Reservoirs, dams and irrigation systems have shifted global patterns of water scarcity over three decades, “causing a distinct pattern of beneficiaries and losers”, according to recent research.

The study, published in June in Nature Communications, shows that these interventions have increased water availability for much of the global population, but also created scarcity that mostly occurs downstream.

The researchers say it is the first to provide a global accounting of regional and local water impacts caused by human intervention, and whether it has led to a reshuffle of water scarcity hotspots.

Using five global hydrological models, they examined the evolution of water availability, demand and scarcity globally from 1971 to 2010. They say their method produces scarcity estimates that are more realistic — and greater — than those produced by previous approaches. Read more

The moisture farmers of Tatooine could take a few tips from these projects for harvesting water out of thin air

The Namib desert beetle gathers water from fog that condenses on its bumpy back—which inspired one company to design a self-filling water bottle

Today, deserts cover about a fifth to a quarter of the world, and roughly a billion people live in desert conditions. These regions receive less than 20 inches of rain every year, which means finding fresh water for drinking and cleaning can be time-consuming and even dangerous, especially when it requires a trip to a faraway well or spring. The problems may only get worse if ongoing climate change intensifies droughts and human activities such as irrigtaion dry up many of the world’s accessible freshwater sources. Read more

The answer is far more complicated than it first appears—water doesn’t always turn to ice at 32 degrees Fahrenheit

Water crystallizes into ice at 32 degrees Fahrenheit most of the time, but not always. (Courtesy of Flickr user s.alt)

The title of this post would seem an appropriate question for an elementary-school science exam, but the answer is far more complicated than it first appears. We’ve all been taught that water freezes at 32 degrees Fahrenheit, 0 degrees Celsius, 273.15 Kelvin. That’s not always the case, though. Scientists have found liquid water as cold as -40 degrees F in clouds and even cooled water down to -42 degrees F in the lab. How low could they go? Read more

Surface water seasonality between October 2014 and October 2015 in the Sundarbans in Bangladesh. Dark blue indicates 
Where and when surface water occurs on Earth is vitally important for all life. But that water is constantly in flux. Lakes, rivers and wetlands naturally ebb and flow; humans divert water for their own use and dam it up into reservoirs. Now researchers have mapped millions of high-resolution satellite images to document Earth’s surface water history going back three decades—revealing humanity’s dramatic influence as well as the natural variability of water patterns.

Agricultural engineer Jean-Francois Pekel and colleagues have created a kind of virtual time machine, showing past changes in surface water and providing a baseline for charting the changing future of our watery world. To achieve this feat, Pekel and colleagues used more than 3 million LANDSAT images of Earth’s lakes, wetlands, and rivers taken between 1984 and 2015. They quantified global water system changes over that timeline on a month-to-month basis. Then, they analyzed this veritable ocean of satellite data with the Google Earth Engine cloud-computing platform. Read more

Mars is, largely, a cold, dead world. There’s still some water left at the poles and in the thin air, but for the most part Mars appears quite dry. It wasn’t always this way, however. Billions of years ago, scientists think, Mars was covered in water—peppered with lakes, or maybe even large oceans.

These images show the planet on the last day of Martian spring in the northern hemisphere (just before summer solstice). The annual north polar carbon dioxide frost (dry ice) cap is rapidly sublimating, revealing the much smaller permanent water ice cap.

Yet today most of that water is gone. Researchers think that over the past few billion years the red planet’s water was probably blown off into space, carried away by the solar wind with the planet’s disappearing atmosphere. But new evidence drawn from meteorites here on Earth chunks of Mars that had been blasted into space suggests that Mars might also have vast underground reservoirs. Read more