Another climate and water story

Last week, we featured a series of stories on climate change and water issues and this one slipped by. A study in Nature last week reported how trees physically respond to drought. And the news is not good. Plants undergoing drought stress experience reduced pressure in the xylem (the vessel that transports water from the soil to the leaves).

Head over to NPR to read (or listen to) their piece on the study.

Melting ice sheets and sea level rise

A NASA/ESA study, published in Science this week provides the most thorough representation of the rate of melting ice sheets and corresponding sea level rise to date. Using extensive satellite data, scientists report that the ice sheets covering Greenland and Antarctica are losing more than three times as much ice each year as they were in the 1990s. About two-thirds of the loss occurs from Greenland, with the rest from Antarctica.

Combined, melting of these ice sheets contributed 0.44 inches to global sea levels since 1992. This accounts for one-fifth of all sea level rise over the 20-year survey period. The remainder is caused by the thermal expansion of the warming ocean, melting of mountain glaciers and small Arctic ice caps, and groundwater mining.

“Both ice sheets appear to be losing more ice now than 20 years ago, but the pace of ice loss from Greenland is extraordinary, with nearly a five-fold increase since the mid-1990s,” NASA’s Erik Ivins says.

Ocean acidification and fighting back

Ocean acidification is already having an effect on marine life, according to a study published this week in Nature Geoscience. Shells of live mollusks from the Southern Ocean are showing signs of “severe dissolution.” New Scientist has more information.

Washington State is taking action to curb ocean acidification and protect the state’s large shellfish industry. A report, released this week, outlines plans to target pollution that causes acidification (including carbon emissions and agriculture run-off) and has a $3.3 million backing. More information is available here.

Maybe more coastal states (and nations) will follow Washington’s lead, says the Ocean Conservancy.

A Sad Factoid

A final thought from the editors at grist.org, who note that “if you’re 27 or younger, you’ve never experienced a colder-than-average month.” A truly sobering fact gleaned from the NOAA “State of the Climate” report for October 2012.

Image: Ian Joughin

What if you lived in a saltwater lake that was six times saltier than the ocean, and the water was buried under nearly 20 meters (65 feet) of ice? The temperature is a brisk -13°C and oh yeah, we forgot to mention that the lake lacks oxygen and contains high levels of organic carbon.

Sounds pleasant, right? You’re probably thinking nothing can live there. Wrong.

Lake Vida in Antarctica isn’t exactly teeming with life, but life does exist in its harsh environment. Diverse life, in fact. At least eight new species of bacteria call Lake Vida home according to a new study in the Proceedings of the National Academy of Sciences.

Researchers from the University of Illinois and the Desert Research Institute took samples from the lake in 2005 and 2010, using stringent protocols to avoid contaminating the pristine ecosystem. Scientists estimate that this lake has been isolated from outside influences (including the Sun’s energy!) for almost 3,000 years.

“This study provides a window into one of the most unique ecosystems on Earth,” says lead author Alison Murray. “[It] expands our understanding of the types of life that can survive in these isolated, cryoecosystems and how different strategies may be used to exist in such challenging environments.”

Strategies like food-supply. The researchers have a theory: “Geochemical analyses suggest that chemical reactions between the brine and the underlying sediment generate nitrous oxide and molecular hydrogen,” says co-author Fabien Kenig. “The hydrogen may provide some of the energy needed to support microbes.”

“If that’s the case,” says Murray, “This gives us an entirely new framework for thinking of how life can be supported in cryoecosystems on Earth and in other icy worlds of the Universe.” Think Mars or Europa, says New Scientist.

And also think Vostok and Ellsworth—two more Antarctic lakes that have been isolated millions of years longer than Vida. Scientists are studying those lakes this Antarctic summer. Perhaps they will find life in these harsh conditions, as well?

Image: Peter Glenday, University of Illinois

Or so news reports confirm today.

On February 5, the bundled-up researchers finally reached Lake Vostok, two miles under ice in the middle of the East Antarctic ice sheet. The team has been drilling each Antarctic summer for 14 years to penetrate the large lake, estimated to be the size of Lake Ontario.

Scientists first discovered Lake Vostok in the 1990s, and they believe it has been under ice for at least 15 million years! Imagine what this hidden lake may hold, says Scientific American:

Devoid of light but likely bursting with supersaturated oxygen and other gases, Vostok has long been speculated to be a potential habitat for unique ecosystems of extremophilic microbial life (and who knows what else).

And Wired takes it a step further:

The conditions in Lake Vostok are thought to be similar to the conditions on Jupiter’s moon Europa and Saturn’s tiny moon Enceladus.

But New Scientist spreads some doubt:

…air has accumulated in the lake for millennia, boosting the oxygen concentrations in the water and creating a potentially toxic environment. Some say that as a result, it is likely that the lake is completely sterile.

The work is tricky. In addition to dealing with the harsh weather conditions, the scientists are working hard to not contaminate the untouched waters of Lake Vostok. According to the New York Times, the Russian team’s plan

… was to plug the bottom of the bore hole with an inert fluid, Freon, and to drill the final distance with a heated drill tip instead of a motorized drill. Enough kerosene would be removed to lessen the pressure in the bore hole so that when the lake was reached, lake water would flow up the bore hole, then freezing and forming an icy plug.

As the temperatures begin to drop in one of the coldest places on Earth, the Russian team will pack up to go home, returning to Lake Vostok next December to begin the real scientific work. Will they find life?

Image: NSF

A few years ago, scientists realized that Pine Island Glacier was a major source of that melting ice. (The BBC has a good map showing the location of Pine Island Glacier here, and a Google Earth forum posting displays amazing visualizations of calving from the glacier here.) But what is causing the rapid retreat of the glacier?

To figure this out, researchers launched an autonomous underwater vehicle, or Autosub, designed to dive deep and travel far beneath Pine Island Glacier’s floating ice shelf. With acoustic instruments aboard Autosub, the scientists captured ocean and seafloor measurements, which revealed a ridge almost 1,000 feet high on the sea floor.

Pine Island Glacier was once sitting on top of this underwater ridge, which slowed its flow into the sea. However, due to warm ocean water, in recent decades it has thinned and disconnected from the ridge, allowing glacier ice to move more rapidly from the land into the sea. (Check out a graphic at Discovery News showing this process.)

Lead author Adrian Jenkins, PhD, of the British Antarctic Survey, said “The discovery of the ridge has raised new questions about whether the current loss of ice from Pine Island Glacier is caused by recent climate change or is a continuation of a longer-term process that began when the glacier disconnected from the ridge.

“We do not know what kick-started the initial retreat from the ridge, but we do know that it started some time prior to 1970. Since detailed observations of Pine Island Glacier only began in the 1990s, we now need to use other techniques such as ice core analysis and computer modeling to look much further into the glacier’s history in order to understand if what we see now is part of a long term trend of ice sheet contraction. This work is vital for evaluating the risk of potential widespread collapse of West Antarctic glaciers.”

In 2006, French scientists dug up micrometeorites in Antarctica that appear to have fallen to Earth about 50 years ago. Antarctica seems to be a hotbed for well-preserved meteorites and not just because of the cold.  There is little contamination from terrestrial sources there.

The micrometeorites appear to be from a comet. But it’s the astonishing amounts of two chemicals that is the basis of the researchers’ paper published in the current edition of Science and breaking news on the web today.

Looking at the large amounts of carbon and deuterium the meteorites contained, the scientists hoped to uncover the comet’s origin. While the deuterium could possibly mean it was interstellar, or from outside of the solar system, the scientists concluded that it was from within and possibly from the outer reaches of our solar system.

But that doesn’t answer all of the questions.

Scientific American quotes lead author and cosmochemist Jean Duprat as saying, “One of the main questions we are addressing with these particles is the birth of the solar system, the material out of which the planets are formed.”

Or, as Universe Today puts it, “the meteorites could provide information about the protoplanetary disk that formed our solar system.” And to go even further, New Scientist says that “the cosmic dandruff could help explain how the carbon needed for life wound up on Earth.”

An exciting discovery, to be sure, that may hold many future answers.

Image courtesy of J. Duprat CSNSM-CNRS

Scientists from all over the globe are studying ice core samples to learn from Antarctica’s past and are trying to predict its future.

In a joint mission called the Integrated Ocean Drilling Program or IODP, researchers are drilling and studying geological samples from the seafloor off the coast of Antarctica. “The new cores offer an unprecedented ability to decipher the history of glaciation in Antarctica,” says Jamie Allen, program director in the National Science Foundation (NSF)’s Division of Ocean Sciences, which co-funds IODP. “The climate record they preserve is immensely valuable, especially for testing how well current global climate models reproduce past history.”

Sediments and microfossils preserved within the cores document the onset of cooling and the development of the first Antarctic glaciers, as well as the growth and recession of Antarctica’s ice sheets.

When Antarctica was warm those millions of years ago, atmospheric carbon dioxide levels were more than ten times higher than they are today. Then, in only 400,000 years—a mere blink of an eye in geologic time—concentrations of atmospheric carbon dioxide there decreased. Global temperatures dropped. Ice sheets developed. Antarctica became ice-bound.

Now, the giant ice sheets in Antarctica behave like mirrors, reflecting the sun’s energy and moderating the world’s temperatures. The waxing and waning of these ice sheets contribute to changes in sea level and affect ocean circulation, which regulates our climate by transporting heat around the planet.

“We can read these sediments like a history book,” says co-chief scientist Henk Brinkhuis of Utrecht University in the Netherlands. “And this book goes back 53 million years, giving us an unprecedented record of how ice sheets form and interact with changes in the climate and the ocean.

“Measurements of parameters such as age, temperature, and carbon dioxide concentration increase the accuracy of these models. The more we can constrain the models, the better they’ll perform–and the better we can predict ice sheet behavior.”

Image: John Beck, IODP/TAMU

Scientists from Japan and Australia have confirmed the size and speed of such a current in an article published online yesterday in Nature Geoscience.

The current moves northwest from the eastern edge of the Kerguelen Plateau (pictured in light blue above an orange Antarctica here), in the southern Indian Ocean.

“The deep current along the Kerguelen Plateau is part of a global system of ocean currents called the overturning circulation, which determines how much heat and carbon the ocean can soak up,” one of the paper’s authors, Steve Rintoul, said.

These currents are sometimes called the oceans’ conveyor belt, combining all of the Earth’s oceans into a global system. Another one of these currents is the Gulf Stream that brings warmer water to Northern Europe, keeping its climate mild. It is also the reason for the upwelling that occurs across the world and especially in our own backyard—the North Pacific Ocean.

These currents have sometimes been known to change. “We’re not saying this could happen instantaneously, like the movie The Day After Tomorrow,” lead author Yasushi Fukamachi, an ocean scientist at Hokkaido University in Sapporo, Japan says. “But understanding this kind of current is very important to understanding global climate.”

Alejandro Orsi, a physical oceanographer at Texas A & M University in College Station agrees. According to an article in Nature, he says, “This (current) is significant because it represents a ‘fast lane’ by which climatic and environmental changes affecting the Southern Ocean can propagate northward. Proof that this is already occurring can be seen from the fact that the deep waters near the Kerguelen Plateau already show ‘clear signs’ of reduced salinity relating to changes in the rate of melting of Antarctic ice sheets.”

In other words, by following this large current, scientists hope to follow the affects of climate change.