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A lifeboat from the Titanic, photographed by a passenger from the Carpathia (source: National Archives)

Name of ship: RMS Titanic

• Passengers and crew: 2,207
• Sunk: April 14, 1912,  collided with an iceberg
• Time to sink: 2 hours, 40 minutes
• Deaths: 1,517
• Survival rate: 31.3%

Name of ship: RMS Lusitania

• Passengers and crew: 1,949
• Sunk: May 7, 1915, torpedoed by a German U-boat
• Time to sink: 18 minutes
• Deaths: 1,198
• Survival rate: 38.5%

The tragic voyages of the RMS Titanic and RMS Lusitania have provided a group of economists with an an opportunity to compare how people behave under extreme conditions. (Their article appears in PNAS.) Despite the different reasons for sinking, the tales of the two ships carry some remarkable similarities: Both ships carried a similar composition of passengers and were unable to accommodate everyone aboard on the lifeboats. (In the case of the Titanic there simply were not enough boats for everyone. On the Lusitania, the ship listed to starboard after being struck by the torpedo and the crew was unable to launch all of the lifeboats.) Both captains ordered that women and children be given first priority on the boats. And both ships had a similar survival rate.

The composition of the survivors was very different, though. On the Titanic, women aged 16 to 35 (child-bearing age) were more likely to survive than other age groups, as were children and people with children. On the Lusitania, both women and men aged 16 to 35 were the most likely to have lived through the incident. There were class differences, too. First-class passengers fared the best on the Titanic but the worst—even worse than third-class passengers—on the Lusitania.

What happened? The researchers say it all comes down to time.

The passengers of the Lusitania had less than 20 minutes before their ship sank, and in such a life-and-death situation, social scientists say, “self-interested reactions predominate.” It didn’t matter what the captain ordered. The ship was going down and people reacted selfishly, and in such a situation, it would be expected that people in their prime (16 to 35) would be the most likely to win a seat on a lifeboat. In addition, because there were difficulties in launching those boats, people in that age group would have had an additional advantage because they were more likely to have had the strength and agility to stay on board a rocking boat or to climb back in after falling into the water.

The Titanic, though, sank slowly enough for social norms to hold sway. The passengers generally held to the rule of “women and children first” even though they could have easily overpowered the crew. And first- and second-class passengers may have benefited from the extra time in which they may have had earlier or better information from the crew or had other advantages.

Clouds form in shipping lanes because of emissions from ships' smokestakes. Image courtesy of NASA

One of the most contentious sessions at the American Association for the Advancement of Science meeting this past weekend in San Diego was on geoengineering, the study of ways to engineer the planet to manipulate climate. Intentional ways to do so, I should say—as many of the speakers pointed out, we’ve already pumped so much carbon dioxide into the atmosphere that the planet is warming and will continue to warm throughout this century, even if we started reducing emissions today. This isn’t a political opinion, it’s a fundamental property of the chemistry and longevity of carbon dioxide.

So, what is to be done? Every speaker endorsed reducing the amount of carbon dioxide we release into the atmosphere. As session chair Alan Robock said at the beginning, “just so we’re clear, all of us strongly urge mitigation as the solution for global warming.”

But that’s where the agreement ended.

The disagreements mainly concerned whether it’s more dangerous to propose, test and deploy geoengineering strategies—or to do nothing.

The danger of doing nothing, David Keith pointed out, is that the full consequences of having so much carbon dioxide in the atmosphere are “deeply uncertain.” If there are massive droughts and at the end of the century due to climate change (”an unacceptably huge response” to carbon dioxide), we need to be ready to do something. And according to his research, “if we wanted to, we could do this.”

What could we do? Well, one cheap and easy way to bring down global temperatures would be to scatter sulfur particles in the stratosphere, mimicking the effects of volcanic eruptions and blocking some sunlight. The plume from the 1991 Mount Pinatubo eruption spread across the upper atmosphere and brought down global temperatures for a few years, and aircraft could deliver comparable amounts of sulfur compounds. Calculating the costs of engineering tweaks to existing technologies, Keith says, he found that the technology would be “so cheap it doesn’t matter.”

Another approach is seeding clouds—the thicker and whiter they are, the more sunlight they reflect and the less heat they allow to accumulate in the lower atmosphere. We’re already seeding clouds inadvertently—if you look at satellite images of the oceans, you can see clouds forming in shipping lanes. Emissions from the ships’ smokestacks have particles that cause water vapor to condense as clouds. Philip Rasch calculated ways to manipulate these emissions to maximize clouds, at least in models.

Fiddling with the ocean works, too. Kenneth Coale has been conducting “ocean enrichment” experiments for years, in which he and his collaborators dump iron into the open ocean. Iron spurs more phytoplankton to grow, and phytoplankton take up carbon dioxide from the atmosphere. They eventually die and release carbon dioxide, but some of the carbon is tied up into solid particles (diatom shells and other detritus) that sink to the bottom of the ocean. There have been 15 iron enrichment experiments at many different latitudes, and it seems to work (although they haven’t directly measured long-term carbon storage)—but there’s a downside. (There always is.) The diatoms that dominate the phytoplankton blooms produce demoic acid, a.k.a. the active ingredient in amnesic shellfish poisoning, which can cause neurological damage in people and marine mammals.

And it’s the unintended consequences that make philosopher Martin Bunzl say that people shouldn’t be experimenting with geoengineering at all. “My argument is that no amount of small-scale, limited experimentation will prepare for large-scale implementation.” There’s just no way to get enough data from small tests to tell what geoengineering will do across the planet, and the risks (of disrupting the Asian monsoon cycle, of causing more hurricanes, etc.) are too great to accept.

One risk of even talking about geoengineering came up again and again: moral hazard. The idea is that if people know that there are cheap and easy ways to counter some of the effects of climate change, they won’t bother to do the hard work of reducing what Rasch called “our carbon transgressions.”

Historically, James Fleming pointed out, people have been fantasizing about manipulating the atmosphere for decades (a PDF of his recent Congressional testimony). They fall into two categories: “commercial charlatans and serious but deluded scientists.”

It’s hard to tell how much of an impact these discussions about the technology, risks and ethics of geoengineering will have in the public at large. The geoengineering sessions attracted their own protesters this year—usually it’s the genetically modified crops people who get all the protesters’ attention—but the protesters were less concerned about moral hazard or Asian tsunamis than they were about their pet conspiracy theories.

This time-lapse video, from the BBC/Discovery program Life, shows three-foot-long worms and carnivorous starfish as they chow down on a dead seal at the bottom of the ocean near Antarctica. Kind of gross, but beautiful at the same time, don’t you think?

The 11-part series will air on the Discovery Channel beginning in March 2010.

(Hat tip: Bioemphemera)

What is it? A beaded necklace? Red blood cells? No, it’s the Portuguese Man o’War (Physalia physalis), magnified 30 times. Though it resembles a jellyfish, the Portuguese Man o’War is a siphonophore, a colony of organisms that work together. The sting of the venom in the tentacles’ nematocysysts is incredibly painful, though rarely deadly. This photo, taken by Alvaro Migotto of the University of São Paulo in Brazil, won 6th prize in the 2009 Olympus BioScapes Interational Digital Imaging Competition.

Notorious for its painful, powerful sting, the Portuguese Man o’ War has a gas-filled floating chamber that supports the tentacles, which bear sting cells. Shown are the pink batteries of stinging cells and a delicate muscular band responsible for the high contractibility of the tentacles.

Check out the entire collection of Pictures of the Week on our Facebook fan page.

(Hat tip: Transcription and Translation)

My colleague Megan Gambino visited the Smithsonian Tropical Research Institute earlier this year to watch coral spawn. A report appears in the December issue of the magazine, and she also blogged about the experience over at Around the Mall. We asked her if anything interesting got left out of her previous reports. Yes, lots, she replied, and wrote this:

This past September, I joined marine scientist Nancy Knowlton, of the National Museum of Natural History; her colleague Don Levitan, of Florida State University; and a crew of research divers on their annual coral spawning trip. Just days after the September full moon, a mass coral spawning happens at their study site, a 260-foot arc of reef about 20 minutes by boat from the Smithsonian Tropical Research Institute’s field station in Bocas del Toro, Panama, and each year, since 2000, they have been there to collect data.

Knowlton, a renowned coral reef biologist, has been called Dr. Doom for the grim, but realistic, picture she paints of reefs suffering worldwide. (Her husband Jeremy Jackson, also a prominent marine scientist, is Dr. Gloom.) But she has also been billed as a savior. Vanity Fair, in its May 2007 “Green Issue,” called her a “mind aquatic” that our future, and our lives, may depend on. Along with other marine scientists, Knowlton has been trying to help reefs survive by better understanding coral reproduction.

A close up view of a Montastraea franksi colony spawning (credit: NOAA)

Early in Knowlton’s career, the assumption was that most coral colonies picked up sperm and brooded embryos internally—and some do. But in 1984, Science published the first description of a dramatic mass-spawning event witnessed on Australia’s Great Barrier Reef. Around that time, research biologists were observing the phenomenon in the Caribbean as well. From this, scientists deduced that the majority of corals—called “broadcast spawners”—actually reproduce in this way. Many are hermaphrodites, meaning they release gamete bundles containing both eggs and sperm. But, unable to self-fertilize, they synchronize their spawning with neighboring corals. The more scientists study the annual orgies, the better they have become at predicting when they will happen. The corals appear to use three cues: the full moon and sunset, which they can sense through photoreceptors; and, most likely, a chemical that allows them to smell each other spawning.

Knowlton’s team has been monitoring three closely related coral species—all dominant reef builders in the Caribbean—called the Montastraea annularis complex. What they have found is that M. franksi, one of the species, spawns on average 100 minutes after sunset and M. annularis and M. faveolata, the other two, follow about 100 minutes later, typically five and six days after the September full moon. Over the nine years of the project, the researchers have spotted, flagged, mapped and genetically identified over 400 spawning coral colonies.

As with any long-term study, the scientists’ questions have evolved. At first, they wondered how the three species, spawning at or close to the same time, didn’t hybridize. Their lab tests show that of the three, the early spawner and one of the later spawners are reproductively compatible. But they have found that the hour and a half or so between the species’ peak spawning times is enough time for the gametes to disperse, dilute, age and effectively be rendered unviable. In fact, their data indicates that if corals spawn just 15 minutes out of sync with the majority, their chance at reproductive success is greatly reduced. The looming question now is, what will happen to fertilization rates as coral colonies become few and far between?

By the third of four nights of diving (and no spawning), the suspense was building. The divers playfully suggested playing Barry White as mood music and gorging, pre-dive, on aphrodisiacs like oysters and strawberries.

Around 7:25 PM, just as everyone was slinking into their wetsuits, sea worms called palolo worms began spawning around the boat. The worms break in half and the tail section swims to the surface and releases eggs or sperm in a cloud of bioluminescence.

“This is it,” said Knowlton. “Everybody’s in the mood for sex.”

The water got buggy and electric, and like clockwork, the coral colonies started spawning around 8:20, one triggering another triggering another. The tapioca-like gamete bundles, about two millimeters in diameter and containing about 100 eggs and one million sperm, lifted in unison, slowly drifting to the surface.

The dive team observed 162 different coral colonies set or spawn, and the next night, they saw another 189. Knowlton surfaced that final night, exhilarated. What did you think? She asked each of the divers. Amazing, huh? She didn’t want to get out of the water and grabbed hold of the side of the boat, arching her back, her eyes cast toward the sky. Even the stars looked like gametes.