There are many reasons to worry about the connections between climate change and drought. As temperatures increase, they change precipitation patterns for several reasons. These include changing the rate of evaporation from rivers and lakes, altering the composition of ecosystems, and other impacts. Forests, in particular, play important roles in the hydrological cycle. Some, like Kenya’s Mau forest, are hydrologically critical for large regions. If climate change makes forests change composition, dry out, and burn, it could have big effects on downstream agriculture.
Another major danger is loss of glaciers and summer snowpack. Both play a moderating role when it comes to river levels: accumulating snow in winter and releasing it as meltwater in summer. When rivers lose this buffer, they expand in wet times and shrivel in dry ones. This is dangerous not only for agriculture, but for electrical generation as well. The Colorado River, host to a slew of dams, may encounter serious problems of this sort in coming decades. Lake Mead, located on the Colorado and serving Las Vegas, is drying up dramatically. So will many others. Himalayan glaciers are especially concerning, given how important they are to the flow patterns of major rivers that serve densely populated areas.
Desalination, as an alternative to fresh water use, has major problems of its own – foremost among them that it uses a lot of energy. If that energy is coming from fossil fuels, the use of desalination may well worsen water problems in the long term, by contributing ever more to the stock of greenhouse gasses in the atmosphere.
Responding to all of this requires more than just climate change mitigation. It also requires more intelligent water policies, such as discouraging the overuse of non-renewable aquifers and ensuring that farmers and industrial users of water pay for it at a level that encourages responsible use. People who argue that ‘water is a human right’ and should therefore be free are ignoring the fundamental problem of scarcity. If we allow heavy users unlimited license to take what they want for next to nothing, we risk depriving other people of the more basic right to the quantities required for basic consumption and sanitation. The alternative is to effectively subsidize drought. States should also be thinking about ways in which they can import ’embedded water’ in the form of crops from wetter regions. Growing wheat in deserts is a folly some states have indulged in so far, but may do well to abandon in a more water-constrained (and riverflow-variable) future.
East Africa’s drought
A catastrophe is looming
Sep 24th 2009 | NAIROBI
From The Economist print edition
Governments are at their wits’ end to keep their hungry people alive
THIS year’s drought is the worst in east Africa since 2000, and possibly since 1991. Famine stalks the land. The failure of rains in parts of Ethiopia may increase the number needing food handouts by 5m, in addition to the 8m already getting them, in a population of 80m. The production of Kenyan maize, the country’s staple, is likely to drop by one-third, hitting poor farmers’ families hardest. The International Committee of the Red Cross says famine in Somalia is going to be worse than ever. Handouts are urgently needed by roughly 3.6m Somalis, nearly half the resident population (several million having already emigrated during years of strife). In fractious northern Uganda cereal output is likely to fall by half. Parts of South Sudan, Eritrea, the Central African Republic and Tanzania are suffering too. Rich countries are being less generous than usual. The UN’s World Food Programme says it has only $24m of the $300m it needs just to feed hungry Kenyans for the next six months.
In Mwingi district, in Kenya’s Kamba region, the crops have totally failed. Villagers are surviving on monthly government handouts of maize-meal, rice and a little cooking oil. Worse than the hunger, say local leaders, is the thirst. People are digging wells by hand, but they hit rock. They plead for the means to go deeper but they cannot afford the dynamite or machinery.
In the pastoral areas of northern Kenya, southern Ethiopia and south Somalia the death of livestock on a massive scale has sharpened conflict. Oromo rebels in south and east Ethiopia and Somali secessionists in the east of the country are likely to fight more fiercely. The drought may strengthen the hand of the Islamist Shabab movement, linked to al-Qaeda, in south Somalia; it uses food aid to control the people. Recent cattle raids in northern Kenya have left scores dead, with unprecedented numbers of women and children among the victims. Fighting may intensify until the land becomes greener again.
“The drought cycle in east Africa has been contracting sharply. Rains used to fail every nine or ten years. Then the cycle seemed to go down to five years. Now, it seems, the region faces drought every two or three years. The time for recovery—for rebuilding stocks of food and cattle—is ever shorter. And if the rains fail before the end of this year, an unimaginably dreadful catastrophe could ensue.”
Oddly – and inappropriately – the article above doesn’t mention climate change at all.
Firstly, it is quite possible that climate change partially explains the changing rain conditions now seen in East Africa.
Secondly, it is highly likely that continued unchecked climate change will further exacerbate droughts both there and elsewhere.
The worst part of climate change may be severe drought
And here the whole time we thought the biggest downsides of climate change were polar melt and flooded coastlines. But a new study suggests that what we really need to fear is prolonged drought. Wet your lips and read on.
Bake it to the limit: Aiguo Dai, a scientist at the National Center for Atmospheric Research in Colorado came to that conclusion after analyzing 22 computer models. He thinks that unless greenhouse-gas emissions are cut, large areas of the planet, including the U.S. Southwest, are in for some very long, very damaging dry spells within the next 30 years. Few continents would escape — Dai mentions parts of Asia, southern Europe, and much of Africa, Latin America, and the Middle East — and he believes regions bordering the Mediterranean Sea could suffer “almost unprecedented” drought conditions. Says Dai:
“We are facing the possibility of widespread drought in the coming decades, but this has yet to be fully recognized by both the public and the climate change research community. If the projections in this study come even close to being realized, the consequences for society worldwide will be enormous.”
The drying of the West
The Colorado River and the civilisation it waters are in crisis
STANDING on the Hoover Dam and looking upstream at Lake Mead, America’s largest reservoir, the visitor notices a wide, white band ringing the cliffs. Nicknamed “the bathtub ring”, this discolouration comes from minerals that were once deposited on the volcanic rock by the Colorado River and have become visible as its level has dropped. It is one sign of a water crisis that threatens America’s south-west.
Other reminders abound. Farther upstream there are dry docks, jutting out ominously into desert, where boats were once moored. In one finger of Lake Mead buildings that were abandoned in the 1930s, as the water of the newly dammed river rose and submerged them, have eerily begun reappearing, like a ghost town.
The main reason why Lake Mead, currently only 40% full, has been getting emptier is a decade-long drought. Whether this is a cyclical and normal event, or an early sign of climate change, is unclear. But even if the drought ends, most scientists think global warming will cause flows on the Colorado River to decrease by 10-30% in the next half century, says Douglas Kenney, the director of a water-policy programme at the University of Colorado Law School.
Drought in the South
Bone-dry
Drought has blanketed nearly a third of the lower 48
EVERY year’s weather is worse than the year before’s. Each summer is hotter, each winter more bitter. At least, that’s what people like to grumble; sometimes, though, the impression is actually accurate. According to a report on July 12th by the United States Drought Monitor, nearly 30% of the land in the contiguous United States (the 48 states other than Alaska and Hawaii) is affected by drought. Rainfall is at a fraction of its usual levels, heat at historical highs. Temperatures this week have exceeded 105°F (40°C) in many places—not just in the sweltering South, but in parts of the mid-Atlantic and the Great Plains, where soil soaked by the spring floods adds a horrible humidity.
About 12% of the country is in an “exceptional” drought, the worst category. That swathe of fire is centred on Texas, stretches north into Kansas, and sprawls from Arizona in the west to Georgia in the east (see map). And according to forecasts from the National Oceanic and Atmospheric Administration, things will get worse before they get better.
The National Drought Mitigation Centre at the University of Nebraska at Lincoln has catalogued the consequences, using media reports, government analyses and contributions from the public. It lists more than 1,000 problems in the past six months. There are wildfires in the south-west and water restrictions in the south-east. Fields are scrubby and fallow, and in some counties the ground is riddled with deep cracks. Farmers are struggling to produce crops, and ranchers are worried about watering their cattle. As their losses mount, crop prices have risen. According to a report from the Texas AgriLife Extension Service, wheat was selling at more than $8 a bushel at the beginning of the summer, compared with an average annual price of $5.25 last year. Still, Texas farmers will bring in only an estimated $274m this year; the average for the past five years was more than twice as high.
Across America farmland is parched, corn is wilting, reservoirs are low, rivers are running dry and wildfires have broken out in Utah and Colorado. Serious drought conditions are creeping across most of the contiguous 48 states, and a new report from the National Climatic Data Centre finds that 55% of the continental United States was in moderate to extreme drought and a third in severe to extreme drought as of July 10th (see map).
…
On July 16th the USDA downgraded the quality of domestic corn, rating 38% as “very poor” or “poor”. This was up from 30% the week before, and is a rating not matched since 1988. At the same time 30% of soyabeans were rated in very poor or poor condition, up from 27%.
Drought and climate change
Cloud nein
Is global drought really getting worse?
WHEN the worst drought in 60 years hit America’s corn belt this summer, many people wondered if it was caused by climate change. It is too early to say much about such a recent episode but various studies have attributed earlier individual heatwaves or drought to global warming, notably those in Europe in 2003, Russia in 2010 and the sweltering summer of 2011 in Texas. The most recent (2007) assessment by the Intergovernmental Panel on Climate Change (IPCC) said bluntly: “higher temperatures and decreased precipitation have contributed to changes in drought.” This week a study for the World Bank by the Potsdam Institute for Climate Impact Research argued that “extreme summer temperatures can now largely be attributed to climatic warming since the 1960s.”
Global warming might cause drought because warm air holds on to water vapour, making rain even less likely in places that are already dry. But a study published recently in Nature casts doubt about whether that is actually happening.
The drying of the West
Drought is forcing westerners to consider wasting less water
…
The “ridiculously resilient ridge,” an unusually persistent high-pressure zone, has installed itself off the Pacific coast, stopping precipitation systems from travelling towards the Sierra Nevada, where they typically deposit their moisture. Last month snowpack in the Sierras fell to 12% of average January levels. Rainfall has disappointed for three years. Lake Folsom, near Sacramento, has shrunk so far that an old gold-rush town has been exposed. The rainy season has six weeks or so to go, but there is little sign of respite. California is bracing itself for a brutal fire season.
…
The problem is that 1922 fell in an unusually wet period. For decades that did not matter; the basin states were not big enough to demand their full allocation. No more: five of the seven are among America’s ten fastest-growing states. Moreover, climate change may be reducing supply even as demand rises. In 2012 the FBR said that by 2060 the supply gap from the Colorado could reach 3.2m acre-feet (an acre of water a foot deep is the standard unit for large amounts of the precious liquid).
Mediterranean drought
Explaining the lack of rain in Spain (and Italy)
Dry spells are no longer freak events in southern Europe
“There is strong evidence from climate models and centuries of tree ring data that suggest about one-third to one-half of the severity of the current drought can be attributed to climate change,” observed Benjamin Cook, a climate scientist from Nasa’s Goddard Institute for Space Studies in New York.
Agency scientists added that the data suggested a “megadrought” might already be underway in this region – and that it could last for decades.
The latest update from the US Drought Monitor in December 2020, showed that much of the country’s western states were gripped by extreme or exceptional drought, with Nevada, Utah, Arizona and New Mexico, Colorado and western Texas being the worst affected.
https://www.bbc.com/news/science-environment-56225862