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The Century of Drought

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"The Century of Drought"

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century-of-drought.jpgBritish scientists have issued the harshest warning yet about the devastating impact of unrestrained greenhouse gas emissions: “One third of the planet will be desert by the year 2100.

This stunning new UK research, from the Met Office’s Hadley Centre for Climate Prediction and Research, shows

[The] figure for moderate drought, currently at 25 per cent of the Earth’s surface, rising to 50 per cent by 2100, the figure for severe drought, currently at about 8 per cent, rising to 40 cent, and the figure for extreme drought, currently 3 per cent, rising to 30 per cent.

Within 100 years, some 30 percent of Earth will be rendered essentially uninhabitable, leading to mass migrations and millions of environmental refugees. And this result is based on a greenhouse gas emissions growth scenario that ignores key carbon cycle vicious cycles (such as the tundra melting). The Independent reports: “In one unpublished Met Office study, when the carbon cycle effects are included, future drought is even worse.

The UK study shows that we are already seeing the impact of greenhouse gas emissions on drought: “In the last decade of the 20th century droughts were nearly 25% more widespread than in the previous 40 years.” Climate Progress has noted the undercoverage of the drought-climate link in the major US media, but the British media certainly gets it, as evidenced by the cover story in The Independent. That may be because there is less muzzling of scientists. The Met Office is actually within the UK’s Ministry of Defence.

If only our political leadership were as concerned with the security threat from global warming.

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9 Responses to The Century of Drought

  1. Fergus Brown says:

    I’d be cautious about this one, until the report becomes available: it’s based on a single-model run, a mid-high warming estimate, and comes up with a reasonably predictable result: the PDSI goes up a lot. It is also an example, worthy though The Independent may be, of turning a model run (‘what if?’, or ‘if…then’) into a ‘will be so’. As the report is due to be published, Hadley must have some confidence in the result, but I bet it sounds different when the actual thing is in print in front of us.

    And by the way, thanks for directing me to CS, but I’d already read Gavin’s (and the others’) comments, and understood them. I’ll see if one of Hansen’s cohort will give me an answer…
    Regards,

  2. Joe says:

    On our current path, we are directly headed for a mid-high estimate (I’m guessing that they are modeling something like 750 parts per million of atmospheric CO2 in 2100).

    Since we aren’t taking any action to stop the growth of greenhouse gas emissions, and since all evidence suggests that the tundra and other positive feedbacks are genuine but largely ignored in the models, I don’t think there’s anything wrong with modeling 750 and telling people what that will do to the planet. The notion that you can stabilize at 550 is increasingly becoming a fantasy (especially if you are not trying), and by the IPCC’s Fifth Assessment in 2013, I think this will all be standard received wisdom.

  3. Fergus Brown says:

    I’m with you on this one; such a scenario seems, atm, more likely than the TAR estimates. I also wouldn’t disagree that the consequences would, almost certainly, include increased dorught and some desertification, but you’ll notice that the ’1/3 of the world could be desert’ conclusion appears to stem from the ’1/3 of the world will experience moderate to extreme drought’: the newspaper is conflating the two. I’m fairly sure, too, that the article said that the run chose to exclude some variables, for valid reasons, but, of course, in a ‘full’ run, as in the real world, they would have an impact; I still feel caution is required.
    Regards,

  4. Fergus Brown says:

    As the paper hasn’t been published yet, but this abstract of a different paper has, I thought you would like to see it. This worries me more than the newspaper report:
    Wang, G.L., 2005: Agricultural drought in a future climate: results from 15 GCMs participating in the IPCC AR4. Climate Dynamics, 25, 739-753, 10.1007/s00382-005-0057-9.
    This study examines the impact of greenhouse gas warming on soil moisture based on predictions of fifteen global climate models by comparing the after-stabilization climate in the SRESA1b experiment with the pre-industrial control climate. The models are consistent in predicting summer dryness and winter wetness in only part of the northern middle and high latitudes. Slightly over half of the models predict year-round wetness in central Eurasia and/or year-round dryness in Siberia and mid-latitude Northeast Asia. One explanation is offered that relates such lack of seasonality to the carry-over effect of soil moisture storage from season to season. In the tropics and subtropics, a decrease of soil moisture is the dominant response. The models are especially consistent in predicting drier soil over the US Southwest, the Mediterranean, Australia, and the South Africa in all seasons, and over much of the Amazon and West Africa in the JJA season and the Asian monsoon region in the DJF season. Since the only major areas of future wetness predicted with a high level of model consistency are part of the northern middle and high latitudes during the non-growing season, it is suggested that greenhouse gas warming will cause a worldwide agricultural drought.

  5. [...] Global warming is poised to make this “The Century of Drought.” How ironic then that the two countries racing to see who will produce the most greenhouse gas emissions — China and the United States — are already in the grips of extended droughts. [...]

  6. [...] Hopefully Australia will see the value and urgency in taking climate action before the last puddle dries up, since unrestrained greenhouse gas emissions are projected to accelerate drought and desertification. [...]

  7. [...] engine). Business as usual greenhouse gas emissions may lead to desertification for a stunning 30% of the Earth’s surface! And now we learn: Severe water shortages are likely to constrain future expansion of population, [...]

  8. Larry says:

    Given that warming will increase evaporation and that what goes up must come down, where does the net new rain fall? If it’s toward the poles, doesn’t that mean that currently land that is not arable because of cold and dryness (notably Siberia) becomes arable?

    The bigger picture is that 100 years is plenty of time for us to figure out alternative energy, not to mention learning to manage the earth’s ecosystem to do what we need…

  9. flash games says:

    Since we aren’t taking any action to stop the growth of greenhouse gas emissions, and since all evidence suggests that the tundra and other positive feedbacks are genuine but largely ignored in the models, I don’t think there’s anything wrong with modeling 750 and telling people what that will do to the planet.