It has been a summer of withered crops and wildfires, the U.S.’s driest in the last fifty years, during which 55 percent of the U.S. has experienced a drought. And of the land dedicated to corn production, 87 percent has been dry.
Over at Technology Review, Jessica Leber wrote about an engineering solution to the problem of parched corn: seeds bred or genetically enhanced to resist drought, some of which have been tested this summer and will be sold by three big seed companies next year.
Ulva Island rain forest in New Zealand.
It’s clear that cutting down rain forests to plant crops, however fulfilling in the short-term for a farmer, is a disaster for the millions of species living there. But it could also, in the long term, be a disaster for the farmer. A recent study in Nature combines rainfall data, satellite images showing tree cover, and atmospheric modeling to show that air that has passed over tropical forests often carries at least twice as much water as air that’s passed over less leafy land. That means that large-scale cutting of rain forests can result in catastrophic drought for hundreds of miles around.
The Mayan rain god Chac
Droughts do far worse than brown our lawns—the water shortages and crop damage they mete out, and the fires fed by dry conditions, have effects that last long after rain returns. These events may even have civilization-destroying powers: although doubts remain, many researchers consider drought one of the leading contributors to the collapse of the Maya. And a new study published in Geophysical Research Letters finds that by cutting down forests, Mayans may have directly contributed to the droughts that brought about the downfall of their society.
Like modern civilizations, Mayans felled trees in order to harvest the raw material and clear land for cities and crops. Researchers modeled how this deforestation affected local climate conditions with computer simulations. Cleared land absorbs less solar energy, which means it releases less moisture to contribute to rainfall. By comparing untampered or regrown forest to reconstructions of the tree cover during Mayan occupation, researchers found that razed land could have reduced annual rainfall by 5 to 15 percent. This means that of the estimated drought during the height of Mayan civilization, 60 percent of the rainfall decrease was likely due to deforestation.
Brown rice. White rice. Sushi. Rice pudding. Rice in all its wonderful forms is the main food source of over three billion people, which makes this statistic all the more ominous: Right now, droughts and floods threaten over 25% of Earth’s rice harvests. But that doesn’t faze one group of scientists who have discovered that rice evolved to to resist floods also resist droughts.
The gene Sub1A, which is found in a few strains of rice, is responsible for this dual flood-drought protection. The researchers who discovered it in 1996 feared that a gene that protects a plant against flooding might make it especially sensitive to drought. So UC–Riverside researcher Julia Bailey-Serres and her colleagues were all the more surprised that the Sub1A gene actually makes rice better at coping with water shortage. This welcome trait became apparent after the water-starved plants grew fresh shoots after the researchers subjected the plants to a mock drought in the lab.
So how does a single gene work against both floods and droughts? The gene triggers a stressed plant to go dormant (whether that stress is an overabundance or lack of water) until the environment recovers from that stress. This may seem like an ability of limited use out in the world, but it’s actually important for some plants. After water levels go down at the end of a flood, a rice plant that had grown accustomed to soaking in water becomes dehydrated, as if it were suffering through a drought. As strange as it sounds, drought is a natural process in the flooding cycle, and it’s this fact that tricks the Sub1A gene into allowing rice plants to become dormant during both floods and droughts, conserving energy for up to two weeks, before reawakening after the waters recede or rain finally returns.
This gene for flood tolerance only naturally occurs in certain low-yielding rices in India and Sri Lanka, but scientists have already genetically engineered some high-yielding rice to exhibit this trait—which means that some farmers have also unknowingly been protecting their crops from droughts as well.
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Image: flickr / matsuyuki
“This is probably going to wind up being the first salvo in a pretty significant debate.” That’s what political scientist Cullen Hendrix told New Scientist in November of last year, when a study came out proclaiming the climate change would spur an uptick in civil wars in Africa. He was correct. This week, another study that will be published (in press) in the same journal—Proceedings of the National Academy of Sciences—says there is no proof to back up such a connection.
The argument for a link between global warming and war came from UC-Berkeley economist Marshall Burke, who said that food shortages and drought brought on by climate change could cause 50 percent more armed conflict by 2030 under the scenarios that climate models predict. However, Norwegian political scientist Halvard Buhaug looked at sub-Saharan civil war over the last half century for this week’s study. When he compared the records of military conflict with the records of temperature and rainfall, did not see a correlation between the two.
[Buhaug] found that that there was a strong correlation between civil wars and traditional factors, such as economic disparity, ethnic tensions, and historic political and economic instability. [BBC News]
It’s a good thing that the early English settlers of America were hardy and stubborn, because they certainly didn’t have good timing. The settlers who established the Jamestown colony in Virginia is 1607 arrived during a historic drought, according to the records kept in tree rings, the worst in the area in 800 years. And now researchers have created an even more detailed picture of the dire climate situation those colonists stumbled into, and they did it with the colonists’ trash.
Oyster shells, to be exact.
The telltale oysters were unearthed from a well that sat within the fort at Jamestown, about 100 yards from the [James] river. Among other material dumped into the well, the shells came from three distinct layers up to 3.5 meters deep. The well’s water level originally sat deeper, at a depth of about 4 meters, so Spero and his colleagues suggest that the settlers abandoned the well — which either ran dry during the drought or was infiltrated by salty groundwater — and converted it into a trash pit [Science News].
For years, farmers in Kenya’s arid north have suffered huge losses when droughts wiped out their cattle herds. Now, they have a means to protect their sole source of livelihood when rains fail and grasslands disappear. A new insurance scheme hopes to safeguard cattle-rearers in northern Kenya’s drought-prone Marsabit district by using satellite imagery to track changing landscapes and the subsequent loss of cattle.
The program, launched by the International Livestock Research Institute, is being billed as the world’s first insurance program to track changing pastoral grounds. When the satellite photos reveal that a verdant green landscape has changed to a dry brown, the insurance kicks in and farmers can collect their payments. The program will make things easier for insurance companies–for whom estimating losses in the past has been all but impossible. Partly because it has simply been too expensive for insurers to go and count the number of dead animals which might be spread over a vast rural area [BBC]. The scheme’s launch comes at a time when the Marsabit region has suffered 28 droughts in the last 100 years and four in the past decade alone [Kenya Broadcasting Corporation].
The region today known as Iraq was once known as Mesopotamia, which means “Land Between the Rivers,” and since that ancient time the land between the Euphrates and Tigris rivers has been renowned for its fecund soil and thriving farms. But now the Mesopotamian cradle of civilisation seems to be returning to desert [New Scientist].
Decades of war and mismanagement, compounded by two years of drought, are wreaking havoc on Iraq’s ecosystem, drying up riverbeds and marshes, turning arable land into desert, killing trees and plants, and generally transforming what was once the region’s most fertile area into a wasteland…. “We’re talking about something that’s making the breadbasket of Iraq look like the Dust Bowl of Oklahoma in the early part of the 20th century” [Los Angeles Times], said Adam L. Silverman, a social scientist with the U.S. military.
Fierce dust storms this spring have stained Colorado’s snow-covered peaks with brown, red, and pink dust, and state officials point out that this isn’t just a change in scenery. The darker snow is absorbing more radiation from the sun and is therefore melting faster and sooner than it normally would, which is upsetting the careful water rationing that defines life in the American West. Twelve dust storms barreled into the southern Rockies from the deserts of Arizona, Utah and New Mexico so far this year…. That, coupled with unseasonably warm temperatures, has sped up the runoff here, swelling rivers to near flood stage, threatening to make reservoirs overflow and fueling fears that there will not be enough water left for late-summer crops [Los Angeles Times].
In Colorado, melting snow accounts for about 80 percent of the water that flows through rivers and ends up in the state’s lakes and reservoirs. Colorado water engineer Scott Brinton explains that the early snowmelt could spell disaster for thousands of farmers and ranchers in the region who depend on slowly melting snow to provide water flows over the dry summer months…. “Those people who were relying on the mountain snowpack are going to have difficulty later in the year…. There’s not a whole lot we can do about it,” Brinton said. “We’re telling people, ‘You’ll be getting your water early this year, so use it while it lasts’” [Greenwire]. But scientists note that this may not be just a year of freak storms, it may be a harbinger of things to come.
West Africa has a history of severe, prolonged “mega-droughts,” according to a new study, and researchers say that another one is inevitable, although they can’t say when it might occur. Says lead researcher Tim Shanahan: “It’s disconcerting – it suggests we’re vulnerable to a longer-lasting drought than we’ve seen in our lifetime…. If the region were to shift into one of these droughts it would be very difficult for people to adapt; and we need to develop an adaptation policy” [BBC News].
The study, which examined sediment samples on a lake bottom to trace the climate history back 3,000 years, reveals that the infamous 1970s drought of the African Sahel region, which lasted several decades and killed more than 100,000 people, was actually a “minor” event…. “What’s disconcerting about this record is that it suggests the most recent drought was relatively minor in the context of the West African drought history” [New Scientist], says Shanahan. The researchers found that decades-long droughts similar to the 1970s event occur every 30 to 60 years, but that even more severe, century-long droughts have reoccurred as well. The most recent mega-drought began in 1400 and lasted until 1750, during which time forests grew up in dry lake beds.