With about 10 weeks until the global summit on climate change in Copenhagen, what is the latest science telling us?
In brief, climate-warming predictions of three or four years ago are already out of date. New science suggests an even faster warming than had been thought possible.
In preparation for Copenhagen, the United Nations recently issued a summary report (Climate Change Science Compendium) based on 400 peer-reviewed scientific studies. It found, inter alia, that whereas carbon-dioxide emissions from fossil-fuel burning had grown by 1.1 per cent from 1990 to 1999, the increase was 3.5 per cent from 2002 to 2007.
The growth exceeded the most alarming of the scenarios previously outlined by the United Nations Intergovernmental Panel on Climate Change. The most recent report said: "No region is de-carbonizing its energy supply." The obvious result will be a hastening and intensification of the adverse effects of climate change on the planet.
Few places will be more affected than our Arctic. As the University of Toronto's brilliant physicist Richard Pelletier told a meeting in Ottawa this week, "Canada and Russia are the two countries on Earth in the northern regions that will experience the biggest changes."
If nothing is done to reverse current emission trends, the climate will warm on average by about 3.5 degrees Celsius by 2100, but by twice that amount in the Arctic. It's part of what is called the Northern Hemisphere polar amplification effect. Warming in the Arctic means the retreat of sea ice and the exposure of more water to the sun's rays. This pattern feeds upon itself, since both the water and the atmosphere get warmer.
In 2007, according to the latest UN report, "the sea ice in the Arctic Ocean shrank to its smallest extent on record, 24 per cent less than the previous record set in 2005" and 34 per cent less than the average minimum from 1970 to 2000.
"This is clear evidence on a phenomenon of importance on a planetary scale," it says.
It is also part of a well-understood impact of global warming: that it worsens already extreme weather conditions such as drought and storms.
The insurance industry knows this pattern, which is why rates in areas vulnerable to weather-related disasters have been rising.
Weather anomalies abounded in 2008 and 2009, bringing with them tremendous costs. A few examples: Mexico had its worst drought in 70 years; central and southern Chile its worst drought in 50 years; parts of Argentina, Paraguay and Uruguay the worst drought in 50 years.
The U.S. Southwest experienced its third-worst fire season in 2008 and a persistent drought. Spain and Portugal were struck by severe droughts. Australia had its warmest January since 1950, and drought conditions for a decade continued in some parts. Last month, Australia and New Zealand experienced their warmest August since record-keeping began.
The same anomalies occurred elsewhere in other ways: severe rainstorms, hurricanes, cyclones, floods.
With the scientific evidence continuing to harden, we might expect a focusing of the minds at Copenhagen. Instead, it would appear that hopes for an international agreement have been misplaced.
Some countries, it must be said, are paying more attention to climate change.
India, for example, was previously tone-deaf to pleas that it do something. But with the monsoon cycle being disrupted, Himalayan glaciers disappearing and dry areas becoming even drier, it is now at least willing to talk.
China is proposing to reduce the intensity of its energy use, and is busting ahead with renewable energies, so that it, rather than tardy North American countries, will be manufacturing and selling renewable technologies worldwide.
U.S. President Barack Obama is convinced of the importance of climate change. The House of Representatives has passed a bill, admittedly full of loopholes, that pledges a 17-per-cent reduction in greenhouse-gas emissions by 2020 from 2005 levels. The Senate, however, will water down that target, and almost certainly will not pass a bill before the Copenhagen summit. This week, to show the administration is serious, the Environmental Protection Agency released regulations it could use against large emitters if the Congress does not pass a satisfactory bill.
Despite this welcome attention, gaps among the countries appear too wide for a successful conclusion in Denmark. The most important negotiations are not really there anyway, but rather in Washington and Beijing. If the United States and China, the world's biggest emitters, can make a deal, the rest of the world will follow.
Meanwhile, the signs of science are becoming ever harder to ignore.