California’s Central Valley is one of the world’s most productive crop-growing regions. But growing crops in the vast rich soils requires a lot of water. Some of that water comes from melting Sierra mountain range snow, with a pinch of rainfall mixed into the rivers that are tapped for irrigation. But farmers also pump a lot of their water out of the ground.
A lot of water that is pumped out of the ground evaporates. In some places, that contributes to rising seas, with water being shifted from the land into the oceans.
But in California, scientists have discovered that evaporating Central Valley water turns into clouds that deposit their consignments east of the Sierra, fueling the monsoons of the Southwestern United States and increasing flows in the Colorado River by more than one quarter. The findings were published online Tuesday in Geophysical Research Letters.
California ends up getting some of the water back. Some Colorado River water is diverted and sent west through what the study’s lead researcher, Jay Famiglietti of the University of California at Irvine, dubs an “anthropogenic loop.”
Famiglietti told me that the study illustrates that large-scale water management practices, such as irrigation, can have “profound regional, and even global” impacts.
“We need to understand, much better, what those impacts are,” Famiglietti said.
One of the first things that every botany student learns is the simple process by which trees drink water. The water enters the roots from moisture in the soil and is sucked up the trunk through straw-like xylem to the leaves, where some evaporates. The combined effects of water tension and water cohesion inside the xylem and evaporation from the leaves keeps the water flowing against the force of gravity.
A study of trees growing on Costa Rican mountains revealed that some high-altitude species can pull switcheroos on this widespread drinking system. When the soil is parched and their canopies are saturated by clouds, these trees use their leaves to suck water out of the air and then send the moisture back toward their trunks.
“Water is still moving along a gradient from areas with more water to areas with less water,” Greg Goldsmith, a tropical plant ecologist at the University of California, Berkeley and lead author of the study, which appeared this month in Ecology Letters, told me. “It’s just a different gradient.”
The clouds that nurture these cloud forests are evaporating as the planet warms, meaning the cloud-drinking strategy could doom those trees that rely upon it. That would be bad news for the birds and other wildlife that live in cloud forests, which are some of the world’s most striking and biodiverse ecosystems.
“The phenomenon of water from clouds entering leaves — foliar water uptake — indicates a much tighter relationship between clouds and cloud forest plants than previously known,” Goldsmith said.
It’s not enough for mushrooms to simply produce spores. A little more than one-third of the world’s known fungal species, including mushrooms, puffballs and rusts, use a neat canon-ball trick that sends those spores sailing through the air toward newfound territory.
This trick relies on the detonation of a fluid-filled sac to send so-called ballistospores airborne. It turns out that this neat trick not only helps fungus spread: Scientists recently discovered that these explosions may help keep the rain falling over the Amazon rainforest.
Water cannot condense into a rain drop unless it has something solid, a “seed,” to grow around, such as a speck of dust or a grain of pollen. Lawrence Berkeley National Laboratory researchers searching for the seeds that help clouds form in the Amazon think they have found what they were looking for.
They reported in Science late last month that potassium salts coalesced with organic material to form the seeds that create the Amazon’s clouds. Based in part on an abundance of ballistospores in the atmospheres, the researchers think the salts are squirted out when these spores are ejected from fungus during the night.
Fungi are already known to play a critical role in breaking down old wood and leaves on the forest floor, recycling the nutrients and making them available for plants and animals; and now it appears that they also help to keep the Amazon wet and rainforesty. A pretty neat trick.
Juliane Koepcke remembered the advice of her father, a biologist, when she woke on the floor of the Amazon following a mid-air plane explosion. The injured 17-year old needed to find civilization, so she followed the water. She hobbled along riverbanks for more than a week until she discovered a hut and was rescued.
It’s a common survival technique: If you want to find civilization, follow the water. In tandem with carbon, water is the quintessential chemical essence of life. Cities, towns and villages all around the world cluster around shorelines, rivers and lakes.
That’s what NASA scientists are doing with the landing of the latest Mars rover: They are following clues of water in their decades-old search for extraterrestrial life. [Update — Curiosity landed safely on Sunday night.]
Curiosity is a mobile laboratory the size of a car. It’s the biggest, most expensive and most sophisticated robot ever sent to explore Mars – that cold and windswept wasteland that’s one planet farther from the Sun than Earth.
Without water, there can be no life. At least, not life as as we understand it. Find water and carbon along with a source of energy, however, and you could find life. If we could find life or its fossils on Mars, we could investigate whether the self-replicating nucleic acids that form genes that code life sparked into existence right here on Earth. Or, whether our primordial ancestors rocketed here on a shooting star, perhaps after being dislodged from Mars or from a foreign galaxy.
Based on evidence gathered during previous missions, NASA has no doubt that Mars harbored substantial liquid water reserves in its ancient past. Its landscape has clearly been swished and swirled around. Maybe some of the water is still there, deep beneath the surface, providing shelter for exotic microbial wildlife.
But Curiosity isn’t looking for life.
Instead, the robot will inspect, pick up, zap and analyze rocks and soil in Gale Crater, which may once have been a lake bed, in its search for biosignatures – organic molecules and unusual textures that might have been produced by life. The task is daunting. Even if Mars was once teeming with wildlife, signs of that life may have long since weathered away.
“If we employ Earth’s early geologic record as a guide to prediction of biosignature preservation in the ancient Martian rocks to be sampled,” researcher John Grotzinger and his colleagues wrote in Space Science Review in December, “then we should prepare to be patient.”
Following water on Earth can save a life. Following a trail of evaporated water on an inhospitable planet in a quest for ancient organic compounds is both arduous and expensive (the Curiosity mission cost $2.5 billion, and it is landing at a time when the U.S. is slashing spending on intergalactic studies), but it could help eventually explain the very genesis of life.
Hike away from a reservoir, and something interesting happens. As you walk away from the dam wall, or from any other part of the reservoir’s shore, the sound of chirping birds and buzzing insects often grows louder.
Despite resembling lakes, reservoirs are sterile environments bereft of wildlife. The visually stunning waterbodies are virtual dead zones because their water laps at steep cliffs that restrict shoreline habitat.
Shoreline habitat is a critical environment for birds, young fish and aquatic plants – not to mention the insects and other tiny creatures that more charismatic fauna feast upon. Remove gently sloping shorelines from an ecosystem and you remove much of its wildlife.
The most dramatic example I have experienced is in Yosemite National Park, where San Francisco dammed Hetch Hetchy Valley in the 1930s to create a drinking water reservoir.
The protected, pristine wild lands that surround the flooded meadow and forest environments create an extraordinary contrast: Birds and butterflies are virtually absent around the flooded valley; walk less than a mile in the right direction from the water’s edge and the din of insects and birds becomes aurally dazzling.
Drive away from a reservoir, and something else interesting happens. As you travel farther from the communities that are directly affected by drowned wild land, cheers of support for the presence of the reservoir often grow louder.
A dramatic example of this is playing out in the debate over Hetch Hetchy Valley’s future. San Francisco voters will decide in November whether the city’s water agency will overhaul its water management practices, expand some reservoirs and draw on new sources of recycled water and local groundwater and rainwater. All with the goal of eventually draining and restoring Hetch Hetchy Valley without jeopardizing Bay Area water supplies.
Near Yosemite in Sacramento, the Bee, the city’s hometown newspaper, has long championed efforts to drain the reservoir and restore the habitat into a wilderness mecca for wildlife and visitors. Although Hetch Hetchy is in Sacramento’s backyard, the city and its residents enjoy no real benefits from it.
Less than 100 miles from Sacramento, the Chronicle, one of San Francisco’s hometown newspapers, takes a different stance. Its editorials lambast the ballot initiative, describing it as “insane.” Its views reflect those of local elected officials and Bay Area business groups, most of whom see the reservoir as an indispensable source of snowmelt and cheap hydropower and, consequently, political power for the influential region.
The Chronicle’s owner, Heart Corp., doesn’t just editorialize. The publishing company in late June donated $2,500 to one of the political campaigns that aims to prevent the November ballot measure from passing. The donation, made to Citizens for Reliable Water and a Healthy Environment, came from the corporation’s San Francisco-based land management division.
That’s not a lot of money in the scheme of things, particularly given that ballot measure opponents have already raised more than $150,000 for their fight (supporters have raised more than $100,000, filings show, although I’m told that figure was recently doubled with a single donation), and it’s certainly unlikely to sway the election result. But the donation, combined with the dueling editorials, helps to illustrate how dramatically things can change as you get farther from a reservoir.
Vast regions of the Northern Hemisphere are currently being saturated by monsoons. In many warm climates, including parts of India, Australia and Africa, intense summertime storms satisfy much of nature’s and farmers’ yearly thirsts for water in weeks- to months-long blitzes.
For most of the year, winds blow dry air from North American deserts over Arizona, New Mexico and Texas. But as these southwestern states heat up in July and August, the winds shift and begin flushing vast volumes of water into the region from the gulfs of California and Mexico, fostering the North American Monsoon.
These winds carry moisture overland, but they can’t make it fall from the sky. Clouds must be seeded with tiny particles before they will dissolve into falling rain, and a major seeder of clouds worldwide is dust. Dust can also induce rainfall by altering atmospheric temperatures.
Researchers at the Paciﬁc Northwest National Laboratory in Washington recently used computer models to determine that heating effects of desert dust boost North American Monsoon rainfall by 40 percent. The dust’s seeding properties likely have further impact.
“Our next plan is to include this seeding effect in the model,” lead researcher Chun Zhao told me.
The discovery, published earlier this year in the journal Atmospheric Chemistry and Physics, suggests that monsoons could counterintuitively grow more intense if climate change produces a terrifying phenomenon that’s forecast to afflict the region: Megadrought.
“The deserts during the megadrought will expand outwards, which means creating more desert surface area,” Zhao said. “Our simulations imply that megadrought may emit more dust and increase the precipitation over the Texas and Arizona regions.”
Tortoises, toads and other creatures native to the southwest are well adapted to the wild weather extremes wrought by the region’s seasons. This new research suggests that these extremes are set to exacerbate as the climate changes. There’s a good chance that the rugged creatures of the desert will adapt better to these extremes than we do.
Salmon face a litany of badass predators during their short but meandering lives. After hatching, baby salmon must dodge hungry fish as they swim downstream and into the open ocean. Once in the ocean, they are preyed upon not only by fish and fishermen, but also by sea lions and other marine mammals. After they’ve grown for two to three years, the fish must make the perilous stream run one more time, this time against the current and often into the mouths of waiting bears, in a desperate bid to reach their spawning grounds.
The salmon can’t fight back or use poisons or barbs to defend themselves. Instead, when a predator is near, they lock down, freezing their movements in hopes that they will become invisible to the marauder.
But what happens when the marauder becomes invisible to the salmon? New research suggests that humanity’s wont to pollute has handed such an invisibility cloak to creatures that feast on salmon.
Salmon rely on their keen sense of smell to detect predators. They don’t so much smell the predators, instead they smell a chemical alarm dubbed Schreckstoff that’s released from the shredded bodies of their attacked and battered brethren. But the sense of smell is compromised when the fish swim in water polluted by copper, a common pollutant that flows into streams from mines, farms, buildings and roads.
Washington State University researcher Jen McIntyre set up an experiment to determine whether copper pollution leaves salmon more vulnerable to predators. Into tanks she deposited juvenile coho salmon and a predator species named cutthroat trout, along with Schreckstoff and small amounts of copper.
Salmon that swam in clean water froze in the tanks and managed to escape initial strikes by the trout nine times out of ten. But salmon that were swimming in copper kept blithely on swimming, and they were captured on the first strike 30 percent of the time, often within five seconds.
“They’re not in lockdown mode,” McIntyre said in a statement that coincided with publication of her results in the journal Ecological Applications. “Predators can see them more easily.”
That’s nifty for hungry fish, but not so promising for the populations of salmon that are clinging to survival in polluted waterways around the world.