By Jennifer Chu
For the past three decades, as the climate has warmed, the massive plates of sea ice in the Arctic Ocean have shrunk: in 2007, scientists observed nearly 50 percent less summer ice than had been seen in 1980.
Dramatic changes in ice cover have, in turn, altered the Arctic ecosystem—particularly in summer months, when ice recedes and sunlight penetrates surface waters, spurring life to grow. Satellite images have captured large blooms of phytoplankton in Arctic regions that were once relatively unproductive. When these organisms die, a small portion of their carbon sinks to the deep ocean, creating a sink, or reservoir, of carbon.
Now researchers at Massachusetts Institute of Technology (MIT) have found that with the loss of sea ice, the Arctic Ocean is becoming more of a carbon sink. The team modeled changes in Arctic sea ice, temperatures, currents and flow of carbon from 1996 to 2007, and found that the amount of carbon taken up by the Arctic increased by one megaton each year.
But the group also observed a somewhat paradoxical effect: A few Arctic regions where waters were warmest were actually less able to store carbon. Instead, these regions—such as the Barents Sea, near Greenland—were a carbon source, emitting carbon dioxide to the atmosphere.
While the Arctic Ocean as a whole remains a carbon sink, MIT principal research scientist Stephanie Dutkiewicz says places like the Barents Sea paint a more complex picture of how the Arctic is changing with global warming.
“People have suggested that the Arctic is having higher productivity, and therefore higher uptake of carbon,” Dutkiewicz says. “What’s nice about this study is, it says that’s not the whole story. We’ve begun to pull apart the actual bits and pieces that are going on.”
A paper by Dutkiewicz and co-authors Mick Follows and Christopher Hill of MIT, Manfredi Manizza of the Scripps Institute of Oceanography, and Dimitris Menemenlis of NASA’s Jet Propulsion Laboratory is published in the journal Global Biogeochemical Cycles.
The Ocean’s Carbon Cycle
The cycling of carbon in the oceans is relatively straightforward: as organisms like phytoplankton grow in surface waters, they absorb sunlight and carbon dioxide from the atmosphere. Through photosynthesis, carbon dioxide builds cell walls and other structures; when organisms die, some portion of the plankton sink as organic carbon to the deep ocean. Over time, bacteria eat away at the detritus, converting it back into carbon dioxide that, when stirred up by ocean currents, can escape into the atmosphere.
The MIT group developed a model to trace the flow of carbon in the Arctic, looking at conditions in which carbon was either stored or released from the ocean. To do this, the researchers combined three models: a physical model that integrates temperature and salinity data, along with the direction of currents in a region; a sea ice model that estimates ice growth and shrinkage from year to year; and a biogeochemistry model, which simulates the flow of nutrients and carbon, given the parameters of the other two models.
The researchers modeled the changing Arctic between 1996 and 2007 and found that the ocean stored, on average, about 58 megatons of carbon each year—a figure that increased by an average of one megaton annually over this time period.
These numbers, Dutkiewicz says, are not surprising, as the Arctic has long been known to be a carbon sink. The group’s results confirm a widely held theory: with less sea ice, more organisms grow, eventually creating a bigger carbon sink.
A New Counterbalance
However, one finding from the group muddies this seemingly linear relationship. Manizza found a discrepancy between 2005 and 2007, the most severe periods of sea ice shrinkage. While the Arctic lost more ice cover in 2007 than in 2005, less carbon was taken up by the ocean in 2007—an unexpected finding, in light of the theory that less sea ice leads to more carbon stored.
Manizza traced the discrepancy to the Greenland and Barents seas, regions of the Arctic Ocean that take in warmer waters from the Atlantic (in warmer environments, carbon is less soluble in seawater). Manizza observed this scenario in the Barents Sea in 2007, when warmer temperatures caused more carbon dioxide to be released than stored.
The results point to a subtle balance: an ocean’s carbon flow depends on both water temperature and biological activity. In warmer waters, carbon is more likely to be expelled into the atmosphere; in waters with more biological growth—for example, due to less sea ice—carbon is more likely to be stored in ocean organisms.
In short, while the Arctic Ocean as a whole seems to be storing more carbon than in previous years, the increase in the carbon sink may not be as large as scientists had previously thought.
“The Arctic is special in that it’s certainly a place where we see changes happening faster than anywhere else,” Dutkiewicz says. “Because of that, there are bigger changes in the sea ice and biology, and therefore possibly to the carbon sink.”
Manizza adds that while the remoteness of the Arctic makes it difficult for scientists to obtain accurate measurements, more data from this region “can both inform us about the change in the polar area and make our models highly reliable for policymaking decisions.”
This research was supported by the National Science Foundation and the National Oceanic and Atmospheric Administration.
By Jason Farley
COVID-19 has disrupted our daily lives, and it is poised to completely disrupt the holiday season. As people make holiday plans and think about ways to reduce the risks to their loved ones, a strategy is essential.
Are masks really necessary at family gatherings?<p>If you're gathering with friends and family who don't live in your home, yes. Just because you're with people you know doesn't mean you're safe from the coronavirus. Infection rates are <a href="https://coronavirus.jhu.edu/data/new-cases-50-states" target="_blank" rel="noopener noreferrer">higher now than they have ever been</a> in the U.S., and <a href="https://youtu.be/ehdgceGzQxs" target="_blank" rel="noopener noreferrer">small gatherings have been a source</a> of viral spread. All it takes is one infected person who doesn't know they have the coronavirus to infect others.</p><p>Remember, people can be <a href="https://medical.mit.edu/covid-19-updates/2020/07/how-long-symptom-onset-person-contagious" target="_blank" rel="noopener noreferrer">contagious two to three days</a> before symptoms show – that's one thing that makes this virus so hard to stop. And it's why, even if you feel fine, you should wear a mask.</p><p>The Centers for Disease Control and Prevention now estimates that when both people are wearing masks, the <a href="https://www.cdc.gov/coronavirus/2019-ncov/more/masking-science-sars-cov2.html" target="_blank">likelihood of infection is low</a>.</p>
Who am I protecting when I wear a mask?<p>In a word: everyone. The coronavirus <a href="https://theconversation.com/aerosols-are-a-bigger-coronavirus-threat-than-who-guidelines-suggest-heres-what-you-need-to-know-142233" target="_blank">spreads through respiratory droplets</a> that you send out into the air when you talk, sing or even just breathe. The tiniest of these droplets can float on air currents for long periods.</p><p>Face masks stop many of those droplets, reducing the amount of virus in the air. That lowers your chances of getting infected, and it also lowers the chances that you'll infect someone else.</p><p><a href="https://www.cdc.gov/coronavirus/2019-ncov/more/masking-science-sars-cov2.html" target="_blank">Studies of people who had prolonged exposure</a> to others with COVID-19 have demonstrated how masks can reduce the chance of the virus spreading. In general, <a href="https://www.cdc.gov/coronavirus/2019-ncov/more/masking-science-sars-cov2.html" target="_blank" rel="noopener noreferrer">well-fitted cloth masks</a> made up of multiple layers can stop most large droplets and at least half of the tiny ones. Plastic <a href="https://doi.org/10.1101/2020.10.05.20207241" target="_blank" rel="noopener noreferrer">face shields</a> alone are far less effective. <a href="https://www.washingtonpost.com/health/2020/08/13/cdc-mask-guidance-masks-valves/" target="_blank" rel="noopener noreferrer">Face masks with valves or vents</a> might be good for construction work, but they don't stop the wearer from breathing out virus into the air.</p>
Can I reuse a mask and when should I replace it?<p>Reusable masks should be kept clean and dry. We're moving into cold and flu season, and noses get drippy. A rule of thumb: Anytime a mask is wet to the point that you can discern the wetness, it's time for a new one if it's disposable, or it's time to clean your reusable mask.</p><p>Wetness allows viruses to more easily move through paper or fabric because it allows the threads to move and may reduce the electrostatic charge in the masks that add extra protection with some fabrics.</p><p>In general, you can use a mask that stays clean and dry for about a week before you need to wash or discard it.</p>
How should I clean a cloth mask?<p>Washing your mask is like washing your clothes. You know when it is time.</p><p>In general, <a href="https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/how-to-wash-cloth-face-coverings.html" target="_blank">cleaning your mask weekly</a> should be sufficient. If odors develop before then, it's a good idea to wash it sooner. Odor generally means bacterial buildup.</p><p>Cleaning your mask by hand with soap and water is your best option. Using a general detergent on a gentle cycle in the washing machine is also fine, but that may increase the risk of damage, depending on the quality of the material. COVID-19 is not a hardy virus. Any soap or detergent should work fine. There's no need for special chemicals, bleach or harsh soaps.</p><p>Be careful to remove any inserts before washing. Inserted filters are generally not washable.</p><p>Air drying masks works best. Remember, masks should be completely dry before use. So be sure to have a replacement mask handy while the one you just washed dries.</p><p>Sunlight is always a great source of heat to dry your mask. Also, sunlight has ultraviolet radiation, which has been shown to <a href="http://doi.org/10.1111/php.13293" target="_blank" rel="noopener noreferrer">eliminate coronavirus</a> and is also known to have antibacterial properties.</p>
Can I wear the mask below my nose?<p>Wearing your mask below your nose is, frankly, ridiculous.</p><p>Think about it. If you are breathing through your nose and only covering your mouth, you are effectively eliminating the point of the mask. Properly wearing a mask requires covering both your nose and mouth at all times.</p><p>Studies show that wearing a proper cloth mask or surgical mask while exercising <a href="http://doi.org/10.1513/AnnalsATS.202008-990CME" target="_blank">doesn't affect the flow of oxygen</a> or carbon dioxide in any detectable way. So, unless you have serious heart and lung problems, that isn't an excuse.</p>
How do I safely remove my mask if I’m going to eat or drink?<p>When you <a href="https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/how-to-wash-cloth-face-coverings.html" target="_blank">take your mask off</a>, remove it carefully by the straps without touching anything else and put it somewhere safe, like wrapped in paper in a purse, bag or pocket. Then wash your hands or use hand sanitizer. When you put it back on, wash your hands again.</p>
So, how can I have a safe holiday gathering?<p>The safest way to celebrate this year is to do so with members only within your household. The <a href="https://www.cdc.gov/coronavirus/2019-ncov/daily-life-coping/holidays.html" target="_blank" rel="noopener noreferrer">CDC is now stressing that point</a>, as well. If you do celebrate with friends and relatives from outside your household, you need an action plan to reduce the risk of exposure.</p><p>Here are five recommendations:</p><ul><li>Limit the number of people – fewer people means fewer opportunities for exposure, and you'll have more room to spread out.</li><li>Require masks when not eating or drinking.</li><li>Use physical distancing when eating. Try to seat people <a href="https://doi.org/10.1136/bmj.m3223" target="_blank" rel="noopener noreferrer">at least 6 feet apart</a>. Eat outside if you can.</li><li>Consider being tested for COVID-19 before traveling or gathering. It's not a guarantee, but it can help flag illnesses. Remember to self-isolate between the test and the event.</li><li>Be prepared to self-isolate for 14 days after traveling or participating in any event that involves people from outside your home.</li></ul><p>[<em>Research into coronavirus and other news from science</em> <a href="https://theconversation.com/us/newsletters/science-editors-picks-71/?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=science-corona-research" target="_blank" rel="noopener noreferrer">Subscribe to The Conversation's new science newsletter</a>.]</p><p><em>The map has been updated with New Hampshire announcing a mask mandate effective Nov. 20.</em></p><p><em>Jason Farley is a professor, infectious disease-trained epidemiologist and nurse practitioner at the Johns Hopkins University School of Nursing.<br></em></p><p><em>Disclosure statement: Jason Farley, PhD, MPH, ANP-BC, FAAN receives funding from the National Institutes of Health on the Rapid Acceleration of Diagnostics for COVID-19 and Becton Dickinson for studies on SARS-CoV-2 diagnostics.</em></p><p><em>Reposted with permission from <a href="https://theconversation.com/why-face-masks-belong-at-your-thanksgiving-gathering-7-things-you-need-to-know-about-wearing-them-150130" target="_blank">The Conversation</a>. </em></p>
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By Tara Lohan
How much of U.S. energy demand could be met by renewable sources?
According to a new report from the Institute for Local Self-Reliance, the answer is an easy 100%.
Graphic: ILSR, Energy Self-Reliant States 2020
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By Amol Mehra
Set against rising calls for action to combat growing inequality and the climate crisis, the COVID-19 pandemic underscores the importance of the key drivers of industry and economic reform: workers, communities and the environment.
The Built Environment<p>The built environment – the physical places and structures that we inhabit – is a huge potential change agent in this regard. Buildings and construction account for massive amounts of energy usage and about 40% of global CO2 emissions, providing a clear pathway to shift current consumption and production pathways.</p><p>The construction sector accounts for around <a href="https://www.mckinsey.com/~/media/McKinsey/Industries/Capital%20Projects%20and%20Infrastructure/Our%20Insights/Reinventing%20construction%20through%20a%20productivity%20revolution/MGI-Reinventing-Construction-In-Brief.pdf" target="_blank">13% of the world's GDP </a>and<a href="https://iloblog.org/2020/05/11/the-construction-sector-can-help-lead-the-economic-recovery-heres-how/" target="_blank" rel="noopener noreferrer"> for 7.2% of the global workforce</a>. Many of the jobs linked to these sector have a negative history of labour rights, especially with respect to <a href="https://laborrights.org/issues/migrant-labor" target="_blank" rel="noopener noreferrer">migrant laborers</a>. As <a href="https://iloblog.org/2020/05/11/the-construction-sector-can-help-lead-the-economic-recovery-heres-how/" target="_blank" rel="noopener noreferrer">experts have noted</a>, the scale of the industry and its relative impacts on labour markets and the environment make it a prime agent of transformation of the broader global economy.</p><p>By prioritizing approaches that focus on decarbonization and the promotion of labor rights protections, we can create economic opportunities that promote healthy, regenerative structures. Efforts are starting to seed in this regard, with <a href="https://www.vox.com/energy-and-environment/2020/1/15/21058051/climate-change-building-materials-mass-timber-cross-laminated-clt" target="_blank" rel="noopener noreferrer">increased attention</a> being placed to mass timber and other wood products in construction, as well as the use of natural materials in buildings.</p><p>At the same time, leading human rights organizations are looking more closely at promoting <a href="https://www.ihrb.org/focus-areas/built-environment/commentary-linking-climate-human-rights-built-environment-lifecycle" target="_blank" rel="noopener noreferrer">rights-based approaches</a>.</p>
Not all industries are equal. ourworldindata.org