Since 1938, John Bradfield has called for rivers in Australia to be turned inland, to create a permanently-filled Lake Eyre. Proposals to pipe or channel seawater into Lake Eyre from the Upper Spencer Gulf date back a long time; one such proposal was seriously considered by South Australian Parliament in 1883. Lake Eyre is a usually dry lake which at its lowest point is 15 meter below sea-level. The idea was that flooding Lake Eyre would create clouds and rain for inland Australia. The resulting vegetation would retain moisture and help turn further desert and arid land into fertile soil.
Such hydraulic engineering schemes are part of the history of geoengineering. Unfortunately, the Wikipedia page on hydraulic geoengineering has been deleted. Solar power (solar concentrators, vortex towers, etc) in the desert could power such projects, i.e. pumping water over barriers, powering earth-moving vehicles, etc, possibly complemented by desalination, CO2 air capture, spraying water into the sky, and more. >From the perspective of global warming, such projects will have a number of effects, each constituting either positive or negative forcing in terms of global warming. Water vapor acts as a greenhouse gas, trapping heat - clouds, on the other hand, have a higher albedo than deserts, so clouds will also reflect more sunlight back into space. Vegetation has a lower albedo than desert - vegetation, on the other hand, also draws CO2 from the air and stores it in the soil. I believe that the overall impact will be beneficial, but I'd love to see anyone come up with more calculations to support this. Until now, such projects have been regarded as too expensive, i.e. if the sole purpose was to create fertile land. However, the benefits in terms of climate change may change that picture. Cheers! Sam Carana ---------- Forwarded message ---------- From: Andrew Lockley <[email protected]> Date: Mon, Jun 8, 2009 at 9:30 AM Subject: [geo] Re: Flooding below sea-level: Siphonics Natural Engineering (c) To: [email protected] Cc: geoengineering <[email protected]>, Johnnie Buttram <[email protected]> It seems pretty counter-intuitive to me. Firstly, flooding deserts to create either lakes or vegetation would generally reduce albedo (darken), leading to more solar energy being absorbed, and hence causing temperatures to rise. Secondly, water vapour is a powerful greenhouse gas, and thus increasing its concentration in the atmosphere will cause further net forcing. Thirdly, desert areas predominantly exist in areas of downwelling air. Therefore, the creation of large cloud systems with high albedo over these regions would be unlikely. This is in contrast to tropical forests, which create large clouds through evapotranspiration into rising air. It seems that this approach would not have any immediate climate benefits. It may, however, be a good way to cultivate deserts - although I suspect the maintenance costs, constructions costs and ever-present salinity problem would make it unattractive. Look at the Aral sea region as an example of the difficulties in cultivating in brackish water. A 2009/6/7 Ken Caldeira <[email protected]> > > Folks, > > I ran across this pdf recommending the benefits of flooding sub sea-level > desert areas. > > I believe the author of this document (cc'd) would enjoy your comments. > > Best, > > Ken > > > ___________________________________________________ > Ken Caldeira > > Carnegie Institution Dept of Global Ecology > 260 Panama Street, Stanford, CA 94305 USA > > [email protected]; [email protected] > http://dge.stanford.edu/DGE/CIWDGE/labs/caldeiralab > +1 650 704 7212; fax: +1 650 462 5968 --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "geoengineering" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/geoengineering?hl=en -~----------~----~----~----~------~----~------~--~---
