Archive for November, 2022

Nov 28 2022

The Challenge of Green Aviation

Published by under Technology

There is some good new when it comes to decarbonizing our civilization (reducing the amount of CO2 from previously sequestered carbon that our industries release into the atmosphere) – we already have the technology to accomplish most of what we need to do. Right now the world’s electricity generation is 63.3% from fossil fuels. We have the technology, through wind, solar, geothermal, hydroelectric, and nuclear power, to completely replace this if we wanted to.  We can debate the quickest and most cost-effective path, but there are many options that will work.

About 84.3% of total energy used by the world, however, is from fossil fuel. This includes not only electricity, but transportation, heating, and industrial use (other than through electricity). Of the transportation sector, 92% is ground vehicle (cars, trucks, and shipping). Battery electric vehicle technology is now more than capable of being the primary option for most users, with ranges >300 miles for passenger cars and 500 miles for shipping. Prices still need to come down, but they will as production ramps up.

Another way to look at this is that 73.2% of our carbon footprint comes from all energy, 18.4% from agriculture, 3.2% from waste, and 5.2% from direct industrial processes (like making cement and steel). Agricultural, waste, and industrial sources of carbon are complex, and these mostly require technological advances that we will hopefully chip away at over the next few decades. But we can rapidly eliminate that 73.2% from energy if we want to, with the exception of the 8% of transportation carbon from aviation. That remains a tough nut to crack.

The challenge of aviation is that jets and planes need to be light and have limits on size, so they require an energy source that has high energy density (energy per volume) and specific energy (energy per mass), more so than ground transportation. Right now the optimal fuel for those two features is hydrocarbons. This means that the best option for greener aviation is using biofuels (sustainable aviation fuel). Biofuels can be used with existing aircraft and have similar energy density and specific energy to existing fuels. The carbon footprint is usually not zero, but is much lower than fossil fuels. The carbon footprint of biofuels depends on the feedstock used and the methods of growing used. There are also land and water-use issues with mass-producing biofuels for aviation or other purposes. The best options are those that use waste feedstock.

Continue Reading »

No responses yet

Nov 23 2022

Closed Loop Pumped Hydro

Published by under Technology

I have been writing a lot recently about global warming and energy infrastructure. This is partly because there is a lot of news coming out of COP27, but also because both here and on the SGU there has been some lively and informative discussion on the issue. Also, this is a very complex issue and as people raise new points it sends me down different rabbit holes of information. I am trying to develop the most complete and objective picture I can of the situation.

The goal, of course, is to rapidly decarbonize the energy infrastructure of the world. We not only need to do this, we need to do it quickly and cost-effectively. Further, we need a plan for the next 30 years, and essentially we don’t have any second chances left. If we want to stay as far below 2.0 C temperature rise as possible, and even shoot for that rapidly fading hope of keeping below 1.5 C, then we have one shot. This means that if we have to course correct after 20 years, this may still improve the situation but will likely be too late to meet our climate goals.

I find that the most compelling arguments from experts to be those who advocate essentially doing everything. We should pick the low-hanging fruit, do all the win-wins, but also hedge our bets. If anything we want to overshoot.

One contentious issue has been whether or not it is feasible and advisable to plan on a 100% renewable energy infrastructure. The conversation gets complicated by some technical terms, so let me define them here.

Continue Reading »

No responses yet

Nov 22 2022

Genes and Language

Published by under Culture and Society

There are now approximately 8 billion people on the planet. In addition, there are over 7,100 languages spoken on Earth. One question for anthropologists and linguistic experts is – how closely do genetic relationships match language relationships. Both language and genes are generally inherited from our parents – well, genes absolutely, but language generally. It makes sense that a map of genetic relatedness would closely follow a map of linguistic relatedness. If we zoom out from a single family to a population, the question becomes a bit more complex. Populations can mix genes with other populations. Two populations that derived relatively recently from a common population will likely be genetically similar, and even if their current languages differ, they too likely share a common root and therefore lots of similarities.

What happens, then, when scientists overlay the genetic and linguistic maps of humanity? A recent study does just that. To do this they compiled a massive database, called GeLaTo, or Genes and Languages Together. GeLaTo includes data from “4,000 individuals speaking 295 languages and representing 397 genetic populations.” That is fairly robust, but there is also lots of room for continuing to add information to the database to add more precision and detail to any analysis.

What they found is that the match between genes and language is very good, about 80%. However, that still leaves 20% of identified genetic populations with a language mismatch. How does this happen? It doesn’t take much imagination to think of a scenario where a population takes on the language of another population in their region that is genetically distinct. For example:

Some peoples on the tropical eastern slopes of the Andes speak a Quechua idiom that is typically spoken by groups with a different genetic profile who live at higher altitudes. The Damara people in Namibia, who are genetically related to the Bantu, communicate using a Khoe language that is spoken by genetically distant groups in the same area. And some hunter-gatherers who live in Central Africa speak predominantly Bantu languages without a strong genetic relatedness to the neighboring Bantu populations.

Continue Reading »

No responses yet

Nov 21 2022

Artificial Muscles

Published by under Technology

There are some situations in which biology is still vastly superior to any artificial technology. Think about muscles. They are actually quite amazing. They can rapdily contract with significant force and then immediately relax. They can also vary their contraction strength smoothly along a wide continuum. Further, they are soft and silent. No machine can come close to their functionality.

In engineering parlance, a muscle is an actuator – a component that causes part of the machine to move. Boston Dynamics has produced some impressive results using standard actuators, but even their robots’ movements tend to be, well, robotic – a bit jerky and stilted. Compare that to the movements of a jaguar, for example. Engineers have been working on developing muscle-like actuators for years, with some progress but far from ultimate success.

One of the properties of a biological muscle is called the force-velocity relationship – the faster the muscle fibers contract the more power they produce. A second is the force-length relationship, essentially the longer the muscle the more power it creates. As a recent study points out:

However, it still remains a challenge to realize both intrinsic muscle-like force-velocity and force-length properties in one single actuator simultaneously.

In addition to these properties, to be more muscle-like we would need an actuator that can smoothly vary its power and also have soft components. There are other important properties, such as intrinsic response to load (does the system react to a load by contracting), static force (maintaining a load without moving), and the strength of the material used (how much of a strain can it take). Researchers, therefore, have been essentially trying to duplicate the structure and function of actual muscle to achieve all these properties. In the above study, for example:

This study presents a bioinspired soft actuator, named HimiSK (highly imitating skeletal muscle), designed by spatially arranging a set of synergistically contractile units in a flexible matrix similar to skeletal musculature. We have demonstrated that the actuator presents both intrinsic force-velocity and force-length characteristics that are very close to biological muscle with inherent self-stability and robustness in response to external perturbations.

Continue Reading »

No responses yet

Nov 18 2022

The Potential of Geothermal Energy

Published by under General Science

As we discuss the optimal path forward for the next 30 years to get to net-zero carbon emissions for the energy sector, one big variable is the real-world potential of geothermal energy. Right now in the US geothermal produces 0.4% of our electricity. That is almost negligible, and is not going to help get us to our goal without an order of magnitude or more increase. What is the probability that we can bring significant geothermal online within 20-30 years?

Producing electricity at large scale is mostly about turning turbines, which rotates a magnet within a coil of conducting cable which generates electrical current in the wires. Turbines are turned by two basic methods – mechanical or with steam which in turn is generated by some heat source. Hydroelectric and wind turbines rotate the turbines through mechanical power. Burning fossil fuel or nuclear power plants produce heat to create steam. Solar photovoltaics are the exception because they directly turn sunlight into electricity through the photoelectric effect. But direct solar capture can use sunlight to once again heat a target, create steam, and turn a turbine.

Geothermal energy uses steam created by the natural heat below the surface of the earth to turn a turbine to make electricity. In a recent TEDx talk, Matt Houde who is the cofounder of a geothermal energy company points out that there is enough heat in the ground to power our world for a billion years. It’s a practically unlimited energy source. Why isn’t that, then, problem solved – all the energy we can need for the foreseeable future (arguably longer than human civilization is likely to last on earth) is right beneath our feet? The problem is – that heat is hard to get to.

From my reading it seems that there are three types of geothermal energy depending on our ability to access the heat. Current geothermal, the kind making up that 0.4%, takes advantage of natural hot spring that reach near or at the surface. Boise Idaho, for example, directly heats building from natural hot springs. You can also use near surface heated water to create electrical power. This was the low-hanging fruit of geothermal, but if we want an order of magnitude increase we need to develop what is called advanced geothermal. This approach uses technology developed by the fracking industry to drill down to the heat, inject water if necessary (if water is not already present), and then use that heated water to drive turbines.

Continue Reading »

No responses yet

Nov 17 2022

New Method of Speciation

Published by under Evolution

Evolution requires that speciation events occur – events in which one species becomes two. All that is required for a speciation event to occur is that two populations of the same species stop interbreeding. There are two basic types of speciation: allopatric, where the populations are physically separated by geography, and sympatric, where they live in overlapping ranges but either can’t or don’t interbreed. For the purpose of speciation, interbreeding means producing fertile young.

Allopatric speciation is easy to understand. Most species have a large enough range that they are spread out into definable populations. They may even develop definable characteristics. Populations on the edge of a range, say a prairie species pushing into the desert, will likely develop some adaptions not possessed by the main population. At some point these adaptation may push the population into a range that does not overlap with the parent population. It also may happen that environmental change may doom the parent population to extinction, but the subpopulation’s adaptations allow them to survive as a new species. Sometimes geography simply changes, physically separating species (canyons open up, mountains rise, rivers change their course, land masses move).  Sometimes physical separation may be abrupt, such as when plants and animals find their way to islands and set up a new population, adapting to the new environment (like the Galapagos).

Sympatric speciation has been trickier to understand. Pollen will spread, animals will interbreed. It’s what they do. Research has focused on genetic events that make two populations unable to interbreed, because their offspring would be infertile. This will happen after species diverge sufficiently, but how will they diverge in the first place if they are exchanging genetic material? There must have been some genetic event, even in an individual, that instantly created genetic incompatibility. In plants this is commonly autopolyploid speciation, where the chromosome number is accidentally doubled during reproduction. The offspring cannot interbreed with the parent species because of chromosome number incompatibility. This is why some plants, like potatoes, can have very high numbers of chromosomes.

Continue Reading »

No responses yet

Nov 15 2022

Cache of Ancient Bronze Statues Found

Published by under General Science

Archaeologists have uncovered a large cache of over 50 small bronze statues in the ruins of an ancient temple in Tuscany. The find dates from the second century BCE to the first century ACE. It is being reported as the greatest bronze statue find in 50 years, one of the greatest finds ever, and a significant window into that period of history.

The statues themselves range from small representations of specific body parts, to statues representing the gods and up to a meter in length. These statues were deliberately tossed into a thermal spring within the temple, where they sunk to the bottom and were covered in mud. The mud preserved the statues in relatively good condition for the last two thousand years. Many of the statues also have writing on them, in either Roman or Etruscan. Archaeologists believe that these statues were offerings to the gods intended for healings. The body parts represent the ailment that the offerer wishes to be healed. They also found over 5,000 gold, silver, and bronze coins that were tossed into the spring over those three centuries.

Essentially, this thermal spring and temple were the equivalent of a spa for the wealthy. Bathing in hot springs was a common luxury for the wealthy of the time, and this temple was also clearly not a public place. Rather, this was likely a private location for the wealthy and elite. The bronze statues would have been very expensive, only affordable just to be tossed into the waters by the very wealthy.

It’s easy to become smug from our modern perspective about the primitive behavior of making offerings to imaginary gods in hopes of being healed. But I think the opposite reaction is more appropriate. Certainly making such offerings in the genuine hope of being healed is pure superstition, and also completely useless in terms of effecting real change to one’s health. Given the primitive state of medicine at the time, however, it was also pretty harmless (and an archaeological boon, it turns out). Even the wealthy and powerful did not have access to what we could consider basic health care, and so tossing expensive bronze statues was the best they had.

Continue Reading »

No responses yet

Nov 14 2022

The Lies of Climate Change Denial

Published by under General Science

Whenever I write about climate change here, the deniers show up spouting dubious (to say the least) claims. In my opinion, this is a manifestation of a deliberate political strategy, one that we see with other topics. The strategy is to make up blatant lies, or at least claims without the slightest regard for whether or not they are true, and then spread them through ideologically friendly outlets. Sometimes this may involve amplifying claims that emerge from the most extreme “fever swamps” promoting that ideology. Just keep throwing crap against the wall, and some of it will stick. When these notions make their way into the mainstream media, they are quickly debunked. But by then it’s too late – the damage is done. Long after the false claims are soundly refuted, the rank and file believers will still be quoting them. They are now part of the narrative.

This means that for science communicators and skeptics (but also mainstream journalists), we need to have a working knowledge of these common false claims that are circulating, so that we can respond to them quickly when they emerge. One of the reasons I allow such comments to continue in my blog is because that is one of the ways that I can see which claims are circulating. I don’t mind if they come here – we can handle it. Normally I handle the claims in the comments, but occasionally there is a critical mass of nonsense that is more efficiently dealt with by a post. Here are some recent claims.

Volcanoes emit more greenhouse gas than human activity.

This is an old one, but has remarkable persistence. These claims go through a selection process. Claims survive not because they are true, but because they resonate. In this case, the volcano claim fits the overall narrative that meager human activity is nothing compared to the awesome scale of nature. They want to portray the very idea that we can alter the climate as ridiculous.  Fact, however, get in the way of this narrative.

According to the US Geological Survey:

Published scientific estimates of the global CO2 emission rate for all degassing subaerial (on land) and submarine volcanoes lie in a range from 0.13 gigaton to 0.44 gigaton per year.

That sounds like a lot, but human activity releases 35 gigatons of CO2 each year. That means that human activity releases more than 100 times the CO2 as does all volcanic activity. When I pointed this out in the comments, these easily verifiable scientific facts were dismissed as a liberal conspiracy. Another strategy is to simply shift to another claim, without ever admitting that you were wrong on the first one. In this case just shift over to methane – but that is a loser argument also. Of all the methane released into the atmosphere each year, 60% is due to human causes. All natural sources amount to only 40%, and volcanoes are a minority of that. Most methane on Earth comes from biology.

I do admit it still surprises me when this one is trotted out, because these are easily checkable basic facts. This is a good way to completely squander one’s credibility. I think this says something meaningful about the intellectual process that is being employed by those dedicated to the denial of global warming.


Climate models are simplistic and wrong.

Dismissing climate models is a more complex matter to refute, because this is more than just looking up a couple of numbers. First there is the notion that climate scientists, in producing their models which predict anthropogenic global warming, did not consider natural factors. This is, of course, absurd, and represents non-experts criticizing an entire world-wide community of experts from a profound level of relative ignorance – and doing it with confidence and arrogance. This almost always comes without citations, or by citing only known outliers.

Climate models, from the beginning, have sought to include the latest science available and account for all possible factors. Over the last 50 years climate models have been steadily modified, to account for new scientific data as it comes in. In addition, models have to account for future behavior, such as how much CO2 will the world emit in the future. So they can only give ranges of outcomes based upon explicitly stated assumptions about human behavior in the future. Often models are used to project what will happen under various scenarios – continuing our current trends vs changing course.

One of the best ways to determine how well models predict the climate (how “skillful” they are, in the jargon) is to see how past models predicted later climate change. This has been done multiple time. Here is a 2019 review of 17 climate models. They found:

We find that climate models published over the past five decades were skillful in predicting subsequent GMST changes, with most models examined showing warming consistent with observations, particularly when mismatches between model-projected and observationally estimated forcings were taken into account.

That last bit means the difference between projections of CO2 emissions vs actual CO2 emissions. The bottom line is that the model basically work, and they are continuously getting better as they incorporate the latest science. Computers are also getting more powerful, allowing for more complex climate simulations. But still you will frequently hear things like, “Maybe it’s the sun. All those scientists never thought of that.”

A recent commenter brought up one I had not yet heard – neutrinos warming up the inner Earth and all that heat rising to the surface through ocean vents. The commenter also explicitly states that climate models do not include natural sources of warming. Sure, there is geological sources of heat that affect the climate – and climate scientists are well aware of this factor.  Geothermal ocean heating is a known factor. It has a relatively small magnitude, and there is no reason to think that it has suddenly changed in the last 50 years. But the notion that climate scientists are not away of geothermal heating is just silly.


CO2 causes greening which absorbs excess CO2.

The basic notion that increases in CO2 concentrations in the atmosphere increases plant growth is true. CO2 is an important metabolite for plant growth. But the full story is more complicated, and turning this into a net benefit from climate change is simply not true. The increase in productivity does occur, but also results in a depletion of other nutrients, such as nitrogen, from the soil. It therefore is not sustainable in natural settings (i.e. not farmland where nutrients can be added). Also, plants are not adapted to higher CO2 levels and so they get diminishing returns from higher CO2.

But the main reason this is not a valid argument against the need to mitigate climate change, is that it ignores all the other effects. Increasing temperature and worsening droughts are bad for agriculture. Shifting climate also shifts growing zones away from where they are currently located. Also, the effect on different crops varies. Wheat will benefit, but corn production will drop, while some other crops will see no immediate change. This will be highly disruptive to agricultural infrastructure. Also, as warming continues, the effects of increased temperature and drought will overwhelm any positive effect from CO2.

The notion that plants will simply absorb any excess CO2 is also profoundly naive and just factually incorrect. There is a carbon cycle, which already includes plants absorbing CO2. But plants don’t just sequester CO2, they absorb and emit CO2 in a continuous cycle. The more CO2 there is in the system, the more CO2 there will be in every part of the system (plants, the ocean, the atmosphere, in minerals, etc.). This is already accounted for in climate models.

But sure, we should maximize biomass to help mitigate CO2 release, and stop doing things like cutting down the rainforest. But this is not going to compensate for the 35 billions tons of CO2 humans release every year.







No responses yet

Nov 11 2022

COP27 and the State of the Climate

Published by under General Science

So how are we doing? We’ve been talking about mitigating climate change for literally decades, and the world is currently meeting for the 27th climate summit, COP27. It feels like all we get is dire news about how miserably we are collectively failing to do anything about climate change, but the real news is actually mixed. In some ways we are better off then we were 1-2 decades ago, in others things are worse. Let’s review.

The good news is that the projection of how much the climate will warm on average is better today than it was a decade ago. Warming is measured as the average temperature increase above pre-industrial levels, usually expressed in Centigrade. Right now we are at 1 degree C above baseline. A decade ago if you looked at projections as to where we were headed, the “business and usual” projections were for 3-4 degrees C by the end of the century. Today, the same projections predict only about 2.4 degrees. Business as usual means that we keep going the way we are, including already funded pledges from countries for action to mitigate CO2 release.

It’s also not hard to do better than 2.4. A recent study published in nature extrapolates climate change for a range of scenarios, starting with what they call nationally determined contributions (NDC), which are essentially pledges as of COP26. This is one step beyond business as usual because it includes all pledges, even those not yet funded. They also consider peak warming and warming by 2100. If we reduce greenhouse gas (GHG) emissions temperature will eventually come down, as the effect of GHGs is not permanent. The NDC scenario has peak warming of about 1.8 degrees, but then coming down to about 1.7.

They also include a range of models, from various degrees of NDC to NDC+ and NDC++, including greater mitigation efforts sooner. In the NDC+ range warming will peak at 1.6 but then come down to 1.4. In the most aggressive scenario, NDC++ we can theoretically limit peak warming to <1.5 C, which is the stated goal of the Paris agreement. This entire range of scenarios, even just the NDC where we keep already made pledges, is not horrible. It keeps peak warming below the 2.0 C level where we think the inflection point is for irreversible (on a human timescale) negative consequences.

Continue Reading »

No responses yet

Nov 10 2022

Facial Characteristic, Perception, and Personality

Published by under Neuroscience

A recent study asked subjects to give their overall impression of other people based entirely on a photograph of their face. In one group the political ideology of the person in the photograph was disclosed (and was sometimes true and sometime not true), and in another group the political ideology was not disclosed. The question the researchers were asking is whether thinking you know the political ideology of someone in a photo affects your subjective impression of them. Unsurprisingly, it did. Photos that were labeled with the same political ideology (conservative vs liberal) were rated more likable, and this effect was stronger for subjects who have a higher sense of threat from those of the other political ideology.

This question is part of a broader question about the relationship between facial characteristics and personality and our perception of them. We all experience first impressions – we meet someone new and form an overall impression of them. Are they nice, mean, threatening? But if you get to actually know the person you may find that your initial impression had no bearing on reality. The underlying question is interesting. Are there actual facial differences that correlate with any aspect of personality? First, what’s the plausibility of this notion and possible causes, if any?

The most straightforward assumption is that there is a genetic predisposition for some basic behavior, like aggression, and that these same genes (or very nearby genes that are likely to sort together) also determine facial development. This notion is based on a certain amount of biological determinism, which itself is not a popular idea among biologists. The idea is not impossible. There are genetic syndromes that include both personality types and facial features, but these are extreme outliers. For most people the signal to noise ratio is likely too small to be significant.  The research bears this out – attempts at linking facial features with personality or criminality have largely failed, despite their popularity in the late 19th and early 20th centuries.

Continue Reading »

No responses yet

Next »