1
$\begingroup$

Lake Eyre in Australia has an area of roughly 4,000 square miles, but the basin itself is over 450,000 square miles. If the entire basin were freshwater, how would that affect the Outback's climate?

$\endgroup$
  • $\begingroup$ Over the long term I'd expect it to evaporate and return to 4000 sq miles. Until then you'd have normal weather patterns you'd get from any large body of water. $\endgroup$ – GrandmasterB Jun 16 '15 at 20:13
  • 1
    $\begingroup$ Normal weather patterns I'd get from any large body of water. Which is what, exactly? $\endgroup$ – JohnWDailey Jun 16 '15 at 20:27
  • $\begingroup$ My guess it that the impact will be small. Consider that Central Asia is a desert with a relatively large temperature gradient and yet, it's next to one of the largest closed sea. $\endgroup$ – Vincent Jun 16 '15 at 21:07
  • 1
    $\begingroup$ The −15 m (−49 ft) altitude usually attributed to Kati Thanda–Lake Eyre refers to the deepest parts of the lake floor, in Belt Bay and the Madigan Gulf. The shoreline lies at −9 m (−30 ft). Why is this relevant, because you can't 'flood' that 450,000 square miles, that includes hills, raises and high terrain that channels water towards and ultimately into the lake. Most of Australia would be underwater if you were to put that entire basin underwater. That being said if you'd fill it as much as you could, the depth of your lake would'nt be much more than it's current fill records. $\endgroup$ – Spacemonkey Jun 16 '15 at 21:08
  • $\begingroup$ With those numbers I think you could compare it to any large lake on the planet and have an idea of what impact to expect (i.e. Canada and the US' great lakes cover 94,250 square miles and go down to 406m in depth at the lowest point) $\endgroup$ – Spacemonkey Jun 16 '15 at 21:13
1
$\begingroup$

It's hard to say exactly how a randomly placed large body of water will effect the area's climate. In the long run, GrandmasterB is most likely correct. In the mean time, you will not only change your local climate, but that of a much larger area.

Water has an incredibly high heat capacity. That means that it can store a lot of heat. Essentially, the water will absorb a lot of the heat that would normally be put into the air during the day, and will then slowly release it during the night. Now rather than have really hot days, and really cold nights, I would assume the outback has a more moderate climate.

$\endgroup$
  • $\begingroup$ Are you thinking of river connections and discharges "in the long run"? $\endgroup$ – JohnWDailey Jun 16 '15 at 20:54
  • $\begingroup$ The outback is a pretty dry place. That water is going to evaporate and head elsewhere. It will take a while, but it would probably happen. We can't really know for sure if this will alter weather patterns enough to bring in as much water as is being lost. $\endgroup$ – Jacobm001 Jun 16 '15 at 21:02
  • $\begingroup$ Why this assumption of evaporation? If the lake were big enough and deep enough, couldn't that be avoided? $\endgroup$ – JohnWDailey Jun 16 '15 at 21:25
  • $\begingroup$ @JohnWDailey: No, it'll just take longer. $\endgroup$ – Jacobm001 Jun 16 '15 at 21:26
  • 1
    $\begingroup$ @JohnWDailey: That's not true. The level of the great lakes fluctuates, like any other body of water. The difference between the Great Lakes and the Outback is that the Great Lakes area gets a ton of rain. Follow the link below and see how much water they lose and regain every year. The Outback doesn't get that kind of rain fall. Not even close. glerl.noaa.gov/data/dashboard/GLWLD.html $\endgroup$ – Jacobm001 Jun 16 '15 at 22:09
1
$\begingroup$

If we assume there is a way for the lake to be recharged (otherwise, as noted, it will eventually dry up and revert to the current size), then the presence of a large body of water will do two things:

  1. Moderate the local microclimate. The water will absorb the heat of the day and slowly release it at night, reducing the temperature swings. Over the longer term, it will also tend to reduce the overall temperature during the summer and increase it during the winter (we are talking a very small overall change; there won't be palm lined beaches in winter...)

  2. Affect the larger hydrological cycle. The evaporation of water from the lake will result in a large area receiving rain in the "downwind" area. Given the size of Australia, there is some risk that the evaporated water will actually be deposited outside the boundaries of Australia itself (i.e. the rain falls in the oceans), which would make this a bit pointless as a geoengineering project.

Like all closed basins, the greatest danger is the lake itself will gradually become briny and toxic, since as the water flows in, the sediments and accumulated "stuff" is deposited but cannot leave. As the water evaporates, what is left becomes saltier, and toxins become more concentrated, much like the situation in the Salton Sea in the US or the Aral Sea in central Asia.

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.