Scientists drilled nearly two miles down through the summit of the Greenland ice sheet (white dot, left), to reach bedrock. Isotopes found in the rock indicate that this site and most of Greenland were nearly ice free (right) during the recent geologic past. Graphic: Schaefer et al., 2016 / Nature

7 December 2016 (Columbia University) – Scientists have found evidence in a chunk of bedrock drilled from nearly two miles below the summit of the Greenland Ice Sheet that the ice nearly disappeared for an extended time in the last million years or so. The finding casts doubt on assumptions that Greenland has been relatively stable during the recent geological past, and implies that global warming could tip it into decline more precipitously than previously thought. Such a decline could cause rapid sea-level rise. The findings appear this week in the leading journal Nature.

The study is based on perhaps Earth’s rarest geologic sample: the only bit of bedrock yet retrieved from the ice sheet’s base, more than two decades ago. The authors say that chemical isotopes in it indicate that the surface was exposed to open sky for at least 280,000 years during the last 1.4 million years. The reason would have been natural, probably tied to cyclic natural climate changes that have caused ice ages to wax and wane. The scientists say that in the most conservative interpretation, there might have been only one ice-free period that ended 1.1 million years ago. But, more likely, they say, the ice vanished multiple times for shorter periods closer to the present. Greenland contains about 684,000 cubic miles of ice – enough to raise global sea levels about 24 feet if it were to melt completely.

“Unfortunately, this makes the Greenland ice sheet look highly unstable,” said lead author Joerg Schaefer, a paleoclimatologist at Columbia University’s Lamont-Doherty Earth Observatory. “If we lost it in periods of natural forcing, we may lose it again.” With human-induced warming now well underway, loss of the Greenland ice has roughly doubled since the 1990s; during the last four years by some estimates, it shed more than a trillion tons.

No one knows exactly what it might take to make the ice collapse, or how long that might take. Some models project that it will melt partially or completely over the next 2,500 to 10,000 years, depending on the amount of greenhouse gases humans pour into the air. Ice loss from Greenland now accounts for about a quarter of the current sea-level rise, which is about 3 millimeters a year, but this could accelerate. Projections of sea-level rise during this century hover around 3 or 4 feet, but many, including the one from the Intergovernmental Panel on Climate Change, do not take Greenland into account. More drastic models put the potential rise much higher.

Coauthor Richard Alley, a glaciologist at Pennsylvania State University, said the study “doesn’t say that tomorrow Greenland falls into the ocean. But the message is, if we keep heating up the world like we’re doing, we’re committing to a lot of sea-level rise.” This could take centuries or millennia, he said.

The rock core was recovered in July 1993 by a U.S. scientific team working in southeast Greenland at the highest part of the ice sheet. It took them five summers to drill through 3,056 meters (about 10,000 feet) of ice and sediment. Then they punched 1.55 meters (5 feet) into the underlying bedrock. The ice cores have since formed the basis of many important paleoclimate studies.

Scientists tried early on to analyze the rock as well, but only in the last year or so have lab techniques become sophisticated enough to tease out the needed information, said coauthor Robert Finkel, a scientist at the University of California, Berkeley, and adjunct senior research scientist at Lamont, who participated in the ice drilling.

Within the rock, the scientists found traces of radioactive beryllium-10 and aluminum-26 – isotopes produced by tiny particles from outer space that constantly bombard the planet. The isotopes decay at known rates, and since they cannot be created if the rock is covered with ice, their abundance can be tied to how long ago the rocks were exposed. Modelers agree that the region where the core came from would be one of the last to melt were the ice sheet to disappear. The authors thus concluded that the ice sheet must have been down to less than 10 percent of its current size when this site was ice-free.

The question of how stable the Greenland ice sheet has been in recent geologic times has been controversial. While some recent studies report evidence that it has remained largely unchanged, there is also evidence that it disappeared in the more distant past, and several studies suggest that the ice wasted to various extents at different points in more recent times. Studies of seafloor sediments off various parts of Greenland have found remains of pollen and other materials dated to a periodic warming cycle about 400,000 years ago, and this has been interpreted to mean that Greenland could have been largely ice-free then. Other studies suggest that the ice surface was substantially reduced during the last major warming cycle some 120,000 years ago, raising sea levels by 12 to 18 feet. But these studies give no clear picture of how long such episodes lasted, and the evidence they use is less direct. “Here we have no question – we interrogated the surface directly,” Finkel said. “Was there ice over you or not?”

Jeff Severinghaus, a paleoclimatologist at Scripps Institution of Oceanography who was not involved in the study, called the evidence “very direct and incontrovertible.” The study “challenges some prevailing thought on the stability of the ice sheet in the face of anthropogenic warming,” he said. “We can now reject some of the lowest sea-level projections, because the models underpinning them assume continuous ice cover during the last million years.”

Thomas Stocker, a climate scientist at Switzerland’s University of Bern who also was not involved in the study, said, “It shows that the Greenland ice sheet has been much more dynamic than thought.” He agreed that the results have implications for projections of sea-level rise. 

Scientists have been arguing back and forth about the potential forces that might tip the Greenland ice into quick decline. These could include water percolating from the surface to lubricate the ice sheet’s bottom, or massive ice streams discharging icebergs into the ocean. “This study shows we are missing something big about how the system works, and we need to find out what it is, fast,” Schaefer said.

While the rock core took five years to emerge and more than 20 years for lab techniques to catch up, such research may move faster now. A consortium of U.S. scientists has designed a new drill capable of penetrating deep ice much faster, with the aim of bringing up bedrock rather than ice cores. The apparatus could take a half-dozen samples each year from Greenland or Antarctica said Severinghaus, who is involved in the project. But it has not yet been deployed; the obstacle is funding, which would probably have to come from the U.S. government.

The study’s other authors are Nicolas Young and Roseanne Schwartz of Lamont-Doherty Earth Observatory; Greg Balco of the Berkeley Geochronology Center; Marc Caffee of Purdue University; Jason Briner of the University at Buffalo; and Anthony Gow of the U.S. Army Cold Regions Research and Engineering Laboratory.

Contact

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

Most of Greenland Ice Melted to Bedrock in Recent Geologic Past, Study Says


ABSTRACT: The Greenland Ice Sheet (GIS) contains the equivalent of 7.4 metres of global sea-level rise1. Its stability in our warming climate is therefore a pressing concern. However, the sparse proxy evidence of the palaeo-stability of the GIS means that its history is controversial (compare refs 2 and 3 to ref. 4). Here we show that Greenland was deglaciated for extended periods during the Pleistocene epoch (from 2.6 million years ago to 11,700 years ago), based on new measurements of cosmic-ray-produced beryllium and aluminium isotopes (10Be and 26Al) in a bedrock core from beneath an ice core near the GIS summit. Models indicate that when this bedrock site is ice-free, any remaining ice is concentrated in the eastern Greenland highlands and the GIS is reduced to less than ten per cent of its current volume. Our results narrow the spectrum of possible GIS histories: the longest period of stability of the present ice sheet that is consistent with the measurements is 1.1 million years, assuming that this was preceded by more than 280,000 years of ice-free conditions. Other scenarios, in which Greenland was ice-free during any or all Pleistocene interglacials, may be more realistic. Our observations are incompatible with most existing model simulations that present a continuously existing Pleistocene GIS. Future simulations of the GIS should take into account that Greenland was nearly ice-free for extended periods under Pleistocene climate forcing.

Greenland was nearly ice-free for extended periods during the Pleistocene

Dr Helen McGregor, Australian Research Council (ARC) Future Fellow in the School of Earth and Environmental Sciences at University of Wollongong. Photo: University of WollongongBy Sophie Vorrath
24 November 2016

(RenewEconomy) – Australia’s top climate scientists have come out in support of their American counterparts, in response to news that the incoming Trump Administration will scrap climate research at the country’s top research facility, NASA. […]

Here’s what Australia’s scientists are saying about Trump and NASA:

“Just as we have seen in Australia the attack on CSIRO climate science under the Coalition government, we now see the incoming Trump administration attacking NASA,” said Professor Ian Lowe, Emeritus Professor of Science, Technology and Society at Griffith University and a former President of the Australian Conservation Foundation.

“They obviously hope that pressure for action will be eased if the science is muffled.

“But with temperatures in the Arctic this week a startling 20 degrees above normal, no amount of waffle can disguise the need for urgent action to decarbonise our energy supply and immediately withdraw support for new coal mines,” Prof Lowe said.

“Why a world leader in Earth observation should do this is beyond rational explanation,” said David Bowman, a “fire scientist” and Professor of Environmental Change Biology at The University of Tasmania.

“Earth observation is a non-negotiable requirement for effective, sustainable fire management, and it will be provided by other sources if the US proceeds with this path, such as Europe, Japan and China,” Prof Bowman said.

“So, effectively the US would be ceding intellectual ‘real estate’ to other nations that could quickly become dominant providers of essential information on fire activity.” […]

“My advice to president-elect Trump is to look beyond his advisor Bob Walker’s comments and see exactly the important work done by the NASA Earth science division,” said Dr Helen McGregor, an ARC Future Fellow in the School of Earth Sciences and Environmental Sciences at the University of Wollongong.

“This is not ‘politically correct environmental monitoring’ as Walker asserts but is essential data to ensure society’s health and wellbeing.

“As for climate change science, the division’s reports on global temperatures are solely based on robust data. What’s being politicised here is not the science but the story that the science tells: that the planet is warming. Let’s not shoot the messenger,” Dr McGregor said. [more]

Australian scientists slam Trump’s plans to scrap NASA climate research

On 10 November 2016, scientists on NASA's IceBridge mission photographed an oblique view of a massive rift in the Antarctic Peninsula's Larsen C ice shelf. Icebridge, an airborne survey of polar ice, completed an eighth consecutive Antarctic deployment on 18 November 2016. Photo: John Sonntag / NASA

1 December 2016 (NASA) – On 10 November 2016, scientists on NASA's IceBridge mission photographed an oblique view of a massive rift in the Antarctic Peninsula's Larsen C ice shelf. Icebridge, an airborne survey of polar ice, completed an eighth consecutive Antarctic deployment on 18 November 2016.

Ice shelves are the floating parts of ice streams and glaciers, and they buttress the grounded ice behind them; when ice shelves collapse, the ice behind accelerates toward the ocean, where it then adds to sea level rise. Larsen C neighbors a smaller ice shelf that disintegrated in 2002 after developing a rift similar to the one now growing in Larsen C.

The IceBridge scientists measured the Larsen C fracture to be about 70 miles long, more than 300 feet wide and about a third of a mile deep. The crack completely cuts through the ice shelf but it does not go all the way across it – once it does, it will produce an iceberg roughly the size of the state of Delaware.

The mission of Operation IceBridge is to collect data on changing polar land and sea ice and maintain continuity of measurements between NASA's Ice, Cloud and Land Elevation Satellite (ICESat) missions. The original ICESat mission ended in 2009, and its successor, ICESat-2, is scheduled for launch in 2018. Operation IceBridge, which began in 2009, is currently funded until 2019. The planned overlap with ICESat-2 will help scientists validate the satellite’s measurements.

More: NASA Nears Finish Line of Annual Study of Changing Antarctic Ice

Rift in Antarctica's Larsen C Ice Shelf

The giraffe (Giraffa camelopardalis) is now threatened with extinction, according to the IUCN Red List. Photo: Alicia Wirz / IUCN Photo Library

By Alister Doyle; editing by Mark Heinrich
8 December 2016

OSLO, Norway (Reuters) – Giraffe numbers have declined by as much as 40 percent since the 1980s in a "silent extinction" driven by illegal hunting and an expansion of farmland in Africa, the Red List of endangered species reported on Thursday.

Populations of the world's tallest land creature fell to about 98,000 from an estimated 152,000-163,000 in 1985, according to the List compiled by the International Union for Conservation of Nature (IUCN).

The Red List rated the giraffe "vulnerable" to extinction on current trends for the first time, against a previous rating of "least concern". It said the plunge in numbers in large parts of sub-Saharan Africa had gone largely unnoticed.

"Whilst giraffes are commonly seen on safari, in the media and in zoos, people – including conservationists – are unaware that these majestic animals are undergoing a silent extinction," Julian Fennessy, an IUCN giraffe specialist, said in a statement.[more]

Giraffes suffer 'silent extinction' in Africa: Red List report


CANCUN, Mexico, 8 December 2016 (IUCN) – Over 700 newly recognised bird species have been assessed for the latest update of The The IUCN Red List of Threatened Species™, and 11% of them are threatened with extinction. The update also reveals a devastating decline for the giraffe, driven by habitat loss, civil unrest and illegal hunting. The global giraffe population has plummeted by up to 40% over the last 30 years, and the species has been listed as Vulnerable on the IUCN Red List.

Today’s IUCN Red List update also includes the first assessments of wild oats, barley, mango and other crop wild relative plants. These species are increasingly critical to food security, as their genetic diversity can help improve crop resistance to disease, drought and salinity.

The update was released today at the 13th Conference of the Parties to the Convention on Biological Diversity (CBD COP13) in Cancun, Mexico. The IUCN Red List now includes 85,604 species of which 24,307 are threatened with extinction.

“Many species are slipping away before we can even describe them,” says IUCN Director General Inger Andersen. “This IUCN Red List update shows that the scale of the global extinction crisis may be even greater than we thought. Governments gathered at the UN biodiversity summit in Cancun have the immense responsibility to step up their efforts to protect our planet’s biodiversity – not just for its own sake but for human imperatives such as food security and sustainable development.”

Birds: Newly recognised, already threatened

This IUCN Red List update includes the reassessment of all bird species. Thanks to a comprehensive taxonomic review compiled by BirdLife International, working in collaboration with the Handbook of the Birds of the World, the overall number of bird species assessed has reached 11,121.

A total of 742 newly recognised bird species have been assessed, 11% of which are threatened. For example, the recently described Antioquia wren (Thryophilus sernai) has been listed as Endangered as more than half of its habitat could be wiped out by a single planned dam construction. Habitat loss to agriculture and degradation by invasive plants have also pushed the striking Comoro blue vanga (Cyanolanius comorensis) into the Endangered category.

Thirteen of the newly recognised bird species enter the IUCN Red List as Extinct. Several of these have been lost within the past 50 years – such as the Pagan reed-warbler (Acrocephalus yamashinae), O’ahu akepa (Loxops wolstenholmei) and Laysan honeycreeper (Himatione fraithii). All of these species were endemic to islands, and were most likely wiped out by invasive species.

“Unfortunately, recognising more than 700 ‘new’ species does not mean that the world's birds are faring better,” says Dr Ian Burfield, BirdLife’s Global Science Coordinator. “As our knowledge deepens, so our concerns are confirmed: unsustainable agriculture, logging, invasive species and other threats – such as the illegal trade highlighted here – are still driving many species towards extinction." 

IUCN Red List assessments also reveal that some of the world's most popular birds may soon disappear in the wild if appropriate action isn't taken. Iconic species, such as the African grey parrot (Psittacus erithacus) – a prized pet with the ability to mimic human speech – are facing extinction in the wild due to unsustainable trapping and habitat loss. Native to central Africa, the grey parrot has seen its conservation status deteriorate from Vulnerable to Endangered. A study led by BirdLife International discovered that in some parts of the continent numbers of grey parrots have declined by as much as 99%.

The situation is most pressing in Asia, with the rufous-fronted laughingthrush (Garrulax rufifrons), scarlet-breasted lorikeet (Trichoglossus forsteni) and Straw-headed bulbul (Pycnonotus zeylanicus) among a suite of species being uplisted to higher threat categories as a result of the impacts of illegal wildlife trade. There is now evidence that unsustainable levels of capture for the cagebird trade, largely centred on Java, are driving the deteriorating status of many species.

However, there is good news for some of the rarest and most vulnerable birds on our planet – those that exist only on small, isolated islands. The Azores bullfinch (Pyrrhula murina), St Helena plover (Charadrius sanctaehelenae) and Seychelles white-eye (Zosterops modestus) are among the island endemic species to move to lower categories in this IUCN Red List update, as their populations recover from the brink of extinction thanks to tireless conservation efforts.

Giraffe

The iconic giraffe (Giraffa camelopardalis), one of the world's most recognisable animals and the tallest land mammal, is now threatened with extinction. The species, which is widespread across southern and eastern Africa, with smaller isolated subpopulations in west and central Africa, has moved from Least Concern to Vulnerable due to a dramatic 36-40% decline from approximately 151,702-163,452 individuals in 1985 to 97,562 in 2015.

The growing human population is having a negative impact on many giraffe subpopulations. Illegal hunting, habitat loss and changes through expanding agriculture and mining, increasing human-wildlife conflict, and civil unrest are all pushing the species towards extinction. Of the nine subspecies of giraffe, three have increasing populations, whilst five have decreasing populations and one is stable.

A resolution adopted at the IUCN World Conservation Congress in September this year called for action to reverse the decline of the giraffe.

Crop wild relatives

With this update, the first assessments of 233 wild relatives of crop plants such as barley, oats and sunflowers have been added to the IUCN Red List. Habitat loss, primarily due to agricultural expansion, is the major threat to many of these species. The assessments were completed as part of a partnership between Toyota Motor Corporation and IUCN, whose aim is to broaden the IUCN Red List to include the extinction risk of many species that are key food sources for a significant portion of the global population.

Crop wild relatives are a source of genetic material for new and existing crop species, allowing for increased disease and drought resistance, fertility, nutritional value and other desirable traits. Almost every species of plant that humans have domesticated and now cultivate has one or more crop wild relatives. However, these species have received little systematic conservation attention until now.

Four mango species have been listed as Endangered, and the Kalimantan mango (Mangifera casturi) has been listed as Extinct in the Wild. These species are relatives of the common mango (Mangifera indica) and are threatened by habitat loss. Native to South Asia, mangoes are now cultivated in many tropical and sub-tropical countries and they are one of the most commercially important fruits in these regions.

A relative of cultivated asparagus, hamatamabouki (Asparagus kiusianus), which is native to Japan, has been listed as Endangered due to habitat loss caused by urban expansion and agriculture. Loss of habitat is also the main threat to the Anomalus sunflower (Helianthus anomalus) which has been listed as Vulnerable and is a relative of the sunflower (H. annuus). Cicer bijugum, native to Iran and Turkey, is a wild relative of the chickpea (C. arietinum); it has been listed as Endangered due to habitat conversion to agriculture.       

“Crop wild relative species are under increasing threat from urbanisation, habitat fragmentation and intensive farming, and probably climate change,” says Mr. Kevin Butt, General Manager, Regional Environmental Sustainability Director, Toyota Motor North America. “To conserve this vital gene pool for crop improvement we need to urgently improve our knowledge about these species. Toyota is pleased to provide support for the assessment of these and other species on The IUCN Red List.”  

Freshwater species – Lake Victoria

All freshwater molluscs, crabs, dragonflies, and freshwater fishes native to Lake Victoria in central Africa are included in this update. Key threats to Lake Victoria – known as Darwin’s dream pond due to its high biodiversity – include invasive species such as the Nile perch (Lates niloticus), overharvesting, sedimentation due to logging and agriculture, as well as water pollution from pesticides and herbicides.

Contact

Goska Bonnaveira, IUCN Media Relations, m +41 79 276 01 85, e-mail goska.bonnaveira@iucn.org

Ewa Magiera, IUCN Media Relations, m +41 76 505 33 78, e-mail ewa.magiera@iucn.org

New bird species and giraffe under threat – IUCN Red List

Inside President Rodrigo Duterte's brutal antidrug campaign in the Philippines, the basketball court at the Quezon City Jail has become a sleeping area. Photo: Daniel Berehulak / The New York Times

By Daniel Berehulak
7 December 2016

(The New York Times) – You hear a murder scene before you see it: The desperate cries of a new widow. The piercing sirens of approaching police cars. The thud, thud, thud of the rain drumming on the pavement of a Manila alleyway — and on the back of Romeo Torres Fontanilla.

Tigas, as Mr. Fontanilla was known, was lying facedown in the street when I pulled up after 1 a.m. He was 37. Gunned down, witnesses said, by two unknown men on a motorbike. The downpour had washed his blood into the gutter.

The rain-soaked alley in the Pasay district of Manila was my 17th crime scene, on my 11th day in the Philippines capital. I had come to document the bloody and chaotic campaign against drugs that President Rodrigo Duterte began when he took office on June 30: since then, about 2,000 people had been slain at the hands of the police alone.

I witnessed bloody scenes just about everywhere imaginable — on the sidewalk, on train tracks, in front of a girls’ school, outside 7-Eleven stores and a McDonald’s restaurant, across bedroom mattresses and living-room sofas. I watched as a woman in red peeked at one of those grisly sites through fingers held over her eyes, at once trying to protect herself and permit herself one last glance at a man killed in the middle of a busy road.

Not far from where Tigas was killed, I found Michael Araja, shown in the first photo below, dead in front of a “sari sari,” what locals call the kiosks that sell basics in the slums. Neighbors told me that Mr. Araja, 29, had gone out to buy cigarettes and a drink for his wife, only to be shot dead by two men on a motorcycle, a tactic common enough to have earned its own nickname: riding in tandem. [more]

‘They Are Slaughtering Us Like Animals’

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Scott Pruitt Attorney General of Oklahoma arrives to meet with U.S. President-elect Donald Trump at Trump Tower in Manhattan, New York City, U.S., 7 December 2016. Photo: Brendan McDermid / REUTERS

By Valerie Volcovici and Timothy Gardner
7 December 2016

(WASHINGTON) – Donald Trump will pick an ardent opponent of President Barack Obama's measures to curb climate change as head of the Environmental Protection Agency, a Trump transition team source said on Wednesday, a choice that enraged green activists and cheered the oil industry.

Trump's choice, Oklahoma Attorney General Scott Pruitt, fits neatly with the Republican president-elect's promise to cut back the EPA and free up drilling and coal mining, and signals the likely rollback of much of Obama's environmental agenda.

Since becoming the top prosecutor for the major oil and gas producing state in 2011, Pruitt has launched multiple lawsuits against regulations put forward by the agency he is now poised to lead, suing to block federal measures to reduce smog and curb toxic emissions from power plants.

He is also a leading figure in a legal effort by several states to throw out the EPA's Clean Power Plan, the centerpiece of Obama's climate change strategy that requires states to curb carbon output.

In an interview with Reuters in September, Pruitt said he sees the Clean Power Plan as a form of federal "coercion and commandeering" of energy policy and that his state should have "sovereignty to make decisions for its own markets."

Pruitt, 48, has also said he is skeptical of climate change. In an opinion piece in an Oklahoma newspaper this year, he wrote that he believes the debate over global warming is "far from settled" and that scientists continue to disagree on the issue. An overwhelming majority of scientists around the world say manmade emissions are warming the planet. […]

"Scott Pruitt running the EPA is like the fox guarding the henhouse," said Gene Karpinski, president of the League of Conservation Voters, which supported Trump's opponent in the election, Democrat Hillary Clinton.

"Time and again, he has fought to pad the profits of Big Polluters at the expense of public health."

Heather Zichal, a former Deputy Assistant to the President for Energy and Climate Change under Obama, said Trump's choice was alarming.

"You can meet with Al Gore on Monday, pledge to keep Teddy Roosevelt's environmental legacy alive on Tuesday, but if you nominate the Clean Power Act's leading opponent to head the EPA on Wednesday, you're making an unequivocal statement about the direction of your leadership," she said. [more]

Trump to pick foe of Obama climate agenda to run EPA: source

This figure shows the expected increase in the number of summertime storms that produce extreme precipitation at century's end compared to the period 2000 - 2013. Graphic: Andreas Prein / NCAR

By Laura Snider
5 December 2016

BOULDER, Colorado (NCAR) – At century's end, the number of summertime storms that produce extreme downpours could increase by more than 400 percent across parts of the United States — including sections of the Gulf Coast, Atlantic Coast, and the Southwest — according to a new study by scientists at the National Center for Atmospheric Research (NCAR).

The study, published today in the journal Nature Climate Change, also finds that the intensity of individual extreme rainfall events could increase by as much as 70 percent in some areas. That would mean that a storm that drops about 2 inches of rainfall today would be likely to drop nearly 3.5 inches in the future.

"These are huge increases," said NCAR scientist Andreas Prein, lead author of the study. "Imagine the most intense thunderstorm you typically experience in a single season. Our study finds that, in the future, parts of the U.S. could expect to experience five of those storms in a season, each with an intensity as strong or stronger than current storms."

The study was funded by the National Science Foundation (NSF), NCAR's sponsor, and the Research Partnership to Secure Energy for America.

“Extreme precipitation events affect our infrastructure through flooding, landslides and debris flows,” said Anjuli Bamzai, program director in NSF’s Directorate for Geosciences, which funded the research.  “We need to better understand how these extreme events are changing. By supporting this research, NSF is working to foster a safer environment for all of us.”

A year of supercomputing time

An increase in extreme precipitation is one of the expected impacts of climate change because scientists know that as the atmosphere warms, it can hold more water, and a wetter atmosphere can produce heavier rain. In fact, an increase in precipitation intensity has already been measured across all regions of the U.S. However, climate models are generally not able to simulate these downpours because of their coarse resolution, which has made it difficult for researchers to assess future changes in storm frequency and intensity.

For the new study, the research team used a new dataset that was created when NCAR scientists and study co-authors Roy Rasmussen, Changhai Liu, and Kyoko Ikeda ran the NCAR-based Weather Research and Forecasting (WRF) model at a resolution of 4 kilometers, fine enough to simulate individual storms. The simulations, which required a year to run, were performed on the Yellowstone system at the NCAR-Wyoming Supercomputing Center.

Prein and his co-authors used the new dataset to investigate changes in downpours over North America in detail. The researchers looked at how storms that occurred between 2000 and 2013 might change if they occurred instead in a climate that was 5 degrees Celsius (9 degrees Fahrenheit) warmer — the temperature increase expected by the end of the century if greenhouse gas emissions continue unabated.

Prein cautioned that this approach is a simplified way of comparing present and future climate. It doesn't reflect possible changes to storm tracks or weather systems associated with climate change. The advantage, however, is that scientists can more easily isolate the impact of additional heat and associated moisture on future storm formation.

"The ability to simulate realistic downpours is a quantum leap in climate modeling. This enables us to investigate changes in hourly rainfall extremes that are related to flash flooding for the very first time," Prein said. "To do this took a tremendous amount of computational resources."

Impacts vary across the U.S.

The study found that the number of summertime storms producing extreme precipitation is expected to increase across the entire country, though the amount varies by region. The Midwest, for example, sees an increase of zero to about 100 percent across swaths of Nebraska, the Dakotas, Minnesota, and Iowa. But the Gulf Coast, Alabama, Louisiana, Texas, New Mexico, Arizona, and Mexico all see increases ranging from 200 percent to more than 400 percent.

The study also found that the intensity of extreme rainfall events in the summer could increase across nearly the entire country, with some regions, including the Northeast and parts of the Southwest, seeing particularly large increases, in some cases of more than 70 percent.

A surprising result of the study is that extreme downpours will also increase in areas that are getting drier on average, especially in the Midwest. This is because moderate rainfall events that are the major source of moisture in this region during the summertime are expected to decrease significantly while extreme events increase in frequency and intensity. This shift from moderate to intense rainfall increases the potential for flash floods and mudslides, and can have negative impacts on agriculture.

The study also investigated how the environmental conditions that produce the most severe downpours might change in the future. In today's climate, the storms with the highest hourly rainfall intensities form when the daily average temperature is somewhere between 20 and 25 degrees C (68 to 77 degrees F) and with high atmospheric moisture. When the temperature gets too hot, rainstorms become weaker or don't occur at all because the increase in atmospheric moisture cannot keep pace with the increase in temperature. This relative drying of the air robs the atmosphere of one of the essential ingredients needed to form a storm.

In the new study, the NCAR scientists found that storms may continue to intensify up to temperatures of 30 degrees C because of a more humid atmosphere. The result would be much more intense storms.

"Understanding how climate change may affect the environments that produce the most intense storms is essential because of the significant impacts that these kinds of storms have on society," Prein said.

Title: The future intensification of hourly precipitation extremes

Authors: Andreas F. Prein, Roy M. Rasmussen, Kyoko Ikeda, Changhai Liu, Martyn P. Clark, and Greg J. Holland

Journal: Nature Climate Change, DOI: 10.1038/NCLIMATE3168

Extreme downpours could increase fivefold across parts of the U.S.


ABSTRACT: Extreme precipitation intensities have increased in all regions of the Contiguous United States (CONUS)1 and are expected to further increase with warming at scaling rates of about 7% per degree Celsius, suggesting a significant increase of flash flood hazards due to climate change. However, the scaling rates between extreme precipitation and temperature are strongly dependent on the region, temperature, and moisture availability, which inhibits simple extrapolation of the scaling rate from past climate data into the future. Here we study observed and simulated changes in local precipitation extremes over the CONUS by analysing a very high resolution (4 km horizontal grid spacing) current and high-end climate scenario that realistically simulates hourly precipitation extremes. We show that extreme precipitation is increasing with temperature in moist, energy-limited, environments and decreases abruptly in dry, moisture-limited, environments. This novel framework explains the large variability in the observed and modelled scaling rates and helps with understanding the significant frequency and intensity increases in future hourly extreme precipitation events and their interaction with larger scales.

The future intensification of hourly precipitation extremes

In response to a misleading article on global warming, meteorologist Kait Parker tells Breitbart, 'next time you're thinking about publishing a cherry-picked article, try consulting a scientist first' on 6 December 2016. Photo: The Weather Channel

By Shanika Gunaratna
6 December 2016

(CBS News) – In an unusually direct message, the Weather Channel is taking Breitbart to task for using Weather Channel content to “mislead Americans” about climate change.

“Though we would prefer to focus on our usual coverage of weather and climate science, in this case we felt it important to add our two cents,” the Weather Channel wrote in a post on its website Tuesday.

It firmly denied a claim that overall global temperatures are declining, an idea promoted by Breitbart and spread widely on social media.

The company was specifically concerned after Breitbart — the right-wing opinion website that had been led by President-elect Donald Trump’s chief advisor Steve Bannon — used a Weather Channel video clip atop an article that claimed the last three years of weather patterns represent “the final death rattle of the global warming scare.”

Breitbart is the primary megaphone of the alt-right, an extreme right-wing movement promoting white nationalism that has gained new national stature with Bannon’s involvement in the Trump campaign and future administration.

The Weather Channel explained that, while Breitbart had the legal right to use its video clip through a content sharing agreement, it did not want to stand idly by without addressing the article’s specific, erroneous claims. [more]

Weather Channel to Breitbart: Stop using us to mislead public


6 December 2016 (Weather Channel) – Global warming is not expected to end anytime soon, despite what Breitbart.com wrote in an article published last week.

Though we would prefer to focus on our usual coverage of weather and climate science, in this case we felt it important to add our two cents — especially because a video clip from weather.com (La Niña in Pacific Affects Weather in New England) was prominently featured at the top of the Breitbart article. Breitbart had the legal right to use this clip as part of a content-sharing agreement with another company, but there should be no assumption that The Weather Company endorses the article associated with it.

The Breitbart article – a prime example of cherry picking, or pulling a single item out of context to build a misleading case – includes this statement: "The last three years may eventually come to be seen as the final death rattle of the global warming scare." […]

CLAIM: "Global land temperatures have plummeted by one degree Celsius since the middle of this year – the biggest and steepest fall on record."

TRUTH: This number comes from one satellite-based estimate of temperatures above land areas in the lower atmosphere. Data from the other two groups that regularly publish satellite-based temperature estimates show smaller drops, more typical of the decline one would expect after a strong El Niño event.

Temperatures over land give an incomplete picture of global-scale temperature. Most of the planet – about 70 percent – is covered by water, and the land surface warms and cools more quickly than the ocean. Land-plus-ocean data from the other two satellite groups, released after the Breitbart article, show that Earth’s lower atmosphere actually set a record high in November 2016. [more]

Note to Breitbart: Earth Is Not Cooling, Climate Change Is Real and Please Stop Using Our Video to Mislead Americans

Standing Rock Sioux water protectors, 'Oceti Sakowin', march against the Dakota Access Pipeline project, 13 November 2016. Photo: Redhawk / Standing Rock Rising

Cannon Ball, North Dakota, 4 December 2016 (Stand With Standing Rock) – The department of the Army will not approve an easement that will allow the proposed Dakota Access Pipeline to cross under Lake Oahe. The following statement was released by Standing Rock Sioux Tribal Chairman Dave Archambault II.

Today, the U.S. Army Corps of Engineers announced that it will not be granting the easement to cross Lake Oahe for the proposed Dakota Access Pipeline. Instead, the Corps will be undertaking an environmental impact statement to look at possible alternative routes. We wholeheartedly support the decision of the administration and commend with the utmost gratitude the courage it took on the part of President Obama, the Army Corps, the Department of Justice and the Department of the Interior to take steps to correct the course of history and to do the right thing.

The Standing Rock Sioux Tribe and all of Indian Country will be forever grateful to the Obama Administration for this historic decision.

We want to thank everyone who played a role in advocating for this cause. We thank the tribal youth who initiated this movement. We thank the millions of people around the globe who expressed support for our cause. We thank the thousands of people who came to the camps to support us, and the tens of thousands who donated time, talent, and money to our efforts to stand against this pipeline in the name of protecting our water. We especially thank all of the other tribal nations and jurisdictions who stood in solidarity with us, and we stand ready to stand with you if and when your people are in need.

Throughout this effort I have stressed the importance of acting at all times in a peaceful and prayerful manner – and that is how we will respond to this decision. With this decision we look forward to being able to return home and spend the winter with our families and loved ones, many of whom have sacrificed as well. We look forward to celebrating in wopila, in thanks, in the coming days.

We hope that Kelcey Warren, Governor Dalrymple, and the incoming Trump administration respect this decision and understand the complex process that led us to this point. When it comes to infrastructure development in Indian Country and with respect to treaty lands, we must strive to work together to reach decisions that reflect the multifaceted considerations of tribes.

Treaties are paramount law and must be respected, and we welcome dialogue on how to continue to honor that moving forward. We are not opposed to energy independence, economic development, or national security concerns but we must ensure that these decisions are made with the considerations of our Indigenous peoples.

To our local law enforcement, I hope that we can work together to heal our relationship as we all work to protect the lives and safety of our people. I recognize the extreme stress that the situation caused and look forward to a future that reflects more mutual understanding and respect.

Again, we are deeply appreciative that the Obama Administration took the time and effort to genuinely consider the broad spectrum of tribal concerns. In a system that has continuously been stacked against us from every angle, it took tremendous courage to take a new approach to our nation-to-nation relationship, and we will be forever grateful.

Standing Rock Sioux Tribe’s Statement on U.S. Army Corps of Engineers Decision to Not Grant Easement

 

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