Deepwater Horizon Fail

The Deepwater Horizon aflame 21 April 2010

How Could This Happen?

BP has provided its first analysis of what went wrong on the Deepwater Horizon that led to 11 deaths and the nation's biggest single maritime oil release. As expected, lots of things had to go wrong at once.

Big disasters in complex systems usually require a cascade of errors and flaws. The Apollo 13 explosion, which had an unlikely chain of six design errors, operational failures and accidents that had to happen before the tank blew, was typical.

So what, specifically, happened on Deepwater Horizon?

BP's Analysis

BP's team of internal and outside experts has presented its 193-page report, and BP has made it available here. There is also an executive summary and a video summary.  

The presentation says this is not meant to be "the definitive or final word on what happened." The study team didn't have access to some witnesses or some physical evidence. The analysis was highly technical, and describes what they think happened in a complex and specialized system of hardware.

The Deepwater Horizon Rig

BP's Findings:

• "We concluded that there was no single action or inaction that caused the accident."
• "The accident was the culmination of a complex and interlinked series of mechanical failures, human judgements, engineering design, operational implementation and team communication."
• The team found eight interrelated or contributing factors:
• Hydrocarbons got into the production casing through the shoe track because of failures of the cement and shoe track barriers. Probably the cement slurry that was used was not correct, contributing to this failure.
• The annulus cement barrier also failed, also possibly because the cement used was incorrect or incorrectly applied.
• The results of the negative pressure test that was supposed to show well integrity was inconclusive, but the well team incorrectly accepted these results as showing the well was intact.
• Instrument readings over a 40 minute period showed that hydrocarbons were entering the well, but the crew did not notice or properly interpret these signals until the hydrocarbons were already in the riser and rushing toward the surface.
• Once the crew realized that well integrity had failed, the actions they took failed to regain control of the well.
• After the flow of hydrocarbons reached the rig it was routed to a mud-gas separator, which is designed to safely manage only small amounts of hydrocarbons. It should have been vented overside away from the rig through the available 14-inch lines. Hydrocarbons emitted by the mud-gas separator were vented on the rig and were able to penetrate into its spaces.
• Gas was drawn into the engine rooms through their ventilation systems creating a potential for ignition, but the rig's fire and gas system failed to prevent such ignition.
• The resulting explosion and fire disabled crew-operated controls to the blow-out preventer. The blow-out preventer should still have been able to stop the flow with its automatic systems, but lax maintenance and inspection of the BOP, or other problems, meant these automatic systems did not work.

This is obviously only a preliminary analysis. If the blow-out preventer had functioned properly it would have saved the day even after all the other errors and failures. Just saying "it failed to operate" covers a lot. Now that it has been recovered it will be analyzed in turn. Probably we will find that, like Apollo 13's oxygen tank no. 2, a number of faults, misjudgments, miscommunications, errors and design flaws were required to cause it to fail.

Implications--Can It Happen Again?

One would think that such chains of error and accident would be so unlikely that we don't have to worry about another rig failing. That is obviously not accurate.

Another rig will not fail in exactly the same way, but we have already had an explosion/fire on another Gulf of Mexico rig in the brief time since the Macondo blowout. And remember the Piper Alpha disaster in 1988 (167 deaths) and the Ixtoc I blowout in 1979 (where the blow-out preventer also didn't do its job).

With more and more rigs of greater and greater complexity in tougher and tougher environments we should expect such disasters in the future. This is just a cost of using oil.

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The image of the burning rig is in the public domain, available here.
The diagram is from the presentation slides accompanying BP's report, available in PDF here.

Geoengineering No Simple Solution

Can we use geoengineering to avoid the worst effects of climate change caused by increasing atmospheric carbon dioxide? Don't count on it, say two recent scientific articles.

[Crossposted from sister blog A Very Different Earth.]

Sea Level Rise Can't Be Halted By Geoengineering

Researcher from China/Finland, the UK and Denmark modeled the effect of various geoengineering ideas on sea level rise. Their paper "Efficacy of geoengineering to limit 21st century sea-level rise" appears in the Proceedings of the National Academy of Sciences (abstract and access here). (They deserve thanks for making their paper open access.)

They find "sea-level rise by 2100 will likely be 30 cm higher than 2000 levels despite all but the most aggressive geoengineering under all except the most stringent greenhouse gas emissions scenarios." This means that even if we spend trillions on vast projects, and even if those projects work as planned, unless we also adopt tough measures to cut emissions sea level still goes up a foot.

And they say "Loss of low-lying land, combined with asset exposure to urban flooding due to the combined effects of climate change (sea-level rise and increased storminess), may reach 10% of projected global gross world product (GWP) in the 2070’s."

There are two things to consider when digesting that statement:

• The authors are only talking about a meter of sea level rise in this century, at the lower end of current projections, and
• The current recession cut the global economy by less than 2% from what it might have been without the recession. Imagine 10%.

They modeled several proposed projects:

• Giant mirrors in space--These reduce climate forcing from the Sun's radiation, but leave greenhouse gases in the atmosphere where they continue to have their other negative effects such as ocean acidification. Also this project would be enormously expensive.
• Who could think that launching 20 million tonnes of mirrors into space could be less of a blow to the economy than cutting greenhouse gas emissions by reducing coal use? 
• For comparison, the International Space Station weighs only 370,000 tonnes, and it has taken a decade to get it up there. It is the most expensive object ever constructed. It has been estimated to cost €100 billion over its 30-year life. Could taxpayers afford €5 trillion?
• Aggressive afforestation, replanting cut forests and planting trees to create new forests, might be able to take some CO₂ out of the atmosphere, reducing that climate forcing. But CO₂ could only be reduced by about 45ppm. Humans have put more than a hundred ppm of CO₂ into the atmosphere over the past century or so, and are adding about 2ppm per year. So models still showed significant sea level rise.
• Increasing biochar levels in the soil would reduce the CO₂ levels by even less--about 35ppm.
• Aggressive conversion from petroleum and coal to biofuels with capture and storage of the resulting CO₂ from their combustion could reduce atmospheric CO₂ 180ppm by 2100.
• A combination of afforestation, biochar sequestration and biofuels with carbon capture and storage could take 250ppm of CO₂ out of the atmosphere and might keep sea level rise to "only" 20 to 40 cm.
• Injecting SO₂ into the atmosphere, equivalent to a major volcanic eruption every year and a half, could reduce global temperature rise a degree or so, but would leave the CO₂ in the atmosphere. Such a project might reduce sea level rise by 20cm or so. And if the program were ever ended warming would bounce back in a short time, with accompanying sea level rise.
  
• And see the other findings below for more problems with SO₂ injection.

In the end they conclude "Substituting geoengineering for greenhouse gas emission abatement or removal constitutes a conscious risk transfer to future generations."

Geoengineering Helps Some But Hurts Others

Researchers from Carnegie Mellon and Oxford studied the regional impacts of various geoengineering concepts. Their work is reported in Nature Geoscience. (Abstract only here. Unfortunately these researchers did not make their findings open access.)

They modeled solar-radiation management by adding reflecting aerosols to the stratosphere. Previous modeling studies suggested that such an approach could stabilize global temperatures and reduce global precipitation. Their findings:

Our results confirm that solar-radiation management would generally lead to less extreme temperature and precipitation anomalies, compared with unmitigated greenhouse gas emissions. However, they also illustrate that it is physically not feasible to stabilize global precipitation and temperature simultaneously as long as atmospheric greenhouse gas concentrations continue to rise. Over time, simulated temperature and precipitation in large regions such as China and India vary significantly with different trajectories for solar-radiation management, and they diverge from historical baselines in different directions. Hence, it may not be possible to stabilize the climate in all regions simultaneously using solar-radiation management. Regional diversity in the response to different levels of solar-radiation management could make consensus about the optimal level of geoengineering difficult, if not impossible, to achieve.

So shooting millions of tonnes of SO₂ into the stratosphere can cool the globe, but its effects are uneven. An article in The Economist provides more details:

A particularly salient example of this comes from Asia. There were a number of geoengineering scenarios in which the climate in both India and China in the 2020s looked quite like that of the 1990s, though in all geoengineering scenarios using this particular model India gets a bit wetter than it was before and in most of them China gets a bit drier. Go out to the 2070s, though, and the geoengineering scenarios strong enough to keep China’s temperature 1990s-ish cool India below its baseline temperature, while weaker scenarios that keep India’s temperature at the levels of the 1990s see China heat up.

That said, in both cases all the geoengineering options gave results for both temperature and precipitation closer to 1990s levels than the models projected for a world without geoengineering. In this sense both countries were "winners"—but maximising the benefits for one would still come at the expense of the other. The same lesson seems to apply quite generally across the world. Few if any regions stand out as certain losers from geoengineering if you accept that it is worth trading off a large change in temperature for a smaller drop in precipitation (in terms of change on the levels seen before the geoengineering). But different levels of geoengineering seem optimal for different regions.

So the question would be, who gets to decide what geoengineering to do? Presumably those who pay for it will control which projects get done. And naturally they will undertake projects that benefit themselves, even if they cause harm elsewhere in the world. This would be geopolitically very unfriendly, sort of like declaring war.

If these results hold I doubt we will see much geoengineering until and unless climate change gets so disruptive that the community of nations falls apart and it's every one for itself.

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A Scientific American blog post also covered the sea level rise story.

Glacial Slowness?

Riggs Glacier in Alaska

Glaciers have long been a byword for slowness. But perhaps they are not the slowest thing around.

A recent New York Times editorial quotes Democratic Senator Claire McCaskill of Missouri as saying, when asked why she saw no immediate need to pass a comprehensive energy and climate bill, "You know, it took 50 years on health care."

The U.S. Senate is so sub-glacial in the speed of its deliberations that before it acts on climate change we may find that the glaciers (or more precisely the ice sheets of Greenland and Antarctica) have already voted, and not in our favor. The ice sheets will probably reach their tipping points before the Congress does.

In related news, the U.S. Geological Survey recently published "Glaciers of Asia" the ninth volume of its series "Satellite Image Atlas of Glaciers of the World", which finds "Many of Asia’s glaciers are retreating as a result of climate change." (Press release here.)