Posted by: Dan | April 28, 2009

Habitat Descruction vs Global Warming as Primary Conservation Problem

I came across two related stories recently that instigate a debate more than academic, regarding environmental conservation.

First, a 6-month-old BBC News article that I’d missed, discussed an economics report suggesting that deforestation worldwide “dwarfs the global banking crisis”. The study, on The Economics of Ecosystems and Biodiversity (or TEEB), is accessible here, but the BBC article here says more plainly:

It puts the annual cost of forest loss at between $2 trillion and $5 trillion.

The figure comes from adding the value of the various services that forests perform, such as providing clean water and absorbing carbon dioxide.

The study, headed by a Deutsche Bank economist, parallels the Stern Review into the economics of climate change.

The article elaborates on this TEEB Review:

Key to understanding his conclusions is that as forests decline, nature stops providing services which it used to provide essentially for free.

So the human economy either has to provide them instead, perhaps through building reservoirs, building facilities to sequester carbon dioxide, or farming foods that were once naturally available.

Or we have to do without them; either way, there is a financial cost.

The Teeb calculations show that the cost falls disproportionately on the poor, because a greater part of their livelihood depends directly on the forest, especially in tropical regions.

The greatest cost to western nations would initially come through losing a natural absorber of the most important greenhouse gas.

Just as the Stern Review brought the economics of climate change into the political arena and helped politicians see the consequences of their policy choices, many in the conservation community believe the Teeb review will lay open the economic consequences of halting or not halting the slide in biodiversity.

That’s easy enough to understand. But what is the Stern Review? For consistency, I’m citing the BBC News story for that as well. While the Stern Review on the Economics of Climate Change is accessible here, the BBC summarized its results as:

  • Extreme weather could reduce global gross domestic product (GDP) by up to 1%
  • A two to three degrees Celsius rise in temperatures could reduce global economic output by 3%
  • If temperatures rise by five degrees Celsius, up to 10% of global output could be lost. The poorest countries would lose more than 10% of their output
  • In the worst case scenario global consumption per head would fall 20%
  • To stabilise at manageable levels, emissions would need to stabilise in the next 20 years and fall between 1% and 3% after that. This would cost 1% of GDP

Compare the stats from those two reviews. First, they overlap – deforestation exacerbates global warming and climate change. Second, they’re comparable – that is, whether one is slightly higher than the other, they are well within an order of magnitude from one another. And third, I’m not sure, but they seem marginally more serious than the global banking crisis, but not by an order of magnitude either.

Now, those are studies coming at the problem from the economics side. But with those in mind, I find it interesting to see Carl Zimmer get into a discussion with Brenden Borrell re: Global warming and habitat destruction. It becomes a detailed discussion, with valid points on both sides. And as Brenden notes, mental exercises like this are important:

Battling climate change and saving biodiversity may not always be achieved via the same means and I think it is quite clear that they are often in conflict with one another. No doubt the conflicts will become more serious in the future and folks who care about biodiversity must think carefully about how they want to craft their policies and spend their dollars.

I stand behind the central point of the Slate essay, but I’ll add a bit of nuance to the discussion here. We can all agree that in terms of extinctions, the effects climate change and habitat loss are of the same order of magnitude (i.e. factor of 10).

They’re not always in conflict with each other. Preserving plant biodiversity is one such way – by serving as a carbon sink while at the same time serving as the basis for diverse ecosystems. But the general point is taken – we do indeed need a multi-faceted response to a variety of challenges here.



  1. Hi Dan

    We had a story on our TV news yesterday on New Zealand ornithologists making a visit to North Korea to study the migration of two types of birds from NZ to the arctic. En route the birds stop in Korea. The story is here:

    Ornithologists uncover the secrets of godwits in North Korea

    (Just in case its of interest. Slightly related to the present blog post.)


  2. Hi John,
    Thanks for the link! I hope you’ve been well, and that I didn’t drive you off last year. ;-)

    Good to see you again,

  3. Not sure what happened to it, but John wrote back with another comment:

    “Thanks Dan. By no means did you drive me off! I’ve been in a quiet period online — otherwise occupied …”

    Damn WordPress…


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