tag:blogger.com,1999:blog-5235419263414453422.post7716760962414127135..comments2024-02-23T01:30:06.101-08:00Comments on Early Warning: Should you Trust the PDSI?Stuart Stanifordhttp://www.blogger.com/profile/07182839827506265860noreply@blogger.comBlogger11125tag:blogger.com,1999:blog-5235419263414453422.post-8747809468841148032012-07-23T11:39:10.394-07:002012-07-23T11:39:10.394-07:00Stuart, do you have any insight whether the curren...Stuart, do you have any insight whether the current drought in the mid west will evolve into a multi-year event like in the 30's or 50's?<br /><br />thanks, <br />tessaDiscagehttps://www.blogger.com/profile/04527496973951935823noreply@blogger.comtag:blogger.com,1999:blog-5235419263414453422.post-91291395067855713632010-11-02T19:25:15.821-07:002010-11-02T19:25:15.821-07:00Thanks for the link to Sheffield and Wood, which h...Thanks for the link to Sheffield and Wood, which has a less dramatic presentation than Dai.porsenahttps://www.blogger.com/profile/04362269873149438270noreply@blogger.comtag:blogger.com,1999:blog-5235419263414453422.post-62823284898470262572010-11-01T17:22:47.911-07:002010-11-01T17:22:47.911-07:00porsena - interesting link! And I agree on the fa...porsena - interesting link! And I agree on the face of it there's a contradiction. There's also a paper I'm looking at <a href="http://www.springerlink.com/content/nh10377k006x6141/fulltext.pdf" rel="nofollow">here</a>, which is looking at soil moisture directly in the models. It predicts decreasing moisture in most places, but isn't as dire as the PDSI papers (both Dai, and also papers like <a href="http://journals.ametsoc.org/doi/pdf/10.1175/JHM544.1" rel="nofollow">Burke et al</a>, which says things like "Future projections of drought in the twenty-first century made using the Special Report on Emissions Scenarios (SRES) A2 emission scenario show regions of strong wetting and drying with a net overall global drying trend. For example, the proportion of the land surface in extreme drought is predicted to increase from 1% for the present day to 30% by the end of the twenty-first century."<br /><br />So there's more to do to reconcile these papers, and also with the paleo evidence. I think it's a very active area of research. <br /><br />One thing to think about is the seasonality. I speculate that you could end up with a situation where total run-off increases, but mainly in the winter and spring, and by the summer you are in drought (so the world's climate moves more toward a mediterranean/California type climate).Stuart Stanifordhttps://www.blogger.com/profile/07182839827506265860noreply@blogger.comtag:blogger.com,1999:blog-5235419263414453422.post-69408331493397194902010-11-01T16:44:42.684-07:002010-11-01T16:44:42.684-07:00Stuart, great thanks for these drought posts! They...Stuart, great thanks for these drought posts! They really woke me up. <br /><br />Porsena, I think the climate model used by Dai has a much more sophisticated treatment of precipitation that the one that Nohara used.Unknownhttps://www.blogger.com/profile/01415105955984414239noreply@blogger.comtag:blogger.com,1999:blog-5235419263414453422.post-53360629882262636842010-11-01T15:06:06.383-07:002010-11-01T15:06:06.383-07:00Stuart, the fit between the PDSI and river dischar...Stuart, the fit between the PDSI and river discharge in your graphs above made me think about the changes in precipitation projected by climate models. <br /><br />Global climate models have suggested that there should be a small net increase in global precipitation and a redistribution of rainfall from the tropics into temperate and northern latitudes. The temperate element looks to be underestimated in the forecast PDSI. <br /><br />There's an interesting <a href="http://journals.ametsoc.org/doi/abs/10.1175/JHM531.1" rel="nofollow"> paper by Nohara and co-authors</a> that looks at the projected change in river hydrographs for 24 of the world's major rivers. The authors ran a hydrological model on the output of 19 different GCM simulations with the A1B scenario, a vision of the future that some of us feel projects an unreasonably large consumption of fossil fuels. <br /><br />The pattern found in the Nohara study reflects the shift in precipitation from the tropics to temperate and northern regions. Only seven of rivers were projected to show a decrease in annual discharge. The Nile, for example, whose region shows a severe drought in Dai's PDSI forecast for 25 years out, showed an increase of 12.7% by the end of the century. The Mississippi, also showing severe drought in the PDSI forecast, showed a change of 0.2% in its annual mean discharge and very little seasonal change either. <br /><br />I think I'm going to need more convincing that future drought patterns will be as Dai projects.porsenahttps://www.blogger.com/profile/04362269873149438270noreply@blogger.comtag:blogger.com,1999:blog-5235419263414453422.post-13118491211329899892010-11-01T13:51:46.531-07:002010-11-01T13:51:46.531-07:00Another great tutorial, Stuart.
> the PDSI see...Another great tutorial, Stuart.<br /><br />> the PDSI seems to be a decent approximate indicator of drought<br /><br />Yes. For the messy, messy real world, I'd say it's a very good indicator.<br /><br />> humans can certainly do a lot of adaptation over the course of thirty years<br /><br />Undoubtedly we can, but adaptation on this scale is likely to cause a sustained increase in the real price of food. Not good for the billion or so living on less than $2 a day. I think you're still right to be worried by this.Greghttps://www.blogger.com/profile/11939046017258198038noreply@blogger.comtag:blogger.com,1999:blog-5235419263414453422.post-57955676560538865792010-11-01T12:13:06.471-07:002010-11-01T12:13:06.471-07:00I see,
thanks for link to the articles, I have re...I see,<br /><br />thanks for link to the articles, I have read some of them. If Cina really wants to scale up renewables, I think prices will go up... how much, that will have to be seen,<br /><br />regards,<br />AlexAlexander Achttps://www.blogger.com/profile/16845172528191878930noreply@blogger.comtag:blogger.com,1999:blog-5235419263414453422.post-21825846923871183042010-11-01T11:52:55.321-07:002010-11-01T11:52:55.321-07:00Alexander: I've tracked the story a bit. I d...Alexander: I've tracked the story <a href="http://earlywarn.blogspot.com/search/label/rare%20earths" rel="nofollow">a bit</a>. I don't think we are close to fundamental limits on rare earths. It's more a story of China cornering the market, and then jacking up the price (as well as using it as a club in foreign policy disputes).Stuart Stanifordhttps://www.blogger.com/profile/07182839827506265860noreply@blogger.comtag:blogger.com,1999:blog-5235419263414453422.post-56184402418262138062010-11-01T11:49:25.960-07:002010-11-01T11:49:25.960-07:00brett:
Yes. I'm not a fan of this, but it do...brett:<br /><br />Yes. I'm not a fan of this, but it does seem to me likely that climate change will lead to ever further increases in human management of landscapes because they won't be coping with our ealier effects (just as we are more and more involved in managing endangered species, because they can't cope with the reduction and splintering of their habitats). There will be more and less responsible ways of doing this, but I see even very responsible stewards having to deal with this issue. Eg suppose you manage a nature preserve, and the existing trees are burning or dying of disease. It's probably going to make more sense to try to figure out some other non-traditional tree species that can cope with the emerging conditions than it will be to do nothing.Stuart Stanifordhttps://www.blogger.com/profile/07182839827506265860noreply@blogger.comtag:blogger.com,1999:blog-5235419263414453422.post-80787873721723186662010-11-01T10:38:50.214-07:002010-11-01T10:38:50.214-07:00"From the perspectives of wild ecosystems, th..."From the perspectives of wild ecosystems, that may not matter much, since anthropogenic climate change is so abrupt compared to the normal rate of change prehistorically. But from the perspective of human-managed landscapes, it matters a lot, since humans can certainly do a lot of adaptation over the course of thirty years (different crops, new more drought-tolerant crops, irrigation in areas where it currently isn't used, etc)."<br /><br />I'm sure those advocating for systemic climate engineering will like this conclusion. Nature is screwed so carte blanche.bretthttps://www.blogger.com/profile/05280209182671727081noreply@blogger.comtag:blogger.com,1999:blog-5235419263414453422.post-23448319428835833242010-11-01T10:14:41.838-07:002010-11-01T10:14:41.838-07:00Stuart, wonderfull!! In between the drought, maybe...Stuart, wonderfull!! In between the drought, maybe you missed this imporatant message:<br /><br />"Shortage of alternative energy minerals will trigger trade wars"<br /><br />http://www.tgdaily.com/sustainability-features/52283-shortage-of-alternative-energy-minerals-will-trigger-trade-wars<br /><br />Limits to growth of alternative energy industry may come sooner than expected,<br /><br />AlexAlexander Achttps://www.blogger.com/profile/16845172528191878930noreply@blogger.com