The Geopocalypse is nigh: A science writing linkfest
The fight for abundant, clean, fresh water will be one of the most important arenas in coming decades. As a professor of mine once said, “The wars that will be waged over energy and water will trump anything that my generation ever had to live through. And I was born in the 1920s.” He later admitted he was trying to shock us into paying attention on the first day of the new semester, but his words rang true enough that they’ve stuck with me over the years.
How the world’s water supplies will be affected by a progressively warming climate is, understandably, a major area of investigation. Because of its importance, I’ve recently pumped out (get it? Hydrology humour) a big pile of journal summaries covering a wide swath of water science. (Or, maybe it’s the fact that the AGU happens to have a journal called Water Resources Research.)
Shrinking Alpine glaciers spell trouble for Europe’s rivers – As I live in the lap of aqueous luxury, resting my head within a tank of gas of a quarter of the world’s fresh water, it’s easy to forget that many countries’ supplies are less abundant and less stable. In western Europe, a web of well-known and important rivers—like the Danube and the Rhine—draw some of their water from glaciers nestled in the Swiss Alps. The total volume of glacier water feeding the rivers was never very high, but some new research showed that what was particularly important was when the water seeped down from the mountains. Glacier melt peaks in the summer, exactly when other sources tend to dry up. The relative importance is only amplified when drought strikes the region. While this is nice to know on its own (who needs bottled glacier water when it’s right there in the river?), it becomes sort of scary when you realise that glacier run-off will all but disappear by the end of the century.
Groundwater depletion’s contribution to sea level rise increasing - Climate change is coming. We’re more-or-less locked in to 2°C of warming and the myriad consequences that entails. One of the easier effects of warming world to get your head around is sea level rise. Heat goes up, land-locked ice goes down, ocean goes up. Or, heat goes up, water expands, ocean goes up [but not much, see below]. But there is another important factor, and it goes like this: Farmer settles in the desert, massive quantities of groundwater are pumped up for irrigation, water makes its way to the oceans, oceans go up. In order to figure out exactly how tall the stilts should be on your beach-side cottage (you have one, right? Can I visit? I’ll bring candy.) we need to know how much each of these sources has contributed to the 17 centimeters of sea level rise we’ve already seen over the past 100 years. It turns out that groundwater depletion accounts for around 13 millimetres of it. But, the irrigation-driven part of the equation is ramping up rapidly. Between 2000 and 2008, we pumped a quarter of what we drew from the ground in the entire stretch from 1900 to 2000. This new study falls a bit under some previous estimates (which I wrote about here and here), and above some others.
Was ocean acidification responsible for history’s greatest extinction?- Another major water-related worry of climate change is the very really threat of ocean acidification. As the ocean absorbs more carbon dioxide (which it will inevitably do as atmospheric levels rise), some
fancy chemistry will slowly drive down the ocean’s pH, and ramp up its hostility to cute little crustaceans, corrals, and anything else that relies on the water maintaining its current carbonate balance. As if to drive the point home, a new study suggests that the greatest extinction of all time may have been fuelled by ocean acidification.
Other water-related stories:
The quandary of peat:
While water issues may be one of the most widely publicized dilemmas coupled to climate change, I’d say that the biggest wild card award goes to permafrost peatlands. These frozen-marsh-muck landscapes store absolutely massive quantities of carbon, enough to quadruple atmospheric carbon dioxide levels if it all got out. Northern peatlands might be just waiting to bust at the seams, or they could become a giant sink for greenhouse gases as mosses and shrubs colonize the newly-opened terrain. The problem is, we just don’t know what’s going to happen with them. Hence, wild card. Two studies came out recently, one trying to figure out how peatlands might react to climate change and one tracking how they’ve changed so far.
For more on northern peatlands, see this interview. Caution: Paywall :(
Other climate changey goodness (both past and future):
Weird things are cool:
Atmospheric waves break on the Moon’s shadow - This one is just plain cool. Apparently, when there is a solar eclipse and the Moon blocks out the Sun’s light, the atmosphere under the Moon’s shadow cools down just enough to trigger acoustic-gravity waves. Wait… what?
[An aside on gravity waves!
The Earth's atmosphere is separated into layers based on buoyancy. Now let's say that as a friendly air packet is casually moseying along above ocean, a small island just totally pops out of nowhere. With nothing else it can do, the air gets forced up over the island, pushing it into an atmospheric layer where it just doesn't belong. Trying to get the air packet back to its rightful home, gravity gets a little bit too eager, and pulls the little air packet into a lower layer where it also doesn't belong. Now buoyancy takes over, and the air packet rises up, again overshooting
its appropriate atmospheric layer. It’s like some messed up version of Goldilocks and the Three Bears, but if Goldilocks was on speed and kept running past the middle bowl, bouncing between the too-hot and too-cold porridge. So that’s one way that gravity waves can be formed, and when they happen to pass through clouds they can look really cool.
Acoustic-gravity waves are like regular gravity waves, but made of sound. No, I don’t get it either.]
So in the new study, the cooling effect of the Moon’s shadow sends these acoustic-gravity waves shooting out from the leading and trailing edges as the shadow traces its path over the surface of the Earth. But, because the waves move through the atmosphere more slowly than the Moon’s shadow passes over the surface of the Earth, the waves end up looking an awful lot like the bow waves and stern wake you get when a boat zips through the water. The researchers used the bow waves and stern wake to figure out that, were the Moon’s shadow a boat, it would be over 1700 kilometers long.
And, because I’m sick of writing little blurbs about studies for which I’ve already written little blurbs…: