Arctic Sea Ice Hits Second-Lowest Winter Peak on Record
By Robert McSweeney
Arctic sea ice has experienced its maximum extent for the year, reaching 14.48 million square kilometers (approximately 5.59 million square miles) on March 17—the second smallest in the 39-year satellite record.
The run of low extents in recent winters suggests that "profound ice loss is no longer limited to summer but now extends across all seasons," an NSDIC scientist told Carbon Brief.
Meanwhile, in Antarctica, sea ice has already reached its minimum extent following the summer melt season. This also clocked in as the second lowest on record.
As the northern hemisphere emerges from winter, the annual expansion of sea ice in the Arctic slows to a stop. This peak signals the start of the melt season in spring and summer.
Using satellites, scientists can mark this point every year, recording when the Arctic sea ice hit its largest extent and the size it reached. It is one way of monitoring the "health" of the Arctic.
Arctic sea ice extent as of March 22, 2018 for the 2017-18 summer (blue line), along with daily ice extent data for the four previous years: 2016-17 (green), 2015-16 (orange), 2014-15 (brown) and 2013-14 (purple). NSIDC
Early indications suggest that Arctic sea ice reached an annual maximum of 14.48 million square kilometers (sq km) on March 17. This is the second lowest winter peak in the 39-year satellite record—just 60,000 sq km larger than the 2017 record—and 1.16m sq km smaller than the 1981-2010 average. The chart above shows how closely the 2017 (green) and 2018 (blue) extents tracked through their respective winters.
At the point of this winter's peak, there were two particular areas with very low sea ice extents, the NSIDC said—the Bering Sea (in the Pacific Ocean between Russia and Alaska) and the Barents Sea (in the Atlantic Ocean to the north of Scandinavia).
The image below gives a snapshot of the sea ice cover for March 17. The orange line shows the average extent of sea ice for that day over 1981-2010.
Arctic sea ice extent for March 17, 2017. The orange line shows the 1981- 2010 average extent for that day. NSIDC
This year has already been marked by new records, with both January and February seeing the smallest average sea ice cover for their respective months. The winter peak looked set to be a record itself before a spell of cold conditions caused a late growth spurt in mid-March.
#Arctic sea ice still has not reached its annual maximum extent. Cold weather across the area is allowing for a lat… https://t.co/wSi9UlD1i4— Zack Labe (@Zack Labe)1521040682.0
The Arctic winter has been marked by some unusually high temperatures, which has in turn pushed bitterly cold conditions over Europe in recent weeks. The chart below, by Zack Labe at the University of California at Irvine, shows how daily average air temperatures over the Arctic (red line) have spent most of January and February substantially above average (white line).
Daily surface air temperature (at two meters above the surface) for the Arctic, averaged above 80 degrees North. Bold lines show 2018 (red) and 1958-2002 average (white). Zack Labe
"Although Arctic sea ice started this winter about 5cm thicker than the previous year, there was slower growth in December—possibly as a result of the relatively warm weather—and by the end of last month it was around 166cm thick, almost identical to 2017."
Although Arctic sea ice has reached its maximum extent, it will take a little longer for it to reach its peak volume for the season, added Shepherd:
"In most years, Arctic sea ice continues to thicken for a few more weeks after the peak extent is reached as it usually takes a while for summer heat to reach the far North, and so we don't expect the maximum volume to occur until mid-March."
This means that the four lowest maximum extents in the satellite record have all occurred in the past four years, noted the NSIDC.
The pattern shows that it is not just the summer where significant sea ice loss is seen, said Julienne Stroeve, a professor of polar observation and modeling at University College London and senior research scientist at the NSIDC. She told Carbon Brief:
"Profound ice loss is no longer limited to summer, but now extends across all seasons. These winter changes will help hasten the transition towards a seasonal ice-free Arctic."
The chart below, made for Carbon Brief by professor Ed Hawkins of the University of Reading, shows how the Arctic sea ice extent has declined over the satellite era. It shows that it is not just the annual maximum that is decreasing (pale blue line), but also the average for the whole month of March (bold blue line) when the peak usually occurs.
And although the decline for winter sea ice is not as steep as that for summer—shown by the bold red (September average) and the pale red (annual minimum) lines—there is still a prominent downward trend.
Average Arctic sea ice extent for March (bold blue line), the whole year (black), September (bold red) and the annual maximum (pale blue) and minimum (pale red). Data for 1979 to 2018 in million square kilometers. Professor Ed Hawkins
While the Arctic has been gaining ice over the cold, dark winter, Antarctic sea ice has been melting through the southern hemisphere summer.
Antarctic sea ice reached its summer minimum at the end of February, clocking in at 2.18m sq km. This is the second lowest minimum extent in the satellite record, 70,000 sq km larger than the record set in 2017.
The chart below shows how the 2017-18 summer (blue line) compares to previous years in the satellite record. The 2017-18 season was tracking in second place for most of the winter, apart from briefly in February where it dipped lower than 2016-17.
Antarctic sea ice extent as of March 1, 2018 for the 2017-18 summer (blue line), along with daily ice extent data for the four previous years: 2016-17 (green), 2015-16 (orange), 2014-15 (brown) and 2013-14 (purple). NSIDC
The 2017-18 melt season had begun low. Its starting point was the second lowest winter maximum on record in October. It "went downhill from there," explained Dr. Ted Scambos, senior research scientist at NSIDC and lead scientist for their science team. He told Carbon Brief:
"A big factor in the rapid loss in November and December was the growth of a large area of open water within the pack, the Maud Rise Polynya. This is thought to be due to ocean upwelling driven by deep currents that pass over a large seamount [underwater mountain] in the Weddell Sea. This then was breached by the retreating ice edge."
At the point of the minimum last month, "almost every area of the Antarctic coastal ocean had less sea ice than normal," noted Sambos, "except for the western Weddell Sea—pressed against the eastern side of the Antarctic Peninsula—that was normal in extent and fearsomely well-packed." The image gives a snapshot of Antarctica's sea ice at the end of February.
Antarctic sea ice extent for February 28, 2018. The orange line shows the median sea ice edge for 1981-2010. NSIDC
Antarctic sea ice extent has seen a huge amount of variability in recent years. This has taken scientists by surprise, said Scambos, as it follows several decades of relative stability that "appeared to show a slight upward trend in sea ice." He explained:
"The past five years have seen both all-time high levels—in September 2014—and astonishing record lows—in October/November of 2016. Moreover, a new look at early satellite data from the 1960s confirmed that the Antarctic sea ice system is far more sensitive to seasonal and inter-annual weather and climate differences than had been appreciated before."
This variability means that recent changes to Antarctic sea ice "can't really be said to be responding to the general global trend in temperature," said Scambos—unlike sea ice in the Arctic.
While other data shows that "Antarctica's climate and ocean are indeed changing," it may take longer to be able to draw robust conclusions about how sea ice will be affected by human-caused warming, said Scambos:
"It may require another decade or two still before we can say with confidence how Antarctica's sea ice will respond [to climate change]—at least, if the basis is observations."
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Reposted with permission from our media associate Carbon Brief.
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By Ana Maldonado-Contreras
- Your gut is home to trillions of bacteria that are vital for keeping you healthy.
- Some of these microbes help to regulate the immune system.
- New research, which has not yet been peer-reviewed, shows the presence of certain bacteria in the gut may reveal which people are more vulnerable to a more severe case of COVID-19.
You may not know it, but you have an army of microbes living inside of you that are essential for fighting off threats, including the virus that causes COVID-19.
How Do Resident Bacteria Keep You Healthy?<p>Our immune defense is part of a complex biological response against harmful pathogens, such as viruses or bacteria. However, because our bodies are inhabited by trillions of mostly beneficial bacteria, virus and fungi, activation of our immune response is tightly regulated to distinguish between harmful and helpful microbes.</p><p>Our bacteria are spectacular companions diligently helping prime our immune system defenses to combat infections. A seminal study found that mice treated with antibiotics that eliminate bacteria in the gut exhibited an impaired immune response. These animals had low counts of virus-fighting white blood cells, weak antibody responses and poor production of a protein that is vital for <a href="https://doi.org/10.1073/pnas.1019378108" target="_blank">combating viral infection and modulating the immune response</a>.</p><p><a href="https://doi.org/10.1371/journal.pone.0184976" target="_blank" rel="noopener noreferrer">In another study</a>, mice were fed <em>Lactobacillus</em> bacteria, commonly used as probiotic in fermented food. These microbes reduced the severity of influenza infection. The <em>Lactobacillus</em>-treated mice did not lose weight and had only mild lung damage compared with untreated mice. Similarly, others have found that treatment of mice with <em>Lactobacillus</em> protects against different <a href="https://doi.org/10.1038/srep04638" target="_blank" rel="noopener noreferrer">subtypes of</a> <a href="https://doi.org/10.1038/s41598-017-17487-8" target="_blank" rel="noopener noreferrer">influenza</a> <a href="https://doi.org/10.1371/journal.ppat.1008072" target="_blank" rel="noopener noreferrer">virus</a> and human respiratory syncytial virus – the <a href="https://doi.org/10.1038/s41598-019-39602-7" target="_blank" rel="noopener noreferrer">major cause of viral bronchiolitis and pneumonia in children</a>.</p>
Chronic Disease and Microbes<p>Patients with chronic illnesses including Type 2 diabetes, obesity and cardiovascular disease exhibit a hyperactive immune system that fails to recognize a harmless stimulus and is linked to an altered gut microbiome.</p><p>In these chronic diseases, the gut microbiome lacks bacteria that activate <a href="https://doi.org/10.1126/science.1198469" target="_blank" rel="noopener noreferrer">immune cells</a> that block the response against harmless bacteria in our guts. Such alteration of the gut microbiome is also observed in <a href="https://doi.org/10.1073/pnas.1002601107" target="_blank" rel="noopener noreferrer">babies delivered by cesarean section</a>, individuals consuming a poor <a href="https://doi.org/10.1038/nature12820" target="_blank" rel="noopener noreferrer">diet</a> and the <a href="https://doi.org/10.1038/nature11053" target="_blank" rel="noopener noreferrer">elderly</a>.</p><p>In the U.S., 117 million individuals – about half the adult population – <a href="https://health.gov/our-work/food-nutrition/2015-2020-dietary-guidelines/guidelines/" target="_blank" rel="noopener noreferrer">suffer from Type 2 diabetes, obesity, cardiovascular disease or a combination of them</a>. That suggests that half of American adults carry a faulty microbiome army.</p><p>Research in my laboratory focuses on identifying gut bacteria that are critical for creating a balanced immune system, which fights life-threatening bacterial and viral infections, while tolerating the beneficial bacteria in and on us.</p><p>Given that diet affects the diversity of bacteria in the gut, <a href="https://www.umassmed.edu/nutrition/melody-trial-info/" target="_blank" rel="noopener noreferrer">my lab studies show how diet can be used</a> as a therapy for chronic diseases. Using different foods, people can shift their gut microbiome to one that boosts a healthy immune response.</p><p>A fraction of patients infected with SARS-CoV-2, the virus that causes COVID-19 disease, develop severe complications that require hospitalization in intensive care units. What do many of those patients have in common? <a href="https://www.cdc.gov/mmwr/volumes/69/wr/mm6912e2.htm" target="_blank" rel="noopener noreferrer">Old age</a> and chronic diet-related diseases like obesity, Type 2 diabetes and cardiovascular disease.</p><p><a href="http://doi.org/10.1016/j.jada.2008.12.019" target="_blank" rel="noopener noreferrer">Black and Latinx people are disproportionately affected by obesity, Type 2 diabetes and cardiovascular disease</a>, all of which are linked to poor nutrition. Thus, it is not a coincidence that <a href="https://www.cdc.gov/mmwr/volumes/69/wr/mm6933e1.htm" target="_blank" rel="noopener noreferrer">these groups have suffered more deaths from COVID-19</a> compared with whites. This is the case not only in the U.S. but also <a href="https://www.washingtonpost.com/world/europe/blacks-in-britain-are-four-times-as-likely-to-die-of-coronavirus-as-whites-data-show/2020/05/07/2dc76710-9067-11ea-9322-a29e75effc93_story.html" target="_blank" rel="noopener noreferrer">in Britain</a>.</p>
Discovering Microbes That Predict COVID-19 Severity<p>The COVID-19 pandemic has inspired me to shift my research and explore the role of the gut microbiome in the overly aggressive immune response against SARS-CoV-2 infection.</p><p>My colleagues and I have hypothesized that critically ill SARS-CoV-2 patients with conditions like obesity, Type 2 diabetes and cardiovascular disease exhibit an altered gut microbiome that aggravates <a href="https://theconversation.com/exercise-may-help-reduce-risk-of-deadly-covid-19-complication-ards-136922" target="_blank" rel="noopener noreferrer">acute respiratory distress syndrome</a>.</p><p>Acute respiratory distress syndrome, a life-threatening lung injury, in SARS-CoV-2 patients is thought to develop from a <a href="http://doi.org/10.1016/j.cytogfr.2020.05.003" target="_blank" rel="noopener noreferrer">fatal overreaction of the immune response</a> called a <a href="https://theconversation.com/blocking-the-deadly-cytokine-storm-is-a-vital-weapon-for-treating-covid-19-137690" target="_blank" rel="noopener noreferrer">cytokine storm</a> <a href="http://doi.org/10.1016/S2213-2600(20)30216-2" target="_blank" rel="noopener noreferrer">that causes an uncontrolled flood</a> <a href="http://doi.org/10.1016/S2213-2600(20)30216-2" target="_blank" rel="noopener noreferrer">of immune cells into the lungs</a>. In these patients, their own uncontrolled inflammatory immune response, rather than the virus itself, causes the <a href="http://doi.org/10.1007/s00134-020-05991-x" target="_blank" rel="noopener noreferrer">severe lung injury and multiorgan failures</a> that lead to death.</p><p>Several studies <a href="https://doi.org/10.1016/j.trsl.2020.08.004" target="_blank" rel="noopener noreferrer">described in one recent review</a> have identified an altered gut microbiome in patients with COVID-19. However, identification of specific bacteria within the microbiome that could predict COVID-19 severity is lacking.</p><p>To address this question, my colleagues and I recruited COVID-19 hospitalized patients with severe and moderate symptoms. We collected stool and saliva samples to determine whether bacteria within the gut and oral microbiome could predict COVID-19 severity. The identification of microbiome markers that can predict the clinical outcomes of COVID-19 disease is key to help prioritize patients needing urgent treatment.</p><p><a href="https://doi.org/10.1101/2021.01.05.20249061" target="_blank" rel="noopener noreferrer">We demonstrated</a>, in a paper which has not yet been peer reviewed, that the composition of the gut microbiome is the strongest predictor of COVID-19 severity compared to patient's clinical characteristics commonly used to do so. Specifically, we identified that the presence of a bacterium in the stool – called <em>Enterococcus faecalis</em>– was a robust predictor of COVID-19 severity. Not surprisingly, <em>Enterococcus faecalis</em> has been associated with <a href="https://doi.org/10.1053/j.gastro.2011.05.035" target="_blank" rel="noopener noreferrer">chronic</a> <a href="https://doi.org/10.1016/S0002-9440(10)61172-8" target="_blank" rel="noopener noreferrer">inflammation</a>.</p><p><em>Enterococcus faecalis</em> collected from feces can be grown outside of the body in clinical laboratories. Thus, an <em>E. faecalis</em> test might be a cost-effective, rapid and relatively easy way to identify patients who are likely to require more supportive care and therapeutic interventions to improve their chances of survival.</p><p>But it is not yet clear from our research what is the contribution of the altered microbiome in the immune response to SARS-CoV-2 infection. A recent study has shown that <a href="https://doi.org/10.1101/2020.12.11.416180" target="_blank" rel="noopener noreferrer">SARS-CoV-2 infection triggers an imbalance in immune cells</a> called <a href="https://doi.org/10.1111/imr.12170" target="_blank" rel="noopener noreferrer">T regulatory cells that are critical to immune balance</a>.</p><p>Bacteria from the gut microbiome are responsible for the <a href="https://doi.org/10.7554/eLife.30916.001" target="_blank" rel="noopener noreferrer">proper activation</a> <a href="https://doi.org/10.1126/science.1198469" target="_blank" rel="noopener noreferrer">of those T-regulatory</a> <a href="https://doi.org/10.1038/nri.2016.36" target="_blank" rel="noopener noreferrer">cells</a>. Thus, researchers like me need to take repeated patient stool, saliva and blood samples over a longer time frame to learn how the altered microbiome observed in COVID-19 patients can modulate COVID-19 disease severity, perhaps by altering the development of the T-regulatory cells.</p><p>As a Latina scientist investigating interactions between diet, microbiome and immunity, I must stress the importance of better policies to improve access to healthy foods, which lead to a healthier microbiome. It is also important to design culturally sensitive dietary interventions for Black and Latinx communities. While a good-quality diet might not prevent SARS-CoV-2 infection, it can treat the underlying conditions related to its severity.</p><p><em><a href="https://theconversation.com/profiles/ana-maldonado-contreras-1152969" target="_blank">Ana Maldonado-Contreras</a> is an assistant professor of Microbiology and Physiological Systems at the University of Massachusetts Medical School.</em></p><p><em>Disclosure statement: Ana Maldonado-Contreras receives funding from The Helmsley Charitable Trust and her work has been supported by the American Gastroenterological Association. She received The Charles A. King Trust Postdoctoral Research Fellowship. She is also member of the Diversity Committee of the American Gastroenterological Association.</em></p><p><em style="">Reposted with permission from <a href="https://theconversation.com/a-healthy-microbiome-builds-a-strong-immune-system-that-could-help-defeat-covid-19-145668" target="_blank" rel="noopener noreferrer" style="">The Conversation</a>. </em></p>
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