Damage to global environment could pass point of no return

Major UN report about to be issued. New York Times article on this includes:

The human population is living far beyond its means and inflicting damage to the environment that could pass points of no return, according to a major report being issued today by the United Nations. Mr. Zarqawi was killed in an air strike on an isolated house about 30 miles north of Baghdad. Iraqi officials announce the death the next morning, and Al Qaeda confirmed that he had died. Climate change, the rate of extinction of species, and the challenge of feeding a growing population are among the threats putting humanity at risk, according to the United Nations Environment Program in its fourth Global Environmental Outlook since 1997. “The human population is now so large that the amount of resources needed to sustain it exceeds what is available at current consumption patterns,” Achim Steiner, the executive director of the Environment Program, said in a telephone interview.

U.N. Warns of Environmental Threats

UN media release announcing press conference includes:

While the world had spent 30 years debating whether global warming was in fact happening, the cost of climate change was growing ever higher, and a history of lost opportunity after lost opportunity was growing longer, correspondents heard today at a Headquarters press conference upon the launch of a United Nations Environment Programme (UNEP) report. Now the world needed to pay attention to a whole host of environmental concerns, said Achim Steiner, Executive Director of the United Nations Environment Programme, introducing the Programme’s report, entitled “Global Environment Outlook: Environment for Development” (GEO-4). The “GEO-4” report, as it is known, provides an updated assessment of the world’s atmosphere, land, water and biodiversity, 20 years after the issuance of the seminal report by the Brundtland Commission -- “Our Common Future”, which Mr. Steiner called the “previous peak” in environmental awareness and political discourse. “We essentially step before the world today with a report that is, in essence, saying that in all the fundamental major challenges and trends that Brundtland identified 20 years ago, we have not turned the corner,” he said, adding, “That is an extremely sobering analysis.”

He was joined at the briefing by Olav Kjorven, Assistant Administrator and Director, Bureau for Development Policy, UNDP, and Jeffrey Sachs, Director of Columbia University’s Earth Institute and Special Adviser to the Secretary-General on the Millennium Development Goals. Also on hand were a few of the report’s lead authors of the more than 390 experts who helped prepare the document and the more than a thousand people worldwide who peer-reviewed it.

Mr. Steiner explained that “GEO-4” was meant to provide further consolidated evidence, not only of individual locations and phenomena, but of the current system-wide view that a growing range of evidence existed that the world was coming to a brink where events were either uncontrollable or reversible only at high cost and effort. Much of what the report said about that “brink” –- with the use of terms like “tipping points, thresholds, feedback mechanisms, collapsing ecosystems, and dead zones” to describe a host of documented phenomena -- was not that different from the assessment on global warming made by the International Panel on Climate Change (IPCC), he added.

Calling the report “useful, scientifically robust and very sobering”, Mr. Kjorven said it pointed in the direction of priority environmental issues that had critical consequences to humanity’s well-being, and which “scream out for broad action”. The report also emphasized the world’s growing vulnerability, Mr. Steiner said, adding that the phenomena it described were of such a magnitude and moving with such rapidity, that humanity and nature’s normal ability to adapt and adjust to changes were “simply being undermined”.

PRESS">http://www.un.org/News/briefings/docs//2007/071025_UNEP.doc.htm]PRESS CONFERENCE ON LAUNCH OF REPORT BY UNITED NATIONS ENVIRONMENT PROGRAMME, ‘GLOBAL ENVIRONMENT OUTLOOK: ENVIRONMENT FOR DEVELOPMENT’

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Here's a summary of key tipping points - or "tipping elements" as they're called here, in climate systems:
[quote]Anthropogenic forcing could push the Earth’s climate system past critical thresholds, so that important components may “tip” into qualitatively different modes of operation. In the renowned magazine “Proceedings of the National Academy of Sciences” (PNAS) an international team of researchers describes, where small changes can have large long-term consequences on human and ecological systems.

“Society may be lulled into a false sense of security by smooth projections of global change,“ the researchers around Timothy Lenton from the British University of East Anglia in Norwich and Hans Joachim Schellnhuber from the Potsdam Institute for Climate Impact Research report. Global change may appear to be a slow and gradual process on human scales. However, in some regions anthropogenic forcing on the climate system could kick start abrupt and potentially irreversible changes. For these sub-systems of the Earth system the researchers introduce the term “tipping element”.

Drawing on a workshop of 36 leading climate scientists in October 2005 at the British Embassy, Berlin, Germany, a further elicitation of 52 experts in the field, and a review of the pertinent literature, the authors compiled a short-list of nine potential tipping elements. These tipping elements are ranked as the most policy-relevant and require consideration in international climate politics.

Arctic sea-ice and the Greenland Ice Sheet are regarded as the most sensitive tipping elements with the smallest uncertainty. Scientists expect ice cover to dwindle due to global warming. The West Antarctic Ice Sheet is probably less sensitive as a tipping element, but projections of its future behavior have large uncertainty. This also applies to the Amazon rainforest and Boreal forests, the El Niño phenomenon, and the West African monsoon. “These tipping elements are candidates for surprising society by exhibiting a nearby tipping point,” the authors state in the article that is published in PNAS Online Early Edition. The archetypal example of a tipping element, the Atlantic thermohaline circulation, could undergo a large abrupt transition with up to ten percent probability within this century, according to the UN climate report from 2007.

Given the scale of potentially dramatic impacts from tipping elements the researchers anticipate stronger mitigation. Concepts for adaptation that go beyond current incremental approaches are also necessary. In addition, “a rigorous study of potential tipping elements in human socio-economic systems would also be welcome,” the researchers write. Some models suggest there are tipping points to be passed for the transition to a low carbon society.

Highly sensitive tipping elements, smallest uncertainty:

Greenland Ice Sheet - Warming over the ice sheet accelerates ice loss from outlet glaciers and lowers ice altitude at the periphery, which further increases surface temperature and ablation. The exact tipping point for disintegration of the ice sheet is unknown, since current models cannot capture the observed dynamic deglaciation processes accurately. But in a worst case scenario local warming of more than three degrees Celsius could cause the ice sheet to disappear within 300 years. This would result in a rise of sea level of up to seven meters.

Arctic sea-ice - As sea-ice melts, it exposes a much darker ocean surface, which absorbs more radiation than white sea-ice so that the warming is amplified. This causes more rapid melting in summer and decreases ice formation in winter. Over the last 16 years ice cover during summer declined markedly. The critical threshold global mean warming may be between 0.5 to 2 degrees Celsius, but could already have been passed. One model shows a nonlinear transition to a potential new stable state with no arctic sea-ice during summer within a few decades.

Intermediately sensitive tipping elements, large uncertainty:

West Antarctic Ice Sheet - Recent gravity measurements suggest that the ice sheet is losing mass. Since most of the ice sheet is grounded below sea level the intrusion of ocean water could destabilize it. The tipping point could be reached with a local warming of five to eight degrees Celsius in summer. A worst case scenario shows the ice sheet could collapse within 300 years, possibly raising sea level by as much as five meters.

Boreal forest - The northern forests exhibit a complex interplay between tree physiology, permafrost and fire. A global mean warming of three to five degrees Celsius could lead to large-scale dieback of the boreal forests within 50 years. Under climate change the trees would be exposed to increasing water stress and peak summer heat and would be more vulnerable to diseases. Temperate tree species will remain excluded due to frost damage in still very cold winters.

Amazon rainforest - Global warming and deforestation will probably reduce rainfall in the region by up to 30 percent. Lengthening of the dry season, and increases in summer temperatures would make it difficult for the forest to re-establish. Models project dieback of the Amazon rainforest to occur under three to four degrees Celsius global warming within fifty years. Even land-use change alone could potentially bring forest cover to a critical threshold.

El Niño Southern Oscillation (ENSO) – The variability of this ocean-atmosphere mode is controlled by the layering of water of different temperatures in the Pacific Ocean and the temperature gradient across the equator. During the globally three degrees Celsius warmer early Pliocene ENSO may have been suppressed in favor of persistent El Niño or La Niña conditions. In response to a warmer stabilized climate, the most realistic models simulate increased El Niño amplitude with no clear change in frequency.

Sahara/Sahel- and West African monsoon - The amount of rainfall is closely related to vegetation climate feedback and sea surface temperatures of the Atlantic Ocean. Greenhouse gas forcing is expected to increase Sahel rainfall. But a global mean warming of three to five degrees Celsius could cause a collapse of the West African monsoon. This could lead either to drying of the Sahel or to wetting due to increased inflow from the West. A third scenario shows a possible doubling of anomalously dry years by the end of the century.

Indian summer monsoon - The monsoon circulation is driven by a land-to-ocean pressure gradient. Greenhouse warming tends to strengthen the monsoon since warmer air can carry more water. Air pollution and land-use that increases the reflection of sunlight tend to weaken it. The Indian summer monsoon could become erratic and in the worst case start to chaotically change between an active and a weak phase within a few years.

Lowly sensitive tipping elements, intermediate uncertainty:

Atlantic thermohaline circulation - The circulation of sea currents in the Atlantic Ocean is driven by seawater that flows to the North Atlantic, cools and sinks at high latitudes. If the inflow of freshwater increases, e.g. from rivers or melting glaciers, or the seawater is warmed, its density would decrease. A global mean warming of three to five degrees Celsius could push the element past the tipping point so that deep water formation stops. Under these conditions the North Atlantic current would be disrupted, sea level in the North Atlantic region would rise and the tropical rain belt would be shifted.[/quote]
[url=http://www.pik-potsdam.de/news-1/press-releases/tipping-elements-in-the-... elements in the Earth's climate system[/url]

Post I've just made to NY Times; responding to article on Cato Institute report along lines of Lomborg's utterances: warming willl have bad consequences, but we'll become so much richer that no need to do anything to stop them.
Here, inc my belief that notions v wrong; could be economic tipping point, too, closing our window of opportunity to actually do anything re warming.
[quote]After reading much info re warming, I've come to believe that if we dither re action now (not sure why the dithering - fear?), we'll find ourselves so busy dealing with the consequences, devoting so many resources to them, that will become unable to really tackle causes of global warming.

Witness, say, the tornadoes that just struck the US: can't say for sure that a result of warming, but the kind of thing predicted, and which we're likely to see more of. Response needed.

Increase frequency of such weather disasters - and organisations like OXfam already reporting significant increases - and could find it's like trying to put out one fire after another, without energy/resources to tackle problems that have made many of those fires occur.

But, maybe a minority will be rich, relatively insulated; and Cao happy to pander to their ilk.[/quote]