In 1987, when scientists were using early computer models to predict the effect of increasing levels of atmospheric carbon dioxide on global temperatures, their conservative estimate was a warming rate of 0.06°C per decade. Their high estimate was 0.3°C. As a totally improbable but worst-case scenario, they estimated 0.8°C. The actual temperature rise measured in 2005 confirmed a rise half way between their two highest estimates (The Revenge of Gaia by James Lovelock, 2006).
This trend of underestimating climate change effects has again been confirmed by new reports from the UN's Intergovernmental Panel on Climate Change (IPCC), in studies published in the Proceedings of the National Academy of Sciences and in a report from the Global Carbon Project (GPC). All confirm that atmospheric carbon dioxide rates are rising faster than predicted, partly because the world's oceans and land are absorbing proportionally less CO2 than expected, and partly because we are burning more fossil fuels than anticipated. For anyone concerned about the future, the results are sobering.
Surprisingly, despite our recent efforts to reduce CO2 emissions, we are not succeeding. The average annual increase of 1.3 percent in carbon dioxide emissions during the 1990s has actually increased to 3.3 percent since 2000, the highest rate of increase since the Industrial Revolution 200 years ago. And since the 1970s, the actual amount of carbon dioxide emitted to produce a unit of goods has risen rather than fallen, probably due to industrial growth in China, India and other developing nations. Besides becoming less efficient, we are not correcting the trend toward higher levels of atmospheric CO2 ‹ certainly the highest in 650,000 years and likely the highest in 20 million years ‹ simply because there are more people to consume more goods.
As for the other part of the equation, the carbon sinks that have been removing about half of our emitted CO2 from the atmosphere are performing at a lower efficiently than predicted. Warming oceans absorb less carbon dioxide. Weather changes in the Antarctic are reducing the absorbtion capabilities of the southern oceans. Mid-latitude droughts are decreasing plant vitality and their carbon uptake. Of the 10 billion tonnes of CO2 emitted from deforestation and the burning of coal, oil and gas, about 5 percent more is staying in the atmosphere than expected. This is bad news.
Other factors are also tipping the climate struggle against us. Initial research by Dr. Tom Gower in northern Manitoba suggests that, over a 60 year period, the vast boreal forests are now emitting more CO2 rather than they are sequestering ‹ instead of collecting 0.1 tonnes/hectare/year, they are releasing 0.1 tonnes (Quirks and Quarks, CBC radio, Nov. 1/07). Gower attributes this to the positive feedback loop of higher temperatures causing higher insect infestation and larger, more frequent fires. Melting permafrost is also releasing methane, a potent greenhouse gas.
Says Dr. Ken Denman, a lead scientist on the IPCC report, "If the trends of the last few years continue, [the effects of climate change are] going to happen faster than we thought, based on our model projections." And Britain's Dr. Corinne Le Quéré adds, "It's not good news." During the last seven years, the increase in atmospheric concentrations are "beyond our worst scenarios". Professor Martin Parry, co-chairman of the IPCC committee, notes that,"Ten years ago we were talking about these impacts affecting our children and our grandchildren. Now it is happening to us."
Most climatologists agree that, if we are to avoid runaway consequences, we must keep the global temperature from rising above 2°C, or an atmospheric carbon dioxide concentration of 450 parts per million. As Australia's Josep Canadell of the Global Carbon Project reminds us, we are presently at a global temperature of 0.8°C above pre-industrial levels with CO2 up from 280 ppm to 382 ppm. At the current increase of 2 ppm/year, we have a cushion of 68 ppm and less than 35 years to avoid the 2°C appointment with the unthinkable.
As if this challenge were not sobering enough, Professor Parry reminds us that the time delay between existing CO2 levels and climate consequences means we already have "a stock of major impacts" waiting to occur. "[We] cannot mitigate [our] way out of this problem. The choice is between a damaged world or a future with a severely damaged world."
All these warnings are still couched in the emotionally reserved language of scientists committed to a rational and objective appraisal of our planet's environmental condition. Because of discipline, their predictions tend to be conservative. Because of character, they tend to assume a calm detachment that fails to convey the actual ramifications of their message.
Their real message is that we heading toward serious trouble ‹ faster than earlier predictions. Everyone who reads and considers their words should be worried ‹ very worried. This is not a time for public panic. But it is a time for urgent measures. Politicians at all levels of government must be told in the most unambiguous terms that constraints and controls on carbon dioxide emissions must be implemented immediately if we are to curtail this slide toward disastrous climate change. We need science-based caps on CO2 release, carbon taxes, an end to aviation expansion, ecologically sound agricultural practices, and stringent new emission standards for vehicles, vessels and industry. All these measures should be coupled with a whole regime of tax shifting to encourage green options while discouraging CO2 emissions.
If we succumb to our human inclination to postpone reductions in CO2 emissions until an actual crisis is upon us, we will be too late. Avoiding a future of worst-case scenarios requires action today.