Shift of species mean abundance center by ecoprovinces in the eastern United States during the last three decades. 210, Northern Hardwood region; 220, Central Hardwood region; 230, Southern Pine-Hardwood region; 250, Forest-Prairie Transition region (44, 51). All three species centered in ecoprovince 250 shifted westward (rose diagram not shown). “Si*” indicates that the shift is statistically significant (P < 0.05). NS, nonsignificant. Graphic: Fei, et al., 2017 / Science Advances

WEST LAFAYETTE, Indiana, 17 May 2017 (Purdue University) – After analyzing extensive data collected on 86 tree species in the eastern United States, a research team led by Purdue University professor Songlin Fei found that over the past 30 years, most trees have been shifting westward or northward in response to climate change.

“Trees are shifting partially because of climate change, but their responses are species specific,” Fei said. “Deciduous trees like oak and maple are primarily moving westward. Evergreens are responding in a different way. They’re moving northwards.”

The research, based on the analysis of 30 years of data gathered by the U.S. Forest Service, was published in Science Advances on May 17. The study represented data collected on trees from 1980 to 2015.

The study, which outlined divergent responses to climate changed based on species, also revealed that precipitation was a significant factor when considering the impact climate change can have on biodiversity and the sustainability of ecosystems. Many climate change studies have generally shown a strong correlation between changes in temperature and tree shifting.

“Precipitation has a stronger near term impact on species shift than temperature,” said Fei, an associate professor at Purdue’s College of Agriculture and a researcher with Purdue’s Climate Change Research Center.

As a result, most trees in the study were shifting westward to follow changes in moisture. Fei said the westward shift was one of the most surprising findings of the study.

“Yes, we did see some northward shift as we had anticipated,” he said. “But we also found many trees have been moving westward because of changing climate. When analyzing the impact of climate change, precipitation had a much stronger near-term impacts on forests instead of temperatures.”

The study also led the researchers to conclude that fluctuations in average precipitation and temperature are leading to changes in forest composition. As a result, climate change is putting “the resilience and sustainability of various forest ecosystems across eastern United States in question.”

Fei said the findings are significant in that the research team was able to examine the effects of climate change on trait-specific trees using a large amount of data.

“Previous studies have investigated the impacts of climate change, but large scale trait-specific impacts are less understood,” he said.

Fei also said that the research shows the clear impact of climate change based on big data, not just modeling.

“It is not future predictions,” he said. “Empirical data reveals the impact of climate change is happening on the ground now. It’s in action.”

Research authors also included Johanna M. Desprez, Insu Jo and Jonathan A. Knott, all of Purdue’s Department of Forestry and Natural Resources; Kevin M. Potter of North Carolina State University’s Department of Forestry and Environmental Resources; and Christopher M. Oswalt of the U.S. Forest Service Southern Research Station.

During the past 30 years, the period covered by the research, the mean annual temperature in the eastern United States, where data was collected, increased by about 0.16 degree Celsius on average. The northern areas of that region had among the highest temperature increases.

Precipitation patterns also have changed during the 30-year data research period, with increasing temperatures resulting in widespread droughts, as measured by the Palmer Drought Severity Index, in the southern region of the study area. 

Fei said further research will focus on communities of trees, and the impact climate change can have on the sustainability of diverse ecosystems.

“We want to know if there is a community breakdown among groups of species resulting from climate changes,” he said.

Contact

Shari Finnell, sfinnell@purdue.edu, 317.201.2345, Manager of Media Relations, Purdue University College of Agriculture

Trees are moving westward in response to precipitation changes, Purdue University professor reveals


ABSTRACT: Climate change can have profound impacts on biodiversity and the sustainability of many ecosystems. Various studies have investigated the impacts of climate change, but large-scale, trait-specific impacts are less understood. We analyze abundance data over time for 86 tree species/groups across the eastern United States spanning the last three decades. We show that more tree species have experienced a westward shift (73%) than a poleward shift (62%) in their abundance, a trend that is stronger for saplings than adult trees. The observed shifts are primarily due to the changes of subpopulation abundances in the leading edges and are significantly associated with changes in moisture availability and successional processes. These spatial shifts are associated with species that have similar traits (drought tolerance, wood density, and seed weight) and evolutionary histories (most angiosperms shifted westward and most gymnosperms shifted poleward). Our results indicate that changes in moisture availability have stronger near-term impacts on vegetation dynamics than changes in temperature. The divergent responses to climate change by trait- and phylogenetic-specific groups could lead to changes in composition of forest ecosystems, putting the resilience and sustainability of various forest ecosystems in question.

Divergence of species responses to climate change

19 April 2017 (Lamont-Doherty Earth Observatory) – In the first such continent-wide survey, scientists have found extensive drainages of meltwater flowing over parts of Antarctica’s ice during the brief summer. Researchers already knew such features existed, but assumed they were confined mainly to Antarctica’s fastest-warming, most northerly reaches. Many of the newly mapped drainages are not new, but the fact they exist at all is significant; they appear to proliferate with small upswings in temperature, so warming projected for this century could quickly magnify their influence on sea level. An accompanying study looks at how such systems might influence the great ice shelves ringing the continent, which some researchers fear could collapse, bringing catastrophic sea-level rises. Both studies appear this week in the leading scientific journal Nature.

Explorers and scientists have documented a few Antarctic melt streams starting in the early 20th century, but no one knew how extensive they were. The authors found out by systematically cataloging images of surface water in photos taken from military aircraft from 1947 onward, and satellite imagery from 1973 on. They found nearly 700 seasonal systems of interconnected ponds, channels and braided streams fringing the continent on all sides. Some run as far as 75 miles, with ponds up to several miles wide. They start as close as 375 miles from the South Pole, and at 4,300 feet above sea level, where liquid water was generally thought to be rare to impossible.

This is not in the future—this is widespread now, and has been for decades,” said lead author Jonathan Kingslake, a glaciologist at Columbia University’s Lamont-Doherty Earth Observatory. “I think most polar scientists have considered water moving across the surface of Antarctica to be extremely rare. But we found a lot of it, over very large areas.” The data are too sparse in many locations for the researchers to tell whether the extent or number of drainages have increased over the seven decades covered by the study. “We have no reason to think they have,” said Kingslake. “But without further work, we can’t tell. Now, looking forward, it will be really important to work out how these systems will change in response to warming, and how this will affect the ice sheets.”

Many of the newly mapped drainages start near mountains poking through glaciers, or in areas where powerful winds have scoured snow off underlying bluish ice. These features are darker than the mostly snow-covered ice sheet, and so absorb more solar energy. This causes melting, and on a slope, liquid water then melts a path downhill through overlying snow. If the continent warms this century as projected, this process will occur on a much larger scale, say the authors. “This study tells us there’s already a lot more melting going on than we thought,” said coauthor Robin Bell, a Lamont-Doherty polar scientist. “When you turn up the temperature, it’s only going to increase.”

Antarctica is already losing ice, but the direct effects of meltwater, which generally refreezes in winter, are probably negligible for now. The concern among glaciologists is that this could change in the future. Most loss right now is taking place near the edges, where giant, floating shelves of ice attached to the land are being eroded from underneath by warming ocean currents. The shelves, which ring three-quarters of Antarctica, help hold back the land-bound glaciers behind them, and as they lose mass, glaciers appear to be accelerating their march to the sea.

The most dramatic example is the Antarctic Peninsula, which juts far north from the main ice sheet, and where average temperatures have soared 7 degrees Fahrenheit in the last 50 years. In 1995 and 2002, large chunks of the peninsula’s Larsen Ice Shelf suddenly disintegrated into the ocean within days. Scientists now suspect that pooling water was at work; liquid tends to burrow down, fracturing the ice with heat or pressure, or both, until a shattering point is reached. Today, another giant piece of the Larsen is cracking, and could come apart at any time.

Further south, temperatures have remained more or less stable, but many of the newly spotted streams there already make their way from the interior out onto ice shelves, or originate on the shelves themselves. That raises the specter that such collapses could happen across much vaster reaches of Antarctica this century, should warming proceed as expected, said Kingslake.

On the other hand, an accompanying study led by Bell found that a longtime drainage on West Antarctica’s Nansen Ice Shelf may actually be helping keep the shelf together. The elaborate river-like system on the 30-mile-long shelf was first observed in 1909, by a team from the expedition led by British explorer Ernest Shackleton. Aerial imagery and remote sensing since then shows it has remained remarkably stable, efficiently draining excess meltwater during summer through a series of deep sinkholes and a roaring 400-foot-wide waterfall into the ocean. “It could develop this way in other places, or things could just devolve into giant slush puddles,” said Bell. “Ice is dynamic and complex, and we don’t have the data yet.”

Near the other pole, seasonal melt streams and ponds are far more common on the fast-warming Greenland ice sheet, and their growing influence may hold lessons. In recent years as much as 90 percent of Greenland’s ice surface has undergone some degree of seasonal melting. Much of the water probably stays at or near the surface and refreezes in winter. But in some areas, it is plunging through deep holes to underlying rock, lubricating glaciers’ slide to the sea. In others, water may be refreezing near the surface into solid sheets that can more easily channel surface melt to the sea in succeeding seasons. Until recently, icebergs discharged from glaciers were Greenland’s main contributor to sea-level rise. But between 2011 and 2014, 70 percent of the 269 million tons of Greenland’s ice and snow lost to the ocean came directly from meltwater, not icebergs.

Antarctica’s visible drainages may be the tip of the proverbial iceberg. Another study by a separate team published in January revealed that East Antarctica’s Roi Baudouin Ice Shelf harbors a largely invisible liquid drainage just under the snow. The team, led by Utrecht University polar scientist Jan Lenaerts, detected it using radar images and drilling. They suspect that such features lurk in many places. And unlike surface streams, these ones are insulated, so may stay liquid year-round.

Helen Fricker, a glaciologist at Scripps Institution of Oceanography who was not involved the new studies, said of the continent-wide survey, “We knew there were other [melt] zones, but we didn’t know exactly how extensive they are. This is a really nice study, as it does just that.” Douglas MacAyeal, a glaciologist at the University of Chicago also not involved in the studies, said that until recently, “nobody’s been that interested in melting,” because most scientists thought it was relatively rare. Now, he said, “We’re working hard to figure out if this stuff is relevant to sea-level predictions.”

The other authors of the continent-wide study are Jeremy Ely of the University of Sheffield and Indrani Das of Lamont-Doherty. The additional authors of the Nansen Ice Shelf study are Winnie Chu, Indrani Das, Marco Tedesco, Kirsty Tinto, Christopher Zappa and Alexandra Boghosian of Lamont-Doherty; Massimo Frezzotti of ENEA SP in Italy; and Won Sang Lee of the Korea Polar Research Institute.  The research was funded by NASA, the U.S. National Science Foundation, the Old York Foundation and the Korean Ministry of Oceans and Fisheries.

Contact

Kevin Krajick
kkrajick@ei.columbia.edu
(212) 854-9729

Water Is Streaming Across Antarctica


Scientists have discovered that seasonally flowing streams fringe much of Antarctica’s ice. Each red ‘X’ represents a separate drainage. Up to now, such features were thought to exist mainly on the far northerly Antarctic Peninsula (upper left). Their widespread presence signals that the ice may be more vulnerable to melting than previously thought. Graphic: Kingslake et al., 2017 / Nature

ABSTRACT: Surface meltwater drains across ice sheets, forming melt ponds that can trigger ice-shelf collapse1, 2, acceleration of grounded ice flow and increased sea-level rise3, 4, 5. Numerical models of the Antarctic Ice Sheet that incorporate meltwater’s impact on ice shelves, but ignore the movement of water across the ice surface, predict a metre of global sea-level rise this century5 in response to atmospheric warming6. To understand the impact of water moving across the ice surface a broad quantification of surface meltwater and its drainage is needed. Yet, despite extensive research in Greenland7, 8, 9, 10 and observations of individual drainage systems in Antarctica10, 11, 12, 13, 14, 15, 16, 17, we have little understanding of Antarctic-wide surface hydrology or how it will evolve. Here we show widespread drainage of meltwater across the surface of the ice sheet through surface streams and ponds (hereafter ‘surface drainage’) as far south as 85° S and as high as 1,300 metres above sea level. Our findings are based on satellite imagery from 1973 onwards and aerial photography from 1947 onwards. Surface drainage has persisted for decades, transporting water up to 120 kilometres from grounded ice onto and across ice shelves, feeding vast melt ponds up to 80 kilometres long. Large-scale surface drainage could deliver water to areas of ice shelves vulnerable to collapse, as melt rates increase this century. While Antarctic surface melt ponds are relatively well documented on some ice shelves, we have discovered that ponds often form part of widespread, large-scale surface drainage systems. In a warming climate, enhanced surface drainage could accelerate future ice-mass loss from Antarctic, potentially via positive feedbacks between the extent of exposed rock, melting and thinning of the ice sheet.

Widespread movement of meltwater onto and across Antarctic ice shelves

Aerial view of flooding in Sri Lanka, 28 May 2017. Photo: SLAF Media

28 May 2017 (Daily Mirror) – The number of deaths reported in floods and landslides was increased to 151 while 112 people had gone missing, the Disaster Management Centre (DMC) said on Sunday.

In its latest situation report, the DMC said the adverse weather condition had left 52 people injured. In total, 442,299 people of 114,124 families had been affected by the weather calamity.

The South-West monsoon unleashed torrential rains, which ravaged fourteen districts in the western and southern parts of the country on Friday and Thursday.

The disaster is described as one of the worst-ever calamities since the 2003 floods. [more]

Weather calamity: Death toll rises to 151


COLOMBO, Sri Lanka, 27 May 2017 (Agence France-Presse) – Flooding and landslides killed at least 92 people and left another 110 missing in Sri Lanka as the monsoon set in Friday, May 26, dumping record rainfall in many parts of the island, authorities said.

The official Disaster Management Centre (DMC) reported that over 60,000 people were driven out of their homes in the south and western parts of the country.

“There are some areas where we are unable to reach, but relief operations are under way,” deputy minister for disaster management Dunesh Gankanda told reporters in Colombo.

Officials said the toll rose to 92 dead, including a soldier who fell to his death from a helicopter while trying to pull a marooned villager to safety. Another 110 people remain missing. […]

The latest flooding was the worst since May 2003 when 250 people were killed and 10,000 homes destroyed after a similarly powerful Southwest monsoon, officials said.

In the early hours of the day a mountainside collapsed on a women’s hostel at a tea plantation at Neluwa in the island’s south, killing at least 7 women, police said.

DMC officials said the monsoon had been expected on Thursday night, May 25, and ended a prolonged drought that had threatened agriculture as well as hydropower generation.

The rains filled the reservoirs used for hydroelectric projects after low supplies had raised fears of power shortages in June.

But officials said most reservoirs were now so full they were in danger of spilling over and flooding communities living downstream. [more]

Floods, landslides kill at least 92 in Sri Lanka

Screenshot of an appearance by former Republican Speaker Newt Gingrich (Georgia) on 'Fox & Friends', 28 May 2017. He claims, erroneously, that poor nations will 'get crushed' by the the Paris climate accord. In fact, many of the world's poorest countries have been among the strongest advocates for the Paris climate deal. Photo: Fox News Channel

By Max Greenwood
28 May 2017

(The Hill) – Former Republican Speaker Newt Gingrich (Ga.) argued on Sunday that international agreements such as the Paris climate deal ultimately harm developing countries that cannot afford to implement environmental regulations.

"The working poor and the very poor on the planet get crushed by these kind of agreements," Gingrich said on Fox & Friends. "So I am for more economic growth. Wealthier countries are better for the environment, poorer countries inevitably are harder for the environment."

The Paris accord commits both wealthy and poor countries to reducing greenhouse gas emissions and fighting the effects of climate change.

The world's largest greenhouse gas emitters, like the U.S., China, and Europe, pledged in 2015 to limit the global temperature rise over the next 50 years to 3 degrees Celsius.

In fact, many of the world's poorest countries have been among the strongest advocates for the Paris climate deal, because they are considered particularly susceptible to the effects of climate change.

Leaders from some of the least-developed countries have argued that the pledge isn't enough and that they must commit to limiting the temperature rise to only 1.5 degrees Celsius.

President Trump refused on Saturday to join fellow Group of Seven leaders in a pledge of support for the 195-nation climate agreement. He tweeted Saturday morning that he has not yet decided whether he will keep the U.S. in the deal and that a decision would be made this week.[more]

Gingrich: The poor ‘get crushed’ by deals like Paris climate accord

Evolution of deforestation pressure in the Jamanxim forest, 2006 to 2017. Martins, H., Ribeiro, J., & Souza Jr., C. 2017.  Graphic: Imazon

By Fabiano Maisonnave
23 May 2017

MANAUS (Folha De São Paulo) – Unchanged, the Senate ratified on Tuesday (23) two provisional measures that reduce the protection of 597 thousand hectares [1.48 million acres] of protected areas in the Amazon, equivalent to four municipalities of São Paulo.

Provisional measures 756 and 758, which paved the way for the legalization of grileiros and squatters, had been approved by the House last week and are now being sanctioned or vetoed by President Michel Temer.

The most affected conservation area is the Jamanxim National Forest, in the region of Novo Progresso (PA), which can lose 486 thousand hectares (37% of the total). The change provides for this area to be transformed into an Environmental Protection Area (APA), which allows livestock and mining.

The Senate has maintained the parliamentary amendment that provides for the withdrawal of 10,400 hectares of the National Park of San Joaquim (SC), located thousands of kilometers from Pará, initial scope of provisional measures.

Members of the Paraense bank, defenders of the provisional measures argue that the amendment aims to pacify the region and regularize the ownership of the land.

For environmentalists and scholars, however, the legalization of invasions will encourage more land grabbing of protected areas.

"By transforming illegally occupied areas of forests and national parks into APAs, the category of protected conservation unit that allows occupation and is the most deforested in the Amazon, the government encourages the invasion and deforestation of conservation areas throughout the country", says researcher Elis Araújo, of the NGO Imazon, based in Belém. [Translation by Google.]

Senado ratifica redução na proteção de áreas de conservação na Amazônia

Railway coal depot with limestone karst background. Viet Nam, Quảng Ninh, Cẩm Phả. Photo: garycycles8 / Flickr

By David Brown
26 May 2017

(Mongabay) – Shaken by news that Vietnam had confirmed plans to build another 40 gigawatts worth of coal-fired power plants by 2030, World Bank President Jim Yong Kim ad libbed a few lines into a May 2016 speech to an audience of government and business leaders. “If Vietnam goes forward with 40GW of coal, if the entire region implements the coal-based plans right now, I think we are finished,” Kim said. “That would spell disaster for us and our planet.”

The people in Hanoi who make energy policy were very likely startled to learn that what Vietnam does or does not do as it develops its energy sector has world-shaking importance. In a mere quarter century Vietnam has raced from the back of the 3rd World pack to middle-income status. In the process, however, Vietnam’s economic growth has had an outsized environmental impact; between 1991 and 2012, the country’s GDP grew by 315 percent, while its greenhouse gas emissions rose by 937 percent.

Now that China, which took the “capitalist road” a decade earlier than Vietnam, is stepping up to the challenge of climate change and taking bold steps to clean its air, its neighbor Vietnam risks becoming the new pariah polluter. […]

As sites for big hydro were used up, Hanoi’s attention turned to coal.  In 2011, it announced plans to construct 90 new coal-fired power plants by 2025. That forecast has been revised to zero out a plan to build several nuclear power plants and, after Vietnam signed on to the Paris Agreement on CO2 emissions reductions, to promise a substantial role for wind and solar power. However, there’s little doubt that Vietnam will stick to a coal-centered strategy thru 2030 (when coal will supply more than 50 percent of nation’s electric power) and probably beyond.

Coal is relatively abundant in Vietnam. Exploiting fields in the nation’s northeast corner, Vinacomin can produce about 50 million tons of high-BTU coal annually, or roughly 40 percent of estimated demand in 2030. The rest of the coal Vietnam will need then is likely to be lower BTU coal from Indonesia or Australia. Leaving externalities aside, coal is cheap and likely to remain so. Further, provided they like the price they’re offered per kilowatt-hour,investors will front the entire cost of new coal-fired power plants. [more]

Vietnam makes a big push for coal, while pledging to curb emissions

A screen shot taken from one of the “daily intelligence updates” developed by a shadowy international mercenary and security firm, known as TigerSwan, that targeted the movement opposed to the Dakota Access Pipeline with military-style counterterrorism measures, collaborating closely with police in at least five states. Photo: TigerSwan / The Intercept

By Alleen Brown, Will Parrish, and Alice Speri
27 May 2017

(The Intercept) – A shadowy international mercenary and security firm known as TigerSwan targeted the movement opposed to the Dakota Access Pipeline with military-style counterterrorism measures, collaborating closely with police in at least five states, according to internal documents obtained by The Intercept. The documents provide the first detailed picture of how TigerSwan, which originated as a U.S. military and State Department contractor helping to execute the global war on terror, worked at the behest of its client Energy Transfer Partners, the company building the Dakota Access Pipeline, to respond to the indigenous-led movement that sought to stop the project.

Internal TigerSwan communications describe the movement as “an ideologically driven insurgency with a strong religious component” and compare the anti-pipeline water protectors to jihadist fighters. One report, dated February 27, 2017, states that since the movement “generally followed the jihadist insurgency model while active, we can expect the individuals who fought for and supported it to follow a post-insurgency model after its collapse.” Drawing comparisons with post-Soviet Afghanistan, the report warns, “While we can expect to see the continued spread of the anti-DAPL diaspora … aggressive intelligence preparation of the battlefield and active coordination between intelligence and security elements are now a proven method of defeating pipeline insurgencies.”

More than 100 internal documents leaked to The Intercept by a TigerSwan contractor, as well as a set of over 1,000 documents obtained via public records requests, reveal that TigerSwan spearheaded a multifaceted private security operation characterized by sweeping and invasive surveillance of protesters. [more]

Leaked Documents Reveal Counterterrorism Tactics Used at Standing Rock to “Defeat Pipeline Insurgencies”

The first page of Environmental Protection Agency's spending cut plan. The EPA has issued a new, more detailed plan for laying off 25 percent of its employees and scrapping 56 programs including pesticide safety, water runoff control, and environmental cooperation with Mexico and Canada under the North American Free Trade Agreement. New EPA documents reveal even deeper proposed cuts to staff and programs. Graphic: EPA / The Washington Post

By Chris Mooney and Juliet Eilperin
5 April 2017

(The Washington Post) – Environmental Protection Agency officials are proposing to eliminate two programs focused on limiting children’s exposure to lead-based paint, which is known to cause damage to developing brains and nervous systems.

The proposed cuts, outlined in a 64-page budget memo revealed by The Washington Post on Friday, would roll back programs aimed at reducing lead risks by $16.61 million and more than 70 employees, in line with a broader project by the Trump administration to devolve responsibility for environmental and health protection to state and local governments.

Old housing stock is the biggest risk for lead exposure — and the EPA estimates that 38 million U.S. homes contain lead-based paint.

Environmental groups said the elimination of the two programs, which are focused on training workers in the safe removal of lead-based paint and public education about its risks, would make it harder for the EPA to address the environmental hazard. [more]

Trump’s EPA moves to dismantle programs that protect kids from lead paint

Sections of the newly exposed bed of Kluane Lake contain small pinnacles. Wind has eroded sediments with a harder layer on top that forms a protective cap as the wind erodes softer and sandier sediment below. These pinnacles, just a few centimeters high, are small-scale versions of what are sometimes termed “hoodoos.” Photo: Jim Best / University of Illinois

By Hannah Devlin
17 April 2017

(The Guardian) – An immense river that flowed from one of Canada’s largest glaciers vanished over the course of four days last year, scientists have reported, in an unsettling illustration of how global warming dramatically changes the world’s geography.

The abrupt and unexpected disappearance of the Slims river, which spanned up to 150 metres at its widest points, is the first observed case of “river piracy”, in which the flow of one river is suddenly diverted into another.

For hundreds of years, the Slims carried meltwater northwards from the vast Kaskawulsh glacier in Canada’s Yukon territory into the Kluane river, then into the Yukon river towards the Bering Sea. But in spring 2016, a period of intense melting of the glacier meant the drainage gradient was tipped in favour of a second river, redirecting the meltwater to the Gulf of Alaska, thousands of miles from its original destination.

The continental-scale rearrangement was documented by a team of scientists who had been monitoring the incremental retreat of the glacier for years. But on a 2016 fieldwork expedition they were confronted with a landscape that had been radically transformed.

For hundreds of years, the Slims carried meltwater northwards from the vast Kaskawulsh glacier in Canada’s Yukon territory into the Kluane river, then into the Yukon river towards the Bering Sea. But in spring 2016, a period of intense melting of the glacier meant the drainage gradient was tipped in favour of a second river, redirecting the meltwater to the Gulf of Alaska, thousands of miles from its original destination.

The retreat of the Kaskawulsh glacier has resulted in a drastic change in the destination of its meltwater. Source: Nature Geoscience. Graphic: The Guardian

The continental-scale rearrangement was documented by a team of scientists who had been monitoring the incremental retreat of the glacier for years. But on a 2016 fieldwork expedition they were confronted with a landscape that had been radically transformed.

Dan Shugar, a geoscientist at the University of Washington Tacoma and the paper’s lead author, added: “The water was somewhat treacherous to approach, because you’re walking on these old river sediments that were really goopy and would suck you in. And day by day we could see the water level dropping.” […]

Prof Lonnie Thompson, a paleoclimatologist at Ohio State University who was not involved in the work, said the observations highlight how incremental temperature increases can produce sudden and drastic environmental impacts. “There are definitely thresholds which, once passed in nature, everything abruptly changes,” he said. [more]

Receding glacier causes immense Canadian river to vanish in four days


A view of the ice canyon that now carries meltwater from the Kaskawulsh glacier, seen here on the right, away from the Slims river and toward the Kaskawulsh river. Photo: Dan Shugar / University of Washington Tacoma

ABSTRACT: River piracy—the diversion of the headwaters of one stream into another one—can dramatically change the routing of water and sediment, with a profound effect on landscape evolution. Stream piracy has been investigated in glacial environments, but so far it has mainly been studied over Quaternary or longer timescales. Here we document how retreat of Kaskawulsh Glacier—one of Canada’s largest glaciers—abruptly and radically altered the regional drainage pattern in spring 2016. We use a combination of hydrological measurements and drone-generated digital elevation models to show that in late May 2016, meltwater from the glacier was re-routed from discharge in a northward direction into the Bering Sea, to southward into the Pacific Ocean. Based on satellite image analysis and a signal-to-noise ratio as a metric of glacier retreat, we conclude that this instance of river piracy was due to post-industrial climate change. Rapid regional drainage reorganizations of this type can have profound downstream impacts on ecosystems, sediment and carbon budgets, and downstream communities that rely on a stable and sustained discharge. We suggest that the planforms of Slims and Kaskawulsh rivers will adjust in response to altered flows, and the future Kaskawulsh watershed will extend into the now-abandoned headwaters of Slims River and eventually capture the Kluane Lake drainage.

River piracy and drainage basin reorganization led by climate-driven glacier retreat

 

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