Greenland Ice Sheet Melting 7% Faster Than Previously Thought
By Jeremy Deaton
You might know the feeling—after months of encouraging news from your bathroom scale, you discover the device is broken. The outlook on your weight-loss goal is worse than you realized.
Scientists just went through something similar, except instead of a scale, it was a system of satellites, and instead of your winter weight, it was the Greenland ice sheet.
Zachariae Isbrae, in northeast Greenland.Anders A Bjork/The Ohio State University
Researchers have been tracking Greenland's ice sheet melt by measuring the shrinking mass of the island via satellite. It now seems there was an error in measurement. A new study published in the journal Science Advances finds the ice is melting 7 percent faster than previously thought.
Scientists use satellites to map Earth's gravity field, gathering information about the distribution of mass around the globe. Earth doesn't exert gravity equally in all directions. Where there is more mass, satellites detect a stronger gravitational pull.
Using satellite data, scientists can measure various geophysical phenomena, including the melt of the Greenland ice sheet. As ice dissolves, the island loses mass and exerts a weaker gravitational pull—at least that's the idea.
An artist's rendering of NASA's Gravity Recovery and Climate Experiment satellites measuring Earth's gravity field.NASA/JPL-Caltech
In practice, it's a little more complicated. Satellites can only detect a change in mass. They can't determine how much of that mass is ice, how much is land and how much is mantle ebbing and flowing beneath the Earths' crust.
"[The system] cannot tell the difference between ice mass and rock mass," said study co-author Michael Bevis, professor of Earth sciences at Ohio State. "So, inferring the ice mass change from the total mass change requires a model of all the mass flows within the Earth."
Here's where this gets interesting.
A cross-section of Earth. The Earth's crust rests on a thick layer of mantle. Below that lies the Earth's solid core.NASA/JPL, Université Paris Diderot and the Institut de Physique du Globe de Paris
Tectonic plates are always moving. The plate under North America—including Greenland—has been traveling northwest for millions of years. Around 40 million years ago, Greenland slid over an extra hot column of partially molten rock. This hot spot softened up the crust below the island's east coast. (The hot spot now rests beneath Iceland, where it is driving all manner of volcanic activity—warming hot springs and fueling the country's geothermal power plants.)
The softening of Earth's crust beneath Greenland had consequences during the last ice age, when Greenland's ice sheet was significantly thicker. The weight of all that ice caused the island to sink into the supple crust below. When the ice age passed and the ice began to melt, the island rebounded. Mantle flowed in beneath Greenland, causing the land to rise again. It's still rising today.
You can imagine how this would interfere with satellite readings. The loss of ice is weakening Greenland's gravitational pull. At the same time, the accumulation of mantle is strengthening its gravitational pull.
One of dozens of GPS units researchers used to measure the rise of land.Dana J. Caccamise II/The Ohio State University
Scientists previously accounted for the flow of mantle, but they underestimated its effect. The study's authors used GPS technology to measure the rise of land at various points along Greenland's east coast. They discovered that mantle is gathering beneath Greenland more quickly than they had realized.
What this means is that scientists have been underestimating ice loss by 20 billion metric tons per year. More of the melting is occurring along Greenland's east coast than previously thought.
Water overflow from a lake formed from melted ice carved this 60-foot canyon into the Greenland ice sheet.Ian Joughin, University of Washington
"By refining the spatial pattern of mass loss in the world's second largest—and most unstable—ice sheet, and learning how that pattern has evolved, we are steadily increasing our understanding of ice-loss processes, which will lead to better-informed projections of sea-level rise," said Bevis.
The study has implications for Antarctica—the 800-pound gorilla of global sea-level rise. Scientist will need to deploy more GPS measurement stations at Earth's southern pole to accurately measure the flow of mantle beneath the continent and get a better reading of Antarctic ice melt.
Better data will allow scientists to predict future sea-level rise more accurately. That could prove crucial for coastal cities preparing for the impacts of climate change.
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The last Ice Age eliminated some giant mammals, like the woolly rhino. Conventional thinking initially attributed their extinction to hunting. While overhunting may have contributed, a new study pinpointed a different reason for the woolly rhinos' extinction: climate change.
The last of the woolly rhinos went extinct in Siberia nearly 14,000 years ago, just when the Earth's climate began changing from its frozen conditions to something warmer, wetter and less favorable to the large land mammal. DNA tests conducted by scientists on 14 well-preserved rhinos point to rapid warming as the culprit, CNN reported.
"Humans are well known to alter their environment and so the assumption is that if it was a large animal it would have been useful to people as food and that must have caused its demise," says Edana Lord, a graduate student at the Center for Paleogenetics in Stockholm, Sweden, and co-first author of the paper, Smithsonian Magazine reported. "But our findings highlight the role of rapid climate change in the woolly rhino's extinction."
The study, published in Current Biology, notes that the rhino population stayed fairly consistent for tens of thousands of years until 18,500 years ago. That means that people and rhinos lived together in Northern Siberia for roughly 13,000 years before rhinos went extinct, Science News reported.
The findings are an ominous harbinger for large species during the current climate crisis. As EcoWatch reported, nearly 1,000 species are expected to go extinct within the next 100 years due to their inability to adapt to a rapidly changing climate. Tigers, eagles and rhinos are especially vulnerable.
The difference between now and the phenomenon 14,000 years ago is that human activity is directly responsible for the current climate crisis.
To figure out the cause of the woolly rhinos' extinction, scientists examined DNA from different rhinos across Siberia. The tissue, bone and hair samples allowed them to deduce the population size and diversity for tens of thousands of years prior to extinction, CNN reported.
Researchers spent years exploring the Siberian permafrost to find enough samples. Then they had to look for pristine genetic material, Smithsonian Magazine reported.
It turns out the wooly rhinos actually thrived as they lived alongside humans.
"It was initially thought that humans appeared in northeastern Siberia fourteen or fifteen thousand years ago, around when the woolly rhinoceros went extinct. But recently, there have been several discoveries of much older human occupation sites, the most famous of which is around thirty thousand years old," senior author Love Dalén, a professor of evolutionary genetics at the Center for Paleogenetics, said in a press release.
"This paper shows that woolly rhino coexisted with people for millennia without any significant impact on their population," Grant Zazula, a paleontologist for Canada's Yukon territory and Simon Fraser University who was not involved in the research, told Smithsonian Magazine. "Then all of a sudden the climate changed and they went extinct."
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Transitioning to renewable energy can help reduce global warming, and Jennie Stephens of Northeastern University says it can also drive social change.
For example, she says that locally owned businesses can lead the local clean energy economy and create new jobs in underserved communities.
"We really need to think about … connecting climate and energy with other issues that people wake up every day really worried about," she says, "whether it be jobs, housing, transportation, health and well-being."
To maximize that potential, she says the energy sector must have more women and people of color in positions of influence. Research shows that leadership in the solar industry, for example, is currently dominated by white men.
"I think that a more inclusive, diverse leadership is essential to be able to effectively make these connections," Stephens says. "Diversity is not just about who people are and their identity, but the ideas and the priorities and the approaches and the lens that they bring to the world."
So she says by elevating diverse voices, organizations can better connect the climate benefits of clean energy with social and economic transformation.
Reposted with permission from Yale Climate Connections.
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If weather is your mood, climate is your personality. That's an analogy some scientists use to help explain the difference between two words people often get mixed up.
Size Matters<p>Climates are a bit like woven tapestries. The big picture is important, no question. But so are all the seemingly minor details found inside the larger whole.</p><p><a href="https://research-information.bris.ac.uk/en/persons/tommaso-jucker" target="_blank">Tommaso Jucker</a> is an environmental scientist at the University of Bristol. In an email, Jucker says he'd define the term microclimate as "the suite of climatic conditions (temperature, rainfall, humidity, solar radiation) measured in localized areas, typically near the ground and at spatial scales that are directly relevant to ecological processes."</p><p>We'll talk about that last bit in a minute. But first, there's another criteria to discuss. According to some researchers, a microclimate — by definition — must differ from the larger area that surrounds it.</p><p><a href="https://www.cfc.umt.edu/research/paleoecologylab/publications/Davis_et_al_2019_Ecography.pdf" target="_blank">Forests</a> provide us with some great examples. "The climate near the ground in a tropical rainforest is dramatically different from the climate in the canopy 50 meters [164 feet] above," says University of Montana ecologist <a href="https://www.cfc.umt.edu/personnel/details.php?ID=1110" target="_blank">Solomon Dobrowski</a> in an email. "This vertical gradient among other factors allows for the staggering biodiversity we see in the tropics."</p><p>Likewise, scientists observed that a 2015 partial <a href="https://animals.howstuffworks.com/insects/bees-stopped-buzzing-during-2017-solar-eclipse.htm" target="_blank">solar eclipse</a> caused the air temperature of an Eastern European meadow to <a href="https://rmets.onlinelibrary.wiley.com/doi/full/10.1002/wea.2802" target="_blank">change more dramatically</a> than it did in a nearby forest. That's because trees provide not only shade, but their leaves also reflect solar radiation. At the same time, forests tend to reduce wind speeds.</p><p>All those factors add up. A 2019 review of 98 wooded places — spread out across five continents — found that forests are 7.2 degrees Fahrenheit (4 degrees Celsius) <a href="https://natureecoevocommunity.nature.com/posts/47363-forests-protect-animals-and-plants-against-warming" target="_blank">cooler on average</a> than the areas outside them.</p><p>Now if you hate the cold, don't worry; there's a cozy exception to the rule. According to that same study, forests are usually 1.8 degrees Fahrenheit (1 degree Celsius) warmer than the external environment during the wintertime. Pretty cool.</p>
A Bug's Life<p>When does a microclimate stop being, well, micro? In other words, is there a maximum size we should be aware of when discussing them?</p><p>Depends on who you ask. "In terms of horizontal scale, some have defined 'microclimate' as anything that is less than 100 meters [328 feet] in range," Jucker says. "I'm personally less prescriptive about this."</p><p>Instead, he says the "scale at which we want to measure [a particular] microclimate" ought to be "dictated" by the questions we're trying to answer.</p><p>"If I want to know how temperature affects the photosynthesis of a leaf, I should be measuring temperature at centimeter scale," Jucker explains. "If I want to know if and how temperature affects the habitat preference of a large, mobile mammal, it's probably more relevant to capture temperature variation across [tens to hundreds] of meters."</p><p>For instance, solitary plants have the power to generate itty-bitty microclimates. Just ask <a href="https://www.colorado.edu/geography/peter-blanken-0" target="_blank">Peter Blanken</a>, a geography professor at the University of Colorado, Boulder and the co-author of the 2016 book, "<a href="https://amzn.to/2XN6FT8" target="_blank">Microclimate and Local Climate</a>."</p>
The urban heat island effect is a good example of how microclimates work. NOAA
Microclimates on a Grand Scale<p>It's no secret that our planet is going through some rough times at the macro level. The global temperature is <a href="https://climate.nasa.gov/vital-signs/global-temperature/" target="_blank">climbing</a>; nine out of the <a href="https://www.noaa.gov/news/2019-was-2nd-hottest-year-on-record-for-earth-say-noaa-nasa" target="_blank">10 hottest years on record</a> have occurred since 2005. And by one recent estimate, roughly 1 million species around the world are <a href="https://ipbes.net/sites/default/files/2020-02/ipbes_global_assessment_report_summary_for_policymakers_en.pdf" target="_blank">facing extinction</a> due to human activities.</p><p>"One of the big questions that ecologists and environmental scientists are trying to answer right now is how will individual species and whole ecosystems respond to rapid climate change and habitat loss," says Jucker. "...To me, [microclimates are] a key component of this research — if we don't measure and understand climate at the appropriate scale, then predicting how things will change in the future becomes a lot harder."</p><p>Developers have long understood the impact small-scale climates have on our daily lives. <a href="https://science.howstuffworks.com/environmental/green-science/urban-heat-island.htm#pt0" target="_blank">Urban heat islands</a> are cities that have higher temperatures than neighboring rural areas.</p><p>Plants release vapors that can moderate local climates. But in cities, natural greenery is often scarce. To make matters worse, plenty of our roads and buildings have a bad habit of absorbing or re-emitting heat from the sun. <a href="https://www.google.com/books/edition/Microclimate_and_Local_Climate/LHUZDAAAQBAJ?hl=en&gbpv=1&bsq=urban%20heat%20island" target="_blank">Vehicle emissions</a> don't exactly help the situation.</p><p>Still, it's not like Boston or Beijing are thermal monoliths. Sometimes, the documented temperatures <a href="https://e360.yale.edu/features/can-we-turn-down-the-temperature-on-urban-heat-islands" target="_blank">within a single city</a> vary by 15 to 20 degrees Fahrenheit (8.3 to 11.1 degrees Celsius).</p><p>That's where metro parks and city trees come in. They have nice cooling effects on nearby neighborhoods. "Several cities around the world have developed programs to increase urban green spaces," says Blanken. "Tree planting programs and green roof programs, have been shown to lower surface temperatures, decrease air pollution and decrease surface water runoff (urban flash-flooding) in urban areas."</p>
An "explosive" wildfire ignited in Los Angeles county Wednesday, growing to 10,000 acres in a little less than three hours.
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By Jeff Berardelli
Note: This story was originally published on August 6, 2020
If asked to recall a hurricane, odds are you'd immediately invoke memorable names like Sandy, Katrina or Harvey. You'd probably even remember something specific about the impact of the storm. But if asked to recall a heat wave, a vague recollection that it was hot during your last summer vacation may be about as specific as you can get.
<div id="ecf36" class="rm-shortcode" data-rm-shortcode-id="c2dcc9d48a6cd61f247df1544539a783"><blockquote class="twitter-tweet twitter-custom-tweet" data-twitter-tweet-id="1290959314132361216" data-partner="rebelmouse"><div style="margin:1em 0">Naming heatwaves is a good idea—making the abstract concrete, the invisible visible. Why should hurricanes and wild… https://t.co/hDWgYb79Ob</div> — Ed Maibach (@Ed Maibach)<a href="https://twitter.com/MaibachEd/statuses/1290959314132361216">1596623660.0</a></blockquote></div>
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