critical snowpack in western mountain regions would diminish, impacting reservoirs, flood protection, power production, and the sustainability of many mountain habitats. Some Alpine meadows in the Rocky Mountains would dry up and disappear completely. The sugar maple would migrate north out of the U.S., and changes in large-scale forest processes, "such as fire, insects, droughts, and disease, could put forest productivity in jeopardy." Though these references are just a sampling of what you will find in the EPA's 2002 Climate Action Report to the United Nations, it amounts to a particularly dour environmental prognosis from a conservative, oil industry friendly, Republican administration. More current reports issued by the Intergovernmental Panel on Climate Change merely turn up the immediacy and alarm on similar projections. The situation is unlike any ever confronted by human civilization. Superficially it feels like B-grade science fiction and yet this Godzilla is entirely real.
Two things happen to a planet in the long run. First its atmosphere dissipates, then it dries up. As this happened to Mars, it will happen to Earth no matter what we humans do. It's just that on one course the time frame is in the billions of years. On the other course, our current course, the time frame could be hundreds of years, perhaps tens of years, or sooner. The Artic Climate Impact Assessment of 2004 brings this message home. The ACIA reports that temperatures in the artic region have already risen 3-5 degrees Centigrade and will climb another 3-5 degrees before the end of the century, giving rise to projections that the North Pole will be entirely clear of ice during the summer months by 2090. This is incredible.
The polar ice caps, the planet's chief cooling apparatus, lose their cooling capacity proportionately to their surface area. Further warming eventuates more lost ice area and thus more warming in a frightful positive feedback loop. Along with this loss in cooling capacity, sea levels will climb with the polar runoff, reducing world land mass, critically cutting into already endangered wet lands, and inundating some of the most highly populated areas in the world. The problem is encompassing.
Unfortunately, the positive feedback loop of melting ice mass will contribute to another, thawing of the arctic permafrost. The permafrost contains "an enormous amount of methane (a greenhouse gas with 20 times the heat trapping capacity of CO2) locked up as hydrates in the tundra and mud of the continental shelves."1 As the permafrost thaws it releases this methane. "Some estimates of the potential methane release run as high as .6 billion tons a year, an amount that could more than double the present atmospheric concentration."2 Meaning more warming, more lost ice mass, more thawed permafrost, more freed methane, and so on.
One of our most important protections against carbon dioxide buildup is the great forests of the world which absorb carbon dioxide and respire oxygen. Unfortunately, industrial expanson, human population growth, and a hungry economy have cut deeply into these forests. "Before humans invented agriculture there were 6 billion hectares of forest on Earth. Now there are 4 billion, only 1.5 billion of which are undisturbed primary forest. Half the forest loss occurred between 1950 and 1990. The United States (exclusive of Alaska) has lost one third of its forest cover and 85 percent of its primary forest. Europe has essentially no primary forest left. Its remaining forests are managed plantations of just a few commercial tree species. China has lost three quarters of its forest. The great remaining temperate forests are in Canada and Russia where 1.4 billion hectares remain, half of them never harvested. In the tropics half the original forest cover is gone. Half of what remains has been logged and degraded."3 Again we confront another positive feedback loop. Economic growth, the mantra of modern economics, leads to decreasing forests, which cuts into Earth's natural cycle of carbon dioxide capture, which in turn adds more momentum to the warming trend.
Central to the overall problem is that even minimal temperature changes are enough to affect the ecology and agricultural potential of important pieces of land in the relatively narrow temperate bands on either side of the equator. There could be some net agricultural gains in temperate zones due to higher temperatures and higher carbon densities in the air, but other effects would diminish these gains, particularly changes in the hydrological cycle.
"A warmer Earth speeds up the global water cycle: the exchange of water among the oceans, atmosphere, and the land. Higher temperatures cause more evaporation, and soils will tend to dry out faster. Increased amounts of water in the atmosphere will mean more rain or snow fall."4 The higher frequency and power of hurricanes coming out of the Caribbean Sea, the increase in tornadoes in the southeast United States, the freak snow storms, the flooding in the northeast United States, these are typical of changes in the water cycle. The climate has already begun its transition. Hurricane Katrina is an example of the inherent and omnious potentials.
Say it again. Little changes in temperature mean a lot. Warmer oceans lead to changes in sea life relationships, particularly the deterioration of coral reefs, "the richest ecosystems in the oceans and second richest on the earth, after tropical forests."5 The patterns of migratory birds, based on sensitivities to temperature, would also be changed. 6 Breeding periods of insects would similarly adjust. If, for example, a particular species of bird's migration was necessary to reduce the success of a particular insect's reproduction, even a few days delay could mean a huge multiplier in that insect's population. The same is true with various microbes that exist in fresh and saltwater masses. The presence of these microbes is highly reliant on temperature. The breeding of certain species of fish rely on these microbes being present at the right time and in the correct proportion to ensure their reproduction. This same kind of subtle temperature dependency is also true of tropical diseases. "Diseases that thrive in warmer climates, such as malaria, dengue and yellow fever, encephalitis, and cholera, are likely to spread due to the expansion of the ranges of mosquitoes and other disease carrying organisms and increased rates of transmission. This could mean 50 million to 80 million additional cases of malaria cases per year worldwide by 2100."7 As none of these factors, bird migrations, insect breeding, microbe populations, diseases vectors, or other species' biological clocks respond in the same way, the situation as a whole is very difficult to predict. Anticipating the effects of changes in the climate is much like playing one hundred hands of poker at the same time. It gets difficult keeping track of all the probabilities.
All of the factors mentioned above, starting with the loss of terrestrial ice mass, build with each tiny increment of increased warming. The resultant cascade of effects could very well accelerate as time goes on. We have already wasted fifty years denying this process. A crisis of unknown proportions and time frame hovers in the potentials of a changing climate, but none more so, than in the securing of global food supplies.
A fine fabric of interconnective tissue, climatic and biological, fuses all life from human to bacterial in a diverse and interdependent web of life. To pull on one thread in that web is to alter the entire fabric. In the case of a world population delicately dependent on the harvest of large geographically concentrated areas of mono-cultured crops, temperature and/or weather changes, insect rhythms, the migrations of pollinating birds and bees, could, with little or no warning, do enormous damage to yield. In a situation where our food sources are already nearing a critical cusp, the inclusion of Mother Nature's devastation factor, by weather, blight, or uncontrolled insect populations, means we edge closer and closer to the precipice of hunger and famine. We have taken a dangerous gamble by not controlling our greenhouse gas emissions. Stockpiles of grain have long been our margin of error during disaster. Tomorrow it could be our excess of human population. The time to decarbonize is now.