You Think It's Hot Now? Just Wait.

Figure from Steffen et al.: a global map of potential

tipping cascades. The individual tipping elements are

color-coded according to estimated thresholds in global

average surface temperature (tipping points).

It's getting hotter all over the planet.

This week the temperature in Bar Harbor, Maine, reached 91° F (32.8° C). In my 20 years vacationing here, this is easily the hottest weather I've ever experienced.

Up and down the U.S. east coast, cities are sweltering, and temperatures out west are even hotter, with California seeing all-time high temperatures, including the hottest July on record in some areas, which has fed damaging fires across the state. Death Valley is always hot, but this week has been crazy, with temperatures on August 7 reaching 122° F (50° C).

At the same time, Europe is baking under a "heat dome" that has brought unprecedented high temperatures, including 45° C (113° F.) in Portugal. It's so hot that people aren't even going to the beach.

Global warming is here, folks. I know we're supposed to call it "climate change," because it's much more complex than simply warming, but warming is one of the most obvious consequences.

And yes, a single heat wave doesn't prove anything, and weather is not the same as climate. I know. But a just-released study from Oxford University found that climate change made this summer's heat wave in Europe twice as likely.

And now, a new study published last week in the Proceedings of the National Academy of Sciences, says it could get much, much hotter if we don't do something about it. In this paper, an international team of climate scientists led by Will Steffen and Hans Joachim Schellnhuber explain that, thanks to human activities, the planet is well on its way to a "Hothouse Earth" scenario.

In a Hothouse Earth, global average temperatures would rise 4–5° C (7–9° F) and sea levels will rise 10–60 meters (33–200 feet) above today's levels. This would be catastrophic for many aspects of modern civilization. Many agricultural regions would become too hot and arid to sustain crops, making it impossible to feed large swaths of humanity. Low-lying coastal areas would disappear or become uninhabitable without massive engineering efforts, displacing hundreds of millions of people. As Steffen et al. put it:

"The impacts of a Hothouse Earth pathway on human societies would likely be massive, sometimes abrupt, and undoubtedly disruptive."

That's putting it mildly.

One reason this scenario is happening, as the study explains, is that we are very close to "tipping points" beyond which certain changes cannot be stopped. (We may have already passed some of them.) These include losing the Arctic ice cap in the summer, and losing the Greenland ice sheet permanently: because they are basically white, these massive expanses of ice serve as giant reflectors to send much of the sun's heat back into space. Without the ice, the darker planet surface absorbs far more heat, creating a positive feedback effect. Another example is the melting of the permafrost, land that has been frozen for thousands of years and that contains a great deal of carbon in the form of methane. Once that methane is released, it will create further warming.

We are also likely to lose the Amazon rainforest, all of our coral reefs, and huge swaths of boreal forests. (See here for a global map of these tipping points.)

If this seems grim, Steffen and colleagues point out that we still have time to avoid it. They propose that societies must act collectively to create a "Stabilized Earth" at no more than 2° C above pre-industrial levels, which is possible but not easy:

"Stabilized Earth will require deep cuts in greenhouse gas emissions, protection and enhancement of biosphere carbon sinks, efforts to remove CO2 from the atmosphere, possibly solar radiation management, and adaptation to unavoidable impacts of the warming already occurring."

None of this is beyond our abilities. We know what we need to do, but it requires large-scale, coordinated action that many governments must agree on if it's to have an impact. Unfortunately, humans (and our governments) tend to do nothing until faced with an emergency, and the tipping points leading to a Hothouse Earth may not look like emergencies, not at first. For example, Arctic sea ice has been declining steadily for 25 years or more, but because few people are aware of this (and even fewer experience it first hand), it doesn't seem urgent. Yet it is.

So perhaps this summer's heat wave can serve as a wake-up call that we need to pay more attention to our planet's health. Otherwise it's going to get a lot hotter.

The new Star Trek series gets biology terribly, terribly wrong.

The new Star Trek: Discovery series is based on a massive scientific error. Can it survive?

It didn't have to be this way. Those of us who have followed Star Trek through its many TV series and movies, including the excellent trio of recent moves (2016's Star Trek Beyond is the latest) were eager to jump on board the newest show, Star Trek: Discovery.

Despite some rather uneven acting in the pilot, I was willing to give it a chance. So were millions of other Star Trek fans.

But alas, the writers have stumbled into a scientific error so egregious, and so entangled in the entire plot line, that I fear the new Star Trek cannot recover. (Note: a few mild spoilers ahead.)

Episodes 4 and 5, released on October 8 and 15, revealed that the USS Discovery, the ship that the series revolves around, has an advanced form of transport that allows it to travel anywhere in the universe instantaneously. Unlike all previous Star Trek transport tech, this one uses a biological mechanism, based on mushrooms.

Yes, you read that right. The DASH (Displacement Activated Spore Hub) drive uses mushroom spores as its power source. They've discovered a special fungus whose root system extends "throughout subspace" all over the galaxy. Using spores from this fungus, the ship can jump into subspace (or something like that) and jump out somewhere else in real space, light years away, in a matter of seconds. As bizarre and this sounds, the worst is yet to come.

To power its DASH drive, the Discovery maintains a large greenhouse full of spore-producing mushrooms. (Mycologists might love this, but how big a fan base can they be?) The problem for the Discovery, in the first few episodes, is that the experimental drive will only let them jump short distances.

Then they discover the tardigrade. Tardigrades are a real thing: they are microscopic animals, only 0.5 millimeters long, that live all over the planet. Here's a picture of one:

Electron microscope image of Milnesium tardigradum,
from E. Schokraie et al., PLoS ONE 7(9): e45682.

They are also surprisingly cute for a microscopic animal, and they are colloquially known as water bears, moss piglets, or space bears. "Space bears" comes from their ability to survive in extreme environments, possibly including interplanetary space.

Star Trek Discovery's tardigrade is, shall we say, rather different. It looks a bit like the picture shown here, but it's the size of a large grizzly bear, incredibly strong, and extremely fierce. On the show they call it a "giant space tardigrade."

But that's not all. Thanks to a unique biological property that the show's writers apparently misunderstood, the space tardigrade can access the mushroom network to travel throughout the universe, wherever and whenever it chooses.

Here's how the space tardigrade accomplishes this remarkable feat of interstellar travel, as explained by Michael Burnham, the show's central character (in Episode 5, "Choose your pain"):

"Like its microscopic cousins on Earth, the tardigrade is able to incorporate foreign DNA into its own genome via horizontal gene transfer. When Ripper [the space tardigrade] borrows DNA from the mycelium [the mushroom], he's granted an all-access travel pass."

And just like that, not only the tardigrade but the entire spaceship jump across the galaxy. Is this sounding a bit crazy? It should.

Horizontal gene transfer (HGT) is a real thing. It's a process through which bacteria sometimes take up DNA from the environment and integrate it into their own genomes. Animals can't do HGT, but rather infamously, a paper was published in December 2015 that made the bold claim that tardigrades had a unique ability to absorb all kinds of DNA. That paper was instantly controversial in the scientific community, and not surprisingly its findings were being disputed in the Twittersphere within days of its appearance. Surprisingly, the same journal (PNAS) that published the bogus HGT claim published a second paper just a few months later showing that tardigrades do not absorb foreign DNA into their genome. That plus a third paper showed that the original paper had mistakenly identified contaminating DNA as part of the tardigrade's own genome. This rapid correction of the record was a win for science; I've used this example to demonstrate to my undergraduate class how sloppy science (the first paper) can lead one astray.

So: a minor scientific controversy, quickly debunked.

Until, that is, one of the Star Trek writers got their hands on it. Apparently one of them heard the tardigrade story, perhaps someone who'd had a bit of biology in college (I'm guessing here), and got so excited that they turned it into a wildly implausible premise for an intergalactic space drive.

The idea of using horizontally transferred DNA for space travel is so nutty, so bad, that it's not even wrong. Even if tardigrades could absorb foreign DNA (they can't), how the heck is this supposed to give them the ability to tap into the (wildly implausible) intergalactic spore network? DNA that's been taken up through HGT isn't connected to the source any longer. This is no more plausible than asserting that people could connect to the mushroom network by eating a plate of mushrooms. And how would the space-traveling tardigrade take the entire ship with it? Are we supposed to assume it's creating some kind of mushroom-DNA field?

Star Trek has had faster-than-light warp drives for 50 years. Although physically implausible, warp drive isn't laughably ridiculous. The DASH drive is.

And now the entire series seems to be based on a combination of magic (an intergalactic mushroom network in subspace) and scientific errors (horizontal gene transfer by tardigrades).

I can't watch this nonsense. I'm willing to suspend disbelief for the sake of a good story (warp drive!), but I can't accept obviously bogus claims. I don't know how the Star Trek writers can get themselves out of this one, but if they don't, then Star Trek Discovery is finished. If they're reading this, here's my plea: ditch the DASH drive and find something to replace it–and for god's sake, hire a competent science consultant.

PNAS and the eHarmony dating site: a perfect match

Well, here's a shocker.  eHarmony, the online dating service, commissioned a survey that found out that couples who get married after meeting online are more satisfied than other couples.

I'm sure there's no bias in that survey.

But here's another shocker: a leading scientific journal just published the eHarmony survey as a bona fide scientific study.  The lead author is a consultant to eHarmony (and a former advisory board member) and another author is eHarmony's former research director, Gian Gonzaga.  According to the published paper, Gonzaga designed the study.

The journal in question is the Proceedings of the National Academy of Sciences (PNAS), a high-profile journal that is published by the prestigious U.S. National Academies.

Why would PNAS publish an article that is basically an advertisement for eHarmony.com?  I'm sure the editors at PNAS would argue that it's a well-executed scientific study, but they sure got lots of publicity, with articles in the Los Angeles Times, USA Today, and Nature, not to mention a short piece in Forbes. (And yes, I'm doing it too.) A cynic might point out that both eHarmony and PNAS got what they wanted.

But what about the study itself?  Well, let's take a look.  The study, titled "Marital satisfaction and break-ups differ across on-line and off-line meeting venues," is based on a survey of 19,131 people who got married between 2005 and 2012.  6,654 of these people met online, 35% of the total, which is a surprisingly high percentage.

The headline result is the claim that couples who met online have "higher marital satisfaction." People who met this way reported a satisfaction of 5.64, on average, versus 5.48 for those who met offline.  That's a very small absolute difference, but with such large numbers in the survey, even this small difference is, in a narrow technical sense, statistically significant. The satisfaction scale ranged from 1 "Extremely Unhappy" to 7 "Perfect."  So all this fuss and publicity is over a difference between 5.5 and 5.6 in a survey.

But the higher average satisfaction might have nothing to do with how the couples met.  In my reading of the study, it seems much more likely that other factors explain the difference.

Several things are immediately obvious when one looks at the composition of the online versus offline couples.  The online couples are significantly older, wealthier, and more educated: for example, 40.5% of those who met their spouse online reported an income of $100,000 or more, compared to just 26.1% of the offline couples.  These factors alone could explain the difference in marital happiness.

The authors claim that they controlled for all of these confounding factors, and that the marital satisfication score was still significantly higher for online couples. Alas, they don't provide enough details, even in their supplementary data, to evaluate this claim. I guess we're just supposed to trust them. (Note: I believe them when they say they controlled for these variables.  I'm just not sure precisely how they did it, or if the control function really eliminated all bias.) They did recruit two independent statisticians as co-authors, which is supposed to assure us that they were unbiased. But these steps wouldn't eliminate bias that might have crept in earlier, when the eHarmony-sponsored survey was being conducted.

The article also reports the marital satisfication score of specific online dating sites. Guess which one scores the highest? That's right: eHarmony.  Why am I not surprised?

At the end of the article, the authors speculate about why couples who met online might have more satisfaction in their marriages.  (This assumes, of course, that the effect is real.)  They suggest that

"among on-line dating sites, it is also possible that the various matching algorithms may play a role in marital outcomes."  

There it is!  That's the conclusion that eHarmony wanted.  I think they got their money's worth.

In many ways, this study seems like the often-criticized studies funded by drug manufacturers that find small but significant benefit for the sponsors' drugs. Certainly there's a difference here, in that the only result is that someone might be convinced to try an on-line dating site, which might not be harmful at all.

It seems that eHarmony has found another perfect match: PNAS and eHarmony.com.

(Note: The authors did make all their raw data available, a feature that is still quite rare in scientific publishing.  They deserve kudos for doing so.  I've long advocated for more openness in data release and these authors have done the community a service by releasing theirs.)