A Blog by Robert Krulwich

Noah (and his ark) Updated, Improved for Our Time

Instead of the Noah you know, the one who built the ark, sheltered all those animals, sailed for 40 days and 40 nights and got to see God’s rainbow, instead of him, I want you to meet a new one. An updated version.

This Noah shows up in a tough little essay written by Amy Leach, of Bozeman, Montana, who knows her science, knows there’s a flood coming—a flood of humans, seven billion and counting, already swamping the Earth, crowding the land, emptying the sea, and her more modern Noah—informed, practical, not inclined to miracles—has a different plan. He announces,

water color painting with text reading ''unfortunately, animals. we are not going to be able to bring all of you with us this time.''
Illustration by Robert Krulwich

The old Noah, you may remember, squeezed eight humans (wife, kids, their spouses) and at least two of every critter, big and small, onto his crowded ship. But the new Noah, being more practical, feels he can winnow a little. “Everybody” is a lot of animals, more than you know. Back in the day, Amy Leach writes,

pink watercolor background with two drawings of frogs peeking up over the text, which talks about what it would be like to bring two of every creature onto noah's ark
Illustration by Robert Krulwich

And, honestly, (I’m thinking to myself), if the world lost a scorpion or two, would anyone notice? Or want them back? And blotchy toads, biting little flies—some animals are hard to keep going on a tight, crowded ship. On the last voyage, dormitory assignments were beyond difficult.

And all those supplies? Amy Leach writes how the first Noah would have had …

a yellow watercolor background covered with text about collecting food for animals
Illustration by Robert Krulwich

This doesn’t mean we don’t care, new Noah says to the animals. We definitely, absolutely want to bring a bunch of you with us. But, we’ve got to be practical.

Even if our ark has grown to the size of a planet, carrying everybody through is not going to be logistically possible, which is why, he says,

blue watercolor background with black text on it about being in charge of a future noahs ark where not all animals are included
Illustration by Robert Krulwich

And anyway, that first Noah? He lived in a different age, a time they call the Holocene, before humans began to dominate and crowd out the other species. Back then, there weren’t as many people. And there were more kinds of animals, closer by, hiding in the woods, clucking in the yard, so the world was more various then, more intimate, more riotous, and thinking about it (a little wistfully, if only for a moment), the new Noah quietly recalls that on that first ark …

yellow watercolor background with text on top related to how noahs ark would be different today than it was in the Old Testament
Illustration by Robert Krulwich

And now, animals, it’s time for many of you to step away. You’ve had your unruly eons. They were wild, unplanned, noisy, great fun. Natural selection ran the world. Crazy things happened. Those were good times, Amy’s essay concludes …

blue watercoor with black text on top that reads''But the future belongs to us.''
Illustration by Robert Krulwich

Amy Leach is a writer living in Bozeman. Her collection of very short pieces—about jellyfish, beaver, salmon, plants that go topsy turvy and stand on their heads—are collected in a wonderful little book called “Things That Are.” In this column I do to Amy what the new Noah is doing to our planet: I edited her down, sliced, diced, slimmed (lovingly, I hope), trying to give you a taste for her fierce, crazy prose. But like the planet, she’s wilder in the original, so I hope you go there and sample the unedited version.

A Blog by Carl Zimmer

Whales on the Wrong Side of the World

In May 2010, a whale showed up on the wrong side of the world.

A team of marine biologists was conducting a survey off the coast of Israel when they spotted it. At first they thought it was a sperm whale. But each time the animal surfaced, the more clearly they could see that it had the wrong anatomy. When they got back on land, they looked closely at the photographs they had taken and realized, to their shock, that it was a gray whale. This species is a common sight off the coast of California, but biologists had never seen one outside of the Pacific before.

Aviad Scheinin, one of the marine biologists on the survey, posted the news on the web. “Nice Photoshopping,” someone replied.

Three weeks later, Scheinin got one more bit of news about the whale. It was photographed off the coast of Spain, having traveled 1864 miles. Then it disappeared.

After three years, a second gray whale appeared off the coast of Namibia in 2013. Comparing photographs, scientists could see that it was a different animal than the one that visited Israel. After lingering along the coast of Namibia for a month, the whale vanished.

These two sightings have left whale experts startled. In an interview with the Orange County Register, one scientists compared the feeling to walking down a street in California and seeing a giraffe.

But according to a new study, these two whales may be a hint of the new normal. Gray whales may be poised to move into the Atlantic, because we’re opening a path for them through the Arctic. But it’s not an unprecedented invasion. To some extent, it’s a case of history repeating itself.

A feeding gray whale. Davis Melzer/National Geographic
A feeding gray whale. Davis Melzer/National Geographic

California’s gray whales give birth each winter in the lagoons of the Baja Peninsula. Then they migrate up the west coast to the Arctic for the summer. They power these tremendous migrations–the longest of any mammal–by ramming their mouths into the sea floor and filtering out tiny crustaceans from the sediment. When they rise back up to the ocean’s surface, they bring with them wide muddy plumes.

Aside from the California population, the only other known population of gray whales is a small group of animals on the western side of the Pacific. But scientists have had hints for a long time that gray whales might once have lived in the Atlantic as well.

In the eighteenth century, whaling ships off the coast of New England chased what naturalists at the time referred to as “scrag whales.” Their descriptions of scrag whales are a match for gray whales. In the 1800s, fossil-collectors picked up whale vertebrae on the coast of England. Many years later, paleontologists found that the bones belonged to gray whales.

These findings suggested that gray whales once lived in both the Atlantic and Pacific. That’s the case today for other filter-feeding whales (known as baleen whales). Species such as humpback whales and fin whales split into Atlantic and Pacific populations a couple million years ago and have remained distinct ever since.

Scientists suspected that gray whales spread across both oceans millions of years ago. Later the planet has cooled, creating an icy Arctic that formed a barrier between the two populations. The gray whales of the eastern Pacific would migrate as far north as they could manage before reaching the ice, and then head back south. Presumably the Atlantic gray whales had a similar migration. Isolated for millions of years, the gray whales of the two oceans might well have evolved into different species. If that were true, then whalers must have driven the Atlantic gray whale species to extinction, while sparing the Pacific one.

Engraving of gray whale by Charles Scammon, 1872
Engraving of gray whale by Charles Scammon, 1872

To explore the mystery of these whales further, a team of researchers has taken a fresh look at the fossils of Atlantic gray whales. Instead of just observing the anatomy of the bones, the scientists probed them for ancient DNA. They also measured the amounts of carbon isotopes in the bones to determine their age. The fossils ranged in age from just a few hundred years old to over 50,000 years old.

The scientists were able to use all this information to draw a family tree of gray whales, showing how Atlantic and Pacific gray whales were related to each other. They could also estimate how long ago the branches split apart.

The gray whale’s tree turned out to be different from those of other baleen whales. The Atlantic and Pacific populations of gray whales are not a pair of ancient, distantly related lineages. Instead, the Atlantic gray whales are actually made up of at least four different lineages. And each of the Atlantic branches is most closely related to a different branch of Pacific gray whales.

In other words, Pacific gray whales have periodically swum across the Arctic Ocean and into the Atlantic and established populations that survived for millennia. The scientists can identify several waves of immigration. One took place about 79,000 years ago, and then three others happened more recently, between about 10,000 and 5,000 years ago.

The timing of these colonizations is telling: the whales appear to have moved into the Atlantic whenever it was warm enough for them to get through. Between 135,000 and 70,000 years ago, the climate was so warm that the Bering Strait was open year-round, giving gray whales access to the Arctic Ocean. Once these gray whales got to the Atlantic, they then endured until at least 5,000 years ago.

Then a new ice age began. Glaciers grew, sea levels dropped, and gray whales could no longer get across the Arctic. Sixty thousand years passed before the ice age ended with a sudden burst of warmth. And that’s when new waves of gray whales came into the Atlantic. The Arctic then cooled somewhat, closing the door once more.

Now we are warming the Arctic again by releasing greenhouse gases into the atmosphere. If history is any guide, global warming in decades to come may open up the Arctic for Pacific gray whales, some of whom may wander off their regular migrations and end up in the Atlantic.

These gray whales will encounter an ocean far different from the ocean their cousins arrived in thousands of years ago. They will have to deal with busy shipping lanes where they may get killed in collisions, along with oil drilling and industrial fishing operations. On the other hand, the authors of the new study predict that the gray whales will have lots of good habitat to live in. As sea levels rise, there will be more shallow shelves where the whales can scoop up mud to find food. Today, a gray whale outside the Pacific seems like a case of Photoshopping. Soon, however, we may be photoshopping a whole ocean of whales.

A Blog by Brian Switek

Reinventing the Mammoth

The first groaner of the TEDxDeExtinction conference cropped up less than an hour into the program.  Paleontologist Michael Archer was on stage, wrapping up his talk on possibly recreating the gastric brooding frog and the thylacine – two species totally lost from Australia in recent time. Archer laid out the technological particulars of the plans, as well as where the animals might live, but at the end he took a turn for the transcendentalist in justifying the difficult endeavor to resurrect these creatures. Since our species played a prominent role in wiping out both species, Archer argued, we have an obligation to “restore the balance of nature that we have upset.” If I had brought a flask with me, I might have taken a strengthening sip of whiskey right then.

There is no such thing as “the balance of nature.” If sifting through the fossil record has taught me anything, it’s that change is the rule. Balance is only a temporary illusion created by the difficulties of envisioning life on a geological scale. That, and quite a few conversations with practically-minded ecologists and biologists, means that I’ve become a bit allergic to snuggly phrases that are often trotted out to emphasize the inherent goodness of nature – whatever “nature” means – in a way that suggests we can simply restore the complexity of life to a stable state that the ghosts of Thoreau, Emerson, and Muir would honor us for. And the irritation of that line kept with me throughout the rest of the day. Perhaps the closing appeal to the balance of nature was a trifling throwaway, yet that one line underscored the problematic nature of the major proposal the assembled speakers and guests had been called to consider – that we can, and should, resurrect lost life to take some of the tarnish off our ecological souls. The concept falls under the banner of “de-extinction.”


A Blog by Carl Zimmer

The Sooty Greenhouse: My New Story For Yale Environment 360

Soot from a diesel-fueled truck. Image: EPA/ Wikipedia

The soot we loft into the sky is a remarkably mysterious player in the climate game. At Yale Environment 360, I report on the most comprehensive study yet of soot, which reveals that it’s trapping huge amounts of heat. Yet getting rid of all the soot we put in the atmosphere wouldn’t change the climate much. Check out my piece for the solution to that paradox.

A Blog by Carl Zimmer

Life Under A Faint Sun

If you could have looked up at the sky 4 billion years ago, you would have seen a sun much dimmer than ours today. And if you looked down at the Earth’s oceans, you would have seen an expanse of bobbing waves.

That’s a problem–a simple one, but a big one. And scientists have been wrestling with it for fifty years.

The brightness of the sun over the past 4.5 billion years. From Feulner 2011 http://arxiv.org/abs/1204.4449

The evidence for these two facts about the early Earth–a dim sun and liquid oceans–were already strong in the 1960s. Astronomers have compared our sun today to other stars of different sizes and ages, and they’ve been able to reconstruct much of its history. The sun started out about 70% as bright as today. It slowly grew brighter; even two billion years ago (2.5 billion years after the Earth formed), the sun was still just 85% as bright as today.

On its own, the faint young sun could not have kept the Earth from freezing over. And yet there are lots of signs in ancient rocks that the Earth was wet. Tiny crystals dating back over 4 billion years have a chemistry that required liquid water. Ancient rocks known as pillow lavas must have formed as molten Earth oozed out into sea water.

As early as the mid-1960s [pdf], scientists realized that these two lines of evidence posed a paradox: what is now known as the Faint Young Sun Paradox. It was a serious problem that required serious thought. It didn’t just mean that the evidence from geology and astronomy wasn’t meshing together. It also added a puzzle to the rise of life on Earth. Life would have had a hard time getting started on a planet of ice.

In 1972, Carl Sagan and his colleague at Cornell George Mullen proposed a solution to the paradox: the greenhouse effect. When radiation from the sun hits the Earth, some of it bounces back into space, but some of it lingers, thanks to heat-trapping gases in the atmosphere. The early Earth would have released gasses from its rocks, creating the first atmosphere. If it had the right chemistry, Sagan and Mullen argued, it might have been able to keep the Earth warm enough to melt ice. They suggested ammonia as a plausible heat-trapper on the young planet.

Unfortunately, ammonia turned out to be a bad solution. Other scientists figured out that ultraviolet rays from the sun would have destroyed any built up ammonia in the atmosphere in less than a decade. That’s not much of a defense against the deep freeze.

But ammonia is not the only greenhouse gas in the game. Today, carbon dioxide and methane are two important molecules keeping our planet warm (and warmer). Scientists have tried for years to narrow down the possible range of the two gases on the early Earth. It’s a very tricky puzzle, because scientists know that there are many factors that can influence their concentrations. And there were factors on the early Earth that we don’t experience today, such as a fairly steady bombardment of comets and giant meteors. Making matters even more complicated, greenhouse gases are not always greenhouse gases. Once the proportion of methane to carbon dioxide gets too high, it produces an organic haze that bounces radiation back into space, cooling the planet.

The consensus today is that methane and carbon dioxide may have warmed the early Earth a fair amount, but not enough to solve the paradox. So scientists are looking at other possible factors. Clouds may have helped. The early Earth rotated quickly through a 14 hour day, which may have changed how the oceans circulated–and thus how they trapped heat. But wide scope still remains for more ideas.

Today in Science, Robin Wordsworth and Raymond Pierrehumbert of the University of Chicago offer two new players to the Faint Young Sun game. They argue that a pair of molecules that have hitherto been neglected–hydrogen (H2) and nitrogen (N2)–could have made up a lot of the difference between the sun’s feeble glow and the Earth’s life-sustaining warmth.

There’s hardly any molecular hydrogen in our atmosphere today, because it easily skips out of the atmosphere into space. But Wordsworth and Pierrehumbert argue that such an escape would have been much harder for hydrogen on the early Earth, partly because it couldn’t get as big of a boost from ultraviolet rays from the sun. They estimate that hydrogen could have made up as much as thirty percent of the atmosphere. They also argue that nitrogen levels were three times higher than today.

On their own, nitrogen and hydrogen don’t do a very good job of trapping the sun’s heat. But when they crash into each other, their structure briefly changes, allowing them to absorb radiation. Wordsworth and Pierrehumbert built a model of a hydrogen and nitrogen-rich early atmosphere and found that as the molecules crashed into each other, they soaked up a lot of heat–enough, they argue, to heat the planet 10 to 15 degrees centigrade. That would go a long way to resolving the Faint Young Sun Paradox.

This new study probably won’t bring the fifty-year debate to a halt. In an accompanying commentary, James Kasting at Penn State argues that nitrogen is too heavy to absorb much radiation, even in the midst of a collision. Instead, Wordsworth and Pierrehumbert are stocking the cabinet that aspiring chefs can raid when they are trying to come up with new recipes for the early Earth.

If hydrogen and nitrogen do turn out to be part of the answer to the Faint Young Sun Paradox, they may have some fascinating implications about life on Earth–and elsewhere. Molecular hydrogen is fine dining for certain types of microbes known as methanogens. As soon as they evolved, they would have been able to feast on a sky full of hydrogen. By devouring the Earth’s protective hydrogen, they might have cooled the planet until it experienced its first glaciers. And beyond Earth, we may need to expand our concept of what kind of planet could support life. If they turn out to have a rich supply of hydrogen and nitrogen, they may offer a toasty incubator for aliens.

Image: “The ‘Fighting Temeraire’ Tugged to her Last Berth to be Broken up” by William Turner, via Wiki-Paintings

A Blog by Carl Zimmer

Climate Relicts: My new story for Yale Environment 360

I’m among the 800,000 people in Connecticut without power thanks to Irene, so I won’t be blogging much for the foreseeable future. But before I get to other matters like dragging branches around, let me point you to my latest piece for Yale Enivronment 360. I take a look at a new concept called the climate relict. Around the world, there are pockets of plants and animals living hundreds of miles away from their main species ranges. They were left behind in refuges at the end of the last Ice Age, as others moved towards the poles in response to the warming climate. As the climate now warms even more, climate relicts have a lot to teach us about how to manage biodiversity. Check it out.

[Update: bad link to Yale e360 fixed]

A Blog by Carl Zimmer

Warming up, turning sour, losing breath

We like to think about risks with simple arrows. If A, then B. If wildfires break out, some people may lose their homes. If an oil pipeline leaks, it can pollute the soil. But if you put a wildfire and an oil pipeline leak together in the same place at the same time, the whole becomes a lot nastier than sum of its parts.

The world’s oceans face three different major risks from the carbon that we put in the air. That extra carbon (9.2 billion tons in 2009 alone) is acidifying the ocean, warming it, and possibly even stripping it of oxygen. I’ve written about all three of carbon’s impacts in recent years, but I’ve chosen to write about them independently. That’s standard practice in journalism: you select one narrowly defined topic and explore it as deeply as you can in the space you’ve got. But these three impacts are all hitting the same ocean all at once, and they’re interacting with each other as they do. In a new paper in the Philosophical Transactions of the Royal Society, the environmental scientist Nicolas Gruber warns that this “triple whammy” could prove to be more than the sum of its parts–especially in parts of the world where all three may hit particularly hard, such as the waters off the coast of California.

Over the past 250 years, the ocean has soaked up about 30 percent of all the carbon dioxide we’ve released. When carbon dioxide dissolves into sea water, it lowers the ocean’s pH. This process is known as ocean acidification, which is a bit of misnomer. After all, the ocean’s pH, which has dropped from 8.2 to 8.1 over the past two centuries, is still officially alkaline (acids have a pH below 7). But arguing over a label for this transformation is a pointless distraction from the magnitude of what we’ve done. The pH scale is logarithmic, meaning that sea water with a pH of 8 contains ten times more positively charged atoms than sea water with a pH of 9. We’ve raised the total number of hydrogen ions in the ocean by thirty percent. That’s a lot of ions.

If the rate of carbon emissions continues to rise, we will add even more. Under the most optimistic scenarios, the pH will drop to 7.9 or 7.8. All those extra ions will alter the lives of marine organisms. It will be harder for some animals to form calcium carbonate skeletons, for example. A lower ocean pH will alter photosynthesis as well, along with the growth of some fishes and other animals. While scientists have a clear understanding of the chemistry of ocean acidification, they’re only beginning to learn about the possible biological impacts. But the National Research Council warned last year that ocean acidification could have a big impact on people as well, as it slams the fisheries and aquaculture on which we increasingly depend.

The oceans can only sop up a fraction of the carbon dioxide we put in the air. As a result, the concentration of carbon dioxide in the atmosphere has steadily risen. And that CO2 has been trapping some of the sun’s energy, and thus warming the atmosphere. The oceans have warmed up as a result; the surface of the sea has warmed .7 degrees C over the past century. As the oceans continue to warm, the extra heat will have its own impact on life. It will allow some species to thrive in some places; it will shift the ranges where others can survive. And it will put stress on the species–such as corals–that are pretty much stuck in one place.

Global warming may also strip oxygen from the oceans. Warm water holds less dissolved oxygen, and as the ocean heats up, scientists expect that the circulation of water from its top to its bottom will slow down. As oxygen gets used up in the deep ocean, there will be less coming down to replace it. (Fertilizer run-off and other pollution on land is also producing low-oxygen dead zones in the Gulf of Mexico and elsewhere.)

Scientists are only starting to come to terms with how we’re altering the oxygen in the ocean, so the details are still fuzzy. They have yet to measure the world-wide trend of ocean oxygen, for instance. But they have managed to measure declines in some regions of the sea. There’s also an oddly high level of oxygen in the atmosphere, which may be coming from the ocean.

In his new paper, Gruber surveyed the projections over the next century for all three factors–temperature, pH, and oxygen–around the world. These projections spread across a wide range, in part because there’s still a lot of uncertainty in the science, and in part because the future of carbon depends on what our species chooses to do in the next few decades. But some patterns do look pretty clear, as illustrated in two figures I adapted from Gruber’s paper:

The warming of the oceans will not be uniform, for example. The biggest warming will come in the Arctic, as the sea ice disappears and can no longer bounce much of the incoming radiation away. It’s possible that the rise in termpature will cause a boom in photosynthetic plankton, which will support a bigger ecosystem. But the warmer temperature may speed up the chemistry of all life in the Arctic ocean, and much of the carbon drawn down by a booming Arctic ecosystem may quickly end up back in the atmosphere. What’s more, the surface of the Arctic ocean may mix even less with the deep ocean. If that happens, then less carbon dioxide will be stored in the deep ocean. Both changes could speed up the accumulation of carbon in the atmosphere.

Acidification will also hit some parts of the world harder than others, thanks to the temperature and chemistry of each region. Gruber warns that it will become seriously difficult for animals to form calcium carbonate skeletons in the Arctic Ocean surface waters in a decade. The ocean around Antarctica may cross this threshold in the second half of this century. By the end of the century, this acidified zone will spread into the North Atlantic and North Pacific as well. Corals, shellfish, and other organisms that depend on calcium carbonate for their skeletons could all be affected in these regions.

Projecting changes in oxygen is a much rougher science, Gruber warns, but all the models foresee a worldwide drop of somewhere between 1 and 7 percent of the ocean’s oxygen in the next century. Again, however, the real story is in the regional differences. In much of the world’s oceans, the oxygen levels may barely drop at all. But in some places, oxygen may drop far enough that it will threaten the well-being of animals that depend on high levels of the gas, such as fish and crustaceans. The impact in each part of the world will depend on how high oxygen levels are right now, and how rapidly new oxygen is delivered from other parts of the sea.

Each of these changes poses risks to the health of the ocean. But combined, each risk may be able to make the others bigger. Low oxygen speeds up ocean acidification, for example, while ocean acidification can speed up the loss of oxygen. As organic matter breaks down, it reacts more with oxygen that’s rich in carbon. Some studies also suggest that in a CO2-rich ocean, it’s harder to get energy from food. Animals under this stress will need more oxygen to survive–precisely when oxygen levels may be dropping. Making matters worse, the warmer water will speed up metabolism, increasing the demand for oxygen even more.

These synergies will be stronger in some parts of the world than others, because changes in temperature, pH, and oxygen are different in different parts of the world. Gruber put together this map shown below.

The circles mark hotspots where carbon’s triple whammy may hit hardest of all.  Along the coast of California, for example, marine life depends on nutrients that well up from the deep ocean, and a warming ocean will slow down that delivery. It’s also naturally at a low pH and has relatively few carbonate ions, making it especially vulnerable to acidification. Making matters even worse, the waters off of California are low in oxygen, so a further drop could have a big effect on them.

Gruber points out that up till now, scientists have focused on just one kind of impact carbon is having on the oceans. They’ve barely begun to explore how each impact mingles with the others. I see this mingling as a challenge in my own work as a writer. A tangled web of risks is hard to explain, let alone pitch in a lede. But nature doesn’t much care about a simple story.

Reference: Nicolas Gruber, “Warming up, turning sour, losing breath: ocean biogeochemistry under global change.” Phil. Trans. R. Soc. A (2011) 369, 1980–1996 doi:10.1098/rsta.2011.0003

Photo: Cocoa Dream at Flickr

A Blog by Carl Zimmer

Outlook: Warm, Grim, Cloudy: My story on global warming and extinctions in tomorrow's NY Times

In tomorrow’s New York Times, I take a look into nature’s crystal ball. Scientists have long been warning that we may be headed into Earth’s sixth mass extinction. But most projections just carry forward the causes of recent extinctions and population plunges (overfishing, hunting, and the like). Global warming is already starting to have an effect on many species–but it’s a minor one compared with the full brunt that we may experience in the next century.

I’ve written in the past about studies scientists have carried out to project what that impact will be like. I decided to revisit the subject after reading a spate of provocative papers and books recently. While the scientists I talked to all agree that global warming could wreak serious havoc on biodiversity in coming decades, they’re debating the best way to measure that potential harm, and the best way to work against it. We all crave precision in our forecasts, but biology is so complex that in this case we may well have to live without it. Check it out.

[Image: Photo by DJ-Dwayne/Flickr]

A Blog by Carl Zimmer

Gasp! My new article on global warming and oxygen

gasping fish440It’s becoming increasingly clear that global warming may trigger many changes beyond the obvious change in temperature. Earlier this year I wrote about how rising carbon dioxide is driving down the pH of the oceans, with some potentially devastating consequences. Today in Yale Environment 360 I look at a potential change that’s also starting to get scientists very worried: a drop in the oxygen dissolved in the world’s oceans. Check it out.

[Image: Christopher Sebela on Flickr]