Lakes on Greenland Ice Sheet Drain in Chain Reaction, Destabilizing Sheet and Raising Sea Levels
A research team led by the University of Cambridge found that the lakes of meltwater that form on the ice sheet in the summer drain in a chain reaction that increases the flow of the ice sheet, destabilizing it and increasing sea level rise, the University of Cambridge reported in a press release.
It had long been known that these lakes could drain quickly on an individual basis. They can last months, then drain through more than one kilometer (approximately 0.621 miles) of ice within hours.
However, this study used a combination of observation and three-dimensional modeling to show that the lakes do not drain in isolation. Instead, the melting of one lake can trigger the melting of lakes up to 80 kilometers (approximately 49.71 miles) away.
The process begins when a lake drains and the water it contained ends up on the bottom of the ice sheet. This causes the sheet to flow faster, which destabilizes it and leads to the formation of more fractures. Other lakes then drain through these new fractures in a chain reaction that can speed the flow of the ice sheet by up to 400 percent.
A model of the lake-melting chain-reaction process. Nature Communications
Researchers observed 124 lakes drain within a span of five days, and found evidence for crevices opening 135 kilometers (approximately 83.9 miles) inland from the ice sheet's edge, which is farther than thought possible.
The study therefore contradicts the findings of the Fifth Assessment Report by the Intergovernmental Panel on Climate Change, published in 2014, which held that melt water on the surface of the ice sheet did not impact its flow.
"This growing network of melt lakes, which currently extends more than 100 kilometres inland and reaches elevations as high as 2,000 metres above sea level, poses a threat for the long-term stability of the Greenland ice sheet," the study's lead author and member of Cambridge's Scott Polar Research Institute Dr. Poul Christoffersen said in the press release.
This isn't the first study in recent years to suggest the Greenland ice sheet is in more trouble than previously believed. In 2016, scientists found the ice sheet was melting 7 percent faster than they had thought.
While the Polar Portal reported that the ice sheet actually gained a small amount of mass in 2017 due to heavy winter snows and a cool summer, the National Oceanic and Atmospheric Administration calculated that the sheet could only regain the mass it has lost since 2002 after 80 years like this one.
According to Global Citizen, the ice sheet, which is seven times the size of the United Kingdom and two miles thick, is currently contributing to global sea level rise at a rate of one millimeter (approximately 0.04 inches) per year. If all the ice in the sheet were to melt, it would raise sea levels by more than 20 feet.
This is unlikely to happen any time soon, but that doesn't mean there's nothing to worry about.
"When we say the ice sheet is melting faster, no one saying it's all going to melt in next decade or the next 100 years or even the next 1,000 years but it doesn't all have to melt for more people to be in danger," Dr. Joe Cook, a glacial microbiologist at Sheffield University, told Global Citizen. "Only a small amount has to melt to threaten millions in coastal communities around world."
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By Alexandra Rowles
Oregano is a fragrant herb that's best known as an ingredient in Italian food.
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By Emily Grubert
Natural gas is a versatile fossil fuel that accounts for about a third of U.S. energy use. Although it produces fewer greenhouse gas emissions and other pollutants than coal or oil, natural gas is a major contributor to climate change, an urgent global problem. Reducing emissions from the natural gas system is especially challenging because natural gas is used roughly equally for electricity, heating, and industrial applications.
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What RNG Is and Why it Matters<p>Most equipment that uses energy can only use a single kind of fuel, but the fuel might come from different resources. For example, you can't charge your computer with gasoline, but it can run on electricity generated from coal, natural gas or solar power.</p><p>Natural gas is almost pure methane, <a href="https://www.eia.gov/energyexplained/natural-gas/" target="_blank">currently sourced</a> from raw, fossil natural gas produced from <a href="https://www.eia.gov/energyexplained/natural-gas/where-our-natural-gas-comes-from.php" target="_blank">deposits deep underground</a>. But methane could come from renewable resources, too.</p><p><span></span>Two main methane sources could be used to make RNG. First is <a href="https://www.epa.gov/ghgemissions/inventory-us-greenhouse-gas-emissions-and-sinks" target="_blank">biogenic methane</a>, produced by bacteria that digest organic materials in manure, landfills and wastewater. Wastewater treatment plants, landfills and dairy farms have captured and used biogenic methane as an energy resource for <a href="http://emilygrubert.org/wp-content/uploads/2019/02/eia_860_2017_map.html" target="_blank">decades</a>, in a form usually called <a href="https://www.eia.gov/energyexplained/biomass/landfill-gas-and-biogas.php" target="_blank">biogas</a>.</p><p>Some biogenic methane is generated naturally when organic materials break down without oxygen. Burning it for energy can be beneficial for the climate if doing so prevents methane from escaping to the atmosphere.</p>
Renewable Isn’t Always Sustainable<p>If RNG could be a renewable replacement for fossil natural gas, why not move ahead? Consumers have shown that they are <a href="https://www.nrel.gov/analysis/green-power.html" target="_blank">willing to buy renewable electricity</a>, so we might expect similar enthusiasm for RNG.</p><p>The key issue is that methane isn't just a fuel – it's also a <a href="https://www.eia.gov/environment/emissions/ghg_report/ghg_overview.php" target="_blank">potent greenhouse gas</a> that contributes to climate change. Any methane that is manufactured intentionally, whether from biogenic or other sources, will contribute to climate change if it enters the atmosphere.</p><p>And <a href="http://doi.org/10.1126/science.aar7204" target="_blank">releases</a> <a href="https://doi.org/10.1016/j.wasman.2019.07.029" target="_blank">will happen</a>, from newly built production systems and <a href="https://theconversation.com/why-methane-emissions-matter-to-climate-change-5-questions-answered-122684" target="_blank">existing, leaky transportation and user infrastructure</a>. For example, the moment you smell gas before the pilot light on a stove lights the ring? That's methane leakage, and it contributes to climate change.</p><p>To be clear, RNG is almost certainly better for the climate than fossil natural gas because byproducts of burning RNG won't contribute to climate change. But doing somewhat better than existing systems is no longer enough to respond to the <a href="https://doi.org/10.1038/nclimate2923" target="_blank">urgency</a> of climate change. The world's <a href="https://www.ipcc.ch/sr15/chapter/spm/" target="_blank">primary international body on climate change</a> suggests we need to decarbonize by 2030 to mitigate the worst effects of climate change.</p>
Scant Climate Benefits<p><a href="https://iopscience.iop.org/article/10.1088/1748-9326/ab9335/meta" target="_blank">My recent research</a> suggests that for a system large enough to displace a lot of fossil natural gas, RNG is probably not as good for the climate as <a href="https://investor.southerncompany.com/information-for-investors/latest-news/latest-news-releases/press-release-details/2020/Southern-Company-Gas-grows-leadership-team-to-focus-on-climate-action-innovation-and-renewable-natural-gas-strategy/default.aspx" target="_blank">is publicly claimed</a>. Although RNG has lower climate impact than its fossil counterpart, likely high demand and methane leakage mean that it probably will contribute to climate change. In contrast, renewable sources such as wind and solar energy do not <a href="https://www.eia.gov/environment/emissions/carbon/" target="_blank">emit climate pollution directly</a>.</p><p>What's more, creating a large RNG system would require building mostly new production infrastructure, since RNG comes from different sources than fossil natural gas. Such investments are both long-term commitments and opportunity costs. They would devote money, political will and infrastructure investments to RNG instead of alternatives that could achieve a zero greenhouse gas emission goal.</p><p>When climate change first <a href="https://www.nytimes.com/1988/06/24/us/global-warming-has-begun-expert-tells-senate.html" target="_blank">broke into the political conversation</a> in the late 1980s, investing in long-lived systems with low but non-zero greenhouse gas emissions was still compatible with aggressive climate goals. Now, zero greenhouse gas emissions is the target, and my research suggests that large deployments of RNG likely won't meet that goal.</p>
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For all its posturing on climate change, the Democratic Party has long been weak on the actual policies we need to save us from extinction. President Barack Obama promised his presidency would mark "the moment when the rise of the oceans began to slow," and then embraced natural gas, a major driver of global temperature rise, as a "bridge fuel." Climate legislation passed in the House in 2009 would have allowed industries to buy credits to pollute, a practice known to concentrate toxic air in black and brown neighborhoods while doing little to cut emissions.
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Bayer's $10 billion settlement to put an end to roughly 125,000 lawsuits against its popular weed killer Roundup, which contains glyphosate, hit a snag this week when a federal judge in San Francisco expressed skepticism over what rights future plaintiffs would have, as the San Francisco Chronicle reported.
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By Charli Shield
When an elephant dies in the wild, it's not uncommon to later find its bones scattered throughout the surrounding landscape.
Elephant Burial Grounds<p>Highly social creatures that form deep familial bonds, elephants have long been observed gathering at the site where a peer or family member has died — often spending hours, even days, quietly investigating the bodies or the bones of other dead elephants.</p><p>Although the popular idea that dying elephants are instinctively drawn to special communal graves — so-called "elephant graveyards" — is a myth, their tendency to go out of their way to visit the bones and tusks of the deceased isn't unlike human rituals at graveyards, says animal psychologist Karen McComb.</p><p>"They spend a lot of time touching and smelling skulls and ivory, placing the soles of their feet gently on top of them, and also lifting them up with their trunks," McComb, who's been studying African elephants for 25 years in Kenya's Amboseli National Park, told DW.</p><p>The most striking part of watching an elephant experience loss, Poole recalls, is the quietude. She still remembers one of the first elephant deaths she witnessed; a mother who birthed a stillborn calf. That elephant stayed with its baby for two days, trying to lift it and defending it from vultures and hyenas.</p><p>"I was so struck by the expression on her face and her body. She looked so dejected. It was really like, 'Oh God, these animals grieve…'. It was just so different," Poole told DW. </p>
Witnessing Emotions in Animals<p>Not all scientists are comfortable concluding that elephants grieve. Among the more than 30 reports of elephant reactions to death that Wittemyer co-reviewed in <a href="https://link.springer.com/article/10.1007/s10329-019-00766-5" target="_blank">a study published in November 2019</a> were accounts of "enormous variation and nuance" he says. "It can be incredibly involved and intricate for extended periods or can be relatively cursory checks."</p><p>In Wittemyer's own experience, it can be difficult not to attribute some kind of emotional experience to the more involved interactions between elephants and their dead.</p><p>He shares the story of an "extraordinary event" involving the death of a 55 year-old matriarch in Kenya in a protected area that happened to be near his place of work. She was visited by multiple unrelated families while she was dying, including another matriarch that exerted such enormous effort attempting to lift her to her feet that she broke her tusk, which Wittemyer says, is "like breaking a tooth." </p><p><span></span>"It was a remarkable example of this heightened emotional state, it was very clearly a very stressful interaction," he says.</p>
A Different Sensory World<p>One factor that limits our ability to fully grasp the way elephants process and respond to loss is our markedly different sensory experiences of the world.</p><p>An elephant's world is fundamentally olfactory — based on smell. Ours is visual. Previous <a href="https://pubmed.ncbi.nlm.nih.gov/25053675/" target="_blank">research</a> has shown elephants possess the most scent receptors of any mammal, and can <a href="https://pubmed.ncbi.nlm.nih.gov/17949977/" target="_blank">use smell</a> to discern the difference between different human tribes from the same local area.</p><p>That could explain why elephants exhibit such interest in sniffing the bones and tusks of others, as a <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1617198/" target="_blank">2005 study</a> from McCombs highlighted. When presented with the skulls and ivory of long-dead elephants and those from other large herbivores, including rhino and buffalo, McCombs and her team found elephants approached and were specifically attracted to the remains of their own species. </p><p>Without access to the smells an elephant picks up on, Wittemyer says "an enormous amount of stuff" could be missed by humans when studying these behaviors.</p>
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