Taking a Walk in the Arctic Woods

Could trees replace tundra in Canada’s Arctic? Perhaps, according to a new report to be released by 35 of the world’s top forestry scientists. (see press release)

While warmer temperatures from global warming will spell destruction for forests in places like the Western US, southern Europe and Australia, Canada’s treeline may expand northward. From the Globe and Mail:

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.

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.

Now, I can already hear certain crowds cynically argue that development in the southern Boreal Forest is no big deal because the forest is expanding northward, but the scientists who authored this report caution:

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.

The report, called “Adaptation of Forests and People to Climate Change – A Global Assessment”and to be presented at a United Nations forum, also adds to the debate over whether forests are our friends or foes in the fight against climate change.
People tend to think of forests as an important brake on global warming because they store massive amounts of carbon. But damage to the globe’s forests caused by climate change — from drought-induced fires to insect infestations — may cause them to cease absorbing carbon, and instead release huge amounts of carbon, making global warming even worse.
Since trees are responsible for absorbing roughly a quarter of all human-induced greenhouse gas emissions, this transformation from so-called carbon sink to carbon emitter would have significant implications. More details here, and here.