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If A Tree Falls in the Forest, But No Scientist Says So ...
Recently, the highly respected Bulletin of the American Meteorology Society ("BAMS" to those in the know), published a special issue consisting of a couple dozen articles investigating the potential impact climate change might have had on various extreme weather events of 2013. This has become somewhat of an annual rite now (see for example the corresponding 2012 special issue), a sort of scientific postmortem on what role climate change might have played in specific weather events.
Photo credit: Shutterstock
It might be tempting to view this volume as an authoritative statement by the scientific community on the role climate change may or may not have had in some high profile, devastating recent extreme weather events. But that would be misguided. The BAMS special issue is not a representative, community-wide scientific assessment like those published by the National Academy of Sciences or Intergovernmental Panel on Climate Change. The editors, instead, have solicited contributions from a relatively small number of groups, so the findings do not necessarily reflect the range of views of the broader scientific community. Some leading climate scientists who were not included in the effort have presented evidence of a greater role for climate change in several of the events dismissed or downplayed by the BAMS articles (see e.g. Kevin Trenberth of NCAR on the September 2013 Colorado floods, Stefan Rahmstorf of the University of Potsdam on the June 2013 Central European floods and Jennifer Francis of Rutgers on the 2013/2014 California Drought).
The California drought is of particular interest since it is both an unprecedented and absolutely devastating ongoing event. The thread potentially connecting that event to climate change is the unusual atmospheric pattern that prevailed during winter 2013/2014. That pattern was associated with a persistent "ridge" of high pressure over the western U.S. (see my previous Huffington Post piece) that caused the jet stream to plunge southward over the central U.S., chilling the eastern third of the country, and to veer northward over the west coast, pushing the warm moist subtropical Pacific air masses that would normally deliver plentiful rainfall (and snowpack) to California well to the north, resulting in bone-dry conditions in California and balmy weather in Alaska.
In fact, there are at least three different mechanisms that are potentially relevant to the connection between the 2013/2014 California drought and human-caused climate change. There is (1) the impact of climate change on the pattern of sea surface temperature (SST) off the west coast. One recent study suggests that climate change favors an SST pattern in the North Pacific that increases the incidence of the atmospheric circulation pattern responsible for the current drought. Then there is (2) the marked decrease in Arctic Sea Ice due to global warming. Studies going back more than a decade show that reduced Arctic sea ice may also favor such an atmospheric circulation pattern. More recent work by Jennifer Francis of Rutgers provides independent support for that mechanism. Finally, there is (3) the effect of global warming on soil moisture. All other things being equal, warming of soils leads to greater rates of evaporation and drying. This mechanism leads to worsened drought even if rainfall patterns are unchanged.
One of the three BAMS articles investigating the climate change connection with the California Drought (by Noah Diffenbaugh of Stanford and collaborators) did find a climate change role. They found that the high pressure ridge responsible for deflecting storms to the north was indeed made more likely by climate change. Even without accounting for increased evaporation due to warmer soils, they conclude that climate change likely increased the probability of the 2013/2014 California drought.
Two of the three BAMS articles, however, argue against a climate change connection. But here's the problem: the experimental design used in these studies completely leaves out all three of the mechanisms described above. These studies only looked at the impact of the overall warming of SSTs, without addressing whether climate change might be favoring the specific pattern of SST tied to the high pressure ridge and consequent drought. Neither of the studies accounts for the possible impact of decreasing Arctic Sea Ice (Indeed, one of the two studies explicitly acknowledges this shortcoming: "Other factors, such as the impact of climate change on the ... SST gradient and storm tracks...and changes in sea ice extent...are not examined"). Finally, neither of the studies account for the impact of warming on soil evaporation. So, the fact that two of the three studies find no climate change connection may simply point to deficiencies in the approaches used. The adage "absence of evidence is not evidence of absence" would appear to apply in spades here.
Predictably, the conflicting findings and mixed message of the BAMS report led to confused and misleading headlines like the LA Times "California drought and climate warming: Studies find no clear link". Contrast that with Stanford's press release "Causes of California drought linked to climate change, Stanford scientists say" and the Sacramento Bee commentary "Droughts likely to be new normal for California."
I fear that the problem here runs far deeper than the specific flaws in the experimental designs of certain studies. What is most problematic is an over-dependence on climate model "detection and attribution" approaches for assessing the impact of climate change on the likelihood of extreme weather events. That machinery fails when the approaches used in these studies fail to capture real-world processes that may be critical to these relationships. The failure to identify a climate change impact may simply represent a failure on the part of the chosen model to capture real world processes, rather than the absence of a climate change influence on the events in question.
I'm troubled that this latter possibility receives such short thrift in many of the articles in the BAMS volume. Indeed, a quote by UK scientist Myles Allen in the New York Times' coverage of the BAMS findings encapsulates the hubris by some climate researchers: "If we don't have evidence, I don't think we should hint darkly all the time that human influence must be to blame somehow." Never mind the caricature of his fellow scientists here as furtively attempting, in the absence of any evidence, to blame every weather event on climate change (who are these scientists that Allen speaks of? I've never read any quotes by climate scientists that could possibly be characterized this way). The real problem is the lack of humility among some scientists when it comes to evaluating the potential impacts that climate change may be having on our environment. As leading climate scientist Kevin Trenberth has put it, "The environment in which all storms form has changed owing to human activities." Trenberth notes that global warming has already increased the average amount of water vapor in the atmosphere by about 4 percent, "extra moisture flowing into the storms that produced the heavy rains and likely contributed to the strength of the storms through added energy."
In other words, climate change has fundamentally altered the atmospheric environment in which all weather takes place, and has very likely increased the frequency and intensity of various types of extreme weather, including more intense flooding events, more extensive continental drought, more extreme heat and more intense storms. Just because an event hasn't been positively "attributed" to climate change in a formal "detection & attribution" study does not preclude speaking about the role climate change may have played, when the event is (a) consistent with expectations in a warming world, and (b) part of a larger trend. A negative finding in an attribution study could be a consequence of deficiencies in the experimental design. And the notion that scientists could possibly publish a peer-reviewed article for every weather event that may have been influenced by climate change is, on its face, absurd.
And so to return to where we started, just as a tree that falls in the forest did so whether or not a scientist was there to observe it, an extreme weather event influenced by climate change was thusly influenced, whether or not a scientist published a peer-reviewed article establishing so. We should keep that in mind when we talk about the ways that climate change is already impacting extreme weather, and likely to impact it further if we do nothing to reduce the ongoing warming of the planet.
Michael Mann is Distinguished Professor of Meteorology at Pennsylvania State University and author of The Hockey Stick and the Climate Wars: Dispatches from the Front Lines (now available in paperback with a new guest foreword by Bill Nye "The Science Guy")
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By Tom Duszynski
The coronavirus is certainly scary, but despite the constant reporting on total cases and a climbing death toll, the reality is that the vast majority of people who come down with COVID-19 survive it. Just as the number of cases grows, so does another number: those who have recovered.
In mid-March, the number of patients in the U.S. who had officially recovered from the virus was close to zero. That number is now in the tens of thousands and is climbing every day. But recovering from COVID-19 is more complicated than simply feeling better. Recovery involves biology, epidemiology and a little bit of bureaucracy too.
How does your body fight off COVID-19?<p>Once a person is exposed the coronavirus, the body starts producing <a href="https://www.mblintl.com/products/what-are-antibodies-mbli/" target="_blank">proteins called antibodies to fight the infection</a>. As these <a href="https://www.statnews.com/2020/03/27/serological-tests-reveal-immune-coronavirus/" target="_blank">antibodies start to successfully contain the virus</a> and keep it from replicating in the body, symptoms usually begin to lessen and you start to feel better. Eventually, if all goes well, your immune system will completely destroy all of the virus in your system. A person who was infected with and survived a virus with no long-term health effects or disabilities has "recovered."</p><p>On average, a person who is infected with SARS-CoV-2 will feel ill for about seven days from the onset of symptoms. Even after symptoms disappear, there still may be small amounts of the virus in a patient's system, and they should stay <a href="https://www.cdc.gov/coronavirus/2019-ncov/if-you-are-sick/steps-when-sick.html" target="_blank">isolated for an additional three days</a> to ensure they have truly <a href="https://health.usnews.com/conditions/articles/coronavirus-recovery-what-to-know" target="_blank">recovered and are no longer infectious</a>.</p>
What about immunity?<p>In general, once you have recovered from a viral infection, your body will keep cells called lymphocytes in your system. These cells "remember" viruses they've previously seen and can react quickly to fight them off again. If you are exposed to a virus you have already had, your antibodies will likely stop the virus before it starts causing symptoms. <a href="https://dx.doi.org/10.5114%2Fceji.2018.77390" target="_blank">You become immune</a>. This is the <a href="https://www.ncbi.nlm.nih.gov/books/NBK27158/" target="_blank">principle behind many vaccines</a>.</p><p>Unfortunately, immunity isn't perfect. For many viruses, like mumps, immunity can wane over time, leaving you <a href="https://www.sciencedaily.com/releases/2016/04/160421145747.htm" target="_blank">susceptible to the virus in the future</a>. This is why you need to get revaccinated – those "booster shots" – occasionally: to prompt your immune system to make more antibodies and memory cells.</p><p>Since this coronavirus is so new, scientists still don't know whether people who recover from COVID-19 are <a href="https://www.cdc.gov/coronavirus/2019-ncov/hcp/faq.html" target="_blank">immune to future infections of the virus</a>. Doctors are finding antibodies in ill and recovered patients, and <a href="https://www.cdc.gov/coronavirus/2019-ncov/hcp/clinical-guidance-management-patients.html" target="_blank">that indicates the development of immunity</a>. But the question remains how long that immunity will last. Other coronaviruses like <a href="https://doi.org/10.1002/jmv.25685" target="_blank">SARS and MERS produce an immune response</a> that will protect a person at least for a short time. I would suspect the same is true of SARS-CoV-2, but the research simply hasn't been done yet to say so definitively.</p>
Why have so few people officially recovered in the US?<p>This is a dangerous virus, so the Centers for Disease Control and Prevention is being extremely careful when deciding what it means to recover from COVID-19. Both medical and testing criteria must be met before a person is <a href="https://www.cdc.gov/coronavirus/2019-ncov/hcp/disposition-in-home-patients.html" target="_blank">officially declared recovered</a>.</p><p>Medically, a person must be fever-free without fever-reducing medications for three consecutive days. They must show an improvement in their other symptoms, including reduced coughing and shortness of breath. And it must be at least seven full days <a href="https://health.usnews.com/conditions/articles/coronavirus-recovery-what-to-know" target="_blank">since the symptoms began</a>.</p><p>In addition to those requirements, the CDC guidelines say that a person must test negative for the coronavirus twice, with the <a href="https://www.cdc.gov/coronavirus/2019-ncov/if-you-are-sick/care-for-someone.html" target="_blank">tests taken at least 24 hours apart</a>.</p><p>Only then, if both the symptom and testing conditions are met, is a person officially considered recovered by the CDC.</p><p>This second testing requirement is likely why there were so few official recovered cases in the U.S. until late March. Initially, there was a <a href="https://www.nytimes.com/2020/03/18/health/coronavirus-test-shortages-face-masks-swabs.html" target="_blank">massive shortage of testing in the U.S.</a> So while many people were certainly recovering over the last few weeks, this could not be officially confirmed. As the country enters the height of the pandemic in the coming weeks, focus is still on <a href="https://www.cdc.gov/coronavirus/2019-nCoV/hcp/clinical-criteria.html" target="_blank">testing those who are infected</a>, not those who have likely recovered.</p><p>Many more people are being tested now that states and private companies have begun <a href="https://www.cdc.gov/coronavirus/2019-ncov/cases-updates/testing-in-us.html" target="_blank">producing and distributing tests</a>. As <a href="https://www.dispatch.com/news/20200406/coronavirus-in-ohio-from-its-rocky-start-testing-for-covid-19-slowly-ramping-up" target="_blank">the number of available tests increases</a> and the pandemic eventually slows in the country, more testing will be available for those who have appeared to recover. As people who have already recovered are tested, the appearance of any new infections will help researchers learn <a href="https://www.statnews.com/2020/03/24/we-need-smart-coronavirus-testing-not-just-more-testing/" target="_blank">how long immunity can be expected to last</a>.</p>
Once a person has recovered, what can they do?<p>Knowing whether or not people are immune to COVID-19 after they recover is going to determine what individuals, communities and society at large can do going forward. If scientists can show that recovered patients are immune to the coronavirus, then a person who has recovered could in theory <a href="https://www.vox.com/2020/3/30/21186822/immunity-to-covid-19-test-coronavirus-rt-pcr-antibody" target="_blank">help support the health care system</a> by caring for those who are infected.</p><p>Once communities pass the peak of the epidemic, the number of new infections will decline, while the number of <a href="https://www.newsweek.com/china-says-passed-peak-coronavirus-epidemic-covid-19-1491863" target="_blank">recovered people will increase</a>. As these trends continue, the risk of transmission will fall. Once the risk of transmission has fallen enough, community-level isolation and social distancing orders will begin to relax and businesses will start to reopen. Based on what other countries have gone through, it will be <a href="https://www.nature.com/articles/d41586-020-00154-w" target="_blank">months until the risk of transmission is low</a> in the U.S.</p><p>But before any of this can happen, the U.S. and the world need to make it through the peak of this pandemic. Social distancing works to slow the spread of infectious diseases and <a href="https://www.cdc.gov/coronavirus/2019-ncov/need-extra-precautions/what-you-can-do.html" target="_blank">is working for COVID-19</a>. Many people will <a href="https://www.yalemedicine.org/stories/2019-novel-coronavirus/" target="_blank">need medical help to recover</a>, and social distancing will slow this virus down and give people the best chance to do so.</p>
By Elizabeth Claire Alberts
The future for the world's oceans often looks grim. Fisheries are set to collapse by 2048, according to one study, and 8 million tons of plastic pollute the ocean every year, causing considerable damage to delicate marine ecosystems. Yet a new study in Nature offers an alternative, and more optimistic view on the ocean's future: it asserts that the entire marine environment could be substantially rebuilt by 2050, if humanity is able to step up to the challenge.
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By Zulfikar Abbany
Bread has been a source of basic nutrition for centuries, the holy trinity being wheat, maize and rice. It has also been the reason for a lot of innovation in science and technology, from millstones to microbiological investigations into a family of single-cell fungi called Saccharomyces.
Chemical leavening<p>If you like a little heft in your loaf, you will need a leavening agent.</p><p>For those short on time, you can use baking soda. That's a chemical compound of sodium bicarbonate mixed with potassium bitartrate, or cream of tartar.</p><p>Soda breads have their traditions in parts of eastern and central Europe, and in Ireland and Scotland, with Melrose loaves and "farls."</p><p>They can taste a bit bland, though, and are often considered only as an emergency solution on Sundays. No disrespect intended: They taste just fine fresh from the oven.</p><p>Whether it's chemical or more "natural," leavening relies largely on the production of carbon dioxide.</p><p>When you mix an acid, such as vinegar, buttermilk, yogurt or apple cider, with an alkaline compound like baking soda, you get CO2. That CO2 creates bubbles, which in turn capture steam in the oven and allow a bread to rise.</p><p><span></span>But it's better with yeast. Tastes better, too. It just takes more time. </p>
What is yeast?<p>There are yeasts all around us — on grains, in the air, in biofuels. It even lives inside us, but that's not always a good thing.</p><p><a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1090575/pdf/1471-2334-5-22.pdf" target="_blank">Candida yeast</a> can cause infections of the skin, feet, mouth, penis or vagina if it builds up too much in the body.</p><p>One of the most common yeasts, however, is <em>Saccharomyces cerevisiae</em>. That's <a href="https://www.dw.com/en/an-early-beer-archaeologists-tap-ground-at-worlds-oldest-brewery/a-45480731" target="_blank">"brewer's"</a> or "baker's" yeast.</p><p>You can get fresh baker's yeast, often in 42-gram (1.48-ounce) cubes, or as dried yeast (quick action or active, which requires rehydration) in a sachet of 7 grams.</p><p>There's little difference: One is compressed and the other is dehydrated and granulated. But they do the same thing, essentially. </p><p>Some commercial yeast producers add molasses and other nutrients. But natural yeast has plenty of useful nutrients in it anyway, including B group vitamins, so who knows whether it's good or necessary to add them. </p>
How does yeast work?<p>When you mix flour, yeast and water, you set off a veritable chain reaction. Enzymes in the wheat convert starch into sugar. And the yeast creates enzymes of its own to convert those sugars into a form it can absorb.</p><p>The yeast "feeds" on the sugars to create carbon dioxide and alcohol. The yeast burps and farts, releasing gases into the mix, and that creates bubbles to trap CO2. </p><p>It's a vital fermentation process that breaks down the gluten in the flour and helps make your bread more digestible.</p><p>The yeast cells split and reproduce, generating lactic and carbonic acid, raising the temperature and ultimately adding flavor to the mix.</p><p>The longer you leave the yeast to do its thing, the better for your bread. Time is more important than the amount of yeast. </p><p>In fact, that's an enduring question — how much yeast? I'll use 20 grams fresh yeast for 500 grams of flour. Others say that's enough yeast for 1 kilo. If you are converting a dry-yeast recipe to fresh yeast, some bakers advise tripling the weight. So, if a sachet of dried yeast is 7 grams, your fresh yeast is 21 grams.</p><p><span></span>But that also depends on the flours you are using, temperatures in the bowl and the room, and a host of other things. You'll just have to experiment and see. No number of books (and I've read a stack on bread) will help as much as trial and error.</p>
Wild yeast: Sourdough<p>So, good bread needs time. If you have a lot of time, why not move it up a notch and grow wild yeast — a sourdough starter — in your own home?</p><p>A sourdough starter is not to be mistaken (as it often is) for the leaven, or "mother," "sponge," or <em>levain</em>. That's more a second stage, a descendant of the starter. You take a scoop from your starter and add it to another flour and water mixture when you prepare the dough for a new loaf. </p><p>The sourdough process utilizes yeasts naturally present in flour and … yet more time. A longer fermentation process allows a richer lactic acid bacteria <em>lactobacilli</em> or LAB to evolve, and that can be healthy for your gut microbiome.</p><p>It's simple enough to start a sourdough starter. All you need is flour, warm water and time.</p><p>Some suggest equal measures of whole-grain flour and water at 28 degrees Celsius (82 degrees Fahrenheit), some say room temperature — just don't let the water exceed 40 C or the yeasts will die. Some suggest two parts flour to three parts water. But it's up to you whether you want a drier or wetter starter. You will know only through experimentation. </p><p>Some say you should filter tap water to remove chemicals like fluoride and avoid using water that's boiled and then cooled. Others say that really doesn't matter.</p><p>The main thing is, keep it clean and give it time. Days, weeks, months and years.</p>
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