Monday, December 10, 2012
Let’s be honest: there is nothing sustainable about the way humans are using the resources of the planet. By almost any measure, we are exceeding the earth’s carrying capacity. Human population, currently numbering 7 billion and projected to hit 9 billion by mid-century, coupled with a rapidly rising per-capita consumption rate underlie all of the other present drivers of global change. Though humans make up less than one half of a percent of the global biomass, we use up 25-32% of the earth’s net primary productivity. Humans have converted 43% of land to agricultural or urban landscapes, with much of the remaining natural landscape fragmented by roads and utilities. This exceeds the physical transformation that occurred at the last global-scale critical transition when 30% of Earth’s surface went from being covered by glacial ice to being ice free. With extinctions rates already 100 to 1,000 times background rates, and projected to increase dramatically in response to anthropogenic global warming, humans are literally altering the course of evolution.
Speaking of climate change, atmospheric concentrations of carbon dioxide have increased by 39% since the Industrial Revolution and, at approximately 400 parts per million (ppm), are now the highest in fifteen million years. We are adding 2.2 ppm per year. At this rate, worldwide carbon dioxide levels will substantially exceed 1,000 ppm by the end of this century. The level of heating that would result from this degree of concentration would be beyond anything seen during any period in which Earth supported complex life. To have even a 50-50 chance of holding temperature increases to the 2°C target agreed to in the Copenhagen Accord, atmospheric concentrations cannot exceed 1 trillion tons. We are already halfway there, and the rate of increase is accelerating. To limit emissions to 1 trillion tons, three-quarters of fossil fuels must be left in the ground as nations switch to renewable energy sources.
And rising temperatures with devastating extreme weather events aren’t the only problem. The oceans, which have been soaking up a lot of the carbon dioxide and masking the full impacts of global warming, are more acidic than at any time in the past 300 million years. Acidification can affect many marine organisms, but especially those that build their shells and skeletons from calcium carbonate, such as corals, oysters, clams, mussels, snails, and phytoplankton and zooplankton, the tiny plants and animals that form the base of the marine food web. Three of the five largest extinctions of the past 500 million years were associated with global warming and acidification of the oceans.
Nor is carbon the only threat to the oceans. According to the UN Food and Agriculture Organization, over 70% of the world’s fish species are either fully exploited or depleted. Further, nitrogen and phosphorous loadings from fertilizer runoff and fossil fuel combustion have created over 400 “dead zones” around the globe. More than 235,000 tons of food is lost each year to hypoxia in the Gulf of Mexico alone. The oceans are in crisis. We have only decades left before the damage we have inflicted on the oceans becomes permanent.
Without belaboring the obvious, the point is that sustainability is a physical concept grounded in science and bounded by the very real limits of the planet’s life support systems. The danger is not that we will run out of oil or natural gas or other stuff but that we will run out of the assimilative capacity of the biosphere and trigger a planetary scale shift in biological systems. It won’t be the end of the world, but it could well be the end of human civilization as we’ve known it.
The problem with thinking about sustainability as an economic concept is perfectly illustrated by the Norway-UK Energy Partnership for Sustainable Growth calling for accelerated oil and gas development in the increasingly ice-free Arctic. British Prime Minister David Cameron and his Norwegian counterpart Jens Stoltenberg called the deal a prime example of sustainable development that will insure the drilling is done in a “safe and environmentally sensitive” manner; provide a “long term gas supply;” create “good jobs;” and generate income for “investment in renewable energy.” The Arctic, of course, has just experienced a record loss of sea ice this past summer. “Sustainable” is not a word scientists would use to describe what is happening in the Arctic. Rather words like “death spiral” and “global disaster” are closer to the mark. There is nothing sustainable about chasing every last molecule of fossil fuel on the planet. “All of the above” is not an energy policy; it’s a bumper sticker.
It’s the ninth inning; we’re behind; there are two outs; and we’re down 0-2 in the count. With his re-election President Obama has one last at bat. A home run would be a carbon tax sending a strong price signal to the market and an aggressive program of investment in clean energy based on a strong national Renewable Electricity Standard as part of a robust plan for economic recovery.
-- Patrick Parenteau