Baffin Island is covered with an austere, Arctic tundra now, but some time later this century it will be capable of sprouting something unusual: a verdant coniferous forest.
The idea that trees might some day spread to many parts of Canada's Far North may seem unlikely, but it is being touted as a realistic possibility in one of the most extensive looks at how the world's forests will cope with further global warming.
Call it a climate-change paradox: While the overall prognosis for the planet's woodlands is dismal because higher temperatures are expected to lead to more droughts, increased insect invasions and fires, trees may prosper in northerly regions where they now don't even exist.
The report, which is being released next week at a forestry forum at the United Nations in New York, says there will be a silver lining for selected areas of northern Canada, Sweden, Finland and Russia. In these countries, the boreal, or northern forests composed of evergreen trees such as black spruce, will grow more productive and start to shift northward.
Besides Baffin Island, forests will be able to spread to most of the Hudson Bay coastline; Southampton Island, perched at the top of Hudson Bay; much of the Ungava Peninsula in Quebec; and near the northern tip of Labrador, possibly as soon as 2070. That time frame would mean the establishment of forests could become possible within the lifetimes of many of today's children, but experts caution that forests naturally spread slowly and may not immediately begin growing despite climate change.
The report was compiled by 35 of the world's top forestry scientists for the International Union of Forest Research Organizations, a Vienna-based arboreal think tank.
In it, the researchers concluded that global warming will likely place severe enough pressure on the world's forests that they will cease being carbon sinks, or net absorbers of carbon dioxide from the atmosphere. This is a worrisome development with major implications because about a quarter of all greenhouse-gas emissions from human activity are absorbed by trees, slowing global warming.
If the world's temperature rises by as little as 2.5 degrees above pre-industrial levels, the scientists predict that, instead of storing carbon, forests - as they burn through massive fires or are destroyed by insects - will start releasing their stores of the greenhouse gas, making global warming even worse.
"We normally think of forests as putting the brakes on global warming, but in fact over the next few decades, damage induced by climate change could cause forests to release huge quantities of carbon and create a situation in which they do more to accelerate warming than to slow it down," said Risto Seppala, a professor at the Finnish Forest Research Institute and chair of the panel that wrote the report.
The forests most at risk are in subtropical and temperate areas, such as the western U.S., northern China, southern Europe, Australia and subtropical Africa. The situation could become so dire in some arid areas of the U.S. West that wood production could "decline to the extent that forests are no longer viable," the report says.
But warmer temperatures will be a boon to woodlands in northern countries, as will the presence of increased carbon dioxide in the air, which will act as a type of natural fertilizer for tree growth in the Arctic.
The projections about Canada in the report were based in part on research from Natural Resources Canada that found the climate in far northern areas would be warm enough to support boreal forest development. This projection is based on a computer model that assumed efforts to curb greenhouse-gas emissions would be unsuccessful.
Experts who worked on the report caution that it may take a long time for new northern forests to get established. One problem is that soils may not be rich enough to immediately support tree growth.
Barring human intervention to plant trees in warming areas, forests naturally spread slowly because it takes years for new trees colonizing an area to be mature enough to produce seeds that can then spread further northward, said Andreas Fischlin, an ecology professor at the Swiss Federal Institute of Technology in Zurich, and one of the report's co-authors. Sometimes seeds move long distances on rivers, ocean currents or animals, and jump to new areas, but this isn't a sure thing, he said.Toronto Globe and Mail
