Although crop albedo modification often comes under the category of solar geoengineering, I wonder if it could be wise to consider it more as part of possible adaptation measures. As mentioned in the article, it's more analogous to green cities and reflective rooftops. Given these crop modifications would also mostly just change regional climate, it really does seem more like an adaptation-thing than "geoengineering". Could be a useful rebrand, of sorts, making the option more palatable in the near-term for policymakers too.
On Wednesday, 16 June 2021 at 8:23:44 pm UTC+10 renaud.derichter wrote: > A brighter future: How whitening the Wheatbelt could cool the climate > *phys.org*/news/2021-06-brighter-future-whitening-wheatbelt-cool.html > <https://phys.org/news/2021-06-brighter-future-whitening-wheatbelt-cool.html> > <https://phys.org/archive/15-06-2021/> > > June 15, 2021 > > by Rockwell McGellin, Particle <https://particle.scitech.org.au/> > [image: A brighter future: how whitening the Wheatbelt could cool the > climate] From space, the line between crops and native vegetation is > stark. Credit: ESA/Copernicus > > There aren't many things humans have made that are visible from outer > space. WA's wheatbelt is one of them—and it could help us fight climate > change. > > The Wheatbelt. 150-odd thousand square kilometers of Australia's > south-west where dark, native vegetation has been replaced with lighter > agricultural crops <https://phys.org/tags/crops/>. The difference in > color is something you can see from orbit, but it might also be something > you can feel from right here on Earth. > > Like an enormous mirror, those crops bounce solar radiation back out to > space. That means WA's Wheatbelt—and the wheat growing there—could become a > crucial part of how southwestern WA adapts to climate change. > > Simulations show that, just by growing slightly lighter-colored crops, we > could reduce monthly mean daily maximum temperatures by 1.0 > <https://doi.org/10.1016/j.wace.2020.100282>–1.2°C > <https://doi.org/10.1016/j.wace.2020.100282>. To understand how a > seemingly tiny change could make such a huge difference, we need to > understand albedo—and an emerging field of climate science called > geoengineering. > > *Let's start with albedo* > > Albedo is a measure of how color affects temperature by reflection and > absorption of radiation. > > "I often use the analogy of wearing a black shirt on a really hot day," > says Dr. Jatin Kala, Senior Lecturer in Atmospheric Science at Murdoch > University's Harry Butler Institute. > > The lighter the color, the higher the albedo and the more light it > reflects. Scientists compare the albedo of different surfaces by giving > them a number between 0 and 1. > > "Albedo 0, you absorb everything, albedo 1 you reflect everything," Jatin > says. > > The same physics makes black cars hotter than white ones. On a larger > scale, it can affect the temperature of cities, countries and even our > entire planet. > > Our polar ice caps reflect a huge amount of radiation. As they melt, they > expose the dark soil beneath, which absorbs more heat so ice melts even > faster. > > (This is called polar amplification. It's one of the horrifying arrays of > unforeseen feedback loops that we're discovering as climate change > intensifies.) > https://youtu.be/sCxIqgZA7ag > Daisyworld is a simple simulation of how colour, climate and crops can > affect each other. Credit: NASA Goddard Space Flight Center > > *Messing with the system* > > What Jatin is proposing is the same concept but on purpose—and on a much > smaller scale. > > "It comes from this idea of geoengineering," Jatin says. "Basically, some > people have thought, "Well, we've been messing with the climate system, > let's mess some more to cool it down.'" > > As far as geoengineering projects go, changing the color of WA's entire > agricultural region is actually pretty modest. > > "People are starting to propose ideas such as putting aerosols in the > stratosphere to mimic what happens when there's a volcanic eruption. Or > let's put mirrors out into space—things which have got a whole bunch of us > very nervous," Jatin says. > > But humans have been changing the land we live on for a while already. > > "If we pay attention to the color of things, that is something we can > actually manage. If we grow huge areas of crops, let's just make all of the > crops more reflective and see what happens." > > *Light simulator* > > Of course, that doesn't mean going out and painting the entire Wheatbelt > overnight. If climate change <https://phys.org/tags/climate+change/> has > taught us anything, it's that messing with systems without some serious > forethought can have disastrous consequences. > > In this case, that forethought is coming from a climate model. It's a > complex calculation incorporating everything from vegetation to soil > type—including how reflective they all are. > > Each 10 square kilometers of land can be represented by a square on a grid > in a climate model. The air above each square is divided the same way. The > model calculates how the temperature of the atmosphere changes as you > change the land below it. > [image: A brighter future: how whitening the Wheatbelt could cool the > climate] It’s easy to see where the agricultural land and the adjacent > National Park begins. Credit: ESA/Copernicus > > Then, starting from the actual climate data, Jatin re-ran the past few > years of WA's weather inside a computer—with a twist. > > Global models, working with much bigger grid cells, had never showed much > change, but zooming in on just WA made a surprising difference. With an > increase of just 0.1 to the crops' albedo <https://phys.org/tags/albedo/>, > average maximum temperatures <https://phys.org/tags/maximum+temperatures/> > over WA dropped by about three times more than the global models predicted. > > *Solution or stopgap?* > > Like most geoengineering projects, painting the Wheatbelt is no > replacement for reducing the amount of carbon we put into the atmosphere in > the first place. > > "It does matter, but it's not going to change global climate," Jatin says. > "What it will change is regional climate <https://phys.org/tags/climate/> > ." > > It's a part of the same toolkit as green spaces in cities and reflective > rooftops in suburbs. It won't fix the problem, but it might help keep > places liveable for longer. > > Color is also just one part of an already pretty complex calculation for > farmers. > > "They want crops that are resilient to drought, and they want crops that > are high yield <https://phys.org/tags/high+yield/>, right? And more and > more with genomics, people are trying to develop crops which are going to > adapt better to lower rainfall and higher temperature and give us decent > yield," Jatin says. > > "But something else we should think of is if you have two crops and they > overall give you the same yield and they have the same drought tolerance, > go for the paler one." > ------------------------------ > > This article first appeared on Particle <https://particle.scitech.org.au/>, > a science news website based at Scitech, Perth, Australia. Read the original > article > <https://particle.scitech.org.au/earth/a-brighter-future-how-whitening-the-wheatbelt-could-cool-the-climate/>. > > > > > -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/geoengineering/d7c0c030-8532-4ec7-9bbc-e6e6ad564dean%40googlegroups.com.
