SEA-LEVEL RISE IS A ‘SERIOUS THREAT’ #CLIMATECHANGE #AUSPOL https://jpratt27.wordpress.com/2017/03/17/sea-level-rise-is-a-serious-threat-climatechange-auspol/
Sea-level rise poses ‘a serious threat’ to millions of Europeans, scientists warn. A new study spells out the threat of sea-level rise in coastal communities.The kind of devastating flooding that occurs once every century along Europe’s northern coastline could become an annual event if greenhouse gas emissions continue to climb, according to a recent study published in the journal Earth’s Future.
New analysis takes into account changes in sea-level rise, tides, waves, and storm surge over the 21st century and found that climate change could prompt extreme sea levels — the maximum levels seen during major storms, which produce massive flooding — to increase significantly along the European coastline by 2100.
This scenario will likely stress coastal protection structures beyond their capacity, leaving much of the European coastline vulnerable to dangerous flooding, according to study authors.
“Unless we take different protection measures, five million people will be exposed to coastal flooding on an annual basis,” said Michalis Vousdoukas, a coastal oceanographer at the Joint Research Centre of the European Commission and lead author of the study.
The study described the projected rise in extreme sea levels as “a serious threat” to coastal communities, noting, “their safety and resilience depends on the effectiveness of natural and man-made coastal flood protection.”
Kevin Trenberth, a scientist with the climate analysis section of the National Center for Atmospheric Research, who was not involved in this research, said the signs of extreme sea levels are already worrisome, not just in Europe, but in the United States as well. “Witness the sunshine flooding in Florida already, the flooding that shows up even with no storm on many streets any time there is a slightly high tide,” he said.
Sea level is going up because the ocean is warming and hence expanding, and because land ice — glaciers, etc. — are melting and putting more water into the ocean. But it is not the gradual rise that matters,” Trenberth said. “Rather, it is the storm surge on top of a high tide riding on top of the increase in sea level that crosses thresholds and causes things to break.”
Richard Alley, professor of geosciences at Pennsylvania State University, who also did not take part in this study, noted that the study didn’t consider the possible collapse of the West Antarctic ice sheet. “If that happens, then sea-level rise and impacts to coasts could be much higher than in this paper,” Alley said. “Rapid West Antarctic collapse could cause enough rise to make many of these other factors of secondary importance. So, the ‘worst case’ in this paper isn’t really the worst case.”
The new paper predicted that some regions could experience an even higher increase in the frequency of these extreme flooding events, specifically along the Mediterranean and the Black Sea, where the present day 100-year extreme sea level could occur as often as several times a year.
“The ‘worst case’ in this paper isn’t really the worst case.”
Information about the number of people at risk from flooding can be used to determine how large the social and economic impact of these events will be, said Marta Marcos, a researcher at the Mediterranean Institute for Advanced Studies in Spain, who was not involved in the new study. “In terms of adaptation strategies and policy-making, it is very relevant,” she said.
The researchers studied changes in extreme sea levels by 2100 under different greenhouse gas scenarios and considered how all these components — mean sea level, tides, waves, and storm surge — will be affected by climate change.
f emissions continue to rise unabated throughout this century, extreme sea levels along Europe’s coastlines could increase by more than 2.5 feet, on average, by 2100. Under a more moderate situation, where greenhouse gas emissions peak in 2040, 100-year extreme sea levels still could jump by nearly 2 feet, on average, by the end of the century — with flooding events occurring every few years — according to study’s authors.
In a related study appearing in Geophysical Research Letters, scientists found that if greenhouse gases continue to rise, there could be disturbing changes by the end of the century in the energy that waves carry to the coast.
In the southern hemisphere, extreme waves could carry up to 30 percent more energy by 2100, according to the study, meaning that stronger waves will become more frequent, and have a greater impact on the coast, said Lorenzo Mentaschi, a researcher at the Joint Research Centre and lead author of the study.
The new study attributed the changes in wave energy to the intensification of weather patterns, like El Niño. The new research will be provided to European Union policymakers. The data will also be made public so it can be used by scientists, engineers, and coastal managers.
Michael Mann, professor of atmospheric science at Pennsylvania State University, said the research once again underscored how climate change, “which has already increased the threat to our coastlines through a combination of sea-level rise and intensified coastal storms, will be catastrophic for coastal communities if we don’t reduce global carbon emissions.”
Marlene Cimons writes for Nexus Media, a syndicated newswire covering climate, energy, policy, art & culture.
Press link for more: Think Progress
The world’s oceans are storing up staggering amounts of heat — and it’s even more than we thought, by Chelsea Harvey, Energy & Enviornment, Washington Post, Mar 10, 2017 The world is getting warmer every year, thanks to climate change — but where exactly most of that heat is going may be a surprise.
As a stunning early spring blooms across the United States, just weeks after scientists declared 2016 the hottest year on record , it’s easy to forget that all the extra warmth in the air accounts for only a fraction of the heat produced by greenhouse gas emissions. In fact, more than 90 percent of it gets stored in the ocean. And now, scientists think they’ve calculated just how much the ocean has warmed in the past few decades.
A new study, out Friday in the journal Science Advances, suggests that since 1960, a staggering 337 zetajoules of energy — that’s 337 followed by 21 zeros — has been added to the ocean in the form of heat. And most of it has occurred since 1980.
“The ocean is the memory of all of the past climate change,” said study co-author Kevin Trenberth , a senior scientist at the National Center for Atmospheric Research.
The world’s oceans are storing up staggering amounts of heat — and it’s even more than we thought https://www.skepticalscience.com/2017-SkS-Weekly-Digest_10.html
International team reports ocean acidification spreading rapidly in Arctic Ocean, EurekAlert, 28 Feb 17, UNIVERSITY OF DELAWARE Ocean acidification (OA) is spreading rapidly in the western Arctic Ocean in both area and depth, according to new interdisciplinary research reported in Nature Climate Changeby a team of international collaborators, including University of Delaware professor Wei-Jun Cai.
The research shows that, between the 1990s and 2010, acidified waters expanded northward approximately 300 nautical miles from the Chukchi slope off the coast of northwestern Alaska to just below the North Pole. Also, the depth of acidified waters was found to have increased, from approximately 325 feet to over 800 feet (or from 100 to 250 meters).
“The Arctic Ocean is the first ocean where we see such a rapid and large-scale increase in acidification, at least twice as fast as that observed in the Pacific or Atlantic oceans,” said Cai, the U.S. lead principal investigator on the project and Mary A.S. Lighthipe Professor of Earth, Ocean, and Environment at UD.
“The rapid spread of ocean acidification in the western Arctic has implications for marine life, particularly clams, mussels and tiny sea snails that may have difficulty building or maintaining their shells in increasingly acidified waters,” said Richard Feely, NOAA senior scientist and a co-author of the research. Sea snails called pteropods are part of the Arctic food web and important to the diet of salmon and herring. Their decline could affect the larger marine ecosystem.
Among the Arctic species potentially at risk from ocean acidification are subsistence fisheries of shrimp and varieties of salmon and crab.
Other collaborators on the international project include Liqi Chen, the Chinese lead principal investigator and scientist with the Third Institute of Oceanography of State Oceanic Administration of China; and scientists at Xiamen University, China and the University of Gothenburg, Sweden, among other institutions…….
Arctic ocean ice melt in the summer, once found only in shallow waters of depths less than 650 feet or 200 meters, now spreads further into the Arctic Ocean.
“It’s like a melting pond floating on the Arctic Ocean. It’s a thin water mass that exchanges carbon dioxide rapidly with the atmosphere above, causing carbon dioxide and acidity to increase in the meltwater on top of the seawater,” said Cai. “When the ice forms in winter, acidified waters below the ice become dense and sink down into the water column, spreading into deeper waters.”https://www.eurekalert.org/pub_releases/2017-02/uod-itr022717.php
Drastic cooling in North Atlantic beyond worst fears, scientists warn https://www.theguardian.com/environment/2017/feb/24/drastic-cooling-north-atlantic-beyond-worst-fears-scientists-warn
Climatologists say Labrador Sea could cool within a decade before end of this century, leading to unprecedented disruption, reports Climate News Network, Guardian, Alex Kirby , 25 Feb 17, For thousands of years, parts of northwest Europe have enjoyed a climate about 5C warmer than many other regions on the same latitude. But new scientific analysis suggests that that could change much sooner and much faster than thought possible.
Climatologists who have looked again at the possibility of major climate change in and around the Atlantic Ocean, a persistent puzzle to researchers, now say there is an almost 50% chance that a key area of the North Atlantic could cool suddenly and rapidly, within the space of a decade, before the end of this century.
That is a much starker prospect than even the worst-case scientific scenario proposed so far, which does not see the Atlantic ocean current shutdown happening for several hundred years at least.
A scenario even more drastic (but fortunately fictional) was the subject of the 2004 US movie The Day After Tomorrow, which portrayed the disruption of the North Atlantic’s circulation leading to global cooling and a new Ice Age.
To evaluate the risk of extreme climate change, researchers from the Environnements et Paléoenvironnements Océaniques et Continentaux laboratory (CNRS/University of Bordeaux, France), and the University of Southamptondeveloped an algorithm to analyse the 40 climate models considered by the Fifth Assessment Report.
The findings by the British and French team, published in the Nature Communications journal, in sharp contrast to the IPCC, put the probability of rapid North Atlantic cooling during this century at almost an even chance – nearly 50%.
Current climate models foresee a slowing of the meridional overturning circulation (MOC), sometimes known also as the thermohaline circulation, which is the phenomenon behind the more familiar Gulf Stream that carries warmth from Florida to European shores. If it did slow, that could lead to a dramatic, unprecedented disruption of the climate system.
In 2013, drawing on 40 climate change projections, the IPCC judged that this slowdown would occur gradually, over a long period. Its findings suggested that fast cooling of the North Atlantic during this century was unlikely.
But oceanographers from EU emBRACE had also re-examined the 40 projections by focusing on a critical spot in the northwest of the North Atlantic: the Labrador Sea.
The Labrador Sea is host to a convection system ultimately feeding into the ocean-wide MOC. The temperatures of its surface waters plummet in the winter, increasing their density and causing them to sink. This displaces deep waters, which bring their heat with them as they rise to the surface, preventing the formation of ice caps.
The algorithm developed by the Anglo-French researchers was able to detect quick sea surface temperature variations. With it they found that seven of the 40 climate models they were studying predicted a total shutdown of convection, leading to abrupt cooling of the Labrador Sea by 2C to 3C over less than 10 years. This in turn would drastically lower North Atlantic coastal temperatures.
But because only a handful of the models supported this projection, the researchers focused on the critical parameter triggering winter convection: ocean stratification. Five of the models that included stratification predicted a rapid drop in North Atlantic temperatures.
The researchers say these projections can one day be tested against real data from the international OSnap project, whose teams will be anchoring scientific instruments within the sub-polar gyre (a gyre is any large system of circulating ocean currents).
If the predictions are borne out and the North Atlantic waters do cool rapidly over the coming years, the team says, with considerable understatement, climate change adaptation policies for regions bordering the North Atlantic will have to take account of this phenomenon.
OMG measurements of Greenland give us a glimpse of future sea rise https://www.skepticalscience.com/omg-greenland-sea-level-rise.html 24 February 2017 by John Abraham If you meet a group of climate scientists, and ask them how much sea levels will rise by say the year 2100, you will get a wide range of answers. But, those with most expertise in sea level rise will tell you perhaps 1 meter (a little over three feet). Then, they will immediately say, “but there is a lot of uncertainty on this estimate.” It doesn’t mean they aren’t certain there will be sea level rise – that is guaranteed as we add more heat in the oceans. Here, uncertainty means it could be a lot more or a little less.
Why are scientists not certain about how much the sea level will rise? Because there are processes that are occurring that have the potential for causing huge sea level rise, but we’re uncertain about how fast they will occur. Specifically, two very large sheets of ice sit atop Greenland and Antarctica. If those sheets melt, sea levels will rise hundreds of feet.
Parts of the ice sheets are melting, but how much will melt and how fast will the melting occur? Are we talking decades? Centuries? Millennia? Scientists really want to know the answer to this question. Not only is it interesting scientifically, but it has huge impacts on coastal planning.
One reason the answer to this question is illusive is that melting of ice sheets can occur from above (warm air and sunlight) or from below (warm ocean waters). In many instances, it’s the melting from below that is most significant – but this melting from below is really hard to measure.
With hope we will have a much clearer sense of ice sheet melting and sea level rise because of a new scientific endeavor that is part of a NASA project – Oceans Melting Greenland (OMG). This project has brought together some of the best oceanographers and ice experts in the world. The preliminary results are encouraging and are discussed in two recent publications here and here.
In the papers, the authors note that Greenland ice loss has increased substantially in recent decades. It now contributes approximately 1/3 to total sea level rise. The authors want to know whether this contribution will change over time and they recognize that underwater processes may be the most important to study. In fact, they note in their paper:
Specifically, our goal is improved understanding of how ocean hydrographic variability around the ice sheet impacts glacial melt rates, thinning and retreat.
In plain English, they want to know how water flow around Greenland affects the ice melt.
Their experiments are measuring a number of key attributes. First, yearly changes in the temperature of ocean water near Greenland. Second, the yearly changes to the glaciers on Greenland that extend into the ocean waters. Third, they are observing marine topography (the shape of the land underneath the ocean surface).
The sea floor shape is quite complicated, particularly near Greenland. Past glaciers carved deep troughs in the sea floor in some areas, allowing warm salty water to reach huge glaciers that are draining the ice sheet. As lead OMG investigator Josh Willis said:
What’s interesting about the waters around Greenland is that they are upside down. Warm, salty water, which is heavy, sits below a layer of cold, fresh water from the Arctic Ocean. That means the warm water is down deep, and glaciers sitting in deep water could be in trouble.
As the warm water attacks marine glaciers (glaciers that extend into the ocean), the ice tends to break and calve, retreating toward land. In some cases, the glaciers retreat until their grounding line coincides with the shore. But in other cases the undulating surface allows warm water to wear the glacier underside for long distances and thereby increase the risk of large calving events.
Oftentimes, when glaciers near the coast break off they uncork other ice that can then more easily flow into the oceans.
Click here to read the rest
Air pollution may have masked mid-20th Century sea ice loss https://www.sciencedaily.com/releases/2017/02/170223124327.htm February 23, 2017
- American Geophysical Union
- Humans may have been altering Arctic sea ice longer than previously thought, according to researchers studying the effects of air pollution on sea ice growth in the mid-20th Century.
Humans may have been altering Arctic sea ice longer than previously thought, according to researchers studying the effects of air pollution on sea ice growth in the mid-20th Century. The new results challenge the perception that Arctic sea ice extent was unperturbed by human-caused climate change until the 1970s.
Scientists have observed Arctic sea ice loss since the mid-1970s and some climate model simulations have shown the region was losing sea ice as far back as 1950. In a new study, recently recovered Russian observations show an increase in sea ice from 1950 to 1975 as large as the subsequent decrease in sea ice observed from 1975 to 2005. The new observations of mid-century sea ice expansion led researchers behind the new study to the search for the cause.
The new study supports the idea that air pollution is to blame for the observed Arctic sea ice expansion. Particles of air pollution that come primarily from the burning of fossil fuels may have temporarily hidden the effects of global warming in the third quarter of the 20th Century in the eastern Arctic, the researchers say.
These particles, called sulfate aerosols, reflect sunlight back into space and cool the surface. This cooling effect may have disguised the influence of global warming on Arctic sea ice and may have resulted in sea ice growth recorded by Russian aerial surveys in the region from 1950 through 1975, according to the new research.
- “The cooling impact from increasing aerosols more than masked the warming impact from increasing greenhouse gases,” said John Fyfe, a senior scientist at Environment and Climate Change Canada in Victoria and a co-author of the new study accepted for publication in Geophysical Research Letters, a journal of the American Geophysical Union.
To test the aerosol idea, researchers used computer modeling to simulate sulfate aerosols in the Arctic from 1950 through 1975. Concentrations of sulfate aerosols were especially high during these years before regulations like the Clean Air Act limited sulfur dioxide emissions that produce sulfate aerosols.
The study’s authors then matched the sulfate aerosol simulations to Russian observational data that suggested a substantial amount of sea ice growth during those years in the eastern Arctic. The resulting simulations show the cooling contribution of aerosols offset the ongoing warming effect of increasing greenhouse gases over the mid-twentieth century in that part of the Arctic. This would explain the expansion of the Arctic sea ice cover in those years, according to the new study.
Aerosols spend only days or weeks in the atmosphere so their effects are short-lived. The weak aerosol cooling effect diminished after 1980, following the enactment of clean air regulations. In the absence of this cooling effect, the warming effect of long-lived greenhouse gases like carbon dioxide has prevailed, leading to Arctic sea ice loss, according to the study’s authors.
The new study helps sort out the swings in Arctic sea ice cover that have been observed over the last 75 years, which is important for a better understanding of sea ice behavior and for predicting its behavior in the future, according to Fyfe.
The new study’s use of both observations and modeling is a good way to attribute the Arctic sea ice growth to sulfate aerosols, said Cecilia Bitz, a sea ice researcher at the University of Washington in Seattle who has also looked into the effects of aerosols on Arctic ice. The sea ice record prior to satellite images is “very sparse,” added Bitz, who was not involved in the new study.
Bitz also points out that some aerosols may have encouraged sea ice to retreat. Black carbon, for instance, is a pollutant from forest fires and other wood and fossil fuel burning that can darken ice and cause it to melt faster when the sun is up — the opposite effect of sulfates. Also, black carbon emissions in some parts of the Arctic are still quite common, she said.
Sea Level Rise Estimate Grows Alarmingly Higher in Latest Federal Report https://insideclimatenews.org/news/24012017/sea-level-rise-global-warming-federal-report-donald-trump
NOAA’s latest report arrives, predicting worst-case scenario of 8 feet of rise by century’s end, just as Donald Trump takes office with pro-fossil fuel policies. New federal estimates say global sea levels could rise faster than previously thought, and the rise may be even worse in many coastal regions of the United States.
A new report, written by scientists with several federal agencies and universities, says that under a worst-case scenario, climate change could raise the oceans an average of more than 8 feet by 2100, about 20 inches more than a previous federal estimate published in 2012. The best case now projected would be an average of about a foot.
The report was delivered just as President Donald Trump took office, immediately working to undo President Barack Obama’s climate policies. On his inauguration day, pages mentioning climate change on whitehouse.gov were removed. Trump has promised policies to increase fossil fuel development in the U.S., and to undo Obama’s major emissions-cutting initiative, the Clean Power Plan.
Sea level rise will likely be worse in some regions of the U.S. because of ocean currents, wind patterns and settling sediments. The authors examined six scenarios with a range of probabilities in an effort to help state and local governments plan for sea level rise. Under all of them, the Northeast should expect higher waters than much of the rest of the globe. The Pacific Northwest and Alaska would likely experience lower-than-average increases under the best-case scenarios.
“The ocean’s not flat,” said William V. Sweet, one of the authors and a scientist at NOAA. “It’s not going to rise like water in a bathtub.”
The six scenarios are based on United Nations models of future greenhouse gas emissions, depending on whether countries rapidly slash pollution or continue burning fossil fuels as usual. The authors determined that the worst-case rise of more than 8 feet has only a 0.1 percent chance of occurring by 2100, even under a business-as-usual emissions scenario, but a rise of more than 1.5 feet is near certain with high emissions.
The increase in the estimates for global sea rise was partly due to new research on the Antarctic ice sheet, which is melting faster and appears to be more fragile than previously estimated, suggesting that some of the more pessimistic scenarios are increasingly likely.
The report also warned that moderate coastal flooding will become 25 times more likely with a 14-inch rise in the seas. That level could come anytime from 2030 to 2080 for most coastal cities, depending on their location and the world’s emissions. It would mean that a flood that now comes once every five years would be expected five times a year.
Sea levels have already risen by more than 8 inches globally since 1880, with 3 inches coming since 1993. Tidal flooding “has increased by an order of magnitude over the past several decades,” the report says, “turning it from a rare event into a recurrent and disruptive problem.”
The authors note that 2 million Americans would likely see their homes permanently flooded if sea levels rise 3 feet. Twice that increase would inundate the homes of 6 million. Only the rosiest scenarios would avoid a 3-foot rise by 2100. The effects of global warming, of course, will continue long beyond that year.
“Even if society sharply reduces emissions in the coming decades,” the authors write, “sea level will most likely continue to rise for centuries.”
By TATSUYUKI KOBORI/ Staff Writer January 11, 2017 Coral bleaching has killed 70.1 percent of the nation’s largest coral reef as of the end of 2016, up from 56.7 percent just a few months earlier, the Environment Ministry said.
Warmer seawater temperatures last summer are believed to have caused coral bleaching to spread to 90 percent of the Sekiseishoko coral reef in Okinawa Prefecture…….http://www.asahi.com/ajw/articles/AJ201701110028.html
New analysis: global sea ice suffered major losses in 2016 http://blogs.discovermagazine.com/imageo/2017/01/07/sea-ice-extent-in-2016-at-both-poles-tracked-well-below-average/#.WHMiWtJ97Gj The extent of sea ice globally took major hits during 2016, according to an analysis released yesterday by the National Snow and Ice Data Center.
At both poles, “a wave of new record lows were set for both daily and monthly extent,” according to the analysis.
In recent years, Arctic sea ice has been hit particularly hard.
“It has been so crazy up there, not just this autumn and winter, but it’s a repeat of last autumn and winter too,” says Mark Serreze, director of the NSIDC.
In years past, abnormal warmth and record low sea ice extent tended to occur most frequently during the warmer months of the year. But for the past two years, things have gotten really weird in the colder months.
In 2015, Serreze says, “you had this amazing heat wave, and you got to the melting point at the North Pole on New Years Eve. And we’ve had a repeat this autumn and winter — an absurd heat wave, and sea ice at record lows.”
Lately, the Southern Hemisphere has been getting into the act. “Now, Antarctic sea ice is very, very low,” Serreze says.
From the NSIDC analysis:
Record low monthly extents were set in the Arctic in January, February, April, May, June, October, and November; and in the Antarctic in November and December.
Put the Arctic and the Antarctic together, and you get his time series of daily global sea ice extent, meaning the Arctic plus Antarctic:
As the graph [on original] shows, the global extent of sea ice tracked well below the long-term average for all of 2016. The greatest deviation from average occurred in mid-November, when sea ice globally was 1.50 million square miles below average.
For comparison, that’s an area about 40 percent as large as the entire United States.
The low extent of sea ice globally “is a result of largely separate processes in the two hemispheres,” according to the NSIDC analysis.
For the Arctic, how much might humankind’s emissions of greenhouse gases be contributing to the long-term decline of sea ice? The graph above [on original] , based on data from a study published in the journal Science, “links Arctic sea ice loss to cumulative CO2emissions in the atmosphere through a simple linear relationship,” according to an analysis released by the NSIDC last December. Based on observations from the satellite and pre-satellite era since 1953, as well as climate models, the study found a linear relationship of 3 square meters of sea ice lost per metric ton of CO2 added to the atmosphere.
That’s over the long run. But over a shorter period of time, what can be said? Specifically, how much of the extreme warmth and retraction of sea ice that has been observed in autumn and winter of both 2015 and 2016 can be attributed to humankind’s emissions of greenhouse gases?
“We’re working on it,” Serreze says. “Maybe these are just extreme random events. But I have been looking at the Arctic since 1982, and I have never seen anything like this.”
Greenland Ice Melt Could Push Atlantic Circulation to Collapse New research gives a glimpse of the potential long-term consequences of anthropogenic warming, Hakai Magazine, January 3, 2017
In the North Atlantic, east of North America and south of Greenland, the ocean’s upper layers are much warmer than one might presume given the extreme latitude. This unexpected warmth is a product of the Atlantic Meridional Overturning Circulation (AMOC), a vitally important system of ocean currents that moves warm salty water northward from the tropics and cold fresher water south. The AMOC looms large in the Earth’s climate: it is responsible for redistributing nutrients throughout the Atlantic Ocean and is a major driving force controlling the climate on both sides of the pond.
Ocean currents all experience fluctuations, which can dramatically change the distribution of nutrients, heat, and fish. The best known example is probably the El Niño-Southern Oscillation, in which unusually warm water occasionally disrupts the Pacific Ocean’s Humboldt Current that flows north from Chile toward Peru. El Niño events can shift the jet stream south, cause excessive rainfall and devastating floods, and temporarily collapse fish stocks.
To date, most climate research suggests that the AMOC is relatively stable and carries water throughout the ocean in a reliable, repeating cycle. But anthropogenic climate change seems to have made the current weaken slightly, raising the question of whether more dramatic shifts are in store. As of the most recent Intergovernmental Panel on Climate Change report, a shutdown of the circulation from further warming is considered unlikely. Yet a new study says that the unprecedented melting of Greenland’s massive ice sheets, previously overlooked in most climate modeling, will result in the AMOC weakening, and maybe even collapsing, within the next 300 years……..https://www.hakaimagazine.com/article-short/greenland-ice-melt-could-push-atlantic-circulation-collapse
Scientists say the global ocean circulation may be more vulnerable to shutdown than we thought, WP, Intense future climate change could have a far different impact on the world than current models predict, suggests a thought-provoking new study just out in the journal Science Advances. If atmospheric carbon dioxide concentrations were to double in the future, it finds, a major ocean current — one that helps regulate climate and weather patterns all over the world — could collapse. And that could paint a very different picture of the future than what we’ve assumed so far.
The Atlantic meridional overturning circulation, or AMOC, is often described as a large oceanic conveyor belt. It’s a system of water currents that transports warm water northward from the Atlantic toward the Arctic, contributing to the mild climate conditions found in places like Western Europe. In the Northern Atlantic, the northward flowing surface water eventually cools and sinks down toward the bottom of the ocean, and another current brings that cooler water back down south again. The whole process is part of a much larger system of overturning currents that circulates all over the world, from pole to pole.
But some scientists have begun to worry that the AMOC isn’t accurately represented in current climate models. They say that many models portray the current as being more stable than real-life observations suggest it actually is. Recent studies have suggested that the AMOC is weakening, although there’s some scientific debate about how much of this has been caused by human activities and how much by natural variations.
[In Greenland, a once doubtful scientist witnesses climate change’s troubling toll]
Nevertheless, the authors of the new study point out, many climate models assume a fairly stable AMOC — and that could be affecting the predictions they make for how the ocean will change under future climate change. And because overturning circulation patterns have such a significant effect on climate and weather all over the world, this could have big implications for all kinds of other climate-related projections as well.
“This is a very common and well-known issue in climate models,” said the new study’s lead author, Wei Liu, a postdoctoral associate at Yale University, who conducted the work while at the University of California at San Diego. “I wanted to see, if I use a corrected model, how this will affect the future climate change.”
Liu and colleagues from the UC-San Diego and the University of Wisconsin at Madison took a commonly used climate model and corrected for what they considered to be the AMOC stability bias. Then they ran an experiment to see how the correction would affect the model’s projections under future climate change. They instantaneously doubled the atmospheric carbon dioxide concentration from present-day levels in both the corrected and uncorrected models, and then they let both models run for hundreds of simulated years.
The differences were striking. In the uncorrected climate model, the AMOC weakens for a while, but eventually recovers. In the corrected model, however, the AMOC continues to weaken and after 300 years, it collapses altogether.
[Why scientists are so worried about sea-level rise in the second half of this century]
In a commentary also published today in RealClimate, Stefan Rahmstorf, an oceans physics expert at the Potsdam Institute for Climate Impact Research, explained how such a collapse could occur when the AMOC gets too weak.
“Freshwater continually flows into the northern Atlantic through precipitation, rivers and ice-melting,” he wrote. “But supply of salty waters from the south, through the Gulf Stream System, balances this. If however the current slows, there is less salt supply, and the surface ocean gets less salty.”
Because freshwater is less dense than salty water, this process can lead to a kind of stratification, in which the lighter freshwater gets stuck on the surface of the ocean and can’t sink to the bottom when it reaches the cooler north. When this happens, the overturning process that drives the current back down south again can’t occur.
“There is a critical point when this becomes an unstoppable vicious circle,” Rahmstorf wrote. “This is one of the classic tipping points in the climate system.”
The resulting climate consequences, compared to the uncorrected model, are also dramatic. Without the usual transport of warm water into the north, the corrected model predicts a marked cooling over the northern Atlantic, including in the United Kingdom, Iceland and northwestern Europe, as well as in the Arctic, where sea ice begins to expand.
Because the AMOC is part of a larger global conveyor system, which ferries warm and cold currents between the equator and both poles, the model predicts disruptions in other parts of the world as well. Without cold water moving back down south again, the corrected model indicates a stronger warming pattern south of the equator than what’s predicted by the uncorrected model, causing a polarization in precipitation patterns over the Americas — more rain for places like northeastern Brazil and less rain for Central America. The model also predicts a greater reduction in sea ice for the Antarctic.
All this doesn’t necessarily mean that everything we thought we knew about the future climate is wrong……..https://www.washingtonpost.com/news/energy-environment/wp/2017/01/04/scientists-say-the-global-ocean-circulation-may-be-more-vulnerable-to-shutdown-than-we-thought/?utm_term=.59c29620139f
Sea ice hit record lows in November, EurekAlert, 6 Dec 16 UNIVERSITY OF COLORADO AT BOULDER Unusually high air temperatures and a warm ocean have led to a record low Arctic sea ice extent for November, according to scientists at the National Snow and Ice Data Center (NSIDC) at the University of Colorado Boulder. In the Southern Hemisphere, Antarctic sea ice extent also hit a record low for the month, caused by moderately warm temperatures and a rapid shift in circumpolar winds.
“It looks like a triple whammy–a warm ocean, a warm atmosphere, and a wind pattern all working against the ice in the Arctic,” said NSIDC director Mark Serreze.
Arctic sea ice extent averaged 9.08 million square kilometers (3.51 million square miles) for November, 1.95 million square kilometers (753,000 square miles) below the 1981 to 2010 long-term average for the month. Although the rate of Arctic ice growth was slightly faster than average, total extent actually decreased for a brief period in the middle of the month. The decrease in extent measured 50,000 square kilometers (19,300 square miles) and was observed mostly in the Barents Sea, an area of the Arctic Ocean north of Norway, Finland, and Eastern Russia.
NSIDC scientists said the decrease in extent is almost unprecedented for November in the satellite record; a less pronounced and brief retreat of 14,000 square kilometers (5,400 square miles) happened in 2013. November 2016 is now the seventh month this year to have hit a record low extent in the 38-year satellite monitoring period. The November extent was 3.2 standard deviations below the long-term average, a larger departure than observed in September 2012 when the Arctic summer minimum extent hit a record low………
In the Southern Hemisphere, sea ice surrounding the continent of Antarctica declined very quickly early in the month and set a record low. The average extent for November was 14.54 million square kilometers (5.61 million square miles), 1.81 million square kilometers (699,000 square miles) below the 1981 to 2010 average. This was more than twice the previous record departure from average set in November 1986 and was 5.7 standard deviations below the long-term average.
NSIDC scientists said that higher-than-average temperatures and a rapid shift in Antarctic circumpolar winds appear to have caused the rapid decline in Antarctic sea ice……..
NASA scientist and NSIDC affiliate scientist Walt Meier said, “The Arctic has typically been where the most interest lies, but this month, the Antarctic has flipped the script and it is southern sea ice that is surprising us.” https://www.eurekalert.org/pub_releases/2016-12/uoca-sih120616.php
The Big Blue Elephant in the Room, A Medium Corporation Dr. Sylvia A. Earle & John Bridgelan, 26 Nov 16
Although the recent UN General Assembly meetings in New York City included the largest gathering of world leaders ever to address climate change, the largest factor in our climate cycle was missing from the discussions — the ocean.
Disregard for the ocean as the primary driver of climate and weather might be forgiven 50 years ago, but now we know: the living ocean governs planetary chemistry; regulates temperature; generates most of the oxygen in the sea and atmosphere; powers the water, carbon, and nitrogen cycles; and holds 97 percent of Earth’s water and 97 percent of the biosphere. Quite simply, no ocean, no life. No blue, no green. If not for the ocean, there would be no climate to discuss or anyone around to debate the issues……
Whatever the rationale, it is not rational that Earth’s dominant feature is not sufficiently addressed in important policy discussions about energy, the environment, economy, health, and security. It is especially perplexing that the ocean is getting short shrift in the current climate policy discussions.
Much attention is given to the impact of burning of fossil fuels on accelerated warming, inundated shorelines, and adaptation strategies for where and how people will live in the future. Far less note is being accorded to the changes in ocean chemistry as excess carbon dioxide absorbed by the ocean is increasing the acidity of the water. This is why it is so important to have Years of Living Dangerously helping to document the climate change impacts in our oceans and sharing it with the public. In Episode 5, Joshua Jackson travels to Australia’s Great Barrier Reef to look at the devastating impacts of ocean warming on the world’s largest reef system, and he explores the predicted impact of ocean acidification. In the Philippines, he looks at the impact of climate change in a place where hundreds of millions of people rely on healthy reefs for food, income and protection from storms……..https://medium.com/@yearsoflivingdangerously/the-big-blue-elephant-in-the-room-29d1a0c5f423#.p6e58alfv
US Military Plans to Dump 20,000 Tons of Heavy Metals and Explosives Into the Oceans Tuesday, 15 November 2016 By Dahr Jamail, Truthout | Report The US Navy has been conducting war-game exercises in US waters for decades, and in the process, it has left behind tons of bombs, heavy metals, missiles, sonar buoys, high explosives and depleted uranium munitions that are extremely harmful to both humans and marine life.
Truthout recently reported that the Navy has admitted to releasing chemicals into the oceans that are known to injure infants’ brains, as well as having left large amounts of depleted uranium in US coastal waters. Now, the Navy’s own documents reveal that it also plans to use 20,000 tons of heavy metals, plastics and other highly toxic compounds over the next two decades in the oceans where it conducts its war games.
According to the Navy’s 2015 Northwest Training and Testing environmental impact statement (EIS), in the thousands of warfare “testing and training events” it conducts each year, 200,000 “stressors” from the use of missiles, torpedoes, guns and other explosive firings in US waters happen biennially. These “stressors,” along with drones, vessels, aircraft, shells, batteries, electronic components and anti-corrosion compounds that coat external metal surfaces are the vehicles by which the Navy will be introducing heavy metals and highly toxic compounds into the environment.
Just some of the dangerous compounds the Navy will be injecting into the environment during their exercises are: ammonium perchlorate, picric acid, nitrobenzene, lithium from sonobuoy batteries, lead, manganese, phosphorus, sulfur, copper, nickel, tungsten, chromium, molybdenum, vanadium, trinitrotoluene (TNT), RDX [Royal Demolition eXplosive] and HMX [High Melting eXplosive], among many others.
“None of these belong in the ocean’s food web, upon which we all depend,” Karen Sullivan, a retired endangered species biologist who cofounded West Coast Action Alliance, which acts as a watchdog of Naval activities in the Pacific Northwest, told Truthout. “Nor will the Navy be willing to clean it up, or even contribute to medical tests for people whose health may suffer.”……http://www.truth-out.org/news/item/38374-us-military-plans-to-dump-20-000-tons-of-heavy-metals-and-explosives-into-the-oceans
A Horrifying New Study Found that the Ocean is on its Way to Suffocating by 2030, The Inertia, Alexander Haro MAY 2, 2016 It seems that every week, a new study comes out showing just how much damage we’re doing to our planet. This last one’s a doozy, though: according to Matthew Long, an oceanographer at the National Center for Atmospheric Research, if we continue along the road we’re on, the ocean could begin to suffocate in about 15 years. Actually.
The study was published a few days ago in Global Biogeochemical Cycles, which is not The National Enquirer and is a publication entirely based on science. Long’s not some quack, either. He’s a dyed-in-the-wool scientist with a Ph.D. in Oceanography from Stanford University, an M.S. in Environmental Engineering (Hydrology) from Tufts University, and a B.S in Environmental Engineering. That is a man who likes facts.
According to Ocean Scientists for Informed Policy, “ocean deoxygenation refers to the loss of oxygen from the oceans due to climate change.” It’s not up for debate, either: it is a cold and hard fact that both climate change and ocean deoxygenation are happening, and no amount of climate change deniers stamping their feet will change it.
“Long-term ocean monitoring shows that oxygen concentrations in the ocean have declined during the 20th century, and the new IPCC 5th Assessment Report (AR5 WG1) predicts that they will decrease by 3-6% during the 21st century in response to surface warming,” the website explains. “While 3-6% doesn’t seem like much, this decrease will be felt acutely in hypoxic and suboxic areas, where oxygen is already limiting. […] To put this in context, a highly optimistic emissions scenario of atmospheric CO2 levels of 550 ppm by 2100 would lead to a 1.2°C warming of the upper ocean. Therefore, these declines in oxygen are changes we should be prepared to see.”
While it seems obvious that an ocean deprived of oxygen is a bad thing, let’s break it down real quick: Almost everything in the ocean depends on the oxygen in the water to survive. Of course, there are a few things that don’t–whales, dolphins, turtles, and other creatures that surface to breathe–but for the most part, everything takes oxygen from the water. If those things die, that’s a pretty massive big ball rolling towards everything else being dead.
So how does climate change affect the ocean? Well, the ocean is warming up, and a warm ocean doesn’t take in as much oxygen from the atmosphere, for starters. There’s the whole sea level rising issue, which is just way too big to go into here. But possibly the most concerning part of the whole thing has to do with phytoplankton, which are one of the smallest, most prolific, and really fucking important creatures on earth. If you believe National Geographic, “fish, whales, dolphins, crabs, seabirds, and just about everything else that makes a living in or off of the oceans owe their existence to phytoplankton, one-celled plants that live at the ocean surface. Phytoplankton are at the base of what scientists refer to as oceanic biological productivity, the ability of a water body to support life such as plants, fish, and wildlife.”
Warmer water doesn’t mix well with colder water. As the surface warms, the phytoplankton that float around up there most of the time don’t get down deep as often, and those little guys are responsible for about half of the oxygen in the ocean……….
According to the predictive study, vast portions of the Pacific–Hawaii and the western edge of the Americas included–will be seriously deprived of oxygen somewhere between 2030 and 2040, which would most likely mean massive die-offs of very important creatures.
Although Long’s study is far more telling than any other before it, it’s not really anything all that new. Back in 2010, Scripps Institution of Oceanography warned about the dangers of something called “oxygen minimum zones”, which are exactly what they sound like: large portions of the ocean, usually very deep, that don’t have enough oxygen to really sustain much life. “A major concern is that these so-called oxygen minimum zones (OMZs) will expand in the future as the upper ocean warms and becomes more stratified,” wrote Scripps scientist Ralph Keeling.
What does it all come down to? Well, more and more, it seems we’re already too far gone. Every day, we’re passing tipping points. Long, who seems a little frustrated that no one in charge is listening to him or anyone else that has been screaming about a host of environmental issues, made his point very clear. “This inexorable force of human-induced warming will clearly result in widespread ocean deoxygenation in the future,” he said.
And like it or not, our lust for carbon is causing it. “This latest study adds one more item to the list of insults we are inflicting on the oceans through our continued burning of fossil fuels,” said Michael Mann, a climate scientist at Penn State University. “Ocean life and marine ecosystems must now simultaneously contend with the triple threat of warming waters, increased acidity, and now, we’re learning, lower oxygen levels. Any one of these challenges alone would be daunting. “We have yet another reason to be gravely concerned about the health of our oceans, and yet another reason to prioritize the rapid decarbonization of our economy.” http://www.theinertia.com/environment/a-horrifying-new-study-found-that-the-ocean-is-on-its-way-to-suffocating-by-2030/