Nov 20, 2012

Why 4 degrees will end the world as we know it: World Bank

The World Bank has produced an alarming report that puts in context the risks of inaction on emissions reduction and climate change. It doesn't make for pleasant reading.

The World Bank yesterday released a report prepared by the Potsdam Institute spelling out what the world is likely to experience if it warmed by 4 degrees -- that's looking increasingly likely by the end of the century without some serious policy changes by governments globally. The report essentially attempts to summarise much of the research literature that has built up since the 2007 fourth IPCC Assessment Report and puts it in the context of the path we’re on unless we start taking this problem seriously. It doesn't make for pleasant reading. World Bank President Dr Jim Yong Kim says "it is my hope that this report shocks us into action", as he believes "a 4 degree world can, and must, be avoided". For the World Bank, with a primary purpose to help impoverished nations out of poverty, "the lack of action on climate change not only risks putting prosperity out of reach of millions of people in the developing world, it threatens to roll back decades of sustainable development". The chart below provides an impression of the alternative emission paths and their likely implications for temperature rise. According to the report, we are on a path illustrated by the red line. However, if governments follow through on the pledges they've made at the UN's Copenhagen and Cancun summits then it would put us on the purple line, giving a mean temperature rise estimate of 3 degrees. But even this path still carries a 20% chance of temperature exceeding 4 degrees. If governments don't make good on their pledges then the red line would imply a 40% chance of warming above 4 degrees.

Median estimates of temperature rise from probabilistic projections for several scenarios

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35 thoughts on “Why 4 degrees will end the world as we know it: World Bank

  1. Mark Duffett

    Given geological evidence of coral reefs thriving at CO2 concentrations far in excess of 450 ppm, “coral reefs would stop growing at a CO2 concentration of about 450ppm” is probably an oversimplification. While currently dominant coral species begin to labour under these conditions, it’s certain that other, better adapted species currently restricted to niches will come to the fore. Reef systems as a whole will thus be maintained – if (and yes, it’s a biggie) there is enough time for the system adaptation to occur.

  2. Microseris

    Mark, I would prefer not to watch whole suites of species go extinct and wait for development of new ecosystems, just because we are too lazy and selfish to act.

    If it was war, who would argue about the personal sacrifice and action required or associated costs. However the potential outcomes look far worse than any war – a habitable planet.

  3. Al Black

    “It doesn’t make for pleasant reading.”
    Fortunately it doesn’t make credible reading either: the so-called research is just a rehash of dated and largely discredited IPCC material: The Himalayan glaciers are not melting, nor are the ice-caps on Greenland or Antarctica, and the Antarctic sea ice continues to grow: the exact opposite of what the IPCC models predicted. Polite Peer review articles say “the Antarctic ice spread has the effect of limiting confidence in the models’ predictions”. That means the World Bank is pontificating on outdated conclusions: What runaway warming?

  4. Merve

    Al, your claims should read “a few Himalayan glaciers are not melting, though most are, the ice caps on Greenland are melting faster than anticipated, the Antarctic sea ice is growing to a small degree with normal bounds, as expected, but the overall sea ice is shrinking dramatically. Overall, the global cryosphere is shrinking faster than expected”. Your statement is either wrong, or leaving out that you are looking at a few cherries amongst the global melt.

  5. Harry1951

    Al Black: pray tell what is your source for the “largely discredited IPCC material”? BTW, no one is talking about “runaway warming”. That reads suspiciously like a “straw man” argument to me.

  6. Observation

    Now I am skeptical. What is the world bank up to with this report. I smell a rat!

  7. Brent Hoare

    Isn’t it hilarious when some random anonymous internet guy chimes into a serious debate, and with a ridiculous rhetorical rant claims to know better than respected climate scientists, in this case the Potsdam Institute and a panel of eminent peer reviewers?

    Or it would be if the promotion of such wrong-headed ideas did not help to create the political space for the Opposition’s silly non-policy on carbon pricing and climate change.

  8. floorer

    “Poles apart: satellites reveal why Antarctic sea ice grows as Arctic melts”, copy and hit google and that will take you to the article in the Guardian/Environment/Climate Change section. No point putting up a direct link it will only go into moderation. Btw do you why the Arctics melting faster than the Antarctic? Because hot air rises, boom boom, all my own work can you tell?

  9. fractious

    Mark Duffett @1
    That ‘“coral reefs would stop growing at a CO2 concentration of about 450ppm” is probably an oversimplification’ is doubtless true.

    However, your claim “it’s certain that other, better adapted species currently restricted to niches will come to the fore” is similarly oversimplified. Where – given coral reefs are not contiguous – would these “other, better adapted species” come from? How would they migrate given that it isn’t simply a case of elevated temperature as a cause of their demise but sea level rise and (notably) rapidly falling oceanic alkalinity?

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