Cutting Down Trees to Save the Earth

PNAS will print a study next Tuesday that takes a closer look at the effects of deforestation at specific latitudes. The study suggests that deforestation of higher latitudes may lead to a greater cooling effect than leaving areas intact or implementing afforestation plans. Needless to say, their findings have riled some folks.

Part of what they found was already accepted. Forests on and around the equator (mostly rain forests) are exceedingly good at cycling water back into the atmosphere. When the forests are removed en masse, this evapotranspiration is greatly reduced, allowing the constant solar radiation at the equator to pound with no protective cloud cover to reflect the rays. Couple this effect with the massive release of carbon dioxide into the atmosphere and you have a deadly cocktail. This is consistent with other studies that have been done. Generally speaking, leaving the rain forest intact is a boon for our planet's biosphere.

Removing the taiga, the boreal forest, however, could help to cool the planet, according to their models. Replacing the forest with "grasses and shrubs" increases the brightness of the surface (albedo), especially during the snowy winters. This reflects much of the radiation leading to far cooler temperatures, even when factoring in the release of CO₂ into the atmosphere.

The researchers admit this is an extreme model in both cases. The scale of deforestation necessary to produce such results are impossible, but illustrative. The study isn't really about providing a remedial measure for the future - purging the taiga and its altitudinal equivalents of trees - it's importance lies in its analysis of biome-specific studies of factors influencing climate.
I've already noticed a few neo-cons taking a hold of this study and using it as a point of attack on conservation (or hippiedom, as they ignorantly like to call it), treating it as an apologist study for logging. The researchers have also been accused of working with the timber industry by anonymous - presumably ferociously liberal - callers.

Luckily, the they have their head on straight about it. One of them, Ken Caldeira of the Carnegie Institute of Washington, told Nature:

One main reason to fear global warming is the need to protect ecosystems. To destroy forests would confuse the narrow goal [of fighting climate change] with the broader goal of protecting the environment.

Couldn't have said it better myself. This is the issue. Global warming is only one symptom of a far greater and far more complex problem. I see far too many "green" bloggers boiling things down to simplistic problems and simplistic results; they are committing the same sin as the detractors of conservation. We will accomplish nothing simply by switching to cloth diapers and fair trade coffee or, as Katherine Sharp has said, by buying sustainably-harvested bamboo salad bowls. These things might be helpful in changing people's minds, perhaps, but they are a drop in the bucket compared to the necessity of studies like these.

When environmentalists begin assuming things without regard for the science, we will fail. As Tolstoy once said, "What an immense mass of evil must result... from allowing men to assume the right of anticipating what may happen." Let us try and address the problem as best we can while keeping our minds open for potentially conflicting details and leaving room for modifications.

This is the second article I've read this month where researchers are attempting to untangle the effects of climate from other factors affecting ecosystems. The first, published in Ecology last month, looked at the effects of climate on butterfly diversity. I'll hopefully find the time to look more closely at that study soon.