13 August 2007

It's going to take more...

...than simply planting trees. Planting trees is nice, and it should continue (in a sensible, environmentally-sound way). However, new research suggests that trees aren't going to help as much as we previously believed. This is seen in both the tropics and in mid-latitude areas.

Data collected on forests in Panama and Malaysia has revealed that global warming could reduce the growth of trees in tropical rainforests by 50 percent, besides severely affecting their ability to remove carbon dioxide from the air.

While 10 years of bathing North Carolina pine tree stands with extra carbon dioxide did allow the trees to grow more tissue, only those pines receiving the most water and nutrients were able to store significant amounts of carbon that could offset the effects of global warming,

The gist of both of these items is that trees aren't as effective at storing CO2 as hoped. Vegetation doesn't show a simple linear relation whereby enhanced CO2 leads to more tree growth for ever and ever. There is a limit, which could easily be reached sooner rather than later. Maybe we can push it, as observed in the second item

In order to actually have an effect on the atmospheric concentration of CO2, the results suggest a future need to fertilize vast areas," Oren added. "And the impact on water quality of fertilizing large areas will be intolerable to society. Water is already a scarce resource

I would think that it is not just water quality, but also nutrient runoff from the fertilizer creating algal blooms in the ocean. These blooms can lead to 'dead zones' like those recently observed off the Oregon coast and in the Gulf of Mexico. More of humanity's hubris.

In a bit of apparently good news

Deforestation of the Amazon rain forest in Brazil fell by about a third in the 12 months through July to the lowest rate in at least seven years, the government said on Friday.

An estimated 9,600 square km (3,707 sq miles) of the world's largest rain forest were cleared in the year ended July 31, compared to a revised 14,039 sq km (5,417 sq miles) the previous year, the environment ministry said.

Any progress is good, but losing a million or so hectares a year is still a lot; it was considered problematic 7 years ago when last that low.

A better idea is consider attacking the root cause -- the wasteful, consumptive nature of western society – rather than attempting another in a series of house-of-cards technological quick fixes. Tree planting and other measures are important for mitigation of climate change, they are just not the whole story. In closing, consider this thought from the blog Climate Frog:

One thing we don't want is for people to be sold on taking actions that do little to change the trend toward climate change while offering them a feeling of complacency that, "Now I've done something to help. I can relax now."

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