Climate Central

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  1. The European Space Agency has been the main eye in the sky formonitoring the Larsen C ice shelf and calving event that gave birth to iceberg A68 earlier this month.

    But NASA isn’t blind to what’s going on by any means. And on Tuesday, the agency released an image that rivals the satellite views its European counterpart has been sharing for months.

    Behold the a shot of the iceberg captured between July 14 and July 21 by the Landsat-8 satellite.

    Landsat-8 captured iceberg A68 as it shifted away from the Larsen C ice shelf over the period of July 14-21.
    Credit: NASA Goddard

    It might look like a film negative but it’s much more high tech than that. Landsat-8 has a thermal infrared sensor on board, which captures images based on temperature. In the case of this image, the black is the cooler ice while the bright white is the warmer ocean waters surrounding it.

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    The image is equal parts eye candy and scientific goldmine. The dark patches between the ice shelf and iceberg A68 show the icy detritus left behind in the wake of the massive calving event. The thin slivers of white cutting across the iceberg alsoreveal more details of how the elemental forces of wind and water are clawing away at its massive edifice, which contains enough ice to fill 463 million Olympic swimming pools.

    The gray areas laced with white on the right side of the image show the sea ice that iceberg A68 will have to push through as currents carry it off into the Weddell Sea and points yet unknown.

    So yeah, NASA has delivered a pretty spectacular and informative satellite image. Your move, ESA.

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  2. Anew law in New Jersey aims to shrink the state’s climate footprint and feed the hungry by drastically reducing the amount of wasted food that ends up in landfills.

    The law requires the state to develop a plan over the next year to cut the state’s food waste by half by 2030. The bipartisan measure, which passed the state legislature without a single dissenting vote and was signed last week by Gov. Chris Christie, mirrors an Environmental Protection Agencygoal for the entire country set under the Obama administration in 2015.

    Food waste in a compost bin.
    Credit: Jeremy Brooks/flickr

    “The beauty of the bill is it’s going to get at two long-festering problems — climate and hunger — at the same time,” saidEric Goldstein, a senior attorney for the Natural Resources Defense Council in New York City. “The states are going to have to take the lead on issues like climate and this new law holds the hope of tackling one piece of that problem.”

    Up to 40 percent of the food produced in the U.S. ends up uneaten and tossed into the garbage. So much food is thrown away every year that it adds up to the equivalent of about20 pounds of food per person every month. Discarded food also wastes cropland and energy that are used in the production of food.

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    Worldwide, processing wasted food generates about3.3 billion tons of greenhouse gases annually. That means if food waste were a country, it would be the world’s third-largest climate polluter after China and the U.S., according to the U.N. Food and Agriculture Organization.

    When leftovers and rotting fruit and vegetables are tossed out and end up in the dump, they become a major climate problem. Decomposing food pollutes the atmosphere with methane, a greenhouse gas34 times as powerful in warming the climate as carbon dioxide over the course of a century.

    Larry Hajna, spokesman for the New Jersey Department of Environmental Protection, said that while New Jersey has implemented more effective methane emissions controls at its landfills over the past 30 years, much of the state’s garbage is shipped to landfills out of state where New Jersey officials have no control over emissions.

    Less methane will be emitted from those landfills and the climate will benefit if the amount of food New Jerseyans discard is cut drastically, he said.

    At least five states either ban organic waste from landfills or mandate food waste recycling to some degree,according to the Harvard Food Law and Policy Clinic.

    California mandates organic food waste recycling and requires businesses to cap the amount of food they send to the landfill each year. Connecticut and Rhode Island also require many businesses to cap the amount of food thrown out. Massachusetts and Vermont have a weight limit on food waste both individuals and businesses can throw away.

    A compost bin in New York City.
    Credit: Nick Normal/flickr

    New York City, San Francisco, Seattle and Austin, Texas, also have organic waste recycling or composting mandates for homes or businesses to prevent food waste from ending up in a landfill.

    Mark Milstein, director of the Center for Sustainable Global Enterprise at Cornell University, said state laws mandating food waste reductions create business opportunities for recyclers, composters and others.

    “You’ve exacerbated climate change with a harmful greenhouse gas. There are more productive uses for that (wasted) material,” Milstein said.

    “We can compost it, turn it into fuel,” he said. “If you’re going to prevent the waste in the first place, rethink how people buy food, how they utilize food. Those are all potential business opportunities.”

    The New Jersey legislature is considering — but has not yet passed — other bills that may help implement the state’s new food waste law.

    One billwould require supermarkets, restaurants and other large generators of food waste to separate discarded food from other trash and recycle it. Other proposals would establish new food labeling standards to reduce waste and incentivize food donations.

    If New Jersey’s food waste reduction program is successful, it may pave the way for other states to follow, Goldstein said.

    “We think the law has real potential,” he said. “It gets the ball rolling, which is a significant thing.”

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  3. Recent summers on the vast, white expanse of the Greenland ice sheet have featured some spectacular ice melt, including an alarming period in 2012 when nearly the whole surface showed signs of melt. But this summer has instead seen several bouts of snow, staving off a big summer melt. So what gives?

    Meltwater lakes poke through a surface of fresh snow after a summer snowstorm in Greenland. The snow helped to briefly stymie summer melt.
    Click image to enlarge. Credit: Jason Box/ESA

    While it may seem contradictory, those snows are actually something Greenland may see more of with global warming, as the atmosphere becomes primed to dump more heavy precipitation. And while that snow may insulate the ice sheet against major melt this year, focusing on one summer risks missing the forest for the trees. Because make no mistake, Greenland is still melting, dumping water into the ocean and causing global sea levels to steadily rise.

    “We’re still pumping a lot of ice” out to sea, Marco Tedesco, who studies Greenland at Columbia University’s Lamont-Doherty Earth Observatory, said.

    As Arctic temperatures rise at about double the rate of the planet as a whole, Greenland’s surface has been melting at a steady clip, contributing about 30 percent of the foot of global sea level rise since 1900. And summer is prime melt season, when the sun’s rays beat down on the ice, causing meltwater to pool on the surface and drain down through the ice sheet and out to sea.

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    Those rising seas will slowly inundate coastal cities; many already see more so-called sunny day flooding, impeding traffic and flooding basements. The surging waters pushed ashore by hurricanes and other storms is also getting higher and causing more costly damage.

    Several recent summers have seen particularly stark ice loss: At the peak of the 2012 melt season, about 97 percent of the ice sheet surface was melting — that melt season alone contributed 1 millimeter of global sea level rise. Last year, the melt season started two months early thanks to high temperatures across parts of the island.

    Both the extreme October 2016 snowfall and the summer 2017 snows over Greenland are evident in this chart of Greenland's surface mass balance. That mass balance is about 1.2 times higher than normal, whereas during the record warm summer of 2012, it was about 1.2 times lower than normal.
    Click image to enlarge. Credit: Jason Box/polarportal.org

    But this year has been noticeably different. It all started in October, when big snowstorms “really loaded Greenland up,” Jason Box, a glaciologist at the Geological Survey of Denmark and Greenland, said. “That really preconditioned this year for low melt because it thermally insulates the darker ice below.”

    Essentially, it takes a lot more solar energy to get rid of that layer of bright, white snow, which reflects more solar rays back to space than darker layers of ice or meltwater.

    While there were some bouts of melting earlier in the summer, the weather has since shifted. In recent weeks, summer snows have topped up that already unusually high snow load. Right now, the ice sheet’s surface has about 1.2 times the amount of mass than normal; at the same point in 2012, it had 1.2 times less than normal, Box said.

    Also inhibiting summer melt this year is the unusually southerly position of the jet stream, caused by a climate pattern called the North Atlantic Oscillation. “That’s keeping Greenland relatively cold,” Box said.

    While snowy weather may seem at odds with a warming world, Greenland could actually see more of it as temperatures rise. A warmer atmosphere can hold more moisture, which means that when storms pass through, they drop more precipitation. When temperatures are below freezing, as they are for much of Greenland through most of the year, that means more snowfall. (Rain has been falling at the expense of snow in the lower third of the island as temperatures rise above freezing, though.)

    How the albedo of the Greenland ice sheet in July 2017 compared to the average for July from 2000-2009. Albedo is a measure of how reflective a surface is, wither higher albedo being more reflective. The higher albedo around the margins of the ice sheet, where summer melt is highest, shows the impact of summer snows in muting that melt.
    Click image to enlarge.Credit: Jason Box/NASA

    Previous research by Box using ice cores — long cylinders drilled out of the ice sheet that let scientists sample hundreds of years of ice layers — showed that in the past, snowfall has increased over the ice sheet as temperatures have risen.

    For the first decade or so of this century, there were more clear skies over Greenland, and so increased melt. But atmospheric patterns seem to have flipped around in recent years, and Tedesco and others are still working on figuring out how changing atmospheric patterns might be influencing snowfall and melt on the ice sheet to better predict how it will progress with future warming.

    This year’s excess snowfall doesn’t mean that melt isn’t still happening, though. Melt has already picked back up since the last summer snow earlier this month, Box said. In fact, he expects that that snow will now be a layer of slush he’ll have to trudge through when he arrives on the ice sheet this week to check on a network of weather stations.

    The snow could, however, balance out the year’s melt, Box said, with the ice sheet ending up with no net loss of ice for the year — the first year that will have happened in two decades.

    One year without a net loss also doesn’t buck the long-term trend of Greenland losing ice, both from surface melt and from ocean waters eating away at glaciers that flow out to sea.

    The increase in snowfall “is about four or five times smaller than the increase in surface melting,” Box said. So “the Greenland ice sheet is losing mass overall.”

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  4. A Nebraska-sized chunk of the world’s forests was decimated in 2015 because of wildfire, logging and expanding palm oil plantations, according to a new study. The loss is part of a continuing trend of deforestation that could have devastating implications for the climate.

    About 49 million acres of forest disappeared worldwide in 2015, mainly in North America and the tropics, putting the year’s global deforestation level at its second-highest point since data gathering began in 2001. In all, the globe lost 47 percent more forested land in 2015 than it did 16 years ago,according to the study by Global Forest Watch.

    Areas shaded in pink show points that have lost trees at least 16 feet in height due to deforestation, wildfire or some other cause of mortality between 2001 and 2015. Credit: Global Forest Watch

    Deforestation accounts for more than 10 percent of the global carbon dioxide emissions driving climate change. Dense tropical forests are also critical to keeping the climate stable because they suck up large amounts of human carbon pollution from the atmosphere, storing it in tree trunks, leaves, roots and soil.

    Using satellite data provided by Google and the University of Maryland, Global Forest Watch researchers measured the death or removal of trees at least 16 feet tall.  

    2014 was a record-breaking year for tree-cover loss when nearly 60 million acres of forests disappeared. 2015 saw less, but it’s too soon to say whether deforestation is truly on a downward swing because of uncertainty in some of the data, study co-authorMikaela Weisse, a research analyst for Global Forest Watch at the World Resources Institute, said.

    For example, Canada, Russia and the U.S. saw the most forest cover loss in 2015, mainly because of wildfire, pest infestations and commercial logging. But the study says the actual level of forest loss in those countries is difficult to determine because there is insufficient available data on logging and natural tree re-growth.

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    It’s unclear exactly how much carbon dioxide was released into the atmosphere from deforestation in 2015 because the organization has not completed a study of climate pollution related to forest loss, Weisse said.

    Canada, Russia and the U.S. — among the most heavily forested nations on earth — are routinely among the top countries losing the most forestland because of their large size, large temperate forests and frequency of wildfire, Weisse said.

    Weisse said she is most concerned about man-made deforestation in the tropics, where human-caused destruction of dense, carbon-rich forests is rising quickly. Papua New Guinea, for example, saw a 70 percent increase in tree cover loss due to deforestation for palm oil plantations and logging — more than any country on record.

    Indonesia and Papua New Guinea sawmassive wildfires in 2015, contributing to major tree cover loss there. The wildfires consumed parts of Borneo, Sumatra and the island of New Guinea, scorching large swathes of jungle during a significant drought brought about by a major El Niño event in the Pacific Ocean, which was one of the strongest on record.

    The wildfires had a significant impact on the climate because of the carbon dioxide released into the atmosphere as the dense forest incinerated, saidAidy Halimanjaya, a deforestation consultant for the Indonesian government and a climate change finance researcher who is unaffiliated with the study.

    She said she Indonesia will continue to see major wildfires unless the government finds a way to manage the landscape more sustainably.

    Deforestation on the island of Sumatra.
    Credit: CIFOR/flickr

    In Africa, expandingpalm oil plantations in Sierra Leone contributed to a 12-fold increase in deforestation in 2015 compared to 2001. Palm oil plantation expansion has long been a major driver of deforestation in the tropics, especially in Indonesia.

    One bright spot in the study is Colombia, where the deforestation rate has fallen 50 percent since its peak in 2007. The study says there is no consensus on why deforestation has slowed there, but Colombia’s government has committed to reaching zero net deforestation by 2020.

    Many countries have taken steps to stop deforestation, but the study shows that those efforts have not been enough to slow it down, saidGustavo Silva-Chavez, a project manager for Forest Trends, a U.S.-based nonprofit, who is unaffiliated with the study.

    Brazil, for example, saw its carbon emissions from deforestationfall by 80 percent between 2003 and 2015.

    “That was huge,” Silva-Chavez said. “Unfortunately, in the last two years those emissions are going up. Despite our best efforts, emissions are still increasing.”

    If the deforestation trend continues, it will become increasingly less likely that countries will stop global warming from exceeding 2°C (3.6°F) above pre-industrial levels — the primary goal of theParis Climate Agreement, he said.

    “If emissions from forests stay the same or increase, there’s no way to avoid dangerous climate change,” Silva-Chavez said.

    Editor's Note:  An earlier version of this story incorrectly referred to the area of forested land lost globally in 2015. The area lost — 49 million acres — is equivalent in size to Nebraska, not Mississippi. Nebraska is about 59 percent larger than Mississippi.

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  5. Estimates of just how much sea levels will rise and inundate coastal areas vary widely. One of the reasons is that scientists just aren’t sure how quickly the vast ice sheets of Antarctica might melt into the sea because of the myriad triggers causing the ocean warming that is fueling that melt.

    West Antarctica's massive Pine Island Glacier is seen out the window of NASA's DC-8 research aircraft as it flies at an altitude of 1,500 feet in October 2009. Pine Island Glacier is one of the fastest-retreating glaciers in Antarctica.
    Click image to enlarge. Credit: NASA/Jane Peterson

    New research suggests one more unexpected culprit: Changing winds at one end of the continent could actually be setting off a series of changes, like a set of falling dominoes, that pushes warm water below the ice at the other end, thousands of miles away.

    Finding these pieces of the Antarctic melt puzzle and putting them together will help scientists better pin down how much sea level rise is in store as the world warms, and when cities from Miami to Shanghai may largely disappear from the map.

    Sea levels have already risen by about 8 inches since the beginning of the 20th century from a combination of melting polar ice and the expansion of ocean waters as they absorb some of the excess heat trapped by human-emitted greenhouse gases. And while 8 inches may not seem like much, it is already causing more costly damage from coastal flooding.

    Storm surges created by hurricanes and other storms, like Hurricane Sandy, are stronger and higher than in the past, and there are more instances of so-called sunny day flooding, when tidal forces push water into the streets of Miami, Norfolk, Va., and other coastal cities.

    The last Intergovernmental Panel on Climate Change report estimated that the world could see another 10 to 40 inches of sea level rise by 2100, but that is considered a fairly conservative estimate. More recent research has suggested that Antarctic melt alone could push sea levels up by 3 feet by the end of the century, which would devastate coastal communities around the world.

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    Much of that melt could come from key areas of Antarctica where fast-retreating glaciers could destabilize large sections of the ice sheet. The primary driver of their melt is warm water pushing in under the floating sections of the glaciers, called ice shelves. As the water eats away at the ice from below, the thinner ice shelves exert less force on the glaciers, allowing them to flow faster to the sea, raising sea levels.

    Scientists thought that changing local wind patterns — themselves linked to warming — could be pushing the water under the ice shelves, with the altered winds blowing over the ocean surface near West Antarctica providing the push. 

    They didn't expect changes to winds across the continent to be a factor, but that's what climate scientist Paul Spence noticed when he was looking at climate models. He saw that certain changes in East Antarctica created a big warming signal in West Antarctica, which is some 3,700 miles away.

    This image shows the path of the Kelvin waves that interact with the Antarctic Circumpolar Current and push warmer waters under the ice shelves of the West Antarctic Peninsula.
    Credit: Ryan Holmes/NCI

    What seems to be happening is that the changes in winds along the East Antarctic coast cause sea levels to drop near the coastline, which sets off large-scale waves (not quite like those that break on the ocean's surface) that travel along the coastline at more than 400 mph. When these waves hit the steep topography off the western coast of the Antarctic Peninsula, they pull the warm water of the current called the Circumpolar Deep Water toward the coast.

    The work of Spence and his colleagues, detailed July 17 in Nature Climate Change, shows that this process can cause significant warming under the ice shelves.

    “These coastal wave phenomena are found all over the ocean, but their influence on climate (and Antarctic melt) was never recognized. Indeed, it’s kind of strange and unexpected that they can drive glacial melting,” Spence, of the Climate Change Research Centre of the University of New South Wales in Australia, said.

    This finding, though, is only one potential piece of the puzzle, and one that still needs to be investigated more to figure out exactly what is happening and how local and long-distance changes might be interacting and which is most important.

    “This is another episode of the complex saga of understanding the complexity of ice-ocean-atmosphere interactions in Antarctica,” Eric Rignot, a climate scientist with NASA and the University of California, Irvine, who studies Antarctic ice shelves but wasn’t involved in the study, said. “It is, however, important to not only look at the impact this may have in West Antarctica but also on the vulnerable parts of East Antarctica, especially the Wilkes Land sector and its large sea level rise potential.”

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