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Hikers ascend through the smog of  Los Angeles, one of six cities where researchers studied the effects of air pollution on the heart. By Flickr User Jason Morrison

One morning a couple of years ago, I decided to take a jog around the perimeter of my hotel in Delhi, India. A little bit of exercise might mitigate the crushing jetlag after my 24-hour flight from California, I thought. Within a minute or two of sucking in the city’s soot-filled air, my lungs and eyes were scorched. While I knew that Delhi’s air quality was bad, I had no idea it’s the 12th worst in the world—nor was I aware of precisely how damaging air pollution can be to the body.

As we’ve written about recently, researchers have discovered that smog can cause lung cancer and that nano-particles in the air burrow through cell membranes, possibly damaging the lungs and the circulatory system. But a new study published today in the journal PLOS Medicine shows that exposure to fine particulate matter in the air may be linked to a faster hardening of the arteries in otherwise healthy people, which can lead to increases in stroke and heart attack.

The study, conducted by researchers from University of Michigan and University of Washington, followed nearly 5,500 people—all heart-disease-free—from six American metro areas (Baltimore; Chicago; Los Angeles; New York City; Winston Salem, North Carolina and St. Paul, Minnesota). Scientists began the study by conducting ultrasound tests to measure the thickness of each participant’s right common carotid artery, which supplies blood to the head, neck, and brain.

Residents of New York City participated in a study that linked air pollution to increased risk of heart attack and stroke. By Flickr user JRGCastro

The participants’ home addresses were then recorded, and the researchers tapped the Environmental Protection Agency’s Air Quality System, a database of air quality levels gathered by monitors throughout the country, to gauge the amount of fine particulate matter in their neighborhoods. The scientists were able to factor in variables including proximity to major streets and highways, which allowed for a great deal of precision–air pollution concentrations varied, as it turned out, even within specific neighborhoods. Within the next five years, the thickness of each participant’s artery was tested once more. The scientists estimated their exposure to fine particulate matter during the period between the exams.

What they found was that exposure to higher concentrations of fine particulate air pollution correlated with an accelerated thickening of the arteries. Conversely, reductions in air pollution were linked with a slower progression of arterial thickening. Such a thickening or hardening of the arteries can eventually block the flow of blood to the head, resulting in stroke, or to the heart, causing heart attack.

“Linking these findings with other results from the same population suggests that persons living in a more polluted part of town may have a 2 percent higher risk of stroke as compared to people in a less polluted part of the same metropolitan area,” study author Sara Adar said in a statement.

The findings may also help shed light on previous studies that have linked chronic air pollution exposure and death, and may encourage lawmakers to support clean air standards. “Our findings furthermore bolster recent reports that falling pollution levels in the United States after the adoption of the Clean Air Act are associated with reduced mortality and increased life expectancy,” the study authors wrote.

Air quality in the United States is far superior to that in many parts of the world. But where is air quality the worst? The World Health Organization’s database of global air pollution statistics reveals that low- and middle-income regions of the Eastern Mediterranean have the worst air quality overall. Among cities, Ahwaz in Iran is the world’s most polluted. Mongolia’s Ulan Bataar ranks second in air pollution and Delhi comes in 12th.

The W.H.O. rankings are based on the number of parts per million of particles smaller than 10 micrometers (PM10) floating around in the air. Even the filthiest air in the U.S., in California’s San Joaquin Valley, pales in comparison to these other cities. Ahwaz has 372 PM10, while Delhi has 198. Bakersfield, the most polluted city in the U.S., has 38.

The best cities in the U.S. for keeping your arteries free and clear? Santa Fe, New Mexico and Clearlake, California–each with a PM10 of just six. Much healthier choices for a jog the next time around.

Drought and an increased demand for water have stressed the Colorado River, which flows nearly 1,500 miles through seven states and Mexico. Photo by Flickr user Alex E. Proimos

When Alexandra Cousteau, granddaughter of Jacques, recently went to Mexico to explore the southern terminus of the Colorado River, she found mud, sand and dust where water once raged. The expedition was videotaped for a short film (viewable below) produced in conjunction with Cousteau’s nonprofit, Blue Legacy, which raises awareness about water issues. The video was called Death of a River: The Colorado River Delta.

That title, it turns out, is an apt one: Today, the conservation organization American Rivers released its annual ranking of America’s most endangered rivers, and the Colorado topped the list.

The group cites outdated water management as the main malady attacking the Colorado’s health. “A century of water management policies and practices that have promoted wasteful water use have put the river at a critical crossroads,” a statement (PDF) released by the organization reads. “Demand on the river’s water now exceeds its supply, leaving the river so over-tapped that it no longer flows to the sea.”

At one time, the river emptied into the Gulf of California, between mainland Mexico and the Baja Peninsula. In fact, this river mouth can still be found on maps, including Google’s, because it’s supposed to be there. But a recent study (PDF) conducted by the Bureau of Reclamation (a division of the U.S. Department of Interior) determined that the entire river and its tributaries are siphoned off to meet the drinking, bathing and toilet-flushing needs of 40 million Americans throughout seven states, including Arizona, California, Colorado, New Mexico, Nevada, Utah, and Wyoming. It also irrigates 5.5 million acres of land and helps meet the electrical-power appetite of much of the West through hydro-power facilities. Nearly two dozen Native American tribes depend on it, and it’s the centerpiece of 11 national parks, most famously the Grand Canyon.

“Growing demands on the Colorado River system, coupled with the potential for reduced supplies due to climate change may put water users and resources relying on the river at risk of prolonged water shortages in the future,” the study authors write. “Ultimately,” they add, “the Study [sic] is a call to action.”

Low water levels at the Colorado River’s Hoover Dam, on the Arizona-Nevada border. Photo by Flickr user Remon Rijper

But what action is needed? Water conservation, water reuse and water augmentation–replacing water drawn from wells–the authors say. Specifically, landowners and municipalities must boost their agricultural, municipal and industrial water conservation agendas, as well as improve their energy water-use efficiency. Solutions for the most challenging regions include finding ways to import water, reuse waste water and desalinize ocean and brackish water.

Scientists acknowledge some solutions they’ve looked into are easier said than done and that not all are viable in every region. For instance, options like importing water to Southern California via submarine pipelines, water bags and icebergs (PDF), along with watershed management techniques like weather modification (aka cloud-seeding) are a bit pie-in-the-sky.

The Colorado isn’t the only endangered river, by far. Georgia’s Flint River, the San Saba River in Texas, Wisconsin’s Little Plover River, the Catawba River in the Carolinas and Minnesota’s Boundary Waters were all also red-flagged by American Rivers this year.

The challenge for all of these rivers, including the Colorado, only grows in the future. Climate-change-induced drought is working against them. American Rivers notes (PDF) that changes to climate are expected to reduce the Colorado River’s flow by as much as 10 to 30 percent by the year 2050. It could leave yet more sand and mud behind, making parts of the American West and Southwest even more parched.

Scientists believe the absence of seed-dispersing birds is thinning the forests on the island of Guam. Photo by Isaac Chellman

Visitors to Guam’s forests find them quiet–eerily so: No chirping of birds can be heard overhead. But slithering in the shadows on the ground are snakes, each some six feet long. Brown tree snakes made their debut on Guam, the southernmost island in the Mariana Archipelago, when islanders were rebuilding after World War II. Most likely, they were stowaways in lumber shipments heading north through the Pacific Ocean from New Guinea. They quickly began feasting on the birds and small lizards they discovered in Guam’s dense forests, and–free to slither through the mountainous terrain without predators of their own–they completed an invasion of the island at a pace of one mile per year. By the late 1940s, the forests had largely fallen silent, and now, all of Guam’s native bird species are history.

Last fall, scientists from Rice University and the University of Guam published one of the first studies of the island’s extinct forest birds, which include species such as the Mariana fruit dove, Guam flycatcher and Rufous fantail. They focused on how the absence of birds has caused a spike in the spider population, which is 40 times greater on Guam than nearby islands.

Now, the researchers are turning their attention to the issue of Guam’s thinning forests—a consequence, they also believe, of the bird deficit. This summer they’ll launch a four-year study of 16 tree species, looking at how the loss of birds, which scatter seeds, is affecting tree distribution.

The brown tree snake has obliterated nearly all of Guam’s bird species since it was introduced during World War II. Photo by Isaac Chellman

The study has its roots in an a-ha moment that lead scientist Haldre Rogers recently had while conducting another seed-dispersal study in Guam’s forests. “I noticed that there seemed to be a lot of gaps [in the trees] and that the pioneer tree species–such as papaya and sumak–were difficult to find on Guam, compared to nearby islands,” she explained to Surprising Science. She discovered that there were in fact twice as many such gaps on Guam per unit area of forest. 

Pioneer trees, which are the first to appear after a disruption to the ecosystem and thrive in the full sunlight of open spaces in the forest, have small seeds that are consumed by small birds. “Without birds to move their seeds to these sunny spots in the forest, these quick-growing trees may be less likely to germinate or grow to their full size,” Rogers hypothesized.

The problem with such thinning is that it could change the structure of Guam’s forests. “There’s a concern that [they] may become filled with open areas and start to look more like Swiss cheese than a closed canopy forest,” Rogers said. In other words, what were once cool, dark forests could transform into hot, open sunny ones.

There are other possible explanations for the tree-thinning: An undiscovered forest disease could be targeting pioneer species, or mammals like pigs and deer might have a strong taste for the trees. But according to Rogers, there isn’t strong evidence to support either of these scenarios. The upcoming study will attempt to determine the cause definitively.

The Mariana fruit dove was driven to extinction by the brown tree snake on Guam and is highly endangered on other islands in the Mariana Archipelago. Photo by Isaac Chellman

To that end, the researchers will cut down individual trees in various spots within Guam’s forests, creating new gaps in the forest. They’ll also remove trees from locations on two nearby islands that are still brimming with birds. Then they’ll monitor how long it takes the spaces to fill in and take note of which seedlings thrive on Guam versus on the other islands. It may seem that to get their results they’re destroying what they’re trying to study, but in actuality they’re taking down a tiny percentage of the island’s trees–20 total.

Guam’s situation is similar to that of tropical regions worldwide. “Animals involved in seed-dispersal are in decline in a lot of tropical forests around the world right now,” the co-principal investigator of the study, Amy Dunham, said in a statement. “It’s very important to understand the implications of those declines.” So far scientists have looked into the role of endangered mammals like lemurs, giant tortoises (PDF) and African forest elephants (PDF) in seed dispersal, but the upcoming study will be one of the first to focus on endangered birds.

It’s also the rare study to examine what happens when seed dispersal completely ceases–Guam being the only place in the world to experience whole-island forest bird loss in modern times. “The situation on Guam–which is tragic–provides us with a unique opportunity to see what happens when all seed-dispersal services provided by animals are lost from an entire ecosystem,” Dunham said. 

The snakes, meanwhile, continue to dominate the island of Guam. The U.S. Department of Agriculture traps approximately 6,000 brown tree snakes each year, and yet there are still nearly two million slithering around the island. The snakiest patches contain 14,000 of the reptiles per square mile–one of the highest snake concentrations in the world.

In February, the Department of Agriculture embarked on a new tactic for tackling the snake problem: dropping dead mice laced with acetaminophen, which is fatal to them, into the jungle. ”We are taking this to a new phase,” Daniel Vice of the Department of Agriculture’s branch that focuses on wildlife services in Hawaii, Guam and other U.S. held Pacific Islands, said in a recent interview. “There really is no other place in the world with a snake problem like Guam.”

Wetlands, such as this marsh above, buffer communities against flooding. Photo by Flickr user daryl_mitchell

In the aftermath of Superstorm Sandy last fall, New York Governor Andrew Cuomo joked to President Barack Obama that New York “has a 100-year flood every two years now.” On the heels of flooding from 2011′s Hurricane Irene and Tropical Storm Lee, it certainly seemed that way. Given that climate change has sparked multiple major storms and raised sea levels, and that urban and agricultural development have impeded our natural flood-management systems, chronic flooding could be here to stay.

Wetlands, which include swamps, lagoons, marshes and mangroves, help mitigate the problem by trapping floodwaters. “Historically, wetlands in Indiana and other Midwestern states were great at intercepting large runoff events and slowing down the flows,” environmental engineer Meghna Babbar-Sebens of Oregon State University said in a recent statement. ”With increases in runoff, what was once thought to be a 100-year flood event is now happening more often.”

One key problem is that most of our wetlands no longer exist. By the time the North American Wetlands Conservation Act (PDF) was passed in 1989, more than half of the wetlands in the United States had been paved over or filled in. In some states, the losses are much greater: California has lost 91 percent of its wetlands, and Indiana, 85 percent. In recent years, scientists have been honing the art of wetlands restoration, and now a recent study published in the journal Ecological Engineering by scientists at Oregon State University is helping to make new wetlands easier to plan and design.

Scientists are using an Indiana watershed to study how wetlands can be created or restored to help stem the effects of climate change. Photo by Flickr user Davitydave

The research focused on Eagle Creek Watershed, ten miles north of Indianapolis, and identified nearly 3,000 potential sites where wetlands could be restored or created to capture runoff. Through modeling, the scientists discovered that a little wetland goes a long way. “These potential wetlands cover only 1.5% of the entire watershed area, but capture runoff from 29% (almost a third) of the watershed area,” the study authors wrote.

Their next step was to begin developing a web-based design system to allow farmers, agencies and others to identify areas optimal for new or restored wetlands and to collaborate in designing them. The recently launched system, called Wrestore, uses Eagle Creek as a test-piece.

A new web tool analyzes different components of a watershed; Indiana’s Eagle Creek Watershed steam network is pictured here. Map courtesy of Wrestore

The tool has a variety of functions: It helps identify a region’s rivers and streams, divides watersheds into smaller sub-watersheds and shows where runoff is likely to collect—places conducive to building wetlands. If a city wants to reduce flooding in its watershed, the site’s interactive visualization engine displays various conservation options and allows groups of city planners to collaborate on the design of new wetlands.

“Users can look at various scenarios of implementing practices in their fields or watershed, test their effectiveness via the underlying hydrologic and water quality models, and then give feedback to an ‘interactive optimization’ tool for creating better designs,” Babbar-Sebens, lead author of the study and the lead scientist on the web tool, told Surprising Science.

It provides an easy way for landowners to tackle such environmental challenges. “The reason we used a web-based design system is because it gives people the flexibility to try and solve their problems of flooding or water quality from their homes,” Babbar-Sebens said.

As the spring flood season approaches and environmental degradation continues throughout the nation, a new tool for mitigating wetland loss with targeted, minimal wetland gain is certainly a timely innovation. Babbar-Sebens and her team have been testing it out on Eagle Creek Watershed and will be fine-tuning it throughout the spring. ”There is a lot of interest in the watershed community for something like this,” she said.

An island of ice breaking away from Greenland’s Petermann Glacier (in the center of the photo)  in the summer of 2010. By NASA

On the morning of July 16, 2010, a hunk of ice four times the size of Manhattan cracked away from the tongue of Greenland’s Petermann Glacier and drifted to sea as the largest iceberg since 1962. Just two years later, another massive section of ice calved from the same glacier. Icebergs like these don’t stay put in the Arctic–they get picked up by currents and ushered to warmer climates, melting along the way.

According to a new study published in the journal Geophysical Research Letters, Greenland’s melting glaciers and ice caps sent 50 gigatons of water gushing into the oceans from 2003 to 2008. This comprises about 10 percent of the water flowing from all ice caps and glaciers on Earth. The research comes on the heels of a study last year that showed the ice sheets of Greenland and Antarctica are disappearing three times faster than in the 1990s, and that Greenland’s is melting at an especially accelerated rate. In the new study, scientists were able to put an even finer point to the ice-melt situation by separating out the glaciers and ice caps from the ice sheet, which blankets 80 percent of the island. What they discovered is that Greenland’s glaciers are actually melting more quickly than the ice sheet.

Studies such as these demonstrate the impacts of a warming climate on Greenland’s glaciers. But, as they say, a picture is worth a thousand words. Visual evidence of this liquefaction is captured by NASA satellites, which are able to take snapshots of calving glaciers and document longer-term ice melt. NASA displays photos of the glaciers in its State of Flux photo gallery, along with a rotating collection of satellite images that illustrate other changes to the environment, including wildfires, deforestation and urban development.

The photos, with their “now-you-see-it, now-you-don’t” quality, illustrate how glaciers are fast becoming ephemeral. Here are a few stark examples:

Greenland’s Helheim Glacier can be seen retreating and thinning from 2001 (left) to 2003 (center) to 2005 (right). By NASA 

The set of images above shows the edge of Greenland’s Helheim Glacier, located on the fringe of the Greenland Ice Sheet, as captured by a satellite in 2001, 2003 and 2005. The calving front is marked by the curved line through the valley, while bare ground appears brown or tan and vegetation is red.

According to NASA, when warmer temperatures initially cause a glacier to melt, it can spark a chain reaction that accelerates the thinning of the ice. As the edge of the glacier begins to liquefy, it crumbles, creates icebergs and eventually disintegrates. The loss of mass throws the glacier off balance, and further thinning and calving occurs, a process that stretches the glacier through its valley. Total ice volume decreases then shrinks the glacier as calving carries ice away. Helheim’s calving front stayed put from the 1970s until 2001, at which point the glacier began hasty cycles of thin, advance, and dramatic retreat, ultimately moving 4.7 miles toward land by 2005.

Greenland’s Petermann Glacier on June 26, 2010 (left) , before a massive iceberg broke away, and on August 13, 2010, after the break. By NASA

The massive calving event at Petermann Glacier in 2010 is pictured in these two images. The glacier is the white ribbon on the right side of each photo, and its tongue extends into the Nares Strait, which appears as a bluish-black stripe across the center of the right image and is heavily flecked with white chunks in the photo on the left. In the first image, the tongue of the glacier is intact; in the second, a huge chunk of ice has broken off and can be seen floating away through the fjord. This iceberg was 97 square miles in size–four times bigger than the island of Manhattan.

Greenland’s Petermann Glacier on July 16, 2012 (left and center), before a major calving event, and July 17, 2012, after an iceberg broke off. By NASA

In the summer of 2012, a second massive iceberg crumbled away from the Petermann Glacier. In these images, the glacier is the white ribbon snaking up from the bottom right. If you follow the tongue up, you’ll see that it appears intact in the photos at left and center (though the center image has an ominous crack spanning its width), which were taken the day before the calving occurred. The photo on the right shows that it crumbled as the glacier calved.

Given that Greenland experienced an exceptionally warm summer in 2012 and temperatures were higher than average this winter, 2013 is primed for more melting and massive icebergs. Last year’s ice-melt season lasted two months longer than the average since 1979, and this year’s is already off to an inauspicious start. It kicked off on March 13 with the sixth-smallest sea-ice area on record for Greenland, according to the National Snow and Ice Data Center. What will the new summer calving season bring?