Mathematics predicts a sixth mass extinction

In the past 540 million years, the Earth has endured five mass extinction events, each involving processes that upended the normal cycling of carbon through the atmosphere and oceans. These globally fatal perturbations in carbon each unfolded over thousands to millions of years, and are coincident with the widespread extermination of marine species around the world.

Scientists have analyzed significant changes in the carbon cycle over the last 540 million years, including the five mass 
extinction events. They have identified 'thresholds of catastrophe' in the carbon cycle that, if exceeded, would lead
 to an unstable environment, and ultimately, mass extinction [Credit: MIT]

The question for many scientists is whether the carbon cycle is now experiencing a significant jolt that could tip the planet toward a sixth mass extinction. In the modern era, carbon dioxide emissions have risen steadily since the 19th century, but deciphering whether this recent spike in carbon could lead to mass extinction has been challenging. That's mainly because it's difficult to relate ancient carbon anomalies, occurring over thousands to millions of years, to today's disruptions, which have taken place over just a little more than a century.

Now Daniel Rothman, professor of geophysics in the MIT Department of Earth, Atmospheric and Planetary Sciences and co-director of MIT's Lorenz Center, has analyzed significant changes in the carbon cycle over the last 540 million years, including the five mass extinction events. He has identified "thresholds of catastrophe" in the carbon cycle that, if exceeded, would lead to an unstable environment, and ultimately, mass extinction.

In a paper published in Science Advances, he proposes that mass extinction occurs if one of two thresholds are crossed: For changes in the carbon cycle that occur over long timescales, extinctions will follow if those changes occur at rates faster than global ecosystems can adapt. For carbon perturbations that take place over shorter timescales, the pace of carbon-cycle changes will not matter; instead, the size or magnitude of the change will determine the likelihood of an extinction event.

Taking this reasoning forward in time, Rothman predicts that, given the recent rise in carbon dioxide emissions over a relatively short timescale, a sixth extinction will depend on whether a critical amount of carbon is added to the oceans. That amount, he calculates, is about 310 gigatons, which he estimates to be roughly equivalent to the amount of carbon that human activities will have added to the world's oceans by the year 2100.

Does this mean that mass extinction will soon follow at the turn of the century? Rothman says it would take some time -- about 10,000 years -- for such ecological disasters to play out. However, he says that by 2100 the world may have tipped into "unknown territory."

"This is not saying that disaster occurs the next day," Rothman says. "It's saying that, if left unchecked, the carbon cycle would move into a realm which would be no longer stable, and would behave in a way that would be difficult to predict. In the geologic past, this type of behavior is associated with mass extinction."

History follows theory

Rothman had previously done work on the end-Permian extinction, the most severe extinction in Earth's history, in which a massive pulse of carbon through the Earth's system was involved in wiping out more than 95 percent of marine species worldwide. Since then, conversations with colleagues spurred him to consider the likelihood of a sixth extinction, raising an essential question:

"How can you really compare these great events in the geologic past, which occur over such vast timescales, to what's going on today, which is centuries at the longest?" Rothman says. "So I sat down one summer day and tried to think about how one might go about this systematically."

He eventually derived a simple mathematical formula based on basic physical principles that relates the critical rate and magnitude of change in the carbon cycle to the timescale that separates fast from slow change. He hypothesized that this formula should predict whether mass extinction, or some other sort of global catastrophe, should occur.

Rothman then asked whether history followed his hypothesis. By searching through hundreds of published geochemistry papers, he identified 31 events in the last 542 million years in which a significant change occurred in Earth's carbon cycle. For each event, including the five mass extinctions, Rothman noted the change in carbon, expressed in the geochemical record as a change in the relative abundance of two isotopes, carbon-12 and carbon-13. He also noted the duration of time over which the changes occurred.

He then devised a mathematical transformation to convert these quantities into the total mass of carbon that was added to the oceans during each event. Finally, he plotted both the mass and timescale of each event.

"It became evident that there was a characteristic rate of change that the system basically didn't like to go past," Rothman says.

In other words, he observed a common threshold that most of the 31 events appeared to stay under. While these events involved significant changes in carbon, they were relatively benign -- not enough to destabilize the system toward catastrophe. In contrast, four of the five mass extinction events lay over the threshold, with the most severe end-Permian extinction being the farthest over the line.

"Then it became a question of figuring out what it meant," Rothman says.

A hidden leak

Upon further analysis, Rothman found that the critical rate for catastrophe is related to a hidden process within the Earth's natural carbon cycle. The cycle is essentially a loop between photosynthesis and respiration. Normally, there is a "leak" in the cycle, in which a small amount of organic carbon sinks to the ocean bottom and, over time, is buried as sediment and sequestered from the rest of the carbon cycle.

Rothman found that the critical rate was equivalent to the rate of excess production of carbon dioxide that would result from plugging the leak. Any additional carbon dioxide injected into the cycle could not be described by the loop itself. One or more other processes would instead have taken the carbon cycle into unstable territory.

He then determined that the critical rate applies only beyond the timescale at which the marine carbon cycle can re-establish its equilibrium after it is disturbed. Today, this timescale is about 10,000 years. For much shorter events, the critical threshold is no longer tied to the rate at which carbon is added to the oceans but instead to the carbon's total mass. Both scenarios would leave an excess of carbon circulating through the oceans and atmosphere, likely resulting in global warming and ocean acidification.

The century's the limit

From the critical rate and the equilibrium timescale, Rothman calculated the critical mass of carbon for the modern day to be about 310 gigatons.

He then compared his prediction to the total amount of carbon added to the Earth's oceans by the year 2100, as projected in the most recent report of the Intergovernmental Panel on Climate Change. The IPCC projections consider four possible pathways for carbon dioxide emissions, ranging from one associated with stringent policies to limit carbon dioxide emissions, to another related to the high range of scenarios with no limitations.

The best-case scenario projects that humans will add 300 gigatons of carbon to the oceans by 2100, while more than 500 gigatons will be added under the worst-case scenario, far exceeding the critical threshold. In all scenarios, Rothman shows that by 2100, the carbon cycle will either be close to or well beyond the threshold for catastrophe.

"There should be ways of pulling back [emissions of carbon dioxide]," Rothman says. "But this work points out reasons why we need to be careful, and it gives more reasons for studying the past to inform the present."

Author: Jennifer Chu | Source: Massachusetts Institute of Technology [September 20, 2017]

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North Atlantic right whale population decline confirmed

NOAA Fisheries researchers and colleagues at the New England Aquarium have developed a new model to improve estimates of abundance and population trends of endangered North Atlantic right whales, which have declined in numbers and productivity in recent years. The findings are published in the journal Ecology and Evolution.

A North Atlantic right whale mother and calf, sighted June 8, 2014, during an aerial survey by the Northeast 
Fisheries Science Center [Credit: NOAA Fisheries/Christin Khan, NEFSC]

Between 1990 and 2010, the abundance of North Atlantic right whales increased just under three percent per year, from about 270 animals in 1990 to 482 in 2010. After relatively steady increases over that time, abundance has declined each year since 2010 to 458 animals in 2015. The analysis shows that the probability that the population has declined since 2010 is estimated at 99.99 percent. Of particular concern is decline of adult females in the population, estimated at 200 in 2010 but 186 in 2015, the known deaths of 14 North Atlantic right whales this year, and the widening gap between numbers of males and females.

"Although our work directly reveals a relatively small decrease, the subtext is that this species is presently in dire straits," said lead author Richard Pace.

Pace is a large whale researcher at NOAA's Northeast Fisheries Science Center. Other authors include NEFSC whale researcher Peter Corkeron, and Scott Kraus of the New England Aquarium.

The new statistical method reported today provides a clearer and timelier picture of North Atlantic right whale numbers. While both existing methods and the new statistical method for estimating North Atlantic right whale numbers show a decline in the population since 2010, the new estimates are less affected by changes in whale distribution, less reliant on sighting frequency, and better account for animals that are still alive but are not frequently seen.

Right whale (Eubalaena glacialis) skim feeding, with baleen clearly visible 
[Credit: NOAA Fisheries/Elizabeth Josephson, NEFSC]

In the past few years, these whales have not aggregated as consistently at the times and places where they have in the past. This reduces the likelihood that they will be sighted since survey efforts are most efficient when conducted while whales are coming together in larger groups to feed, calve, and care for young. This change in behavior has made the census-based estimate of their populations less reliable than in the past, and led to development of the new statistical model for estimating abundance.

The New England Aquarium has conducted research on right whales for more than three decades and also maintains the North Atlantic Right Whale Catalog. All methods for estimating abundance rely extensively on this record. The catalog combines information on individually identified North Atlantic right whales collected through annual surveys undertaken by a variety of researchers. The result is a comprehensive photographic census of the population for at least the past 25 years.

For this study, data from more than 61,000 sightings were reviewed. Analysis included sighting histories from 658 whales, including 280 females, 328 males and 50 animals of unknown sex. Of the 658 whales seen during the study period of 1990 to 2015, 247 were first seen before 1990.

NOAA Fisheries works directly with fishermen and shipping companies to reduce harm that can be caused if whales entangle in gear or collide with ships, two well-documented causes of whale deaths and serious injuries, and with researchers throughout the region to understand the biology and condition of animals in the population. The agency is also assisting Canadian officials and scientists with their efforts to reduce risks to these whales in Canadian waters.

Source: NOAA Northeast Fisheries Science Center [September 19, 2017]

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Emerging disease further jeopardizes North American frogs

A deadly amphibian disease called severe Perkinsea infections, or SPI, is the cause of many large-scale frog die-offs in the United States, according to a new study by the U.S. Geological Survey.

This tadpole shows signs of a severe Perkinsea infection [Credit: William Barichivich, USGS]

Frogs and salamanders are currently among the most threatened groups of animals on the planet. The two most common frog diseases, chytridiomycosis and ranavirus infection , are linked to frog population declines worldwide. The new study suggests that that SPI is the third most common infectious disease of frogs.

Scientists with the USGS studied 247 frog die-offs in 43 states from 1999 through 2015. The researchers found that SPI caused 21 of the mass mortalities in 10 states spanning from Alaska to Florida, all involving tadpoles. Up to 95 percent of the tadpole populations died during the SPI mortality events.

"Amphibians such as frogs are valuable because they serve as pest control by eating insects like mosquitos, and they are food for larger predators," said Marcos Isidoro Ayza, a USGS scientist, University of Wisconsin-Madison post-doctoral fellow and the lead author of the study. "They're also exceptional indicators of ecosystem health. Like the proverbial canary in a coal mine, amphibians let us know when something in our environment is going awry."

This photomicrograph shows a liver of a frog with a severe Perkinsea infection [Credit: ​​​​​​(USGS]

The SPI die-offs occurred in tadpoles of 11 frog species, including the critically endangered dusky gopherfrog in its only remaining breeding locations in Mississippi. Most of the SPI events occurred in states bordering the Atlantic Ocean and Gulf of Mexico. However, SPI was also detected in Alaska, Oregon and Minnesota.

"Habitat loss, habitat fragmentation and disease are among the factors that contribute to amphibian declines," said Jonathan Sleeman, director of the USGS National Wildlife Health Center. "This study indicates that SPI is an additional disease that can further threaten vulnerable frog populations."

SPI is caused by a tiny one-celled parasitic organism called a protist. The SPI-causing protist, called Perkinsea, is highly resistant to disinfection agents such as common bleach. As a result, it is difficult to prevent the spread of Perkinsea, and SPI is able to reoccur at known locations.

"SPI in frogs may be under-diagnosed because it is not a disease for which they are typically screened," Isidoro Ayza said. "Incorporating routine screening of critical habitats for infected frogs is crucial to help understand the distribution of this destructive disease."

The disease kills tadpoles by causing multi-organ failure, and there is no cure or treatment for SPI at this time. SPI is not known to affect humans or pets.

Source: US Geological Survey [September 19, 2017]

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When it comes to the threat of extinction, size matters

Animals in the Goldilocks zone -- neither too big, nor too small, but just the right size -- face a lower risk of extinction than do those on both ends of the scale, according to an extensive global analysis.

Extinction risks are greater for animals at the small and large ends of the scale 
[Credit: Oliver Day, Oregon State University]

Reporting today in the Proceedings of the National Academy of Sciences, researchers who determined body masses for thousands of vertebrate animal species showed that the largest and smallest species face a greater risk of extinction than do mid-sized animals.

Disproportionate losses at the large and small ends of the scale raise the likelihood of significant changes to the way natural ecosystems function in forests, grasslands, oceans and even rivers and streams -- "the living architecture of the planet," the researchers wrote.

"Knowing how animal body size correlates with the likelihood of a species being threatened provides us with a tool to assess extinction risk for the many species we know very little about," said William Ripple, a distinguished professor of ecology at Oregon State University and lead author of the study.

Ripple and colleagues from the United States, Australia and Switzerland looked at the more than 27,000 vertebrate animal species assessed by the International Union for the Conservation of Nature in the so-called Red List. About 4,400 are threatened with extinction.

Among the groups of animals evaluated were birds, reptiles, amphibians, bony fishes, cartilaginous fishes (mostly sharks and rays) and mammals.

The largest animals are threatened principally with harvesting by humans. "Many of the larger species are being killed and consumed by humans, and about 90 percent of all threatened species larger than 2.2 pounds (1 kilogram) in size are being threatened by harvesting," said Ripple.

"Harvesting of these larger animals takes a variety of forms including regulated and unregulated fishing, hunting and trapping for meat consumption, the use of body parts as medicine and killing due to unintentional bycatch," the authors wrote.

Meanwhile, threats to the smallest animals may be grossly underestimated. The smallest species with high extinction risk consist of tiny vertebrate animals generally less than about 3 ounces (77 grams) in body weight. These diminutive species are mostly threatened by loss or modification of habitat. Examples include the Clarke's banana frog, sapphire-bellied hummingbird, gray gecko, hog-nosed bat and the waterfall climbing cave fish. Small species that require freshwater habitats are especially imperiled.

Different conservation strategies will be needed to address threats to the largest and smallest animals, the scientists said. Well known mammals at the large end of the scale -- whales, elephants, rhinos, lions -- have been the target of protection programs, but conservation attention is also needed for large-bodied species that are not mammals. They include large fish, birds, amphibians and reptiles such as the whale shark, Atlantic sturgeon, Somali ostrich, Chinese giant salamander and the Komodo dragon.

Human activity seems poised to chop off both the head and tail of the size distribution of life, the authors added, which will fundamentally restructure many ecological communities.

Source: Oregon State University [September 18, 2017]

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New climate risk classification created to account for potential 'existential' threats

A new study evaluating models of future climate scenarios has led to the creation of the new risk categories “catastrophic” and “unknown” to characterize the range of threats posed by rapid global warming. Researchers propose that unknown risks imply existential threats to the survival of humanity.

Researchers projected warming scenarios that vary based on what societal actions are taken to reduce emissions 
[Credit: Scripps Institution of Oceanography at UC San Diego]

These categories describe two low-probability but statistically significant scenarios that could play out by century’s end, in a new study by Veerabhadran Ramanathan, a distinguished professor of climate and atmospheric sciences at Scripps Institution of Oceanography at the University of California San Diego, and his former Scripps graduate student Yangyang Xu, now an assistant professor at Texas A&M University.

The risk assessment stems from the objective stated in the 2015 Paris Agreement regarding climate change that society keep average global temperatures “well below” a 2°C (3.6°F) increase from what they were before the Industrial Revolution.

Even if that objective is met, a global temperature increase of 1.5°C (2.7°F) is still categorized as “dangerous,” meaning it could create substantial damage to human and natural systems. A temperature increase greater than 3°C (5.4°F) could lead to what the researchers term “catastrophic” effects, and an increase greater than 5°C (9°F) could lead to “unknown” consequences which they describe as beyond catastrophic including potentially existential threats. The specter of existential threats is raised to reflect the grave risks to human health and species extinction from warming beyond 5°C, which has not been experienced for at least the past 20 million years.

The scientists term warming probability of five percent or less as a “low-probability high-impact” scenario and assess such scenarios in the analysis “Well Below 2°C: Mitigation strategies for avoiding dangerous to catastrophic climate changes,” which appears today in the journal Proceedings of the National Academy of Sciences.

Ramanathan and Xu also describe three strategies for preventing the gravest threats from taking place.

“When we say 5 percent-probability high-impact event, people may dismiss it as small but it is equivalent to a one-in-20 chance the plane you are about to board will crash,” said Ramanathan. “We would never get on that plane with a one-in-20 chance of it coming down but we are willing to send our children and grandchildren on that plane.”

The researchers defined the risk categories based on guidelines established by the Intergovernmental Panel on Climate Change (IPCC) and previous independent studies. “Dangerous” global warming includes consequences such as increased risk of extreme weather and climate events ranging from more intense heat waves, hurricanes, and floods, to prolonged droughts. Planetary warming between 3°C and 5°C could trigger what scientists term “tipping points” such as the collapse of the West Antarctic Ice Sheet and subsequent global sea-level rise, and the dieback of the Amazon rainforest. In human systems, catastrophic climate change is marked by deadly heat waves becoming commonplace, exposing over 7 billion people to heat related mortalities and famine becoming widespread. Furthermore, the changes will be too rapid for most to adapt to, particularly the less affluent, said Ramanathan.

Risk assessments of global temperature rise greater than 5°C have not been undertaken by the IPCC.  Ramanathan and Xu named this category “unknown??” with the question marks acknowledging the “subjective nature of our deduction.” The existential threats could include species extinctions and major threats to human water and food supplies in addition to the health risks posed by exposing over 7 billion people worldwide to deadly heat.

With these scenarios in mind, the researchers identified what measures can be taken to slow the rate of global warming to avoid the worst consequences, particularly the low-probability high-impact events. Aggressive measures to curtail the use of fossil fuels and emissions of so-called short-lived climate pollutants such as soot, methane and HFCs would need to be accompanied by active efforts to extract CO2 from the air and sequester it before it can be emitted.  It would take all three efforts to meet the Paris Agreement goal to which countries agreed at a landmark United Nations climate conference in Nov 2015.

"This report shines a bright light on the existential threat that climate change presents to all humanity," said Calif. Governor Edmund G. Brown Jr., who has collaborated with Ramanathan on carbon neutrality measures in the state. "Scientists have many ideas about how to reduce emissions, but they all agree on the urgency of strong and decisive action to remove carbon from the economy."

Xu and Ramanathan point out that the goal is attainable. Global CO2 emissions had grown at a rate of 2.9 percent per year between 2000 and 2011, but had slowed to a near-zero growth rate by 2015.  They credited drops in CO2 emissions from the United States and China as the primary drivers of the trend. Increases in production of renewable energy, especially wind and solar power, have also bent the curve of emissions trends downward. Other studies have estimated that there was by 2015 enough renewable energy capacity to meet nearly 24 percent of global electricity demand.

Short-lived climate pollutants are so called because even though they warm the planet more efficiently than carbon dioxide, they only remain in the atmosphere for a period of weeks to roughly a decade whereas carbon dioxide molecules remain in the atmosphere for a century or more. The authors also note that most of the technologies needed to drastically curb emissions of short-lived climate pollutants already exist and are in use in much of the developed world.  They range from cleaner diesel engines to methane-capture infrastructure.

“While these are encouraging signs, aggressive policies will still be required to achieve carbon neutrality and climate stability,” the authors wrote.

The release of the study coincides with the start of Climate Week NYC in New York, a summit of business and government leaders to highlight global climate action. Ramanathan and colleagues will deliver a complementary report detailing the “three-lever” mitigation strategy of emissions control and carbon sequestration on Sept. 18 at the United Nations. That report was produced by the Committee to Prevent Extreme Climate Change, chaired by Ramanathan, Nobel Prize winner Mario Molina of UC San Diego, and Durwood Zaelke, who leads an advocacy organization, the Institute for Governance and Sustainable Development, with 30 experts from around the world including China and India.

Source: University of California - San Diego [September 14, 2017]

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Old fish few and far between under fishing pressure

Like old-growth trees in a forest, old fish in the ocean play important roles in the diversity and stability of marine ecosystems. Critically, the longer a fish is allowed to live, the more likely it is to successfully reproduce over the course of its lifetime, which is particularly important in variable environmental conditions.

A large, old yelloweye rockfish [Credit: Victoria O'Connell]

A new study by University of Washington scientists has found that, for dozens of fish populations around the globe, old fish are greatly depleted -- mainly because of fishing pressure. The paper, published in Current Biology, is the first to report that old fish are missing in many populations around the world.

"From our perspective, having a broad age structure provides more chances at getting that right combination of when and where to reproduce," said lead author Lewis Barnett, a UW postdoctoral researcher at the School of Aquatic and Fishery Sciences and the Joint Institute for the Study of the Atmosphere and Ocean.

In forestry, a tree farm with only 20-year-old trees may be healthy and productive, but the loss of old-growth trees should not go unnoticed. The giant trees have unique traits that support a number of animal and plant species and make for a diverse, robust ecosystem. In a similar sense, the same is true for old fish.

"More age complexity among species can contribute to the overall stability of a community," Barnett said. "If you trim away that diversity, you're probably reducing the marine food web's ability to buffer against change."

The designation of an "old fish" varies from species to species, depending on life history. Some types of rockfish might live to 200 years, while few herring live past age 10.

After female fish release eggs, many factors must align for a healthy brood to hatch and grow to adult size. Because the marine environment is so variable, species might go a whole decade between successful broods. Older fish in a population have more years to produce eggs, increasing the chance for success over time.

The face of an old halibut fish [Credit: Andrea Pokrzywinski]

"In the marine world, the success rate of producing new baby fish is extremely variable," said co-author Trevor Branch, a UW associate professor of aquatic and fishery sciences. "I think of old fish as an insurance policy -- they get you through those periods of bad reproduction by consistently producing eggs."

In addition to having more opportunities to reproduce, older fish also behave differently than younger fish. As they age, some fish change what they eat and where they live in the ocean. They also take on different roles in the marine food web, sometimes becoming a more dominant predator as they get older, and bigger.

When you take old fish out of the mix, the diversity and stability of an ecosystem can suffer, the authors explain.

"Big fish are in a lot of ways different from smaller fish," said co-author Tim Essington, a UW professor of aquatic and fishery sciences. "Having that diversity acts as a hedge against risk and helps stabilize the system a bit."

The researchers looked at model output gathered from commercial and recreational fisheries and scientific observations that describe the status of fish populations over the years. In their analysis of 63 populations living in five ocean regions worldwide, they found that the proportion of fish in the oldest age classes has declined significantly in 79 to 97 percent of populations, compared with historical fishing trends or unfished figures, respectively. The magnitude of decline was greater than 90 percent in 32 to 41 percent of the groups.

This is mainly due to fishing pressure, the researchers say. In general, the longer a fish lives, the more encounters it has with fishing gear, and the greater the likelihood it will be caught. However, some environmental factors like disease and pollution might also contribute to the loss of old fish.

These findings could inform fisheries management, which often sets limitations based on the total weight of fish caught over a season without considering factors such as the size or age of a fish. The authors suggest fishing methods to protect young and old fish by prohibiting the harvest of fish below and above a specific size range. Other solutions include closing certain areas to fishing permanently, or rotating areas where fishing can take place each year to let fish grow older and bigger -- similar to agricultural crop rotations that allow the soil to recover between planting cycles.

Author: Michelle Ma | Source: University of Washington [September 14, 2017]

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Earth's oldest trees in climate-induced race up the tree line

Bristlecone pine and limber pine trees in the Great Basin region are like two very gnarled, old men in a slow-motion race up the mountaintop, and climate change is the starting gun, according to a study from the University of California, Davis.

Gnarled, dead bristlecone pine trees, which can live more than 5,000 years, stand where young limber pine grow 
around them. Limber pine is beginning to colonize areas of the Great Basin once dominated by bristlecones 
[Credit: Brian Smithers/UC Davis]

The study, published in the journal Global Change Biology, shows that the tree line has been steadily moving upslope over the past 50 years in the Great Basin. The region extends from California's Sierra Nevada, across Nevada to Utah's Uinta Mountains. Its north and south are framed by the Columbia and Colorado rivers' watersheds.

The study also found that limber pine is successfully "leapfrogging" over bristlecone pine. They are growing in soils once almost completely dominated by bristlecone pine, and they are moving upslope at a faster rate than the bristlecone pine.

Charging upslope

"We are seeing very little regeneration anywhere in bristlecone ranges except in the tree line and, there, limber pine is taking all the good spots," said the study's corresponding author Brian Smithers, a Ph.D. candidate in the Department of Plant Sciences at UC Davis. "It's jarring because limber pine is a species you normally see further downslope, not at tree line. So it's very odd to see it charging upslope and not see bristlecone charging upslope ahead of limber pine, or at least with it."

Dead bristlecone pines stand among limber pine trees on the California side of the White Mountains, 
part of the Great Basin region [Credit: Brian Smithers/UC Davis]

The study concludes that if bristlecone pine trees are unable to advance upslope because they are blocked by limber pine, bristlecones could face a reduction of their range and possibly local extinctions.

Earth’s oldest living trees

Bristlecone pine trees are Earth's oldest individual trees and can live for more than 5,000 years. No spring chicken, limber pine trees can live 2,000 years or more.

Both tree species have seen many climate changes during their time on Earth -- from extremely warm periods to ice ages -- and have slowly advanced across the landscape. Over millennia, bristlecone pine trees have moved from the lowlands of the Great Basin up to the current tree line. But, the study notes, neither bristlecone nor limber pine have ever experienced climate change and temperature increases as rapidly as what has been occurring in recent decades.

Bristlecone pine trees grow on soils and in conditions where few other species can live. But limber pines in the 
Great Basin region, such as California’s White Mountains, are beginning to give them some competition 
[Credit: Brian Smithers/UC Davis]

Legacy effects

Smithers said he doesn't expect bristlecone pine adult trees to be impacted much by current climatic shifts, as those trees are well-established. But how, if and where new bristlecone pine trees will regenerate is less certain, particularly as other species like limber pine take up valuable space for them to germinate.

"The things we're doing today have legacy effects for thousands of years in the Great Basin," Smithers said. "When those trees do start to die, they won't likely be replaced because it's just too hot and dry."

The study suggests that land managers identify the specific bottlenecks for a species to live long enough to reproduce, and focus on that stage. For long-lived trees like bristlecone and limber pines, the bottleneck is at the time of their initial establishment, not hundreds and thousands of years into their adulthoods.

Author: Kat Kerlin | Source: University of California - Davis [September 14, 2017]

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Climate change challenges the survival of fish across the world

Climate change will force many amphibians, mammals and birds to move to cooler areas outside their normal ranges, provided they can find space and a clear trajectory among our urban developments and growing cities. But what are the chances for fish to survive as climate change continues to warm waters around the world?

Fish species in many river systems, including the John Day River pictured, will face the challenge of coping 
with warmer waters in the future [Credit: University of Washington]

University of Washington researchers are tackling this question in the first analysis of how vulnerable the world's freshwater and marine fishes are to climate change. Their paper, appearing online in Nature Climate Change, used physiological data to predict how nearly 3,000 fish species living in oceans and rivers will respond to warming water temperatures in different regions.

"Climate change is happening. We need tools to try to identify areas that are going to be the most at risk and try to develop plans to conserve these areas," said lead author Lise Comte, a postdoctoral researcher in the UW's School of Aquatic and Fishery Sciences. "It's important to look at the organisms themselves as we cannot just assume they will all be equally sensitive to these changes."

The researchers compiled data from lab experiments involving nearly 500 fish species, conducted over the past 80 years by researchers around the world. These standardized experiments measure the highest temperatures fish are able to tolerate before they die. This analysis is the first time these disparate data from lab experiments have been combined and translated to predict how fish will respond in the wild.

The researchers found that overall, sensitivity to temperature changes varied greatly between ocean-dwelling and freshwater fish. In general, marine fish in the tropics and freshwater fish in higher latitudes of the Northern Hemisphere were the most at risk when water temperatures warmed, the analysis showed.

This figure shows the risk that freshwater fish (top) and marine fish (bottom) could exceed their thermal limits 
by the year 2070. Blue indicates a low risk and red shows a high risk [Credit: University of Washington]

"Nowhere on Earth are fish spared from having to cope with climate change," said senior author Julian Olden, a UW professor of aquatic and fishery sciences. "Fish have unique challenges -- they either have to make rapid movements to track their temperature requirements, or they will be forced to adapt quickly."

Using years of data -- and relying on the fact that many fish species are taxonomically related and tend to share the same thermal limits -- the researchers were able to predict the breaking-point temperature for close to 3,000 species. Regional patterns then emerged when those data were paired with climate-model data predicting temperature increases under climate change.

For example, fish in the tropical oceans are already living in water that is approaching the upper range of their tolerance. They might not have much wiggle room when temperatures increase slightly. By contrast, in freshwater streams in the far north, fish are accustomed to cooler water temperatures but have much less tolerance for warming waters. Since the effects of climate change are acutely felt in high latitudes, this doesn't bode well for fish in those streams that have a small window for survivable temperatures.

Fish will either migrate, adapt or die off as temperatures continue to warm, the researchers explained. Given past evolutionary rates of critical thermal limits, it's unlikely that fish will be able to keep up with the rate at which temperatures are increasing, Olden said. The ability to move, then, is imperative for fish that live in the most critical areas identified in this analysis.

Currently, dams and other infrastructure may block fish from getting where they might need to be in the future; fish ladders and other means to allow fish to circumvent these barriers could be more readily used, although the effectiveness of these structures is highly variable.

Additionally, actions to restore vegetation along the edges of streams and lakes can help shade and reduce water temperature for the benefit of fish.

"Fishes across the world face mounting challenges associated with climate change," Olden said. "Looking forward, continued efforts to support conservation strategies that allow species to respond to these rapid changes are needed."

Author: Michelle Ma | Source: University of Washington [September 13, 2017]

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Back from the dead: how to revive a lost species

Scientists from around the world are hoping to return a lost species of giant tortoise to one of the world-famous Galápagos islands.

In 2008 the researchers found tortoises with the distinctive saddleback shells such as the adult tortoise, right, 
on Isabela Island in the Galápagos [Credit: Luciano Beheregaray, Flinders University]

The discovery of DNA links or ‘high ancestry’ to extinct Floreana species of giant tortoise means the mega-herbivore could one day be returned to the island for repatriation via a captive-breeding program – perhaps within the next five years.

Professor Luciano Beheregaray, Head of the Molecular Ecology Group at Flinders University, says the conservation effort will be a major milestone in jump-starting the recovery of the Foreana Island’s exotic ecosystem which critically depends on the mega herbivore.

The exciting discovery, outlined in Scientific Reports, describes how the discovery was made after an international expedition to a remote volcano on Isabela Island in the Galápagos found many giant tortoises with high ancestry from the extinct Floreana Island tortoise (Chelonoidis elephantopus).

Giant tortoises were transported by helicopter and then ship from the volcano’s slopes to the Galápagos National Park Breeding Center on the central island of Santa Cruz.

DNA analyses used by the experts from the US, Belgium, Ecuador, Greece, Italy and Australia, then assigned the ancestry of the relocated tortoises using reference databases containing data from all extant and extinct species of Galápagos giant tortoises.

The 23 relocated tortoises found to have high ancestry to the extinct Floreana species are now being used in a genetically-informed captive breeding program that aims to repatriate this species to Floreana Island.

“Our discovery and the captive breeding program raises the possibility that the extinct Floreana species could be revived,” says  ARC Future Fellow Professor Beheregaray, from Flinders University’s College of Science and Engineering (Biological Sciences).

Charles Darwin wrote about the harvesting of the species of tortoise found only on Floreana Island, which was exterminated within 15 years of his visit to the Galápagos in 1835.

Tortoises were removed from Floreana more than two centuries ago by mariners looking for food.

However, in 2008 the researchers found tortoises with the distinctive saddleback shells on Isabela, an island where native species have dome-shaped shells (see photo).

Several DNA-based analyses were then used to show that these animals were descendants of the Floreana species.

The latest study’s coordinator Adalgisa Caccone, from Yale University, says it was ironical that the haphazard translocations by mariners killing tortoises for food some 200 years ago has now created the unique opportunity to revive this lost species today.

As a result of that discovery, the Galápagos National Park, together with the Galápagos Conservancy, carried out an ambitious, logistically complex, and strenuous expedition in late 2015 to find and relocate genetic relatives of the extinct species of tortoise and to launch a breeding program aimed at restoring them to their native island.

“That expedition was a success,” says Professor Beheregaray.

Species are being lost at an unprecedented rate due to human-driven environmental changes. The cases in which species declared extinct can be revived are rare.

The geneticists are now working together with the Galápagos National Park and the Galápagos Conservancy to implement a monitored breeding program with the animals relocated from Isabela Island.

This program will strive to preserve in future generations the diversity of the breeders and to maximise the Floreana species’ genomic representation in their offspring.

The current plan is to release young tortoises on the island within five years.

Source: Flinders University [September 13, 2017]

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Study: Asia's glaciers face massive melt from global warming

Scientists say one-third of the ice stored in Asia's glaciers will be lost by the end of the century even if the world manages to meet its ambitious goal of keeping global warming below 1.5 degrees Celsius, affecting water supplies for millions of people on the continent.

International trekkers pass through a glacier at the Mount Everest base camp, Nepal. Scientists say a third of the ice stored 
in Asia’s glaciers will be lost by the end of the century even if global warming stays below 1.5 degrees Celsius 
[Credit: AP/Tashi Sherpa]

In a paper published in the journal Nature, researchers in the Netherlands also examined what would happen if average global temperatures rise beyond 1.5 degrees Celsius (2.7 degrees Fahrenheit) by the end of the century. They concluded that almost two-thirds of the ice in Asia's glaciers could vanish, if no effort is made to curb climate change.

"In regions where glacier melt water is an important part of the river flow, the retreating glaciers can become a problem," Philip Kraaijenbrink, a University of Utrecht geographer who led the study, said.

"There are many people living in basins that have their rivers originating in Asia's high mountains, such as the Indus, Ganges and Brahmaputra," Kraaijenbrink said. "In these basins, the river water is used for irrigation of cropland, drinking water and for hydropower dams."

The 1.5-degree target was set at the international climate conference in Paris two years ago, but experts say it would require a massive shift to the world economy.

In total, the researchers compared 110 climate simulations and found that high mountain glaciers in Asia tended to experience greater levels of warming than the global average. All glaciers analyzed already are losing mass except those in the Kunlun Mountains of western China.

A Kashmiri nomad tends to his heard of sheep and goats as he crosses a glacier near Dubgan, 70 kilometers (43 miles) 
south of Srinagar, India. Scientists say a third of the ice stored in Asia’s glaciers will be lost by the end of the century
 even if global warming stays below 1.5 degrees Celsius. Bakarwals are nomadic herders of India's Jammu-Kashmir 
state who wander in search of good pastures for their cattle. Every year in April-May more than one hundred thousand 
people from the nomadic Bakarwal tribes arrive in the meadows of Kashmir and parts of Ladakh from areas of the
 Jammu region with their flocks of cattle and sheep. After crossing snowy mountains with their cattle and belongings, 
Kashmir valley's lush green meadows become their home from April to September, after which they begin their 
return journey. This seasonal shifting of "homes" ensures a regular flow of income for the families 
[Credit: AP/Dar Yasin]

Taking into account the effect on melting levels of rubble covering some of the glaciers, they concluded that the amount of ice lost from Asian glaciers is almost proportional to the amount of warming they experience, though with some regional variations.

"Even if temperatures stabilize at their current level, mass loss will continue for decades to come until a new equilibrium is reached," the researchers said.

Kraaijenbrink acknowledged that a scenario in which global warming remains under 1.5 degrees Celsius is optimistic.

"We are aware that more extreme, business-as-usual scenarios are possibly a more likely future," he said.

In a comment published along with the study, J. Graham Cogley of Trent University in Canada said the researchers' glacier model "has some innovative features that might raise eyebrows among glaciologists, but it is difficult to find fault with it as a pioneering effort."

"The authors have shown that achieving the 1.5 Celsius target will conserve a substantial fraction of Asia's water resources and that, if we fail in this regard, we will pay in direct proportion to the extent of the failure," Cogley said.

Author: Frank Jordans | Source: The Associated Press [September 13, 2017]

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Rising CO2 leading to changes in land plant photosynthesis

Researchers led by Scripps Institution of Oceanography at the University of California San Diego have determined that major changes in plant behavior have occurred over the past 40 years, using measurements of subtle changes in the carbon dioxide (CO2) currently found in the atmosphere.

Photo: MistikaS/iStock

The two main isotopes, or atomic forms, of carbon are carbon-12 (12C) and carbon-13 (13C). As CO2 has risen since the late 19th century, the ratio of 13C to 12C in atmospheric CO2 has decreased. That's in part because the CO2 produced by the combustion of fossil fuels has a low 13C/12C ratio. There are other factors in nature as well, however, that have influenced the rate of decrease in the isotopic ratio. The measured rate of decrease in the isotopic ratio turns out to be different than what scientists previously expected.

The Scripps-led team updated the record of CO2 isotopic ratios that has been made at Scripps since 1978 using air samples collected at Hawaii's Mauna Loa and the South Pole. The researchers confirmed that the discrepancy exists and considered several reasons for it. They concluded that no combination of factors could plausibly explain the changes in the CO2 isotopic ratio unless plant behavior was changing in a way that influences how much water plants need for growth.

The work helps to understand the details of how leaves are responding to changes in CO2. Prior to this study, it was already clear that plants behave differently when they are exposed to higher atmospheric CO2 levels because CO2 influences the behavior of stomata, the microscopic holes in leaves that allow a leaf to take up CO2. These holes also allow water to evaporate from the leaf, which must be replenished by water supplied to the roots to avoid drying out. With more CO2 in the atmosphere, a plant can afford to have smaller or fewer stomata, thus allowing more photosynthesis for the same amount of water.

But measuring exactly how much more efficient plants have become at using water has not been easy. This study provides a new method for measuring this effect, because as a leaf becomes more efficient at using water, this also influences how it takes up the different carbon isotopes in CO2. When that factor is included as a variable, the ratio of the two forms of CO2 conforms much more closely to expectations. The National Science Foundation, the Department of Energy, NASA, and the Eric and Wendy Schmidt Fund for Strategic Innovation supported the study, "Atmospheric evidence for a global secular increase in carbon isotopic discrimination of land photosynthesis," which appears in the journal Proceedings of the National Academy of Sciences.

The research supports a long-standing hypothesis introduced by plant biologists, that posits plants will achieve an optimum response to rising CO2 levels in the atmosphere.

"This optimal model predicts nearly proportional scaling between water-use efficiency and CO2 itself," said study lead author and Scripps scientist Ralph Keeling, who also maintains the internationally renowned Keeling Curve data set measuring atmospheric CO2 since 1958. "Optimal or near optimal behavior has been found in smaller studies on individual plants, but this paper is the first to show that it may be evident at the scale of the entire planet."

The increase in the efficiency of photosynthesis documented in this study has likely helped plants offset a portion of human-induced climate change by removing more CO2 from the atmosphere than they would have otherwise.

"The full implications are still far from clear, however, and any benefits may be more than offset by other negative changes, such as heat waves and extreme weather, biodiversity loss, sea level rise, and so on," said Keeling.

Source: University of California - San Diego [September 12, 2017]

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How openings in Antarctic sea ice affect worldwide climate

In 1974, images acquired from NOAA satellites revealed a puzzling phenomenon: a 250,000 square kilometer opening in the winter sea ice in the Weddell Sea, south of South America. The opening, known as a polynya, persisted over three winters. Such expansive ice-free areas in the ocean surrounding Antarctica have not been seen since, though a small polynya was seen last year.

A polynya, or an opening in the sea ice, was present in the Southern Ocean in the 1970s. This image shows the sea ice 
concentration averaged over three September months 1974-1976 during the Weddell Polynya, made with data from 
the NIMBUS-V satellite from the National Snow Ice Data Center [Credit: University of Pennsylvania]

In a new analysis of climate models, researchers from the University of Pennslyvania, Spain's Institute of Marine Sciences and Johns Hopkins University reveal the significant global effects that these seemingly anomalous polynyas can have. Their findings indicate that heat escaping from the ocean through these openings impacts sea and atmospheric temperatures and wind patterns around the globe and even rainfall around the tropics. Though this process is part of a natural pattern of climate variability, it has implications for how the global climate will respond to future anthropogenic warming.

"This small, isolated opening in the sea ice in the Southern Ocean can have significant, large-scale climate implications," said Irina Marinov, a study author and assistant professor in Penn's Department of Earth and Enviromental Science in the School of Arts & Sciences. "Climate models suggest that, in years and decades with a large polynya, the entire atmosphere warms globally, and we see changes in the winds in the Southern Hemisphere and a southward shift in the equatorial rain belt. This is attributable to the polynya."

The study appears in the Journal of Climate. Marinov coauthored the work with Anna Cabre, a former postdoc in Marinov's lab and now an oceanographer with the Institue of Marine Sciences in Barcelona, and Anand Gnanadesikan, a professor in the Department of Earth and Planetary Science at Johns Hopkins.

Typically, the Southern Ocean is covered in ice during the Southern Hemisphere's

winter. Polynyas occur when warm subsurface waters of North Atlantic and equatorial origin mix locally with cold surface waters, a process known as open-ocean convection.

Until recently, climate scientists and oceanographers believed that atmospheric and ocean conditions around the tropics were the primary drivers in affecting conditions outside the tropics. But in the last few years, Marinov and collaborators and others have shown that the opposite is also true: the Southern Ocean has an important role in affecting tropical and Northern Hemisphere climates.

Marinov's team uncovered a natural climate pattern originating from openings in the sea ice of the Weddell Sea. This 
diagram shows the Weddell Sea surface temperature (in black) and Southern Ocean sea ice cover percentage (red) for 
500 years in the researchers' climate model simulation. At bottom: the temperature in the Weddell Sea is shown over 
sea depth for the same 500 years of the simulation. In non-convective years the heat is stored in the Southern Ocean 
subsurface, the surface is cold and there is extensive sea-ice. In convective years the subsurface heat is released 
from the deep ocean, heating the surface ocean and melting the sea ice, resulting in polynyas 
[Credit: University of Pennsylvania]

In the current work, Marinov and colleagues used powerful models that simulate past and future climate to determine how the effects of polynya ripple out around the globe.

Their model indicated that polynyas and accompanying open-ocean convection occur roughly every 75 years. When they occur, the researchers observed, they act as a release valve for the ocean's heat. Not only does the immediate area warm, but there are also increases in overall sea-surface and atmospheric temperatures of the entire Southern Hemisphere and, to a lesser extent, the Northern Hemisphere, as well.

Changes in north-south temperature gradients lead to changes in wind patterns as well.

"We are seeing a decrease in what we call the Southern Hemisphere westerlies and changes in trade winds," Marinov said. "And these winds affect storms, precipitation and clouds."

Among these changes in precipitation is a shift in the Intertropical Convergence Zone, an equatorial belt where trade winds converge, resulting in intense precipitation. When a polynya occurs, this rain belt moves south a few degrees and stays there for 20 to 30 years before shifting back.

"This affects water resources in, for example, Indonesia, South America and sub-Saharan Africa," said Marinov. "We have a natural variation in climate that may be, among other effects, impacting agricultural production in heavily populated regions of the world."

Given these broad-scale implications of a Southern Ocean phenomenon, Marinov underscores the need to increase monitoring in the region. She is part of an effort called SOCCOM, for Southern Ocean Carbon and Climate Observations and Modeling, placing robotic floats in the Southern Ocean to collect data on ocean temperature, salinity, carbon, nutrients and oxygen.

"We're also urging people to keep a close eye on the satellites to look for other polynyas, this year and going forward," Marinov said.

Earlier research by Marinov's group and collaborators suggested that, under climate change, polynyas may become less frequent. As sea ice melts it freshens the top layer of the sea surface, making it lighter and less likely to mix with the heavier bottom waters. Marinov notes that the fact that no significant polynyas opened up from the mid-1970s until last year may have contributed to the so-called "climate hiatus" in the late 1990s and early 2000s, when global average surface temperatures appeared to stall in their otherwise persistent upward climb.

"During this hiatus period abnormal amounts of heat were stored in the subsurface ocean waters" Marinov said. "Most research has attributed this hiatus to a prolonged La Nina period, resulting in a storage of heat in the low-latitude Pacific. But I think that a lack of a Weddell Sea polynya also contributed, storing more heat in the Southern Ocean and preventing the additional release of heat to the atmosphere."

The work raises many new questions, such as how a decreasing sea ice extent, including the recent breaking off of a massive chunk of the Antarctic peninsula, will affect the frequency of polynyas and how the presence or absence of polynyas will affect how much atmospheric temperatures warm in response to anthropogenic climate change.

"This investigating into polynyas and Southern Ocean convection turned out to be a very important and interesting story for the global climate that we think a lot of people will be studying in the next decade," Marinov said.

Source: University of Pennsylvania [September 11, 2017]

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Cold region 'tipping point' now inevitable

The decline of cold regions called periglacial zones is now inevitable due to climate change, researchers say.

Intense soil frost churning at Kilpisjarvi, northwestern Finland, at 800 metres above sea level 
[Credit: uha Aalto]

Periglacial zones, where there is often a layer of frozen ground known as permafrost, make up about a quarter of Earth's land surface and are mostly found in the far north and south, and at high altitudes.

Scientists from the universities of Exeter and Helsinki and the Finnish Meteorological Institute examined natural processes caused by frost and snow which take place in these zones.

Their findings suggest that -- even with optimistic estimates of future carbon emissions -- areas covered by periglacial zones will reduce dramatically by 2050, and they will "almost disappear" by 2100.

This would have a major impact on landscapes and biodiversity, and could trigger climate "feedbacks" -- processes that can amplify or diminish the effects of climate change.

"The results suggest that profound changes can be expected in current periglacial zones regardless of climate change mitigation policies," said Dr Juha Aalto, of the University of Helsinki and the Finnish Meteorological Institute.

"Unfortunately, it seems that many of the frost-driven processes we studied are already at the margin of the climate in which they can exist."

The scientists studied four processes which take place in periglacial zones, including snow accumulation sites and "frost churning" -- which refers to mixing of materials caused by freezing and thawing.

"Our results forecast a future tipping point in the operation of these processes, and predict fundamental changes in ground conditions and related atmospheric feedbacks," Dr Aalto added.

Dr Stephan Harrison, of the University of Exeter's Penryn Campus in Cornwall, said: "The project used very high-resolution climate and land surface models to demonstrate that geological processes and ecosystems in high latitudes (the far north and south) will be fundamentally altered by climate change during this century."

Even based on the optimistic RCP2.6 estimate for future carbon emissions, the researchers predict a 72% reduction in the current periglacial zone in the area of northern Europe they studied.

By 2100, periglacial zones in will only exist in high mountain regions, they say.

Professor Miska Luoto, of the University of Helsinki, said: "The anticipated changes in land surface processes can feedback to the regional climate system via alterations in carbon cycle and ground surface reflectance (light reflected by snow and ice) caused by the increase of shrub vegetation to alpine tundra.

"Our results indicate significant changes in Northern European plant life. Many rare species can only be sustained in areas of intense frost activity or late-lying snow packs, so the disappearance of such unique environments will reduce biodiversity."

The paper is published in the journal Nature Communications.

Source: University of Exeter [September 11, 2017]

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Indicators of global climate change are detected in tropical oceans

Researchers from the University of California, Irvine and NASA's Jet Propulsion Laboratory have reported the first observation of sea level "fingerprints," tell-tale differences in sea level rise around the world in response to changes in continental water and ice sheet mass. The team's findings were published in the American Geophysical Union journal Geophysical Research Letters.

"Scientists have a solid understanding of the physics of sea level fingerprints, but we've never had a direct detection 
of the phenomenon until now," says study co-author Isabella Velicogna, a UCI professor of Earth system science
 and Jet Propulsion Laboratory research scientist, shown here on an expedition to Greenland 
[Credit: Maria Stenzel/UCI]

"Scientists have a solid understanding of the physics of sea level fingerprints, but we've never had a direct detection of the phenomenon until now," said co-author Isabella Velicogna, UCI professor of Earth system science and JPL research scientist.

As ice sheets and glaciers undergo climate-related melting, they alter Earth's gravity field, which causes nonuniform sea level change. Certain regions, particularly in the middle latitudes, are harder hit. For instance, Antarctica-generated sea level rise in California and Florida is as much as 52 percent greater than what's average in the rest of the world.

Cumulative sea level fingerprints calculated from observations of Greenland, Antarctica, glaciers 
and ice caps and land water storage mass changes observed with the GRACE satellites for the time
 period January 2003 to April 2014 [Credit: Isabella Velicogna & Chia-Wei Hsu/UCI]

The team calculated sea level fingerprints using time-variable gravity data collected by the twin satellites of NASA's Gravity Recovery & Climate Experiment between April 2002 and October 2014. During that time, according to the study, the global mean sea level grew by about 1.8 millimeters per year, with 43 percent of the increased water mass coming from Greenland, 16 percent from Antarctica, and 30 percent from mountain glaciers. The scientists verified their calculations of sea level fingerprints associated with these mass variations via ocean-bottom pressure readings from stations in the tropics.

Sea level fingerprints in millimeters per year calculated from observations of the mass loss of Greenland, 
Antarctica, glaciers and ice caps and changes in land water storage using time-variable gravity data collected 
by the twin satellites of the U.S./German Gravity Recovery and Climate Experiment mission between April 2002 
and October 2014. The blue contour (1.8 mm/year) is the average sea level rise if the total addition of mass 
of water to the ocean was spread uniformly over the world’s oceans. The SLF are not uniform and bulge
 around the equatorial regions [Credit: Isabella Velicogna & Chia-Wei Hsu/UCI]

"It was very exciting to observe the sea level fingerprints in the tropics, where they were not expected to be detectable," said lead author Chia-Wei Hsu, a graduate student researcher at UCI. "In the tropics, sea level fingerprint values are very close to global average sea level values, making them harder to detect."

Velicogna added: "We know that sea levels climb faster in the middle to low latitudes versus the high latitudes and that Greenland and Antarctica contribute differently to the process. With our improved understanding through GRACE data and other techniques, we're now able to take any point on the global ocean and determine how much the sea level there will rise as a result of glacier ice melt."

Source: University of California - Irvine [September 08, 2017]

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Hidden Inca treasure: Remarkable new tree genus discovered in the Andes

Hidden in plain sight -- that's how researchers describe their discovery of a new genus of large forest tree commonly found, yet previously scientifically unknown, in the tropical Andes. Researchers from the Smithsonian and Wake Forest University detailed their findings in a study just released in the journal PhytoKeys.

New canopy tree genus Incadendron esseri shown in this altitudinal transect of Manu National Park in Peru 
[Credit: Wake Forest University]

Named Incadendron esseri (literally "Esser's tree of the Inca"), the tree is a new genus and species commonly found along an ancient Inca path in Peru, the Trocha Union. Its association with the land of the Inca empire inspired its scientific name.

So how could a canopy tree stretching up to 100 feet tall and spanning nearly two feet in diameter go undetected until now?

"Incadendron tells us a lot about how little we understand life on our planet. Here is a tree that ranges from southern Peru to Ecuador, that is abundant on the landscape, and yet it was unknown. Finding this tree isn't like finding another species of oak or another species of hickory -- it's like finding oak or hickory in the first place," said Miles Silman, the Andrew Sabin Family Foundation Presidential Chair in Conservation Biology at Wake Forest.

"This tree perplexed researchers for several years before being named as new. It just goes to show that so much biodiversity is unknown and that obvious new species are awaiting discovery everywhere -- in remote ecological plots, as well as in our own backyards," said Kenneth Wurdack, a botanist with the Smithsonian's National Museum of Natural History.

Fruits and leaves of Incadendron esseri, new tree genus found in Peru and Ecuador 
[Credit: Jason Houston]

The tree belongs to the spurge family, Euphorbiaceae -- best known for rubber trees, cassava, and poinsettias -- and like many of its relatives, when damaged also bleeds white sap, known as latex, that serves to protect it from insects and diseases.

Its ecological success in a difficult environment suggests more study is needed to find the hidden secrets that are often inherent in newly discovered and poorly known biodiversity.

Currently the Incadendron is common in several research plots under intensive study as part of the Andes Biodiversity and Ecosystem Research Group, an international Andes-to-Amazon ecology program co-founded by Silman.

For nearly 25 years, Silman has worked to gain greater understanding of Andean species distributions, biodiversity, and the response of forest ecosystems to climate and land use changes over time.

Incadendron esseri branch [Credit: Wake Forest University]

"While Incadendron has a broad range along the Andes, it is susceptible to climate change because it lives in a narrow band of temperatures. As temperatures rise, the tree populations have to move up to cooler temperatures," said Silman.

One of the study's co-authors, William Farfan-Rios, is a Wake Forest graduate student researching tropical forest dynamics and responses to changing environments along the Andes-to-Amazon elevational gradient. Discovering the Incadendron hits particularly close to home for the Cusco, Peru-native. Not only is the new genus vulnerable to climate change, but it is also threatened by deforestation in nearby areas.

"It highlights the imperative role of parks and protected areas where it grows, such as Manu National Park and the Yanachaga-Chemillen National Park," he said. "Hopefully our ongoing study of the Incadendron and the intensive long-term forest monitoring will contribute to best practices in reforestation and forest management."

Source: Wake Forest University [September 07, 2017]

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