The effects of air pollution have manifested in various ways, one of them the expansion of the tropics northwards, creating a drier sub-tropic region. This has been attributed to black carbon particles and ozone emitted by human activities, writes Michael Richardson. And The Economist, in a landmark report, draws attention to the shrinking of the summer Arctic ice. While potentially opening up the Arctic sea to major economic ventures, but could also be ecologically catastrophic for the world at large. Read more
By Michael Richardson for The Straits Times (21 May 2012):
The tropics are expanding. The zone of heat and wetness, where Singapore is anchored by geography, has widened by approximately 0.7 degrees of latitude per decade in recent years, or more than two degrees since 1979.
Ozone depletion in the stratosphere, caused partly by global warming gas emissions from human activity, is known to be the primary driver of tropical expansion in the southern hemisphere. (The stratosphere is the second major layer of Earth’s atmosphere, just above the troposphere that rises from ground and sea level to a height of between 10 and 15 kilometres.)
However, reasons for the extension of the tropics into the northern hemisphere, where the bulk of the world’s population lives, have been a mystery – until last week. Researchers in the United States and Australia now say tropospheric ozone and tiny black carbon aerosol particles, a major component of soot, are most likely to be pushing the boundary of the tropics polewards in the northern hemisphere.
Robert J. Allen, Assistant Professor of Earth Sciences at the University of California, Riverside, who led the study, summarised its findings and consequences: “Both black carbon and tropospheric ozone warm the tropics by absorbing solar radiation. If the tropics are moving poleward, then the sub-tropics will become even drier.”
His team’s findings highlight the increasing attention being given to the role in climate change of so-called short-lived pollutants – black carbon, methane and hydrofluorocarbons, which are used in refrigerants.
Ozone is not directly released into the atmosphere. It is formed by the action of sunlight on other gases, including methane and carbon dioxide. In the stratosphere, ozone is considered to be beneficial as it protects life on Earth from the sun’s harmful ultraviolet radiation.
But at ground level, tropospheric ozone is an air pollutant harmful to human health and ecosystems. It is a big component of urban smog and “haze”, the mixture of smog and smoke from forest fires that periodically cast a pall over Singapore and other parts of Southeast Asia.
A threefold rise in ozone concentration in the northern hemisphere in the past 100 years has made it the third most important contributor to the human enhancement of the global greenhouse effect, after carbon dioxide and methane.
So cuts in these two greenhouse gases have the potential to substantially reduce both tropospheric ozone concentrations and global warming.
The expansion of the tropics also highlights the role in global warming of the Asian growth belt. There, a combination of some of the world’s most populous nations, such as China, India, Bangledesh and Indonesia, and rapid economic development are generating climate-altering substances that are less well-known than carbon dioxide, the main long-lasting greenhouse gas.
In 2011, a team of scientists from the US space agency, NASA, working with UNEP, the United Nations Environment Program, sorted through more than 2,000 soot and methane control measures. They found that just 14 practical steps would deliver nearly 90 per cent of the potential benefits, including restraining global warming by about 0.5 degrees Celsius by 2050, while avoiding as many as 4.7 million premature deaths caused by smog and haze pollution.
They also concluded that application of these steps would raise crop yields by as much as 135 million tonnes due to cuts in ground-level ozone, which blights crops in China, India, Brazil, the US and elsewhere.
In addition, stopping soot emissions could help maintain monsoon patterns and protect endangered ecosystems, such as Asian mountain glaciers and Arctic Sea ice where soot carried by winds from the Asian growth belt has been deposited, absorbing heat from the sun and hastening melting.
Soot results from the incomplete combustion of fossil fuels, wood and other biomass. It can be reduced by measures like installing filters on diesel engines, replacing traditional cooking stoves with more efficient models, modernising brick kilns, and banning the open burning of agricultural waste.
Methane, the main component of natural gas, can be captured from oil and gas wells, leaky pipelines, coal mines, municipal landfills, wastewater treatment plants, farm manure piles and wet rice fields.
All 14 measures selected by the scientists can be applied using existing technologies, and in most cases existing air pollution laws and existing institutions at both national and regional levels. Economic analysis indicates that many of these steps provide more value in benefits than they cost to implement, though the benefits do not necessarily accrue to those who have to apply them.
Another key characteristic of short-lived global warming gases and aerosol particles is that they remain in the atmosphere for only a relatively short time, from several days to three decades. So emission reductions yield a short-term benefit for the climate, health and food production. By contrast, carbon dioxide can stay in the atmosphere for thousands of years.
As a result of this and other research, the US and 12 partners have formed a Climate and Clean Air Coalition. The grouping held its first meeting last month and will meet again in July.
The aim is to increase funding and support for cutting short-lived climate pollutants. But it will only be really effective if India, China, Indonesia and more Asian nations that produce much of the pollution participate in the program.
This will now happen. Leaders of the G-20 leading economies announced at the end of their summit at Camp David in the US at the weekend that those of them not already part of the Climate and Clean Air Coalition had agreed to join.
The writer is a visiting senior research fellow at the Institute of South East Asian Studies.
By The Economist (16 June 2012):
NOW that summer is here, the Arctic is crowded with life. Phytoplankton are blooming in its chilly seas. Fish, birds and whales are gorging on them. Millions of migratory geese are in their northern breeding grounds. And the area is teeming with scientists, performing a new Arctic ritual.
Between now and early September, when the polar pack ice shrivels to its summer minimum, they will pore over the daily sea ice reports of America’s National Snow and Ice Data Centre. Its satellite data will show that the ice has shrunk far below the long-term average. This is no anomaly: since the 1970s the sea ice has retreated by around 12% each decade. Last year the summer minimum was 4.33m square km (1.67m square miles)—almost half the average for the 1960s.
The Arctic’s glaciers, including those of Greenland’s vast ice cap, are retreating. The land is thawing: the area covered by snow in June is roughly a fifth less than in the 1960s. The permafrost is shrinking. Alien plants, birds, fish and animals are creeping north: Atlantic mackerel, haddock and cod are coming up in Arctic nets. Some Arctic species will probably die out.
Perhaps not since the 19th-century clearance of America’s forests has the world seen such a spectacular environmental change. It is a stunning illustration of global warming, the cause of the melt. It also contains grave warnings of its dangers. The world would be mad to ignore them.
Less feedback, please
As our special report shows in detail, the Arctic is warming roughly twice as fast as the rest of the planet. Since the 1950s the lower atmosphere has warmed by a global average of 0.7 degrees Celsius; Greenland’s air has warmed by 1.5 degrees. The main reason appears to be a catalytic warming effect, triggered by global warming. When snow or ice melt, they are replaced by darker melt-water pools, land or sea. As a result, the Arctic surface absorbs more solar heat. This causes local warming, therefore more melting, which causes more warming, and so on. This positive feedback shows how even a small change to the Earth’s systems can trigger much greater ones.
Some scientists also see a tipping-point—another feared term in the climatology lexicon—in the accelerating diminution of the sea ice. The term describes the moment at which the planet shifts from one environmental state to another: in this case, from an Arctic with summer sea ice to one without it. By the end of this century—perhaps much sooner—there will probably be frequent summers with no sea ice at all.
Arctic peoples have also noticed what is going on. Inuit hunters are finding the sea ice too thin to bear their sleds. Arctic governments are starting to see a bonanza in the melt. The Arctic is stocked with minerals that were hitherto largely inaccessible, including an estimated 30% of undiscovered reserves of natural gas and 13% of undiscovered oil reserves. A combination of high commodity prices, proactive governments, technological progress and melting ice will help bring these to market. Encouraged by Arctic governments and dwindling reserves elsewhere, oil companies are flocking north like migrating geese to explore the continental shelves of Alaska, Canada, Greenland, Norway and Russia. Canada and Russia also hope to develop their Arctic shipping-lanes, which the melt is making accessible. Russia’s Northern Sea Route, hugging the Siberian coast, cuts the normal distance between Europe and Asia by more than a third. It will help ferry Russia’s Arctic resources to Asian markets, and could one day be a wider boost to world trade.
These exciting developments carry risks, however. Many fear for Arctic cultures—a Canadian Inuit argues despairingly for her “right to be cold”. Others foresee conflict between Arctic countries scrambling for the region’s resources. Greens warn of environmental risks in developing them: a big oil spill would be disastrous for fragile Arctic ecosystems.
The igloos have gone
Such fears are reasonable, but often exaggerated. Traditional Arctic peoples have been changed far more by Westernisation than they will be by melting ice. None lives in an igloo these days. And everywhere except Russia their rights have been recognised. Nor is conflict much of a worry. The Arctic is no terra nullius. Most of it is demarcated, and Arctic countries have a commercial incentive to keep the peace. Last year Russia and Norway settled an old dispute over their maritime border; soon they will open the border region to oil firms.
The risks of pollution from bilge water, mining effluent and spilt oil are real. Yet the Arctic is not unprotected: it is, by and large, among the most regulated oil provinces. Its development will also be slower and more cautious than greens fear. Even with little sea ice, the Arctic will remain forbiddingly cold, remote, stormy and therefore expensive to operate in.
The worry that needs to be taken most seriously is climate change itself. The impact of the melting Arctic may have a calamitous effect on the planet. It is likely to disrupt oceanic circulation—the mixing of warm tropical and cold polar waters, of which the Gulf Stream is a part—and thawing permafrost will lead to the emission of masses of carbon dioxide and methane, and thus further warming. It is also raising sea levels. The Greenland ice sheet has recently shed around 200 gigatonnes of ice a year, a fourfold increase on a decade ago. If the warming continues, it could eventually disintegrate, raising the sea level by seven metres. Many of the world’s biggest cities would be inundated long before that happened.
Some scientists argue that the perils are so immediate that mankind should consider geoengineering the atmosphere to avert them (see article). They may turn out to be right, but there could be enormous risks involved. A slower but safer approach would be to price greenhouse-gas emissions, preferably through a carbon tax, which would encourage the adoption of cleaner technologies (see article). That shift would be costly, but the costs of inaction are likely to be larger.
In the end, the world is likely to get a grip on global warming. The survival instinct demands it. But it is likely to lose a lot of the unique Arctic first. That would be a terrible pity.
Go to the economist.com for the Special Report on The Artic by James Astill, who says:
“The Arctic is warming twice as fast as the rest of the planet. The retreating ice offers access to precious minerals and new sea lanes—but also carries grave dangers.”