Archive for the 'General Science' Category

Jan 23 2020

Asteroid Not Volcanism Killed the Dinosaurs

Published by under General Science

The popular belief is that an asteroid impact caused the mass extinction at the K-Pg (formerly K-T) boundary 66 million years ago. This is the mass extinction that killed off the non-avian dinosaurs along with 75% of species on Earth. However, in reality there is a raging scientific debate about the exact causes of the extinction event. The two contenders are the asteroid impact, which we know happened right at that time, and extreme volcanism at the Deccan traps in what is now India.

Scientists fall along a spectrum in this debate. At one end there are those who believe the asteroid was the main event, and the volcanic eruptions played little to no role. At the other end are those who believe that climate change caused by the volcanoes, with both global warming from the CO2 and acidification of the oceans, was the main driver of extinction. The asteroid impact, at most, was the coup de grace. In between are those who feel that both events were important to extinction to varying degrees, and we’re just trying to sort out their relative contributions.

The evidence has gone back and forth on this debate, although I think it has been strongly favoring the asteroid impact as the dominant factor. A new study contributes to this debate, and heavily favors the asteroid impact. In fact, the authors argue that their evidence suggests the volcanism at the Deccan traps played no role at all in the extinction. The modeled the outgassing from the Deccan traps and compared the models with the evidence to see which one fit the best. This is what they found:

We found support for major outgassing beginning and ending distinctly before the impact, with only the impact coinciding with mass extinction and biologically amplified carbon cycle change. Our models show that these extinction-related carbon cycle changes would have allowed the ocean to absorb massive amounts of carbon dioxide, thus limiting the global warming otherwise expected from postextinction volcanism.

Essentially the outgassing from the Deccan traps started, according to their model that best fits the evidence, 350,000-200,000 years prior to the impact and extinction. This caused a global warming event of about 2 C, which further lead to a migration of many species toward the poles. However, the outgassing and warming stopped prior to the extinction, the Earth cooled back to its prior baseline, and the various species returned to their previous locations. So the ecosystem has returned to its prior baseline, without any mass extinction, and then the asteroid hit and caused the mass extinction all by itself.

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Jan 14 2020

Communicating The Consensus

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Science communication is an evolving art, backed by some interesting research. However, my overall take on the state of the research is that it is mostly telling us the various ways in which we fail, rather than how to succeed. The latest target if scicomm handwringing is “consensus messaging.” How do we, and should we, communicate the scientific consensus to the public?

This issue is probably most salient to communication about global warming. Those who deny the scientific consensus on AGW frequently deny that there is a consensus and/or deny that a scientific consensus is even meaningful. How should we address this situation. In 2018 Russil argued that consensus messaging is generally ineffective. Instead we should focus on the victims of climate change:

“If we recognize that climate change danger will be mediated by questions of migration, dislocation and refuge, and if climate change communication abandons the legacy of consensus messaging to involve those affected by danger, how might our work unfold differently?”

It’s fine to try new approaches, but my problem with this argument is that essentially nothing works when it comes to changing minds on AGW, and so the fact that any one strategy does not work doesn’t really tell us anything about that strategy, or favor any other.

The concept of consensus does, in fact, exist in science. I wrote about it previously here and here. If the vast majority of scientists agree on some scientific conclusion, that is a consensus. That much is historically undeniable, so the strategy is often to switch to the position that a consensus is meaningless. That’s not how science works. To bolster this position often an example of when a scientific consensus was wrong is brought up. These examples, however, never work to establish the anti-consensus position.

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Dec 30 2019

A Climate Change Lost Decade

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It’s fun and interesting to look back over the last decade and think about what has happened and how far we have come. Round years are arbitrary, but it’s a sufficient trigger to take stock and hopefully gain some perspective on the medium course of history. There is a lot to say about the 2010s, and I may take the opportunity to say more, but I want to discuss in this essay what is perhaps our greatest challenge and disappointment over the last decade. In many ways this has been a lost decade for climate change mitigation.

Over the last decade the scientific evidence (and resulting consensus) that the planet is warming, that humans are the primary driver of this trend, and that the consequences are not likely to be good, has only become greater. The last five years have been the hottest five years on record, and this has been the case for most of the last decade. The year 2016 was the hottest, because it was an El Niño year (short term fluctuations will still be overlaid on top of the longer term trend) but the trend is unmistakable. The story of the world’s ice is more complex, with greater regional and year-to-year variations, but total global ice has been decreasing, and if anything accelerated over the last decade. The Greenland ice sheet in particular experienced accelerated melting. As a result there is a real and growing scientific consensus, north of 97% among relevant scientists, that anthropogenic climate change is happening.

We are also experiencing more extreme weather events. We are seeing more droughts, fires, heat waves, and more powerful storms. In the last decade it become clear that, while the worst consequences of climate change are decades and even centuries in the future, we are starting to see real consequences now.

Economists have started to weigh in as well. Numerous studies were published over the last decade, concluding that – climate change will cost the world many billions of dollars and will reduce economic growth, costing even more. Further, the option of allowing climate change to happen and adapting to the results will likely be the costliest option. In addition to the monetary cost, there is a quality of life cost. Extreme weather causes displacement, psychological trauma, and social upheaval. If you think we are having a refugee crisis now, just wait as flooding increasing and more locations become essentially uninhabitable.

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Dec 19 2019

Sequestered Life

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Researchers may (and I emphasize “may”) have found life in isolated underground pockets of water in South African mines.  What makes this potential find interesting is that this water has been isolated for about 2 billion years. Scanning electron microscopes have found what researchers believe may be a dividing bacterium. If this is confirmed it will be an exciting discovery for a few reasons.

But first – what do we know now? The water was collected from isolated pockets underground. The water is about 7 times as salty as sea water and can get up to about 54 degrees C. This is right at the limit for known extremophiles, but it is possible for bacteria or archaea to exist in these conditions. The evidence for possible life comes mainly from the microscopic images, which are suggestive but not definitive. One of the researchers, Devan Nisson, a graduate student, noted that “It’s possible the shapes were minerals.”

This would not be the first time that geological structures were confused for life. In 1996 researchers famously announced possible signs of life in a meteorite from Mars. Over 20 years later that claim is still not generally accepted. While there remains some controversy, the consensus is that the tiny structures are minerals, not microbes.

Making the claims for life in the South African mines at least plausible is the fact that there are nitrates and sulfates in the water, which could potentially be used by microbes as an energy source. There are abundant small organic acids, which could serve as building blocks and nutrients. So while extreme, it is possible that this water could support life.

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Oct 28 2019

The Golden Rice Saga

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Science Writer Ed Regis has recently published a book, Golden Rice: The Imperiled Birth of a GMO Superfood, in which he tells the tragic story of golden rice. In his telling he does not come off as an ideologue, or someone who kept with an initial dramatic narrative regardless of the facts. Rather, he wished to find the truth, which is often messy and nuanced.

Golden rice is a genetically modified form of rice that is enriched with beta carotene, the precursor to vitamin A. It was developed by a non-profit humanitarian collaborative, is free of patents, and was produced with the intention of making it freely available to farmers in developing worlds. The first version of golden rice was produced in 2002, but this version had very low beta carotene levels. The latest versions, however, have sufficient levels that if current diets containing rice as the staple source of calories were switched to golden rice, it would be enough to avoid vitamin A deficiency.

Vitamin A deficiency is a global pandemic. According to the WHO:

An estimated 250 000 to 500 000 vitamin A-deficient children become blind every year, half of them dying within 12 months of losing their sight.

Golden rice has the potential to significantly reduce this disease burden by fortifying a daily staple with beta carotene. This sounds like a solid win for science, so what turns this into a tragic tale? Of course you know the answer, irrational resistance based on misplaced fears.

Greenpeace has lead the charge against the development and adoption of golden rice, mainly out of their generic resistance to all things GMO. Regis writes:

Over the years since the prototype version was announced, Greenpeace had issued a practically endless stream of press releases, position papers, and miscellaneous other statements about Golden Rice that were filled with factual inaccuracies, distortions, and wild exaggerations of the truth.

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Oct 24 2019

Another Damning Organic Study

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A recent study looks at the carbon emission impact if England and Wales switched entirely over to organic farming. They found:

We predict major shortfalls in production of most agricultural products against a conventional baseline. Direct GHG emissions are reduced with organic farming, but when increased overseas land use to compensate for shortfalls in domestic supply are factored in, net emissions are greater. Enhanced soil carbon sequestration could offset only a small part of the higher overseas emissions.

In their model organic farming did not use fossil-fuel based fertilizer. The nitrogen comes from natural sources, like manure, and also rotation crops that fix nitrogen, such as legumes. This does result in a direct reduction in green-house gas (GHG) emissions, but also results in about a 40% decrease in crop production. That shortfall would have to be made up with increased imports, mostly from Europe. So then we have to calculate what it would take to replace the shortfall in production. This is where there is some variability in the model, because it depends exactly what land is converted to crop production. In the most likely scenarios there would be a net increase in GHG emissions of about 20%.

This is a great example of the law of unintended consequences. When dealing with any complex network, like agriculture, you have to consider the effects of any one change on the overall system. This is not the first study to show that organic farming is a net negative for the environment, and so it is in line with previous research. Further, the disadvantages of organic farming get worse as you try to scale it up.

For example, consider the nitrogen cycle – agriculture is largely a system of recycling nitrogen into food. So for any system you have to consider where all the nitrogen is coming from. Organic farming uses manure, but when the world’s agriculture was limited to manure as a source of nitrogen, that severely limited food production. The green revolution was largely created by the ability to make artificial fertilizer and therefore a non-manure based source of nitrogen. Bottom line – we cannot support the world’s population on manure.

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Oct 15 2019

Impossible Bug Burger

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The market is innovating some burger alternatives in order to reduce demand for beef.  There are potentially three reasons to reduce beef consumption – health, environmental, and ethical. How successful are these replacements?

First let me quickly review the reasons for reducing beef. The health effects of eating red and processed meat are, at present, controversial. I reviewed this question recently at SBM. There is evidence for increased cancer and heart disease from eating large amounts of red and especially processed meat, but the absolute risk is low and the quality of the evidence is low. You can make of this what you will, and that’s the controversy. My take is that if you keep your total calories where they should be for weight maintenance, and eat plenty of fruits and vegetables, the rest takes care of itself.

The ethical concerns are complex and reflect personal values. Again, personally, I don’t have a problem with eating animals after they are dead, as long as they were treated humanely while they were alive and they were slaughtered in a humane way. However, I understand the points on the other side and respect the views of those who wish to avoid meat for ethical reasons. I currently file that away as a personal choice. I don’t think there is ethical justification for outlawing meat, however.

The environmental concerns are also complex, but it is clear that producing a lot of meat is very inefficient. Potatoes, for example, produce 17 times the amount of calories per acre than beef. But some land is better suited for grazing than farming. Cows also produce a lot of methane. Water usage from animals is also high. This does not mean the best thing to do is eliminate meat completely. Rather, as one study indicates, we should use land optimally. Some land is best for growing a certain kind of crop, while another might be best for grazing, while still other land is best left untouched for natural ecosystems.

Whether or not you think we should reduce meat consumption to zero or not, the evidence does suggest that industrialized nations are eating too much meat. So it is reasonable to moderate our meat consumption at the very least.

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Oct 10 2019

Ancient Food Storage

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There are many things we take for granted in modern life, skills that humanity developed over literally hundreds of thousands of years, but also many modern conveniences that are fairly recent. One is food storage – saving food for later consumption.

We began as hunter-gatherers, a lifestyle that involves mostly consuming food right as it is acquired. This creates times of feast and famine, but little consistency or predictability. Without refrigeration and other techniques of food preservation, most foods would not last long. Cooked meat, gathered fruits might last a few days, while nuts and roots might last a bit longer. But that was about it.

Agriculture led to a significant increase in our control over our food supply. We could now store food as dried grains for months. As we cultivated crops, some were selected for storing well. Some hard-skinned squash, for example, can keep for several months. Cheese was a huge discovery, preserving milk calories also for months. Domesticated animals could be “preserved” indefinitely, and then slaughtered when needed. Salting, pickling, smoking, and curing were discovered over time as methods of preserving various foods. Industrialization eventually allowed for things like canning and, of course, refrigeration.

But what was the oldest and first example of humans preserving food for later consumption? Archaeologists think they have discovered it – researchers from Tel Aviv report the finding from Qesem Cave, a paleolithic human settlement from 400,000 years ago. They found evidence that the people living there would preserve deer and other bones for potentially up to 9 weeks, and then break them open to eat the marrow.

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Sep 24 2019

Climate Change Is Accelerating

Published by under General Science

Have you ever traveled with a large group of friends? When a group gets beyond a certain “critical mass” it becomes geometrically more difficult to make decisions. Even going to a restaurant or a movie become laborious. Decision making seems to break down in large groups, especially if there isn’t an established hierarchy or process in place. That’s why the “by committee” cliche exists – group decision making can be a highly flawed and problematic process.

I can’t escape the nagging sensation that the world is having this problem. We seem to be politically frozen and unable to take decisive timely action. We are metaphorically driving toward a cliff, and we can’t even take our foot off the accelerator, let alone apply the brakes.

I am talking, of course, about climate change. The World Meteorological Organization (WMO) compiled data in preparation for a UN summit on climate change in New York (which the US will not, ironically, be attending). They found:

  • 2014-2019 are the hottest 5 years on record
  • Global temperature have risen by 1.1 C since 1850, but  0.2 C between 2011-2015.
  • CO2 release between 2014-2019 was 20% higher than the previous 5 years
  • Sea level rise has been 3.2 mm per year on average since 1993, but is 5mm per year averaged over the last five years.
  • Ice loss is accelerating. For example – “The amount of ice lost annually from the Antarctic ice sheet increased at least six-fold, from 40 Gt per year in 1979-1990 to 252 Gt per year in 2009-2017.”
  • Heatwaves, wild fires, and extreme weather events are increasing and causing increasing damage and costs.

There is a decisive scientific consensus that these facts are basically accurate, that human activity is causing warming, and that the results are not going to be good. There is a growing consensus among economists that the costs of global warming will be huge, in the billions for the US alone. Even if there is still a little uncertainty, there is enough data and enough consensus to act. So what’s holding us back?

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Aug 09 2019

Some Climate Change Cherry Picking

Published by under General Science

There is an industry of misinformation fueling climate change denial. It is often fairly sophisticated, and because it is dealing with a highly complex technical area, it’s easy to create an argument that sounds compelling. This results (as if often evidenced right here in the comments) in people who are confident that they are good skeptics and climate fearmongering is all nonsense. Of course they have to simultaneously believe in a rather absurd conspiracy theory regarding the scientific community, but they make that work somehow too.

Here are a couple of recent examples, both of which involve some subtle cherry picking. The first has to do with electric cars, which are frequently opposed by the denialists, in that they oppose subsidies to help bootstrap the market. This involves the “solution aversion” aspect of climate change denial – deniers are really motivated by the proposed solutions to climate change, which goes against either their politics or other interests. The claim that is often made is that producing electric cars has a higher carbon footprint than gasoline cars, and that if you are charging your car off the grid you are probably getting that electricity from fossil fuels. Therefore – electric cars are worse for the environment.

At the very least, I see climate change deniers delight in how stupid this makes the climate change believers appear.  This is a great example of cherry picking, because the two basic facts are correct but they are not the whole picture. Here, for example, is an article posted by Breitbart claiming that batteries are not green, concluding:

One of the authors, Mats-Ola Larsson at IVL, has made a calculation of how long you have to drive a petrol or diesel before it has released as much carbon dioxide as battery manufacturing has caused.

“The result was 2.7 years for a battery of the same size as the Nissan Leaf and 8.2 years for a battery of the Tesla-size.”

Truly the enduring mystery of why Tesla is now more highly valued than such non-Potemkin U.S. car manufacturers as Ford and General Motors grows more mysterious by the hour.

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