The marine snail Limacina helicina antarctica showing acute levels of shell dissolution in Southern Ocean where deep-water upwelling and ocean acidification combined to reduce aragonite saturation in surface waters. This specimen was alive at capture: Image provided by Nina Bednarsek and Bernard Lézé
A new paper in Nature Geoscience reports the first evidence of marine animals dissolving in acidified waters off Antarctica. The pteropods—also called marine snails or sea butterflies—were found in waters 656 feet (200 meters) deep, alive but suffering severe shell damage from a combination of natural upwelling and human-caused ocean acidification.
Natural upwelling is triggered by strong winds that drive deep cold water from the bottom to the surface. We know that many upwelled waters are corrosive to animals like sea butterflies which use aragonite to build shells. But the saturation horizon for aragonite in the Southern Ocean typically occurs at around 3,280 feet (1000 meters) deep—far below where Limacina helicina antarctica live. So what happened to hoist that horizon line 2,625 feet (800 meters) closer to the surface?
Live Limacina helicina antarctica with intact shell and its wing-like "butterfly" parapodium trailing behind: Russ Hopcroft, University of Alaska, Fairbanks via NOAA Ocean Explorer
"Current predictions are for the saturation horizon for aragonite to reach the upper surface layers of the Southern Ocean by 2050 in winter and by 2100 year round," says co-author Dorothee Bakker from the University of East Anglia.
The answer is ocean acidification (OA)—the result of carbon dioxide from fossil fuel burning leaching from the atmosphere into the ocean and changing its pH. (I wrote more about that here and here and here, and about how ocean chemistry is measured in my "Arctic Ocean Diaries" here.)
Numerous lab experiments have demonstrated that OA has the potential to damage marine organisms who make shells or skeletons. This paper reports the first evidence that OA is already damaging marine life in the Southern Ocean.
And not just any marine life. Marine snails are a vital part of the food web of Antarctic waters, supporting zooplankton, fish, birds, marine mammals, and us. (Read Tom Philpott's piece on the correlation between OA and human food here.)
Marine snails are also important players in the Southern Ocean's carbon cycle—the shuttling of carbon between atmosphere and ocean. In that work they've mitigated a lot of our C02 emissions. Too many for their own good, apparently.
Co-author and science cruise leader, Geraint Tarling from the British Antarctic Survey, says:
Although the upwelling sites are natural phenomena that occur throughout the Southern Ocean, instances where they bring the 'saturation horizon' above 200m will become more frequent as ocean acidification intensifies in the coming years. The tiny snails do not necessarily die as a result of their shells dissolving, however it may increase their vulnerability to predation and infection consequently having an impact to other parts of the food web.
I was struck yesterday reading this report that the population of wild birds in the UK has dropped by 44 million since 1966. The calculation comes from the Royal Society for the Protection of Birds, the British Trust for Ornithology, and others. Today's 166 million nesting birds numbered 210 million in 1966. Which means that for every five birds you might have seen while strolling the British Isles 46 years ago you'll see only four now. Our world grows quieter... Or does it?
Numbers from The Economist: Graphic: Julia Whitty. Photo: Yathin S Krishnappa via Wikimedia Commons
Because at the same time that wild birds are declining worldwide the kingdom of poultry rises. In 1960 there was roughly one chicken for for every person on Earth. Today there are three chickens for every person alive. That's 19-plus billion chickens at any one time—a wildly dynamic number since in the US alone 23 million chickens are killed daily, 269 a second.
Numbers from WATTAgNet.com: Graphic: Julia Whitty. Turkey photo: lynn.gardner via Flickr
To put it bluntly there are shiteloads of birds today. Just not as many in the air or on the waters or in the forests or grasslands or islands like there used to be. Many are in coops and worse. The lucky ones are free range. Globally we now eat almost as much poultry as pork, the number one meat consumed. Domestic birds thrive albeit mostly miserably.
Based on National Audubon Society's Christmas Bird Counts: Graphic: Julia Whitty. Photo: Yathin S Krishnappa via Wikimedia Commons
And wild birds decline. The National Audubon Society's annual Christmas Bird Count reveals that North America's most common birds in decline are down 68 percent since 1967—from 17.6 million to 5.35 million. Some species have declined 80 percent in the past 4.5 decades.
Numbers from the National Audubon Society: Graphic: Julia Whitty. Photo: Dominic Sherony via Wikimedia Commons
What's hopeful for me is that many of these depressing data come from something new and refreshing: the rise of citizen science. The Christmas Bird Count is the largest and oldest citizen science effort underway, according to Wikipedia. It transformed a bloody 19th century ritual—an annual day-after-Christmas no-holds-barred bird hunt to kill whatever, wherever, the more the merrier—into a bird count. Courtesy of the unusual foresight of ornithologist Frank Chapman, an officer in the newborn National Audubon Society. I'm thankful for that. And for where the next 100 years of that awakening might lead us.
During my trip through the Arctic Ocean last month (Arctic Ocean Diaries) we saw a few walrus streaming south through the Chukchi Sea towards the Bering Strait. Winter was on their tails. Or at least soon would be.
There's a lot of urgency just now to figure out exactly where Pacific walruses are feeding and traveling off Alaska. That's because their world is changing so unbelievably fast.
Sea ice extent in the Chukchi Sea as of 12-16 Nov 2012: National / Naval Ice Center
Sea ice—the mobile platforms where walruses haul-out to rest and give birth—is in rapid decline throughout the Arctic. This summer broke the record for lowest ice extent ever seen. There was little to none in the US Arctic—the Chukchi and Beaufort seas—for most of the summer and fall.
The map above shows how little ice is in the Chukchi even now, midway through November. Red, orange, and yellow mark sea ice extents of between four-tenths coverage and ten-tenths coverage. As you can see from the amount of white in the map, there's still a whole lot of open water up there.
Tracks of 40 tagged walrus in the Chukchi Sea during summer 2012. Star marks approximate position of Shell oil well: USGS Alaska Science Center
As part of an ongoing effort towards an Endangered Species listing for Pacific walrus, researchers with the United States Geological Survey have been tagging walruses to see where they're traveling and how they're managing in the presence or absence of sea ice. From this will come a designation of critical habitat.
The map above shows the tracks of 40 walruses tagged this summer. You can start to see which areas are important to them. (For an animated track map that includes the dwindling sea ice margin go here.)
I added the black star on the map to show the approximate position of Shell's well in the virgin seafloor of the Chukchi Sea, Burger Oil Field. (See my earlier post on Shell's drilling efforts and errors.) Sadly, there look to be a lot of walruses using the dangerous waters around that well.
The video explains the USGS research efforts underway, with some gorgeous footage of walruses on ice and off.
Precipitation associated with Sandy, 23-31 Oct 2012 (preliminary): NOAA National Climatic Data Center
According to NOAA's National Climatic Data Center State of the Climate Report, post-tropical cyclone Sandy made landfall with a central minimum pressure of 946 millibars—potentially a record low for the Northeast coast, pending further assessment. The storm also rated as the largest hurricane to form in the North Atlantic in terms of wind spread, with a gale diameter of 945 miles.
This month's report focuses on Sandy as the monster rampaging through October. Here are a few other noteworthy stats associated with that storm:
The observed water level at The Battery in New York City of 13.8 feet set an all-time record there, topping Hurricane Donna's 1960 record by more than three feet.
The Delaware River in Philadelphia set a new record high water level of 10.6 feet, beating out the previous high of 10.5 feet set in April 2011.
Sandy's blizzard dropped more than a foot of snow in six states from North Carolina to Pennsylvania, shattering October monthly and single storm snowfall records. Snowfall totals in the highest elevations approached three feet.
NOAA National Climatic Data Center
Aside from Sandy's mayhem, October was shaping up to be a relatively benign month by 21st century standards. The average temperature in the lower 48 was 53.9°F—0.3°F below the long-term average. That ended a 16-month streak of above-average temperatures starting in June 2011.
But even October couldn't mitigate the bigger picture for the year. The period between January and October 2012 saw the warmest first ten months of any year on record for the contiguous US dating back to 1895.
The national temperature of 58.4°F was 3.4°F above the 20th-century average and 1.1°F above the previous record warm between January and October 2000.
The first 10 months of 2012 racked up as record warm in 21 states.
The first 10 months of 2012 racked up among the 10 warmest in 25 states.
Only Washington state saw temperatures near average for the period.
NOAA National Climatic Data Center
As you can see from this graph, previous record hot years dating back to 1895 were wiped out by 2012's heat so far (click graph for larger image). That heat led to a few other costly complications in terms of drought and crop failures:
January-October 2012 was the 16th driest period on record for the lower 48: precip totals 1.9 inches below the average of 24.78 inches.
Drier-than-average conditions were present from the Southwest, through the Rockies, across the Plains and into the Midwest.
Nebraska and Wyoming were record dry for the period. Nebraska's statewide precipitation total of 11.92 inches was 9.4 inches below average, while Wyoming's precipitation of 6.57 inches was 5.2 inches below average.
The Gulf Coast, parts of the Northeast, and the Pacific Northwest were wetter than average during January-October.
Washington's year-to-date precipitation total was 33.23 inches, 7.36 inches above average, and the fourth wettest January-October on record.
The U.S. Climate Extremes Index (USCEI), an index that tracks the highest and lowest 10 percent of extremes in temperature, precipitation, drought and tropical cyclones across the contiguous U.S., was nearly twice the average value during the January-October period, and marked the second highest USCEI value for the period. Extremes in warm daytime temperatures, warm nighttime temperatures, and the spatial extent of drought conditions contributed to the record high USCEI value.
Thunderstorms over Brazil: NASA astronaut photos via Wikimedia Commons
More than two dozen major climate models are being used to forecast global warming from rising greenhouse gas emissions—notably how much warming will occur when atmospheric carbon dioxide doubles from preindustrial times. At current rates that unhappy milestone will be reached well before 2100. So which models are more accurate?
"Because we have more reliable observations for humidity than for clouds, we can use the humidity patterns that change seasonally to evaluate climate models," says co-author Kevin Trenberth.
For decades the leading models have predicted an average rise of 5 degrees Fahrenheit (2.7 degrees Celsius), with models on the low end predicting a rise of 3 degrees F (~1.6 degrees C) and those on the high end predicting 8 degrees F (5.3 degrees C). Now a new analysis in the leading journal Science suggests that the higher end forecasts are more accurate.
Why? Moisture has a lot to do with it. Clouds, well, they cloud the picture. Satellites observe clouds. But satellite failures, observing errors, and other inconsistencies make it difficult to build a global cloud census consistent over many years. A better measure is water vapor. Satellite estimates of the global distribution of humidity have become more reliable than their estimates of clouds.
Relative humidity is incorporated in climate models to generate and dissipate clouds. So the authors checked the distribution of relative humidity in 16 leading climate models to see how accurately they portray the present climate. They focused on the subtropics, the places where sinking air from the tropics make dry zones, home to most of the world's major deserts.
What they found was that estimates based on observations show relative humidity in the dry zones between about 15 and 25 percent. Whereas many models inaccurately depict humidities of 30 percent or higher. Less humidity equals fewer clouds equals less albedo to reflect sunlight back into space, hence more warming.
The models that best captured the actual dryness currently seen in the subtropics were those with the highest temperature forecasts. Specifically those projecting a global temperature rise of more than 7 degrees F (3.8 degrees C) by the time of doubled C02 levels. The three models with the lowest temperature forecasts were also the least accurate in depicting relative humidity in these zones.
The paper:
John T. Fasullo and Kevin E. Trenberth. A Less Cloudy Future: The Role of Subtropical Subsidence in Climate Sensitivity. Science. DOI: 10.1126/science.1227465.
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