turned the corner on global warming and are taking the necessary steps to mitigate its effects. This is especially true if one holds an unshakeable faith in human ingenuity or subscribes to the “humanity can fix anything with technology” school. Despite increased public awareness, most people still believe the effects of climate change will appear sometime in the vague future, when in actuality the effects are visible today. It seems when things deteriorate gradually, people tend not to notice them. The image of shifting baselines is a compelling one: a little change here, a little change there, and it all starts to seem normal. Thus, people do not see the potential for catastrophe unless something dramatic and immediate occurs. In the time frame of global warming issues, it would probably be too late to do much about the effects or causes of such an event.
The major public focus has been on industrial carbon emissions and sources of efficient energy, but some other serious issues associated with climate change require attention as well. Scientists are learning more every day, and some of what we have been reading in the primary scientific literature indicates potential negative impacts of a magnitude far greater than previously thought.
There has been widespread discussion of melting polar ice and what effects it might have on our world. The effects discussed range from the loss of polar bear habitats to potential economic benefits of new, less costly shipping routes, but there is more. In May 2008, researchers from the University of California at Riverside and Flinders University in Australia published findings revealing a relatively sudden release of methane, a greenhouse gas some twenty-three times more potent than CO2. This release occurred 635 million years ago, causing an abrupt shift in planetary climate from the stable “snowball” ice age to a much warmer, stable state, with little time in between.4The study shows how methane was initially released gradually through destabilization of ice sheets, which, as they melted, released pressure on clathrates—a form of methane ice held stable by temperature and pressure—triggering substantially increased levels of the gas. Clathrates remain present today in their dormant state, both in arctic permafrost and in sediments on the ocean floor. The concern here is that small increases in global temperatures, such as those we are currently experiencing as a consequence of our widespread addiction to oil and coal, may trigger a similar release of methane gas. One scenario by which this could happen would result from the polar regions absorbing more heat if the reflective snow melts sooner each year both over the arctic tundra and the Arctic and Antarctic oceans. Snow and ice, because they are white, reflect light and therefore heat. This reflectance is lost when the snow and ice melt and resulting darker earth and water surfaces absorb the sun's energy as heat. Thus, permafrost, which contains frozen methane, would melt and clathrates would release their methane. The ramifications of these events, which could happen very quickly, would be catastrophic and are thought to be irreversible.5 The resulting substantial increase in methane outgassing could overshadow all benefits gained from current attempts to reduce anthropogenic carbon emissions.
If current estimates are correct for methane release from permafrost, some 100 billion tons could be released into our atmosphere this century. That's a huge number. If one assumes an adult elephant weighs five thousand kilograms, then that's like putting twenty billion elephants into the atmosphere, or 556 million blue whales, or 3.8 million Titanics. One hundred billion tons of methane is 333 times the total mass of humans on earth. Should this catastrophe occur, earth could experience climate warming that is equivalent to 270 years of emissions at today's levels.
Another, more controversial effect of melting polar ice is the resulting change in ocean salinity that could lead to a slowing or stoppage of the thermohaline circulation. This is an oceanographic mechanism whereby warm water from the tropics is carried northward via surface wind-driven currents like the Gulf Stream. As the water moves toward the polar region, it cools and its density increases. This denser water consequently sinks into deep ocean basins, where it moves southward within these basins to resurface again as it is heated. Such upwelling is a source of considerable nutrient cycling in the oceans, and this “ocean conveyor belt” is, in part, responsible for the stability of earth's weather patterns. As freshwater from melting ice enters the oceans in vast quantity, the salinity, and consequently the density, of seawater will change, potentially causing the thermohaline circulation to slow or stop. Speculation on the specific effects of such an occurrence include outcomes ranging from moderate changes in the productivity and climate of Europe, to radical alterations in global weather patterns. Such changes could, among other things, significantly reduce rainfall levels from the Asian monsoon, on which a third of the world's population depends for irrigation of agricultural crops.6
Seawater becomes acidified when CO2 from fossil-fuel combustion and other sources is absorbed from the atmosphere by ocean waters. This creates carbonic acid, which increases the acidity of the oceans from their natural, basic state. If the pH level is too low, calcium carbonate cannot be formed. Since the onset of industrialization, ocean acidification has increased 30 percent, which completely overwhelms any natural mechanisms that might counteract this phenomenon. This process is further exacerbated by deforestation, which is increasing globally as well. Recent research has shown that the time frame for ocean acidification is accelerating, and detrimental effects may emerge in decades, rather than centuries as previously thought.7 A more acidic ocean could, among other things, drive phytoplankton extinct. Under this scenario, not only would the ocean cease to remove carbon from the atmosphere, but there would be no food for fish to eat, and no fish for us to eat. This could threaten global food security and create severe economic impacts, especially in areas that depend on the sea for sustenance. Coral reefs, already threatened, may essentially vanish from most areas by midcentury, leaving coastal communities open to erosion and flooding, causing a further loss of fish habitat and creating economic damages in the billions. Perhaps the start of this will be a more acidic ocean, in which the ecosystems and ecosystem services that we depend on fail to thrive, producers of slime and toxic algal blooms are quite at home, and hypoxia and dead zones abound. Should this come to pass, it will likely happen in the next hundred or so years, but it will take thousands of years to recover to a state that even resembles what we know today.
Other resource management issues, such as overfishing, have little to do with global warming directly but, in the coming decades, will likely have major negative effects on our well-being. Where ocean acidification tends to attack the ecosystem from the bottom up, overfishing tends to work from the top down.
Historically, ocean fisheries have been regarded as infinite resources, able to provide a growing population with everlasting food, fertilizers, and medicines, among other things. To understand why this is so, one need only stand on the beach and look seaward. As one confronts the vastness of the ocean's horizon, the idea that our populations are capable of taking everything useful out of the sea seems ridiculous, arrogant, and impossible. But the reality is otherwise, and humanity is well on its way toward taking far more than the oceans can ever replace. Recent studies indicate that we humans have fished our way to the point where one-third of available stocks are depleted, and we're all proceeding down the food chain with alarming speed. Scientists speculate that unless fisheries management policies are not changed radically and soon, this is the last century in which people will enjoy wild seafood.8
Aside from the 50 billion or so dollars per year that will be lost by the world's fishing fleets,9 the effects of overfishing include substantial loss of biodiversity, incursion of invasive species, worsening water quality (decreasing the oceans’ ability to absorb CO2), and depletion of fisheries to a degree from which they will likely not recover. Most unnerving in the short-term, however, is the fact that hundreds of millions of people depend on fish for their daily sustenance, and as the human population continues to grow exponentially, this demand can only increase.
Population growth is very likely the root of many of our problems. How can our species, dependent as it is on our environment, continue to grow and flourish if the resources we all depend on do not keep pace with population growth? In 1798, Thomas Malthus thought it could not. He postulated, referring primarily to food supply, that “the power of population is indefinitely greater than the power in the Earth to produce subsistence
