It’s easy to see how overwatering our crops would deplete the groundwater supply and cause land nearby to sink, but could it cause sea level to rise on a global scale? Yes, according to a model published in Nature Geosciences, that attributes 42% of the sea-level rise over the past half century to groundwater use.
Ninety percent of readily available freshwater is underground, and water used for drinking or crop irrigation must, of course, be brought above ground. That water then evaporates or flows into rivers, entering the water cycle and eventually the oceans, making them deeper.
Similar populations of seabed-rooted animals separated by 1,500 miles of ice, researchers say, could mean that the West Antarctic Ice Sheet was once a trans-Antarctic seaway. This surprising find has also led researchers to wonder if a warming planet could again cause the thick ice sheet to collapse and give way to a swath of open water.
The team, which published their study in Global Change Biology, found similar but separated bryozoans–creatures also called moss animals–in both the Ross and Weddell Seas while conducting the Census of Antarctic Marine Life. Given that bryozoans don’t move all that much, lead author David Barnes suggests that the isolated populations came from the same, connected habitat.
“Because the larvae of these animals sink and this stage of their life is short–and the adult form anchors itself to the sea bed–it’s very unlikely that they would have dispersed the long distances carried by ocean currents,” Barnes said. “Our conclusion is that the colonization of both these regions is a signal that both seas were connected by a trans-Antarctic sea way in the recent past.” [Wired]
You could plant huge new forests where none have been before. You could blast particles into the sky to block the sun’s radiation. You could put mirrors in space. These planetary hacks could slow global warming, but one thing that none of them could do, most likely, is to stop the rising sea levels that a warming planet will bring.
That’s the contention of John Moore, lead author of a study out in the Proceedings of the National Academy of Sciences. Moore’s team examined five different means that scientists have proposed to hack the planet and save ourselves from anthropogenic global warming. The geoengineering schemes—forestation, atmospheric aerosols, space mirrors, biochar, and the use of biofuels plus carbon sequestration—are focused either on reducing the amount of energy the Earth absorbs or pulling carbon out of the atmosphere. So Moore wanted to see what they could do about a side effect of the extra heat: melting ice raising the global average sea level.
The results weren’t terribly encouraging. Sea levels respond slowly to changes in the planet’s temperature, Moore told Nature News, so “you can’t just slam on the brakes.”
Why is Antarctica’s Pine Island Glacier losing so much ice into the sea? Because, researchers say, it has come unstuck at the bottom.
The Western Ice Sheet in Antarctica contains “enough water to raise global sea levels by several metres,” Christian Schoof writes in an accompanying commentary on the paper in Nature Geoscience, and so the high rate of ice loss in place like Pine Island is a worry. But the force of the atmosphere, even if you accounted for a warming Antarctica, doesn’t explain the melting rate. So the British Antarctic Survey team led by Adrian Jenkins ventured a guess that something else was going on under the ice, and sent a robot to investigate.
What the autonomous underwater bot found was pretty jarring.
In just a few decades — since the 1970s — the relatively warm deep ocean water flowing beneath the cold, buoyant glacier meltwater has encroached inland under the glacier some 30 km, or 18.6 miles, and the pace of the outflow of Pine Island Glacier continues to accelerate [Discovery News].
The tiny islands of the Pacific Ocean appear to be the very the picture of climate change vulnerability—some rise such a short distance above current sea level that it seems like any rise would swallow them up. The Earth’s climate system, though, is a great deal more complex than the simplistic rhetoric that fills the political echo chamber. That’s demonstrated again in a new study that argues some the Pacific’s low-lying islands are actually increasing slightly in land area rather than decreasing. It’s good news, yes—but not without caveats.
First, the specifics. Arthur Webb and Paul Kench published their work, based on decades of aerial and satellite photos, in the journal Global and Planetary Change. During the years spanned by those images, the sea level in the area has been rising by about 2 millimeters per year. Nevertheless, they say that 23 of the 27 Pacific islands they studies either held firm in land area or saw a slight increase. How could this be?
Unlike the sandbars of the eastern US coast, low-lying Pacific islands are made of coral debris. This is eroded from the reefs that typically circle the islands and pushed up onto the islands by winds, waves and currents. Because the corals are alive, they provide a continuous supply of material. “Atolls are composed of once-living material,” says Webb, “so you have a continual growth.” Causeways and other structures linking islands can boost growth by trapping sediment that would otherwise get lost to the ocean [New Scientist].
Remember that time you and your sibling couldn’t stop fighting over a toy, so your mom wouldn’t let either one of you have it? It seems the same thing happens to unhappy neighboring countries and Mother Nature.
The island in the Bay of Bengal that Bangladesh called South Talpatti and India called New Moore or Purbasha appeared after a devastating cyclone, and it appeared right near the territorial boundary between the two. Decades of fighting over the uninhabited speck of land led to no political resolution. But now there’s a perfectly clear geographical resolution: The sea has reclaimed the island, scientists say.
According to oceanographer Sugata Hazra, the island was never very big, peaking at around 1.3 miles by 1.1 miles. The island began shrinking in the 1990s, part of an 81-square-mile decline in land mass in the Bay of Bengal’s Sunderbans mudflats over the last 40 years, Hazra said. And 27 square miles more has been lost to erosion. In the 1990s, the island was only 2 meters above sea level [Los Angeles Times]. Some experts say that in addition to erosion, rising sea levels caused by global warming are also to blame. Oceanographer Sugata Hazra, who discovered the island’s disappearance while looking at satellite photos, argues that sea-level rise caused by climate change was ”surely” a factor in the island’s inundation…. ‘The rate of sea-level rise in this part of the northern Bay of Bengal is definitely attributable to climate change,” he said [Sydney Morning Herald].
Arctic sea ice melting, which scientists have linked to global warming, may be a boon for the shipping industry. As the sea ice continues to melt a shipping passage to Russia’s north is becoming more navigable, and now two German ships are close to completing the first trip from Asia to Europe via the Arctic shortcut. However, walruses that live in the Arctic could care less, since their sea ice habitat is rapidly disappearing.
Thousands of walruses are congregating on Alaska’s northwest coast, a sign that their Arctic sea ice environment has been altered by climate change. Chad Jay, a U.S. Geological Survey walrus researcher, said Wednesday that about 3,500 walruses were near Icy Cape on the Chukchi Sea, some 140 miles southwest of Barrow [AP]. Walruses wear themselves out diving for clams, and need to rest on the sea ice between meals. Since the sea ice is disappearing, they are turning to the shore for a break. Federal managers and researchers worry that so many walruses in one location could lead to a deadly stampede or could drive off prey. Highlighting the animals’ peril, the Obama administration is considering adding walruses to the endangered species list.
The Republic of Maldives has big plans for discarded coconut shells: they can become both a fertilizer and a planet-cooler. The Maldivian government has announced plans to burn the shells and turn them into biochar, a form of high-carbon charcoal that takes a long time to decompose, and which can be used to nourish the soil. It’s one effort of many that the government of the Indian Ocean archipelago hopes will help it achieve carbon neutrality by the year 2020.
The “slow-cooked” organic waste project was launched through a partnership between the Maldives government and the British company Carbon Gold. The scheme would not only reduce organic garbage, it would also decrease dependence on imported fertilizer. Carbon Gold argues that the biochar is an effective way of removing CO2 from the atmosphere. The company says the fertiliser also improves soil fertility…. “Waste that would have rotted or been burnt before is now locked up and put very safely in the soil,” [BBC], says company cofounder Daniel Morrel. Researchers believe that biochar doesn’t break down (and therefore release its carbon) for hundreds of years.
If global warming melts the West Antarctic ice sheet, the thick slab of ice that covers an area the size of Texas, the situation for coastal dwellers around the world may not be as dire as previously estimated. A new study, which has sparked some debate, suggests that the water released by West Antarctica‘s melting glaciers would raise sea levels by about 10 feet, not the 15 to 20 feet that had previously been predicted.
While the results sound like good news, Antarctic experts and the study’s lead author, Jonathan L. Bamber of the Bristol Glaciology Center in England, agreed that the odds of a disruptive rise in seas over the next century or so from the buildup of greenhouse gases remained serious enough to warrant the world’s attention [The New York Times]. They also note that some regions would also experience a larger surge in sea levels than others. “Sea level rise is not uniform across the world’s oceans, partly as a result of disruptions to the Earth’s gravity field,” explained Professor Bamber. “It turns out that the maximum increase in sea level rise is centred at a latitude of about 40 degrees along the Atlantic and Pacific seaboards of North America.” This would include cities such as San Francisco and New York [BBC News].
The 340 residents of Newtok, Alaska will soon be among the first “climate refugees” in the United States. Global warming has battered the tiny coastal town: As average yearly temperatures rise, coastal ice shelves melt as does the permafrost on which the town sits. The Ninglick River has overtaken the town as the ground level simultaneously sinks [Backpacker blog]. As a result, the town’s scattered buildings are connected by a network of boardwalks across the mud.
With the forces of nature arrayed against them, the townspeople have now voted to relocate their town to a new site nine miles inland, on higher ground by the river. “We are seeing the erosion, flooding and sinking of our village right now,” said Stanley Tom, a Yup’ik Eskimo and tribal administrator for the Newtok Traditional Council…. The U.S. Army Corps of Engineers has estimated that moving Newtok could cost $130 million. Twenty-six other Alaskan villages are in immediate danger, with an additional 60 considered under threat in the next decade, according to the corps [CNN].