Archive for the 'General Science' Category

Aug 09 2018

The Climate Tipping Point

Published by under General Science

It’s now pretty clear that as we increase global CO2 levels in the atmosphere, mainly by burning stuff, global average temperatures have been increasing as well. This is predicted based upon the greenhouse effect of CO2 and other gases like methane, amplified by reactive gases like water vapor. The amount of warming that results from a given CO2 increase is called climate sensitivity (specifically the rise in average global temperature averaged over 20 years resulting from a doubling of atmospheric CO2), and there is some debate about exactly what the climate sensitivity is.

Without any feedback effects, from just the primary greenhouse effect of CO2 itself, climate sensitivity is about 1 degree C. However, there are feedback effects, meaning that rising temperatures affect the climate in such a way that more warming results. For example, if the polar icecaps reduce in size, they reflect less light back into space, which results in more warming. Current estimates of climate sensitivity are between 2 and 4.5 degrees C.

However, a new paper published in PNAS argues that climate sensitivity is not the only issue when it comes to predicting future climate change due to increased CO2. Those feedback loops do not only affect climate sensitivity – they also affect climate homeostasis. In other words, at any given amount of CO2 in the atmosphere, taking into consideration all the feedbacks in the climate, an equilibrium will be achieved. There are climate cycles around that equilibrium, but that equilibrium determines long term global average temperatures.

So – what we really need to do is determine where the new equilibrium will settle for any given amount of CO2. This requires predicting not only the effect of feedback loops on the climate, but their effect on each other. The authors argue that several feedback mechanisms can act like a domino effect – on feedback will increase temperatures enough to set off another feedback which increases temperature enough to set off yet another feedback. This whole chain has to work itself out before a new equilibrium is reached.

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Aug 07 2018

How Much Arable Land Is There?

Published by under General Science

This question comes up frequently in discussions of farming practices – how much arable land is there on the Earth, and how much are we currently using? It is a deceptively difficult question to answer. It’s an important question, because as the population grows, we need to grow more food. We can do this my increasing the amount of food each acre of land can produce, by farming more acres of land, or by producing food without land. But if we expand farming acres, where would those more acres come from?

Let’s start with the easy question – right now we are using 11% of all the land on Earth for farming (1.5 billion ha out of a total of 13.4 billion). What percentage of the remaining 89% could be used for farming? The answer is – that depends on your definition of arable land. We can take the upper limit of the estimate of remaining arable land, and then explain why use of that land is problematic.

First, “arable” is a continuum, not a dichotomy. Some land can only be used for a very limited number of potential crops. Other land is highly suitable for many different crops. We won’t count land that is not suitable for farming, even though theoretically it could be used with extreme measures. You can grow corn in the desert, if you import all the water.

If we count all potentially arable land, it is estimated that we are currently using 36% of that land for farming. That means that 64%, or 2.7 billion ha, remain. At first this may seem encouraging, that we have lots of farmable land left. But that figure is very deceptive. Let’s dive into that 64%. The fact is we have already “picked the low hanging fruit.” We have used the best farming land for farming. What remains is largely on the low end of the continuum of suitability. If, for example, land can be used only for olive groves, that is considered arable by the above calculation.

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Jul 09 2018

USDA Tries to Implement Terrible GMO Labeling Law

Published by under General Science

The USDA just ended their public comment period on their proposed execution of the terrible Federal GMO labeling law passed in 2016. The public comments reflect the mess this law is, and why it is a bad idea.

The law simply states that the USDA will develop rules for mandatory labeling of bioengineered food. Here is the relevant definition in the law:

‘‘In this subtitle:
‘‘(1) BIOENGINEERING.—The term ‘bioengineering’, and any similar term, as determined by the Secretary, with respect to a food, refers to a food—
‘‘(A) that contains genetic material that has been modified through in vitro recombinant deoxyribonucleic acid (DNA) techniques; and
‘‘(B) for which the modification could not otherwise be obtained through conventional breeding or found in nature.

The first criterion – in vitro recombinant DNA techniques – is at least fairly specific. However, it does not distinguish cisgenic (from a closely related species) from transgenic (from a distant species). This does not technically include gene silencing, because no new material is being sliced in. Therefore by this definition “GMO” cultivars produced through gene silencing do not need to be labeled ad BE (bioengineered).

Perhaps because this first criterion is not specific to transgenic alterations, the second criterion was added – not obtained through breeding or found in nature. The “found in nature”, however, is very problematic. This is because transgenic gene transfer does occur in nature, – so called horizontal gene transfer. In fact, recently a sweet potato variety was found to have a naturally-occurring transgene from a soil bacteria.

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Jul 06 2018

Land Use and Climate Change

Published by under General Science

There is a strong scientific consensus that the primary driver of climate change is the release of previously sequestered carbon locked away in fossil fuels into the environment. But a new study reminds us that there is another contributor that must be accounted for in climate models – changes in land use.

The core claim of climate change is actually quite simple, and has not been successfully refuted by climate change deniers. So-called “greenhouse gases” in the atmosphere warm the planet because they reflect more infrared radiation back down to the surface, so that less of it escapes the Earth. Without this effect the Earth would be a snowball.

It is irrefutable at this point that adding more greenhouse gases to the atmosphere will increase this effect, resulting in more warming. The only real question is – how much warming? This is where things become ridiculously complex. Climate scientists use models to predict what will happen as more CO2 is released into the atmosphere, but it is very difficult to model a complex system. This is why there are large error bars on projections of future warming.

As a quick aside, carbon dioxide (CO2) is not the only greenhouse gas, but it is the major one. Methane is a more potent greenhouse gas (GHG) than CO2, but it does not last as long in the atmosphere. Within the first 20 years after its release, methane is 84 times as potent a GHG than CO2, but only 34 times if you consider its effects over 100 years. Much less methane is released into the atmosphere than CO2, but it is not negligible and needs to be considered in climate models.

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Jun 21 2018

Iceman Update

Published by under General Science

In 1991 the mummified remains of a 5,300 year old man were found in the Alps on the border of Italy and Austria. The Iceman, also referred to by the nickname, Ötzi (because he was found in the Ötzal mountains) has been the subject of endless study ever since. He represents our best single window into copper-age society.

Scientists continue to learn more and more about Ötzi, what he ate, how he died, what he was doing in the hours before his death, and about the tools he had with him. Recently scientists have published a detailed report looking at the lifecycle of Ötzi’s tools, providing yet more insight.

Before we get to the new info – here is a quick summary of some basic facts about Ötzi. We know that he was shot in the back by an arrow. The arrowhead remains, in fact, in his back as smoking-gun evidence of the cause of death. Amazingly, the presence of the arrowhead was missed on X-rays of Ötzi for years – a great example of inattentional blindness.

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Jun 14 2018

New Review of Antarctic Ice

Published by under General Science

A new review of the past few decades of satellite data published in the most recent edition of Nature tells the story of what is happening to ice on Antarctica. The result is probably exactly what you think – the ice is melting, at an accelerating rate. But the details are interesting.

First, we should note that Antarctica is a continent. There is land under all that ice, unlike the Arctic which is floating ice without any land. This makes a huge difference. While Arctic ice melts, the water fits exactly into the space previously displaced by the ice, so does not result in any sea-level rise. There are other effects to be concerned about, such as the effect on ecosystems and the effects of all that fresh water melting into the North Atlantic.

When ice sitting on top of land melts, however, that is new water finding its way to the sea, resulting in direct sea-level rise. As water gets warmer, it also expands, which further causes sea level rise. Also, the weight of all that ice pushes down the land, and when the mass of that ice decreases the land actually lifts up a bit.

The Antarctic ice system is also more complex than the Arctic. There are different glacier systems, which terminate at the ocean, and then there is the surrounding sea ice. There are several ways to estimate the extent of ice also, not just land coverage. Scientists need to also measure the thickness of the ice, the relationship between land and sea ice, the weight of the ice (the gravity it produces), and look at the under side of the glaciers that can erode away from warm sea water.

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Jun 08 2018

Séralini Fails Replication

Published by under General Science

Gilles-Éric Séralini is a French researcher who came to fame from publishing a study in 2012 claiming that herbicide-tolerant GMO corn, with or without combination with glyphosate herbicide, increased tumor risk in rats. He used this study to call into question the safety of GMOs generally, and to call for long term feeding studies. His results were embraced by the anti-GMO crowd, and to this day are cited as evidence GMOs are not safe.

One small problem, however, is that Séralini’s study was terrible. It immediately came under intense criticism. Specifically, the study had small sample size, and used a strain of rats known to have a high background rate of tumors. The data, therefore, was full of noise and was essentially uninterpretable. This is probably the reason for the lack of statistical analysis – because there were no significant findings. For these reasons in 2013 the study was retracted. In 2014 the paper was republished in a new open-access journal,  Environmental Sciences Europe, without additional peer-review.

It is pretty clear that Séralini is anti-GMO, and this likely biased his research. But regardless, the study methodology is terrible and the results worthless. But it did serve its (what I believe to be its true) purpose – to stoke fears about GMOs and to provide published “scientific” evidence to support the claims of anti-GMO activists.

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Feb 08 2018

Did a Comet Kill the Mammoths

Published by under General Science

Between 12,800 to 11,500 bp (before present) there was a cold period in North America called the Younger Dryas – named after the dryas flower whose pollen is a good marker for such cold periods. During this time the megafauna of North America, including the Mammoth, largely died out. Along with them went the Clovis culture – a big game hunting culture with distinctive stone points.

What caused this period of climate change and mass extinction?

This is a genuine scientific controversy. One group of scientists believe that the melting glaciers dumped fresh water into the northern Atlantic, temporarily shutting down the ocean currents that bring warm water to North America. Another group think that a comet impact is to blame.

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Jan 30 2018

Gattaca

Published by under General Science

The Human Genome Project was started in 1990 and completed in 2003. It took 13 years, multiple labs around the world, and hundreds of millions of dollars to sequence the human genome – this was more than two years ahead of schedule and millions of dollars under budget.

The reason for exceeding expectations is that the technology for sequence the genome was not static – it progressed throughout the project. DNA contains a code of four letters, the nucleotides indicated by the letters G, T, A, and C. This four-letter alphabet creates 64 different three-letter words, which code for different amino acids or operations that control the conversion of the code into proteins. Sequencing the genome essentially consists of discovering the order of these four letters in the string of a DNA molecule.

In 1997 the movie Gattaca, right in the middle of the genome project, portrayed the near future in which a cheek swab would rapidly yield an individual’s genome. It turns out this is not far fetched at all – we are almost living in Gattaca’s near future, at least in terms of sequencing technology. Scientists have just published a report of the nanopore device, which is a hand-held device capable of sequencing an individual’s genome.

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Jan 29 2018

Shameless Organic Fearmongering

Published by under General Science

I and others have long pointed out that anti-GMO fearmongering was largely created by the organic food lobby as a way of smearing their competitors. The strategy is simple – scare people way from genetically modified organisms (GMOs) and offer organic products as a non-GMO alternative. This is nothing new in advertising, create a fear and then offer your product as a safe haven.

A recent video posted by Stonyfield Organic makes the connection between anti-GMO fearmongering and buying organic explicit, as the screen capture shows.

There are many problems with this short video, not the least of which is that they use young girls to parrot their anti-science. Clearly not aiming for subtlety, the first girl declares that GMOs are “monstrous.” To apparently explain what she means, the second girl says that, “They take a gene from a fish and put it into a tomato.”

No, “they” don’t.

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