The world could reduce climate change and save millions of lives with a few simple steps to stop soot and smog, says a new report.
The United Nations Environmental Program put out a report this week on the role of black carbon (soot) and ozone in climate change. The report has been sent to environment ministers around the world.
The world has already warmed to about 0.8 C above pre-industrial levels, the report notes, and is set to reach more than two degrees above those levels by 2050. Two degrees is the maximum amount of warming most scientists say the world can safely manage.
The report calls on governments to take steps to reduce two oft-ignored global warming emissions — black carbon and ozone. Those steps, if implemented worldwide by 2030, would cut our near-term climate warming in half, save millions of lives and preserve millions of tonnes of crops.
Even if the report's numbers are off, says St. Albert air quality specialist Warren Kindzierski, it makes sense that we'd benefit from eliminating these pollutants. "We know these things cause health problems, and if you try and prevent their release or formation in the atmosphere, we're going to reduce the health problems."
Soot and stink
Black carbon consists of tiny particles produced by incomplete combustion, Kindzierski says. "The other term for it is soot." Cooking stoves are a major source in the developing world; here, the big one is cars.
Ozone is a major component of smog, and is produced when nitrogen oxides and other pollutants react with light.
Both substances wreak havoc on climate and health, according to the report. Black carbon darkens snow and ice and absorbs heat, affecting cloud formation and monsoon patterns throughout Asia. It and ozone also damage the heart and lungs, causing early death. Ozone is also toxic to plants.
The study lays out 16 steps that governments should take to reduce emissions of both pollutants. The steps include providing clean-burning stoves to developing nations, reducing flaring and venting of natural gas and putting particle filters on diesel vehicles. It did not list the cost of these measures.
These steps could reduce future warming by about 0.5 C, the report found, or about half the amount of warming that's expected to happen by 2050. It would have an even greater effect on the Arctic, which is warming faster than the rest of the world. The steps would also prevent about 2.4 million deaths and the loss of about 52 million tonnes of crops each year.
Don't forget CO2
More than 90 per cent of Edmonton's particulate matter, which includes soot, and most of its ozone ingredients come from cars, Kindzierski notes, which makes them an obvious place to start reductions. "All we've got to do is get people off the roads." Higher emissions standards for cars and trucks, especially diesel ones, would also help.
But it would be just a start, the report notes — ozone and black carbon are short-term drivers of climate since they don't hang around in the atmosphere for centuries like CO2, and reducing them won't stop climate warming in the long run. "Deep and immediate carbon dioxide reductions" would still be needed to keep the world below two degrees of warming, it noted.
Tackling black carbon is a good idea that would benefit the climate and people's health, says P.J. Partington, climate analyst with the Pembina Institute, but it shouldn't distract us from carbon dioxide. "CO2 is the main temperature knob in our climate system," he said, "and it's one that we can't turn down once we've turned it up. How much CO2 we emit now will determine the warming we face for millennia."
The report can be found at http://www.unep.org/dewa.
