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The Earth’s limitsNew study attempts to define thresholds for man’s impact on planetary processes
Surely the scariest aspect of climate change is the concept of tipping points: sudden and potentially irreversible changes in the earth’s natural processes that render the planet much less hospitable for humankind. The melting of the polar ice caps is perhaps the best-known tipping point, but planetary systems are under pressure from more than just the accumulation of greenhouse gases. A recent article in Nature attempts to define nine planetary boundary conditions that, if transgressed, could have disastrous consequences:
None of these issues is new, but the study breaks ground by attempting to assign hard numbers to the thresholds. The researchers were only able to come up with credible thresholds in seven of the categories (all of them except aerosols and chemical pollution). In three of the categories – climate change, biodiversity loss, and the nitrogen cycles – we have already crossed the boundaries, in some cases by a considerable margin. This is necessarily controversial work, both because the study’s conclusions are subject to such a high degree of uncertainty, and because they brush up against a set of questions that are outside the scope of scientific inquiry. In the study’s own words, “determining a safe distance involves normative judgments of how societies choose to deal with risk and uncertainty.” There are other problems with attempts to define bright lines around natural processes, many of them highlighted in the expert commentaries accompanying the article. For example, the exact thresholds suffer from a degree of arbitrariness. Is an extinction rate 10 times the historical trend really the right limit on biodiversity loss? What about 8 times? Or 15 times? Further, many phenomena aren’t easily tracked via a single metric. Not all agricultural practices are equally intensive, for example, and perhaps land use pressure could be more usefully measured in terms of soil loss or degradation, rather than square acreage devoted to crops. The thresholds themselves inevitably raise difficult questions about tradeoffs between our present wellbeing and the future habitability of the planet. Nitrogen pollution may be a huge problem, but modern agricultural techniques have unquestionably improved the lot of billions of humans (many of whom would simply be dead if not for the modern increase in agricultural productivity). Finally, thresholds will have uncertain effects in the political sphere. In the best case, they will give policymakers clear guidance and foster a broader understanding of an interlinked set of resource issues. In the worst case, the boundaries will provide an excuse for apathy: as we have repeatedly seen, societies can rarely be roused into action until they have already exceeded the margins of safety. Despite these pitfalls, most of the commentaries in Nature voiced support for the idea of attempting to define the operating boundaries within which the Earth will continue to provide a hospitable environment for human development. Climate change presents the biggest and most urgent collective resource problem the world faces, but it isn’t the only one. Image by Nature. Comments
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[Weird -- just yesterday I was remarking that all the denialist trolls have gone dormant. But here comes swborton to resume the great struggle.
Has anyone else noticed how cranks always claim to have "facts" to back them up, facts which no one else is willing or able to hear?]
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This article highlights something that's worried me a lot about environmentalism in the last decade or two. All other ills: pollution for land use problems, heavy metals in our air and water and food, depletion of nearly all ecosystems, etc. have been drowned out in the "debate" over global warming.
In the minds of the folks out there who don't live and breathe environmental issues, this has equated "environmentalism" with "doing something about global warming", to the detriment of all the other environmental issues we already had. But unfortunately, just because the general public isn't worrying about all these other problems, they haven't gone away: in fact, they've pretty much all gotten worse, and many of them are exacerbated even further when you consider their interaction with global warming.
I'm not sure what to do about this; environmental coverage in the media tends to be, like all MSM coverage, shallow, occasional, and distorted. Add to that that there is rarely any followup; the story that starts "remember that story about the fight over the new coal plant 10 years ago? Now people downwind are dying of fine particulates inhalation" rarely gets made.
I welcome suggestions as to how to get folks to realize that environmental problems are bigger than global warming and environmental issues are getting worse as we squeeze the planet's resources ever tighter. I think the Nature study above is a start, but I doubt the mass media will give it much attention.
I can envision the CNN tagline on this study boiling it down to... "Scientists concerned over environment", or the FOX News tagline summarizing the study: "Scientists say majority of environmental issues not critical".
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by phillip Clarke on October 31, 2009 4:03 AM
It seems to me that the anti climate change lobby has in fact used their stance as a justification of the right to pollute, to decimate forests and the environment, clear land, fish out the seas and so on.
So long as we are totally focused on "climate change" many people are all too easily led to believe that the arguments about the increasing toxicity of the air and degradation of land and sea do not matter so long as they are only climate change matters - a result that the polluter denies rather in the manner of Holocaust denial
The article that heads this thread to my mind gets back on track. Everything needed to possibly prevent "climate change" is definitely required for other reasons we all too easily forget. These matters are not "purely academic matters" - climate change is only one risk and indeed perhaps the ONLY one that might just not eventuate
Which said i still think we are at risk myself
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Adam, you wrote:
Nitrogen pollution may be a huge problem, but modern agricultural techniques have unquestionably improved the lot of billions of humans (many of whom would simply be dead if not for the modern increase in agricultural productivity).
Actually, they wouldn't be dead, they would never been born. No animal population can outgrow its food supply over time, so, if agricultural productivity hadn't been increased by "modern agricultural techniques"--most of which involve the use of oil and natural gas in one way or another--the population wouldn't have grown from about 2 billion 80 years ago to almost 6.8 billion today.
Under certain circumstances, an animal population can grow beyond its sustainable food supply, however, which is precisely what our global civilization has done by fueling explosive growth with depleting fossil fuels, pumping irrigation water from aquifers faster than they can be renewed, degrading soil, and so on. If we don't find a new way to feed the world soon, I'm convinced we'll discover firsthand what "population overshoot" means.
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Well written John K. The underlying issue in this graph is the worldwide population increase. If fuels all others. I would like to see how each of these planetary conditions relate to population increase. Some will no doubt have a linear one (for example, off the top of my head, population growth vs. freshwater use) while some will have an exponential relationship (perhaps population growth vs. land use or the nitrogen cycle). Thus as population increases, the rate at which we approach these thresholds can increase at the same rate or exponentially as fast. That may be the actual tipping point, one which we may have already passed.
Looking long-term, it seems we have two paths: we can find a sustainable way to feed a sustainable population (yet to be defined as far as I know, but probably not in the 9 billion range) or we can continue to create unsustainable ways to feed an unsustainable population. We may go on for a while on the second path but it will eventually have serious global consequences, probably recognized far past the point of preventing it.
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I couldn't agree more with the last 2 posts. Toby Hemenway, noted permaculturist, put it succinctly in a talk of his I was lucky enough to hear: agriculture is the means by which we replace functioning ecosystems with more human beings. More recently, we have improved the yield of agriculture by dumping fossil fuels in, netting more human beings per ecosystem converted to agriculture.
Besides netting a huge increase in human population, we've replaced self-sustaining ecosystems with fields that require energy and chemicals as well as lose topsoil at rapid rates.
Permaculture looks to me like its looking for alternatives; not just "going back to nature" - societies don't go backwards - but figuring our what we can keep and what we must fall away. Hemenway seemed intrigued by horticulture - using plants without tilling fields, which is a recent human invention (relatively speaking) and which seems responsible for a lot of destruction, especially the topsoil loss.
I will be reading more about this stuff: we need ideas fast. Unfortunately for some of us, I haven't seen any ideas that purport to sustain 9 billion over the long haul.
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