Comments on: The Century of Drought http://climateprogress.org/2006/10/04/the-century-of-drought/ The Latest on Climate Science, Solutions, and Politics Fri, 08 Aug 2008 20:43:29 +0000 http://wordpress.org/?v=2.1 By: Fergus Brown http://climateprogress.org/2006/10/04/the-century-of-drought/#comment-64 Fergus Brown Wed, 04 Oct 2006 16:42:48 +0000 http://climateprogress.org/2006/10/04/the-century-of-drought/#comment-64 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, 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,

]]> By: Joe http://climateprogress.org/2006/10/04/the-century-of-drought/#comment-65 Joe Wed, 04 Oct 2006 17:13:37 +0000 http://climateprogress.org/2006/10/04/the-century-of-drought/#comment-65 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. 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.

]]> By: Fergus Brown http://climateprogress.org/2006/10/04/the-century-of-drought/#comment-66 Fergus Brown Wed, 04 Oct 2006 17:31:51 +0000 http://climateprogress.org/2006/10/04/the-century-of-drought/#comment-66 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, 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,

]]> By: Fergus Brown http://climateprogress.org/2006/10/04/the-century-of-drought/#comment-67 Fergus Brown Thu, 05 Oct 2006 20:46:31 +0000 http://climateprogress.org/2006/10/04/the-century-of-drought/#comment-67 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. 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.

]]> By: Climate Progress » Blog Archive » A U.S.-China Race with No Winners http://climateprogress.org/2006/10/04/the-century-of-drought/#comment-172 Climate Progress » Blog Archive » A U.S.-China Race with No Winners Mon, 06 Nov 2006 18:02:01 +0000 http://climateprogress.org/2006/10/04/the-century-of-drought/#comment-172 [...] 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. [...] […] 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. […]

]]> By: Climate Progress » Blog Archive » Australia’s Facing Worst Drought for 1000 Years http://climateprogress.org/2006/10/04/the-century-of-drought/#comment-1114 Climate Progress » Blog Archive » Australia’s Facing Worst Drought for 1000 Years Tue, 19 Dec 2006 16:02:00 +0000 http://climateprogress.org/2006/10/04/the-century-of-drought/#comment-1114 [...] 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. [...] […] 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. […]

]]> By: Climate Progress » Blog Archive » Dawn of the Super-Interglacial Drought? http://climateprogress.org/2006/10/04/the-century-of-drought/#comment-2956 Climate Progress » Blog Archive » Dawn of the Super-Interglacial Drought? Fri, 23 Feb 2007 16:41:07 +0000 http://climateprogress.org/2006/10/04/the-century-of-drought/#comment-2956 [...] 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, [...] […] 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, […]

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