WASHINGTON, 26 September 2016 (AP) – A new study paints a picture of an Earth that is warmer than it has been in about 120,000 years, and is locked into eventually hitting its hottest mark in more than 2 million years.
As part of her doctoral dissertation at Stanford University, Carolyn Snyder, now a climate policy official at the U.S. Environmental Protection Agency, created a continuous 2 million year temperature record, much longer than a previous 22,000 year record. Snyder’s temperature reconstruction, published Monday in the journal Nature, doesn’t estimate temperature for a single year, but averages 5,000-year time periods going back a couple million years.
Snyder based her reconstruction on 61 different sea surface temperature proxies from across the globe, such as ratios between magnesium and calcium, species makeup and acidity. But the further the study goes back in time, especially after half a million years, the fewer of those proxies are available, making the estimates less certain, she said.
These are rough estimates with large margins of errors, she said. But she also found that the temperature changes correlated well to carbon dioxide levels.
Temperatures averaged out over the most recent 5,000 years – which includes the last 125 years or so of industrial emissions of heat-trapping gases – are generally warmer than they have been since about 120,000 years ago or so, Snyder found. And two interglacial time periods, the one 120,000 years ago and another just about 2 million years ago, were the warmest Snyder tracked. They were about 3.6 degrees warmer than the current 5,000-year average.
With the link to carbon dioxide levels and taking into account other factors and past trends, Snyder calculated how much warming can be expected in the future.
Snyder said if climate factors are the same as in the past – and that’s a big if – Earth is already committed to another 7 degrees or so of warming over the next few thousand years.
“This is based on what happened in the past,” Snyder said. “In the past it wasn’t humans messing with the atmosphere.” [more]
ABSTRACT: Reconstructions of Earth’s past climate strongly influence our understanding of the dynamics and sensitivity of the climate system. Yet global temperature has been reconstructed for only a few isolated windows of time1, 2, and continuous reconstructions across glacial cycles remain elusive. Here I present a spatially weighted proxy reconstruction of global temperature over the past 2 million years estimated from a multi-proxy database of over 20,000 sea surface temperature point reconstructions. Global temperature gradually cooled until roughly 1.2 million years ago and cooling then stalled until the present. The cooling trend probably stalled before the beginning of the mid-Pleistocene transition3, and pre-dated the increase in the maximum size of ice sheets around 0.9 million years ago4, 5, 6. Thus, global cooling may have been a pre-condition for, but probably is not the sole causal mechanism of, the shift to quasi-100,000-year glacial cycles at the mid-Pleistocene transition. Over the past 800,000 years, polar amplification (the amplification of temperature change at the poles relative to global temperature change) has been stable over time, and global temperature and atmospheric greenhouse gas concentrations have been closely coupled across glacial cycles. A comparison of the new temperature reconstruction with radiative forcing from greenhouse gases estimates an Earth system sensitivity of 9 degrees Celsius (range 7 to 13 degrees Celsius, 95 per cent credible interval) change in global average surface temperature per doubling of atmospheric carbon dioxide over millennium timescales. This result suggests that stabilization at today’s greenhouse gas levels may already commit Earth to an eventual total warming of 5 degrees Celsius (range 3 to 7 degrees Celsius, 95 per cent credible interval) over the next few millennia as ice sheets, vegetation, and atmospheric dust continue to respond to global warming.
By Jonah Engel Bromwich
22 September 2016
(The New York Times) – A report examining the many ways climate change threatens coffee and coffee farmers has alarmed people who are now imagining what it would be like getting through the day without their caffeine fix.
The report, released this month by the Climate Institute, a nonprofit organization in Australia, was commissioned by Fairtrade Australia and New Zealand, the regional hub of the global Fairtrade system.
Though it contains little new research, it has made waves by collating an array of available literature indicating that climate change will have a stark effect on the world’s coffee supply.
The report emphasizes the threat warming temperatures pose to farmland, citing a study from the March 2015 issue of the journal Climatic Change that found climate change “will reduce the global area suitable for coffee by about 50 percent across emission scenarios.”
In addition to the disappearing land on which to grow coffee, the report highlights the way warmer weather is exacerbating the threat of diseases like coffee rust and pests like the coffee berry borer, a type of beetle that a 2011 report said caused annual losses of hundreds of millions of dollars in coffee beans. [more]
Coffee is a key global crop and the second most valuable commodity exported by developing countries, worth around US$19 billion in 2015. Worldwide, around 2.25 billion cups of coffee are consumed each day. Nearly half of all Australians drink coffee regularly. The coffee market is growing, but faces big challenges coming up fast:
- There is strong evidence that rising temperatures and altered rainfall patterns are already affecting coffee yields, quality, pests, and diseases—badly affecting economic security in some coffee regions.
- Without strong action to reduce emissions, climate change is projected to cut the global area suitable for coffee production by as much as 50 per cent by 2050. By 2080, wild coffee, an important genetic resource for farmers, could become extinct.
- Leading global coffee companies, such as Starbucks and Lavazza, publicly acknowledge the severe risks posed by climate change to the world’s coffee supply. Consumers are likely to face supply shortages, impacts on flavour and aroma, and rising prices.
- In the next few decades, coffee production will undergo dramatic shifts—broadly, away from the equator and further up mountains. Production will probably come into conflict with other land uses, including forests.
- Rising CO2 levels may boost the growth and vigour of the coffee plant, but there is no guarantee this ‘fertilisation effect’ will offset the risks imposed by a more hostile climate.
ABSTRACT: Coffee has proven to be highly sensitive to climate change. Because coffee plantations have a lifespan of about thirty years, the likely effects of future climates are already a concern. Forward-looking research on adaptation is therefore in high demand across the entire supply chain. In this paper we seek to project current and future climate suitability for coffee production (Coffea arabica and Coffea canephora) on a global scale. We used machine learning algorithms to derive functions of climatic suitability from a database of geo-referenced production locations. Use of several parameter combinations enhances the robustness of our analysis. The resulting multi-model ensemble suggests that higher temperatures may reduce yields of C. arabica, while C. canephora could suffer from increasing variability of intra-seasonal temperatures. Climate change will reduce the global area suitable for coffee by about 50 % across emission scenarios. Impacts are highest at low latitudes and low altitudes. Impacts at higher altitudes and higher latitudes are still negative but less pronounced. The world’s dominant production regions in Brazil and Vietnam may experience substantial reductions in area available for coffee. Some regions in East Africa and Asia may become more suitable, but these are partially in forested areas, which could pose a challenge to mitigation efforts.
Global warming increases U.S. flooding, and sewage hits the fan – ‘The true extent of sewage overflow is often undocumented and largely unknown’0 comments Posted by Jim at Monday, September 26, 2016
21 September 2016 (Climate Central) – Record rainstorms across the U.S. in the past year have continued to make national news, causing billions of dollars of flood damage and killing dozens. But what has barely made headlines are that these floods often cause massive overflows of untreated sewage into streams, rivers, bays, canals, and even streets and homes. See the full report [pdf].
Climate Central has investigated the extent of these sewage overflows. In most cases, we found reports that millions of gallons of untreated sewage were released into streets and waterways. These overflows can have devastating consequences for public health and the environment: they can trigger dangerous outbreaks of waterborne diseases and are often linked to fish kills. And when sewage overflows into homes and businesses, expensive remediation and decontamination is needed to make them safe again.
Worse was the discovery that the true extent of sewage overflow is often undocumented and largely unknown.
From the 70 sewage overflows we identified that had occurred in the past 20 months, overflows of more than one billion gallons combined were reported, triggering health warnings in dozens of cities. Local officials confirmed that these reported volumes are likely underestimating the true extent of overflows; during these flooding emergencies, there is typically no reliable way to determine how much untreated sewage gets into the waterways. [more]
Record rainstorms across the U.S. in the past year have continued to make national news, causing billions of dollars of flood damage and killing dozens. But what has barely made headlines are that these floods often cause massive overflows of untreated sewage into streams, rivers, bays, canals, and even streets and homes.
Climate Central has investigated the extent of these sewage overflows. In most cases, we found reports that millions of gallons of untreated sewage were released into streets and waterways.
These overflows can have devastating consequences for public health and the environment: they can trigger dangerous outbreaks of waterborne diseases and are often linked to fish kills. And when sewage overflows into homes and businesses, expensive remediation and decontamination is needed to make them safe again.
Worse was the discovery that the true extent of sewage overflow is often undocumented and largely unknown.
From the 70 sewage overflows we identified that had occurred in the past 20 months, overflows of more than one billion gallons combined were reported, triggering health warnings in dozens of cities. Local officials confirmed that these reported volumes are likely underestimating the true extent of overflows; during these flooding emergencies, there is typically no reliable way to determine how much untreated sewage gets into the waterways.
With a backdrop of antiquated and overpopulated sewer systems, the increase in rain and heavy downpours in recent decades -- one of the ongoing impacts of climate change -- continues to trigger overflows that affect millions of Americans every year.
While many cities are working toward upgrading their sewer systems, they can’t eliminate their sewage overflow risks entirely. Climate models project that both overall precipitation, and the amount of rain falling in heavy downpours, will continue to increase this century with continued climate change, which could cause even more overflows.
According to the National Oceanic and Atmospheric Administration (NOAA) and Climate Central’s World Weather Attribution project, the epic rains in Louisiana in August 2016 that flooded 60,000 homes and killed 13, were made nearly twice as likely due to carbon pollution in the atmosphere.
Climate Central’s analysis of more than 3,000 rain gauges nationwide shows that heavy downpours are happening more frequently than they did in the 1950s. We found that all but two of the Lower 48 states have seen an increase in the number of heavy downpours happening each year, on average, compared to the 1950s, and 28 states have seen at least a 25 percent increase in these heaviest events. With downpours projected to be even more frequent and intense as the world continues to warm, we can expect more of these costly and dangerous overflows for many years to come.
By John Abraham
21 September 2016
(Guardian) – Yesterday, 375 of the world’s top scientists, including 30 Nobel Prize winners, published an open letter regarding climate change. In the letter, the scientists report that the evidence is clear: humans are causing climate change. We are now observing climate change and its affect across the globe. The seas are rising, the oceans are warming, the lower atmosphere is warming, the land is warming, ice is melting, rainfall patterns are changing and the ocean is becoming more acidic.
These facts are incontrovertible. No reputable scientist disputes them. It is the truth.
Despite these facts, the letter reports that the US presidential campaign has seen claims that the earth isn’t warming, or it is only a natural warming, or that climate change is a hoax. These claims are false. The claims are made by politicians or real estate developers with no scientific experience. These people who deny the reality of climate change are not scientists.
These claims aren’t new. We see them every election cycle. In fact, for the Republican Party, they are a virtual litmus test for electability. It is terribly sad that the party of Lincoln (the president who initiated the National Academy of Sciences) has been rebuked by the National Academy today. It is sad that the party of Teddy Roosevelt, who created the National Park System, is acting in a way antithetical to his legacy. It is also sad that the party of Nixon, who created the Environmental Protection Agency, now is trying to eliminate that very organization.
20 September 2016 (ResponsibleScientists.org) – On 20 September 2016, 375 members of the National Academy of Sciences, including 30 Nobel laureates, published an open letter to draw attention to the serious risks of climate change. The letter warns that the consequences of opting out of the Paris agreement would be severe and long-lasting for our planet’s climate and for the international credibility of the United States.
A full list of signers follows the text of the letter.
Human-caused climate change is not a belief, a hoax, or a conspiracy. It is a physical reality. Fossil fuels powered the Industrial Revolution. But the burning of oil, coal, and gas also caused most of the historical increase in atmospheric levels of heat-trapping greenhouse gases. This increase in greenhouse gases is changing Earth’s climate.
Our fingerprints on the climate system are visible everywhere. They are seen in warming of the oceans, the land surface, and the lower atmosphere. They are identifiable in sea level rise, altered rainfall patterns, retreat of Arctic sea ice, ocean acidification, and many other aspects of the climate system. Human-caused climate change is not something far removed from our day-to-day experience, affecting only the remote Arctic. It is present here and now, in our own country, in our own states, and in our own communities.
During the Presidential primary campaign, claims were made that the Earth is not warming, or that warming is due to purely natural causes outside of human control. Such claims are inconsistent with reality.
Others argued that no action is warranted until we have absolute certainty about human impacts on climate. Absolute certainty is unattainable. We are certain beyond a reasonable doubt, however, that the problem of human-caused climate change is real, serious, and immediate, and that this problem poses significant risks: to our ability to thrive and build a better future, to national security, to human health and food production, and to the interconnected web of living systems.
The basic science of how greenhouse gases trap heat is clear, and has been for over a century. Ultimately, the strength of that basic science brought the governments of the world to Paris in December 2015. They went to Paris despite pronounced differences in systems of government, in national self-interest, in culpability for past emissions of greenhouse gases, and in vulnerability to future climate change. The leaders of over 190 countries recognized that the problem of human-caused climate change is a danger to present and future citizens of our planet. They made national commitments to address this problem. It was a small but historic and vital first step towards more enlightened stewardship of Earth’s climate system.
From studies of changes in temperature and sea level over the last million years, we know that the climate system has tipping points. Our proximity to these tipping points is uncertain. We know, however, that rapid warming of the planet increases the risk of crossing climatic points of no return, possibly setting in motion large-scale ocean circulation changes, the loss of major ice sheets, and species extinctions. The climatic consequences of exceeding such thresholds are not confined to the next one or two electoral cycles. They have lifetimes of many thousands of years.
The political system also has tipping points. Thus it is of great concern that the Republican nominee for President has advocated U.S. withdrawal from the Paris Accord. A “Parexit” would send a clear signal to the rest of the world: "The United States does not care about the global problem of human-caused climate change. You are on your own." Such a decision would make it far more difficult to develop effective global strategies for mitigating and adapting to climate change. The consequences of opting out of the global community would be severe and long-lasting – for our planet’s climate and for the international credibility of the United States.
The United States can and must be a major player in developing innovative solutions to the problem of reducing emissions of greenhouse gases. Nations that find innovative ways of decarbonizing energy systems and sequestering CO2 will be the economic leaders of the 21st century. Walking away from Paris makes it less likely that the U.S. will have a global leadership role, politically, economically, or morally. We cannot afford to cross that tipping point.
The following signers of this letter do so as individual NAS members and not on behalf of the NAS itself or their Institutions.
By Stephen Feller
24 September 2016
WASHINGTON (UPI) – Residents of Cedar Rapids and other parts of Eastern Iowa spent Saturday reinforcing preparations for floodwaters as some were evacuated from their homes and others were set to be told to leave later tonight.
The National Weather Service on Saturday afternoon issued flood warning for eastern Iowa that river waters would continue to rise, in cases until some time Sunday and others not until the middle of the week, and state officials spent the day moving to protect property and help people get to safety.
As of Saturday afternoon, the National Weather Service said in a forecast that flood warnings would continue deep into next week, with parts of the Shell Rock River not expected to fall below flood stage until Tuesday, the Iowa River not expected to fall below flood stage until Tuesday or Wednesday for much of the state.
Evacuations have been recommended for more than 5,000 people in Cedar Rapids, with Iowa National Guard and other officials working to help where needed and make sure people are aware of the danger posed by floodwaters. The National Guard also will be enforcing a curfew from 8 p.m. Sunday night until 7 a.m. Monday morning in areas that are being evacuated.
Depending on rain, the city is advising residents the river could reach 28 feet deep -- which would inundate homes in the area if rain continues to fall.
"We want you to today take care of your belongings and your pets [on Saturday]," Cedar Rapids Mayor Ron Corbett told the Des Moines Register, explaining the timing for evacuations. "[Sunday], we want you to take care of yourself." [more]
By Kevin Hardy, MacKenzie Elmer and Molly Longman
23 September 2016
(USA TODAY) – Heavy rain has led to record river flooding in northeastern Iowa, with several locations along the Cedar and Shell Rock Rivers either at or nearing all-time record high crests.
Cedar Rapids, the state's second-largest city, is awaiting its turn as the big mass of floodwater surges downstream. With the Cedar River rapidly rising, the mayor of Cedar Rapids promised residents Friday that the city would not be caught "off guard" like it was during 2008 flooding.
The river should crest at 25.3 feet on Monday — well below the June 2008 crest of 31 feet — but still the city's second-highest level on record, the National Weather Service said. Records go back to at least the early 1850s.
Mayor Ron Corbett said there was still time for residents to protect their homes and businesses from flooding caused by the Cedar River, which is expected to crest sometime Monday.
"We still have three days," he said. "We can save a lot in three days."
More rain fell Thursday night and earlier Friday, and the weather service said the threat for flash flooding remained high through the day. Noting the possibility of even more rain in the area, forecasters said at least moderate flooding was likely in several areas.
The town of Osage reached a record high crest Friday and the town of Shell Rock should reach a record high crest Saturday. [more]
By Sandra Leander
5 September 2016
(ASU) – Current models used to predict the survival of species in a warming world might be off target, according to new research that enlisted the help of dozens of spiny lizards in the New Mexico desert.
Nearly 40 percent of the world’s populations of lizards are expected to become extinct by 2080, because the Earth is warming faster than these populations can adapt.
But a new study, published today in Proceedings of the National Academy of Sciences, shows that to make accurate predictions, study models must include much more data about how shade is distributed throughout an animal’s habitat.
“The real fear is that previous research has underestimated the risk of extinction,” said Mike Angilletta, a professor at Arizona State University’s School of Life Sciences and co-author of the study.
“Most models assume that an animal can be anywhere in its environment at any time, which doesn’t account for how much energy an animal spends to regulate its temperature. Animals have to move and search for shade, which makes cooling down more difficult when patches of shade are far apart,” Angilletta said.
“This is a breakthrough paper,” according to Raymond Huey, a professor emeritus of biology at the University of Washington. “Scientists studying climate warming will now be forced to evaluate the spatial distribution of sunny-shady patches, and not just compute the fraction of an area that is sunny or shady. Frankly, that makes our research lives much harder, but also much more interesting.”
Even a small change in body temperature can dramatically affect an organism’s well-being, like when a person’s temperature rises 1 or 2 degrees. Reptiles, including lizards, regulate their body temperatures by moving between warm and cool areas within their home ranges.
It isn’t just the relative proportion of warm and cool areas that affects how well a lizard can regulate its temperatures, Huey said, but also how they are distributed in space.
The spiny lizards in the study regulated their temperatures much more efficiently when they had many small patches of shade, which they could easily reach to cool off, instead one large clump of shade in a wide-open space.
“Depending on the complexity of the environment, previous estimates of extinction may be too high or they might not be high enough,” said Mike Sears, an associate professor of biology at Clemson University and lead author of the study.
Sears has spent 20 years studying lizards. He says the reptiles are especially suited for climate-change studies because “they’re like little thermostats running around.”
What makes this study remarkable, Huey said, is that it tackles three issues at once.
“It develops original and highly sophisticated computer simulations of animal movement patterns in complex thermal environments,” Huey said. “It adds large-scale experiments of real animal movement patterns in the field. Finally, it shows that climate warming, in realistic thermal landscapes, may have more serious effects than predicted so far.”
When Sears first questioned the current models, he built a computer simulation to test their assumptions. Digital lizards followed algorithms that regulated body temperatures most efficiently. In the virtual environment, Sears’ digital lizards told him how much energy they spent on regulating their body temperatures when shade was either clumped together or spaced apart.
When shade was dispersed throughout a simulated environment, the digital lizards were able to regulate their temperatures more efficiently: They required less energy to move from patch to patch. When shade was isolated to one location, the lizards had to move farther away to hunt for food, which required more energy.
Angilletta, Sears and colleagues from two other universities tested their computer model with real lizards near the University of New Mexico’s Sevilleta Field Station.
The researchers fenced in nine arenas, each 20 by 20 meters square. To mimic the shade of the simulations, they stretched equal areas of shade cloth over each arena, but arranged the cloth differently—one big clump of shade, four medium-sized patches of shade or 16 small patches.
Each group of lizards spent two days in each environment, and their body temperatures were monitored through tiny, surgically implanted sensors.
When the lizards were in the arena with one large clump of shade, their temperatures varied 12 percent more than when they were in the arena with four patches of shade, and 10 percent more than when they were in the arena with 16 patches of shade. Thus, more patches mean more careful thermoregulation.
The results corresponded to Sears’ computer model. In the simulations, digital lizards experienced 9 percent more variation in body temperature when shade was provided in one clump compared with either four patches or 16 patches.
Huey likened the lizards’ behavior to running across a hot, sandy beach in bare feet to get from a parked car to the cool sands by the ocean.
“As a young lad, I leaned that spatial distribution of thermal resources mattered,” Huey said. “But Sears and colleagues take this theme to a general and sophisticated new level, and show how the distribution of shade patches affects the ability of lizards to use behavior to regulate their body temperatures, and also why an understanding of that distribution will be critical to predicting biological responses to climate warming.”
The research confirmed Sears’ hunch, that global temperatures aren’t sufficient for predicting how well species survive.
“If we really want to understand how populations of organisms will respond to climate change, we can't use a simple, back-of-the-envelope method,” Sears said. “We need to think on a finer scale than we have been.”
ABSTRACT: Although most organisms thermoregulate behaviorally, biologists still cannot easily predict whether mobile animals will thermoregulate in natural environments. Current models fail because they ignore how the spatial distribution of thermal resources constrains thermoregulatory performance over space and time. To overcome this limitation, we modeled the spatially explicit movements of animals constrained by access to thermal resources. Our models predict that ectotherms thermoregulate more accurately when thermal resources are dispersed throughout space than when these resources are clumped. This prediction was supported by thermoregulatory behaviors of lizards in outdoor arenas with known distributions of environmental temperatures. Further, simulations showed how the spatial structure of the landscape qualitatively affects responses of animals to climate. Biologists will need spatially explicit models to predict impacts of climate change on local scales.
By Ivan Nagelkerken, Sean Connell, and Tullio Rossi
19 September 2016
(Australian Geographic) – Despite appearances, the oceans are far from silent places. If you dunk your head underwater you’ll hear a cacophony of sounds from wildlife great and small, crashing waves, and even rain. And it’s louder still for creatures attuned to these sounds.
However, humans are changing these ocean soundscapes. Our recent research showed that changes caused by people, from ocean acidification to pollution, are silencing the seas' natural noises. (We’re also filling the oceans with human noise).
This is bad news for the species that depend on these noises to find their way. […]
Humans are increasingly dominating the physical and chemical environment. We are altering the carbon cycle through the burning of fossil fuels and the nitrogen cycle by extracting vast amounts of nitrogen for food production and releasing it as waste. Large amounts of this carbon and nitrogen liberation end up in the ocean.
About one-third of the carbon dioxide that humans emit into the atmosphere dissolves in the ocean, leading to increased seawater acidity (or ocean acidification). This is an obvious problem for animals that produce a calcium carbonate shell or skeleton (such as corals, some plankton, and snails). Remarkably, ocean acidification also alters the behaviour of many animals by messing up their brain functioning.
Two of our recent studies (see also here) showed that ocean acidification not only affects sound reception, but also the sounds that ocean ecosystems produce. If we don’t reduce greenhouse gas emissions, rocky reefs could be much quieter in 2100 than now. And snapping shrimps are the reason.
Coastal discharge of nutrients from sewage plants and catchment runoff also degrades kelp forests and seagrass beds. These coasts are more silent than their healthy counterparts. [more]
Polar bears across Arctic face shorter sea ice season – ‘This study shows declining sea ice for all subpopulations of polar bears’0 comments Posted by Jim at Sunday, September 25, 2016
By Michelle Ma
14 September 2016
(UW) – It’s no secret that Arctic sea ice is melting.
Polar bears, the poster child for climate change, are among the animals most affected by the seasonal and year-to-year changes in Arctic sea ice, because they rely on this surface for essential activities such as hunting, traveling, and breeding.
A new University of Washington study, with funding and satellite data from NASA, finds a trend toward earlier sea ice melt in the spring and later ice growth in the fall across all 19 polar bear populations, which can negatively impact the feeding and breeding capabilities of the bears. The paper, published Sept. 14 in The Cryosphere, is the first to quantify the sea ice changes in each polar bear subpopulation across the entire Arctic region using metrics that are specifically relevant to polar bear biology.
“This study shows declining sea ice for all subpopulations of polar bears,” said co-author Harry Stern, a researcher with the UW’s Polar Science Center. “We have used the same metric across all of the polar bear subpopulations in the Arctic so we can compare and contrast, for example, the Hudson Bay region with the Baffin Bay region using the same metric.”
The analysis shows that the critical timing of the sea ice break-up and sea ice freeze-up is changing in all areas in a direction that is harmful for polar bears.
Nineteen separate polar bear populations live throughout the Arctic, spending their winters and springs roaming on sea ice and hunting. The bears have evolved mainly to eat seals, which provide necessary fats and nutrients in the harsh Arctic environment. Polar bears can’t outswim their prey, so instead they perch on the ice as a platform and ambush seals at breathing holes or break through the ice to access their dens.
“Sea ice really is their platform for life,” said co-author Kristin Laidre, a researcher at the UW’s Polar Science Center. “They are capable of existing on land for part of the year, but the sea ice is where they obtain their main prey.”
The new study draws upon 35 years of satellite data showing sea ice concentration each day in the Arctic. NASA scientists process the data, stored at the National Snow and Ice Data Center in Boulder, Colorado.
The center also reports each fall the yearly minimum low for Arctic sea ice. This August saw the fourth lowest in the satellite record.
Across all 19 polar bear populations, the researchers found that the total number of ice-covered days declined at the rate of seven to 19 days per decade between 1979 and 2014. Sea ice concentration during the summer months — an important measure because summertime is when some subpopulations are forced to fast on land — also declined in all regions, by 1 percent to 9 percent per decade.
The most striking result, researchers said, is the consistent trend across all polar bear regions for an earlier spring ice melt and a later fall freeze-up. Arctic sea ice retreats in the springtime as daylight reappears and temperatures warm. In the fall months the ice sheets build again as temperatures drop.
“These spring and fall transitions bound the period when there is good ice habitat available for bears to feed,” Laidre said. “Those periods are also tied to the breeding season when bears find mates, and when females come out of their maternity dens with very small cubs and haven’t eaten for months.”
The researchers found that on average, spring melting was three to nine days earlier per decade, and fall freeze-up was three to nine days later per decade. That corresponds to a roughly 3 ½ week shift at either end — and seven weeks of total loss of good sea ice habitat for polar bears — over the 35 years of Arctic sea ice data.
“We expect that if the trends continue, compared with today, polar bears will experience another six to seven weeks of ice-free periods by mid-century,” Stern said.
The trend appears to be linear and isn’t accelerating or leveling off, Stern added. The researchers recommend that the National Climate Assessment incorporate the timing of spring ice retreat and fall ice advance as measures of climate change in future reports.
The study’s results currently are used by the International Union for Conservation of Nature’s Polar Bear Specialist Group, which completes assessments of polar bears and issues the species’ conservation status. Specifically, the group used the sea ice metric as a measure of polar bear habitat in the IUCN Red List assessment of polar bears. The researchers plan to update their findings each year as new ice coverage data are available.
“It’s nice to see this work being used in high-level conservation goals,” Laidre said.
The study was funded by NASA and the Greenland Institute of Natural Resources. The Cryosphere, where the results are published, is a journal of the European Geosciences Union.
ABSTRACT: Nineteen subpopulations of polar bears (Ursus maritimus) are found throughout the circumpolar Arctic, and in all regions they depend on sea ice as a platform for traveling, hunting, and breeding. Therefore polar bear phenology – the cycle of biological events – is linked to the timing of sea-ice retreat in spring and advance in fall. We analyzed the dates of sea-ice retreat and advance in all 19 polar bear subpopulation regions from 1979 to 2014, using daily sea-ice concentration data from satellite passive microwave instruments. We define the dates of sea-ice retreat and advance in a region as the dates when the area of sea ice drops below a certain threshold (retreat) on its way to the summer minimum or rises above the threshold (advance) on its way to the winter maximum. The threshold is chosen to be halfway between the historical (1979–2014) mean September and mean March sea-ice areas. In all 19 regions there is a trend toward earlier sea-ice retreat and later sea-ice advance. Trends generally range from −3 to −9 days decade−1 in spring and from +3 to +9 days decade−1 in fall, with larger trends in the Barents Sea and central Arctic Basin. The trends are not sensitive to the threshold. We also calculated the number of days per year that the sea-ice area exceeded the threshold (termed ice-covered days) and the average sea-ice concentration from 1 June through 31 October. The number of ice-covered days is declining in all regions at the rate of −7 to −19 days decade−1, with larger trends in the Barents Sea and central Arctic Basin. The June–October sea-ice concentration is declining in all regions at rates ranging from −1 to −9 percent decade−1. These sea-ice metrics (or indicators of habitat change) were designed to be useful for management agencies and for comparative purposes among subpopulations. We recommend that the National Climate Assessment include the timing of sea-ice retreat and advance in future reports.
TUNIS, 25 September 2016 (Associated Press) – Struggling with extremism and economic woes, Tunisia now faces another menace: persistent drought across several regions that is creating new social tensions and threatening farming, a pillar of the economy. Farmland is too parched to cultivate crops and rural protesters have tried disrupting water supplies to the capital, while one legislator is calling for a "thirst revolt."
A lack of rain, combined with years of bad resource management, has left reservoirs and dams at exceptionally low levels that could lead to a "catastrophic situation," said Saad Seddik, who was agriculture minister until last month. With municipal water supplies periodically cut off, residents of some towns are walking several kilometers (miles) to fetch water from public fountains, loading up donkeys with water canisters - if there's any left.
"We come here twice a day, first early in the morning before the dam becomes agitated and dangerous. But what we fetch in the morning isn't enough. So we repeat the trip in the afternoon," but it's still not enough to clean the house or wash clothes, said Hadiya Farhani from the town of Sbikha in the central Kairouan region.
Fellow resident Samir Farhani says the government is concentrating on fighting terrorism "while forgetting that thirst could make us turn into terrorists." Tunisia suffered two major Islamic extremist attacks last year targeting tourists and sees sporadic violence and threats from the Islamic State group in Libya and other radical groups in the region. "We are thirsty. Give us water, we don't need work, just water," he pleaded.
Tunisia has had a string of governments since its Arab Spring revolution in 2011 that have concentrated on fighting extremism and corruption and building a democracy after years of autocracy. Construction is under way on nine new reservoirs and three desalination plants, but water resource management has not been a top government priority. One recent government response: The minister of religious affairs asked imams to hold prayers for rain.
Most of Tunisia's water goes to farming, and drought-related agricultural losses are estimated at 2 billion dinars ($905 million) this year, according to the Tunisian Agriculture and Fishing Union. The grain industry alone is expected to lose 793 million dinars ($359 million) for the 2015/2016 season, it said.
Debts are piling up, and water reserves are down nearly a third from recent historical levels, according to the union. A tomato and potato farmer in Bkalta in the Monastir region, Anis Zouita, normally plants this time of year but fears he won't be able to irrigate. That could lead to a shortage of produce and higher prices for consumers. "We are stuck. We need water for this agricultural season," he said.
He says climate change, and the lack of a long-term government water strategy for this arid country on the edge of the Sahara, are to blame. Prolonged droughts are among many extreme weather phenomena that climate scientists say are becoming more frequent because of man-made carbon dioxide pollution. [more]