Africa's Climate Conflicts

From Yale Environment 360:

“When the Water Ends” . . . tells the story of . . .the increasingly dire drought conditions facing parts of East Africa. To report this video, Evan Abramson, a 32-year-old photographer and videographer, spent two months in the region early this year, living among the herding communities. He returned with a tale that many climate scientists say will be increasingly common in the 21st century and beyond — how worsening drought in parts of Africa, the Middle East, and elsewhere will pit group against group, nation against nation. As one UN official told Abramson, the clashes between Kenyan and Ethiopian pastoralists represent “some of the world’s first climate-change conflicts.” 

But the story recounted in “When the Water Ends” is not only about climate change. It’s also about how deforestation and land degradation — due in large part to population pressures — are exacting a toll on impoverished farmers and nomads as the earth grows ever more barren.

The video focuses on four groups of pastoralists — the Turkana of Kenya and the Dassanech, Nyangatom, and Mursi of Ethiopia — who are among the more than two dozen tribes whose lives and culture depend on the waters of the Omo River and the body of water into which it flows, Lake Turkana. For the past 40 years at least, Lake Turkana has steadily shrunk because of increased evaporation from higher temperatures and a steady reduction in the flow of the Omo due to less rainfall, increased diversion of water for irrigation, and upstream dam projects. As the lake has diminished, it has disappeared altogether from Ethiopian territory and retreated south into Kenya. The Dassanech people have followed the water, and in doing so have come into direct conflict with the Turkana of Kenya.

The result has been cross-border raids in which members of both groups kill each other, raid livestock, and torch huts. Many people in both tribes have been left without their traditional livelihoods and survive thanks to food aid from nonprofit organizations and the UN.

The future for the tribes of the Omo-Turkana basin looks bleak. Temperatures in the region have risen by about 2 degrees F since 1960. Droughts are occurring with a frequency and intensity not seen in recent memory. Areas once prone to drought every ten or eleven years are now experiencing a drought every two or three. Scientists say temperatures could well rise an additional 2 to 5 degrees F by 2060, which will almost certainly lead to even drier conditions in large parts of East Africa.

In addition, the Ethiopian government is building a dam on the upper Omo River — the largest hydropower project in sub-Saharan Africa — that will hold back water and prevent the river’s annual flood cycles, upon which more than 500,000 tribesmen in Ethiopia and 300,000 in Kenya depend for cultivation, grazing, and fishing. . . .

Greenhouse Gas Emissions Increase by 5.5% in 2010

From the Guardian:

Greenhouse gas emissions increased by a record amount last year, to the highest carbon output in history, putting hopes of holding global warming to safe levels all but out of reach, according to unpublished estimates from the International Energy Agency. 

The shock rise means the goal of preventing a temperature rise of more than 2 degrees Celsius – which scientists say is the threshold for potentially "dangerous climate change" – is likely to be just "a nice Utopia", according to Fatih Birol, chief economist of the IEA. It also shows the most serious global recession for 80 years has had only a minimal effect on emissions, contrary to some predictions. 

Last year, a record 30.6 gigatonnes of carbon dioxide poured into the atmosphere, mainly from burning fossil fuel – a rise of 1.6Gt on 2009, according to estimates from the IEA regarded as the gold standard for emissions data.

"I am very worried. This is the worst news on emissions," Birol told the Guardian. "It is becoming extremely challenging to remain below 2 degrees. The prospect is getting bleaker. That is what the numbers say." . . . 

Emissions from energy fell slightly between 2008 and 2009, from 29.3Gt to 29Gt, due to the financial crisis. A small rise was predicted for 2010 as economies recovered, but the scale of the increase has shocked the IEA. "I was expecting a rebound, but not such a strong one," said Birol, who is widely regarded as one of the world's foremost experts on emissions. . . . 

Most of the rise – about three-quarters – has come from developing countries, as rapidly emerging economies have weathered the financial crisis and the recession that has gripped most of the developed world. . . . 

[O]ther factors that made it even less likely that the world would meet its greenhouse gas targets: 

• About 80% of the power stations likely to be in use in 2020 are either already built or under construction, the IEA found. Most of these are fossil fuel power stations unlikely to be taken out of service early, so they will continue to pour out carbon – possibly into the mid-century. The emissions from these stations amount to about 11.2Gt, out of a total of 13.7Gt from the electricity sector. These "locked-in" emissions mean savings must be found elsewhere. . . . 

• Another factor that suggests emissions will continue their climb is the crisis in the nuclear power industry. Following the tsunami damage at Fukushima, Japan and Germany have called a halt to their reactor programmes, and other countries are reconsidering nuclear power. 

"People may not like nuclear, but it is one of the major technologies for generating electricity without carbon dioxide," said Birol. The gap left by scaling back the world's nuclear ambitions is unlikely to be filled entirely by renewable energy, meaning an increased reliance on fossil fuels. 

• Added to that, the United Nations-led negotiations on a new global treaty on climate change have stalled. "The significance of climate change in international policy debates is much less pronounced than it was a few years ago," said Birol. . . .

Resource Conflict in South China Sea

From the Financial Times:

Tensions between China and Vietnam escalated over the weekend as each nation accused the other of violating its sovereignty in the oil-rich South China Sea. 

PetroVietnam, the state-owned oil and gas monopoly, said on Sunday that China had sabotaged Vietnamese oil exploration vessels, the latest accusation between the countries over the disputed waters. . . . 

The renewed tensions come as Liang Guanglie, the Chinese defence minister, and Robert Gates, his US counterpart, prepare to attend the Shangri-La Dialogue, a high-profile annual Asia defence forum in Singapore next weekend. Mr Liang’s appearance will mark the first time a Chinese defence minister has participated in the meeting. 

The Vietnamese harassment claims will put the South China Sea issue back in focus ahead of the regional security meeting, which in recent years has increasingly focused on Chinese maritime behaviour in the disputed waters. South-east Asian countries are concerned about what they perceive to be Beijing’s increasingly assertive behaviour in regional waters.  

The rising tensions have also attracted the attention of Washington. Hillary Clinton, US secretary of state, angered Beijing last July by insisting that the South China Sea was of strategic importance to the US and offering to act as a mediator.

In addition to China and Vietnam, Brunei, Malaysia, the Philippines and Taiwan all claim part or all of the South China Sea, which is believed to contain vast oil and gas reserves and incorporates key trade routes and abundant fish stocks. 

PetroVietnam is working with a number of large international oil companies, including ExxonMobil and Chevron, to explore and develop oil and gas assets in South China Sea waters claimed by Vietnam. Mr Hau said that this latest incident “will impact on the attitudes of foreign investors”. . . .

The encounter took place 120 nautical miles off the coast of Phu Yen province in south-central Vietnam, in waters that are claimed by both China and Vietnam. . . . 

The clash comes just a week after China and the Philippines pledged “responsible behaviour” in the disputed areas and repeated their commitment to a peaceful resolution of conflicting territorial claims. During a visit of Liang Guanglie, China’s minister of defence, to Manila last Monday, officials from both governments pledged to avoid unilateral moves which could raise tension. 

Philippine President Benigno Aquino said after the visit incidents in disputed areas could trigger a regional arms race, and force the Philippines to strengthen its military capabilities. 

Security experts have said that such an arms race is under way already. Several south-east Asian countries are beefing up their air and sea defences – Singapore, Malaysia, Vietnam and Thailand have all acquired or placed orders for frigates, fighter aircraft and submarines.

This has it all: the continued salience of nationalist claims and aspirations, the existence of resource conflict as a basic factor in fueling competition, invocations of the primacy of peaceful settlement alongside actual uses of force, arms races, the demonstrated incapacity of the United States to stay out of any foreign quarrel.

Location of Phu Yen province from Wikipedia:

Shale Oil Boom to Boost US Output by 25% In Decade?

From Clifford Krauss of the New York Times:

More than a dozen companies plan to drill up to 3,000 wells around here in the next 12 months.The Texas field, known as the Eagle Ford, is just one of about 20 new onshore oil fields that advocates say could collectively increase the nation’s oil output by 25 percent within a decade — without the dangers of drilling in the deep waters of the Gulf of Mexico or the delicate coastal areas off Alaska.

There is only one catch: the oil from the Eagle Ford and similar fields of tightly packed rock can be extracted only by using hydraulic fracturing, a method that uses a high-pressure mix of water, sand and hazardous chemicals to blast through the rocks to release the oil inside.

The technique, also called fracking, has been widely used in the last decade to unlock vast new fields of natural gas, but drillers only recently figured out how to release large quantities of oil, which flows less easily through rock than gas. As evidence mounts that fracking poses risks to water supplies, the federal government and regulators in various states are considering tighter regulations on it.

The oil industry says any environmental concerns are far outweighed by the economic benefits of pumping previously inaccessible oil from fields that could collectively hold two or three times as much oil as Prudhoe Bay, the Alaskan field that was the last great onshore discovery. The companies estimate that the boom will create more than two million new jobs, directly or indirectly, and bring tens of billions of dollars to the states where the fields are located, which include traditional oil sites like Texas and Oklahoma, industrial stalwarts like Ohio and Michigan and even farm states like Kansas.

“It’s the one thing we have seen in our adult lives that could take us away from imported oil,” said Aubrey McClendon, chief executive of Chesapeake Energy, one of the most aggressive drillers. “What if we have found three of the world’s biggest oil fields in the last three years right here in the U.S.? How transformative could that be for the U.S. economy?” . . .

Based on the industry’s plans, shale and other “tight rock” fields that now produce about half a million barrels of oil a day will produce up to three million barrels daily by 2020, according to IHS CERA, an energy research firm. Oil companies are investing an estimated $25 billion this year to drill 5,000 new oil wells in tight rock fields, according to Raoul LeBlanc, a senior director at PFC Energy, a consulting firm.

This is very big and it’s coming on very fast,” said Daniel Yergin, the chairman of IHS CERA. “This is like adding another Venezuela or Kuwait by 2020, except these tight oil fields are in the United States.”

In the most developed shale field, the Bakken field in North Dakota, production has leaped to 400,000 barrels a day today from a trickle four years ago. Experts say it could produce as much as a million barrels a day by the end of the decade.

The Eagle Ford, where the first well was drilled only three years ago, is already producing more than 100,000 barrels a day and could reach 420,000 by 2015, almost as much as Ecuador, according to Bentek Energy, a consultancy.. . .

What makes the new fields more remarkable is that they were thought to be virtually valueless only five years ago. “Everyone said the oil molecules are too large to flow in commercial quantities through these low-quality rocks,” said Mark G. Papa, chief executive of EOG Resources.. . .

The new drilling makes economic sense as long as oil prices remain above $60 a barrel, according to oil companies. At current oil prices of about $100 a barrel, shale wells can typically turn a profit within eight months — three times faster than many traditional wells.

But water remains a key issue. In addition to possible contamination of surface and underground water from fracking fluids, the sheer volume of water required poses challenges, especially in South Texas, which faces a severe drought and rapidly diminishing water levels in the local aquifer.

At the rate wells are being drilled, “there’s definitely going to be a problem,” said Bay Laxson, a local water official.

Dave Thompson, regional production superintendent for the oil company SM Energy said the industry knew that water issues were “an Achilles heel.” He said his company was building a system to reuse water in the field.

Be it noted that the projections in the article regarding oil are contradicted by the projections in the article regarding water.  The problem illustrates Stephen Solomon's point that the "unconventional and renewable domestic alternatives" being developed to ensure energy security are "several orders of magnitude more water intensive than the conventional sources they are supplanting."

Update, June13, 2011: Bloomberg has a story ("Drought Threatens Texas Oil Boom") emphasizing the severe water restrictions in Texas brought on by the drought, and notes that the Eagle Ford play is especially voracious in its water needs:

The Eagle Ford’s peculiar geology means it takes three to four times as much water to fracture as the Barnett Shale near Fort Worth, said [Robert] Mace, of the state water board. Fracking a single Eagle Ford well requires as much as 13 million gallons of water, enough to supply the cooking, washing and drinking needs of 40 adults for an entire year, he said.

“This is not the drilling your grandparents knew in west Texas,” said Sharon Wilson, an organizer for Earthworks’ Oil and Gas Accountability Project, which lobbies for tougher government regulation of oil drillers. “It’s a heavy industrial activity with massive amounts of water and chemicals.”

About 94 percent of Texas was in a state of severe, extreme or exceptional drought as of June 7, according to the U.S. Drought Monitor compiled by the U.S. Agriculture Department and the National Drought Mitigation Center. The October-through-May period was the state’s driest since record-keeping began in 1895, said Texas State Climatologist John Nielsen-Gammon.

Municipal water departments, farmers, ranchers and oil drillers near Laredo are relying on water from two reservoirs and underground aquifers filled by last summer’s tropical storm season, said Yarrito, whose job title is Rio Grande Watermaster.

Unless storms bring more rain soon, “we’ll be in trouble,” said Sonny Hinojosa, general manager of Hidalgo Irrigation District No. 2 in San Juan, Texas. The drought has decimated crops, with about 79 percent of the state’s winter wheat, 72 percent of its oats and 36 percent of its corn classified as poor or very poor as of June 6, according to the Agriculture Department in Washington.

The Edwards Aquifer Authority, which oversees underground water supplies around San Antonio and along the northern edge of the Eagle Ford Shale, on June 2 declared a Stage 2 emergency requiring a 30 percent cut in water usage. Other water districts have imposed similar restrictions.

Water consumption by Eagle Ford Shale drillers is forecast to explode during the next 25 years, Mace said. A study to be released later this summer by the Texas Water Development Board and the University of Texas’s Bureau of Economic Geology estimates fracking-water demand in the area will jump 10-fold by 2020, and double again by 2030, he said.

Greens for Nuclear Power

George Monbiot, of the UK Guardian, does not think the world of nuclear power, but he thinks it's a damn sight better than the available fossil fuel alternatives (coal and natural gas). Abandoning nuclear power, he argues, would place an insupportable burden on renewables. He has had a bitter row with Helen Caldicott and other anti-nuclear campaigners over the risks posed by nuclear power. He begins the piece below by defending himself against a range of misrepresentations, but then goes on the attack by identifying seven double standards that anti-nuclear campaigners have used in making their case:

Double standard one: deaths and injuries

We rightly lament the horrible consequences of industrial exposure to radiation. Two workers at Fukushima have so far received radiation burns and 17 have been exposed to levels of radiation considered unsafe. This is and should be a cause for serious concern. It is also worth remembering that no one has yet received a dose of radiation that is known to be lethal as a result of the Fukushima disaster. But if we are concerned about industrial injuries, why do we say nothing about the deaths and injuries in the industry most likely to replace nuclear power?

In China alone, the government estimates that 2,433 people died in coal-mining accidents last year. That's not injuries or exposures. It's deaths. Human rights activists believe that official figures might have been underestimated by a factor of four.

What this means is that, in the normal course of operations, at least six people are killed in Chinese coal mines every day. Even if you accept the official figure, Chinese coal mining alone kills as many people every week as the worst nuclear power accident in history – the Chernobyl explosion – has done in 25 years.

And this is to say nothing of the far larger number of injuries that coal mining inflicts, in particular the hideous lung diseases which plague so many miners and cause long, lingering and terrible deaths. When was the last time you heard an anti-nuclear campaigner drawing attention to this daily carnage?

Double standard two: the science

We emphasise, when debating climate change, the importance of the scientific consensus, and reliance on solid, peer-reviewed studies. But as soon as we start discussing the dangers of low-level radiation, we abandon that and endorse the pseudo-scientific gibberish of a motley collection of cranks and quacks, who appear to have begun with the assumption that it must be killing thousands of people every year, and retrofitted the evidence to match it.

Such people exist in every field, especially those that are politically contentious. We should, by now, have learned to be wary of them. But it seems that the temptation, for people hoping to make the case against nuclear power, is overwhelming.

For a good summary of the scientific consensus on the effects of exposure to both high and low levels of radiation, see the new post by Chris Goodall and Mark Lynas: two environmentalists who have kept their heads in this crisis.

Double standard three: radioactive pollution

If low-level radiation really was the problem that some environmentalists say it is, the focus of their campaign should be coal plants, not nuclear power. As Scientific American notes:

"The fly ash emitted by a power plant – a by-product from burning coal for electricity – carries into the surrounding environment 100 times more radiation than a nuclear power plant producing the same amount of energy."

This is because coal contains trace amounts of uranium and thorium, which are concentrated in the ash. Not only does this expose people living around coal plants to higher doses of radiation than people living around nuclear plants; but the regulations for disposing of fly ash are far weaker than the regulations for disposing of low-level nuclear waste. You may remember the controversy about RWE npower's plan to dump the fly ash from Didcot power station into a lake between the villages of Radley and Abingdon. Where were the anti-nuclear campaigners then? Can you imagine what the outcry would have been if a corporation had planned to fill it with low-level waste from a nuclear plant?

Double standard four: mining impact

Anti-nuclear campaigners emphasise the damage and pollution inflicted by uranium mines. They are right to do so. Some of these mines are hideous, and they are one of the many reasons why we should urgently develop new reactor technologies which sharply reduce the need for fresh supplies. But the impacts of coal mining are massively greater. There are hundreds of times more coal mines than uranium mines, including opencast sites, and a lot of them of them are many times bigger and more destructive than the largest uranium operations. This doesn't make uranium mining right, but it makes the likely switch to coal even more wrong.

Double standard five: costs

One of the most frequent arguments against nuclear power is that it costs too much. Many environmentalists claim that, when all the hidden costs, especially the massive decommissioning liabilities, are taken into account, electricity from atomic plants could cost as much as 5p per kilowatt hour or even more. The highest figure I have come across was the top end of the range of estimates produced by the New Economics Foundation – 8.3p. If this is correct – and I should emphasise that it's an extreme outlier – it suggests that nuclear is an extravagant means of generating low-carbon electricity.

So why do the same people support a feed-in tariff scheme under which we pay 41p per kilowatt hour for rooftop solar electricity?

Double standard six: research

Last week I argued about these issues with Caroline Lucas. She is one of my heroes, and the best thing to have happened to parliament since time immemorial. But this doesn't mean that she can't be wildly illogical when she chooses. When I raised the issue of the feed-in tariff, she pointed out that the difference between subsidising nuclear power and subsidising solar power is that nuclear is a mature technology and solar is not. In that case, I asked, would she support research into thorium reactors, which could provide a much safer and cheaper means of producing nuclear power? No, she told me, because thorium reactors are not a proven technology. Words fail me.

Double standard seven: timing

Anti-nuclear campaigners point out that it takes 10 years or so to build a new nuclear power station, and we haven't got that long, if we are serious about preventing climate breakdown. They are of course quite right: it's too little, too late. But the same problem affects every significant move to decarbonise the energy supply. By the time it has gone through the planning process, a major new grid connection to support an offshore windfarm will take roughly as long to develop as a new nuclear power station. The same goes for the pumped storage facilities required to support a largely renewable power system and for the carbon capture and storage required to reduce the impacts of fossil fuels. As for growing trees …

My point is that we have to take responsibility for every component of our energy supply and the consequences it carries; not just the section of it that's produced by nuclear reactors. And we should apply the same standards to all generating technologies. Otherwise, in the name of reducing risks to people and the planet, we will unwittingly increase them.

Energy Return on Energy Invested (Heavy Oil)

This piece from the Wall Street Journal ("The End of Easy Oil") discusses the development by Chevron of the Wafra heavy oil field straddling the border between Saudi Arabia and Kuwait. The big oil companies, having lost their reserves to nationalization, are forced to engage in high risk projects in exchange for gaining access to oil. On the one hand, the piece suggests that a lot more oil is out there so long as the price is right--Chevron estimates it can make a profit at $60 to $70 a barrel. However, the "energy return on energy invested" for a project like this is low, as this depiction of the process suggests, and the implications for carbon emissions are especially grim.

To get to Wafra's thick oil, workers are injecting steam into the ground to heat the oil and make it less viscous, allowing it to flow to the surface. The technique is tricky, expensive and unproven in the type of rock that holds Wafra's oil.. . . .

Chevron is conducting what amounts to a four-year, $340 million test in a small corner of Wafra. Oil, like molasses, thins when heated. Large silver pipes carry 600-degree-Fahrenheit steam underground, flooding the oil-rich rock. Nearby, a grid of pumps pulls up the oil.

So far, the results have been encouraging. As of November, the wells were producing 1,500 barrels per day, seven times what they produced before steam injection began in 2009. . . .

Using steam to extract oil isn't a new idea. Chevron has been using the method to recover heavy oil at its Kern River field in Bakersfield, Calif., since the 1960s. That field yielded less than 10% of its oil using traditional methods. Using steam injection, Chevron is now on its way to pumping as much as 80% of the crude.

The Wafra project, however, is far more of a challenge than traditional steam projects. As in most of the Middle East, the oil at Wafra is trapped in a thick layer of limestone that also contains minerals that can build up inside pipes and corrode equipment.

An even bigger challenge is getting the two crucial elements for generating steam: water and a source of energy to boil it. Most successful steam projects are in places with easy access to relatively pure water and a cheap fuel source, usually natural gas. Saudi Arabia and Kuwait have little of either.

With no fresh-water sources in the Arabian desert, Chevron has been forced to use salt water found in the same underground reservoirs as the oil. That water is full of contaminants that must be removed before it can be boiled and injected into the ground.

Finding the energy to boil the water will be even tougher. Chevron could use oil instead of natural gas—literally burning oil to produce oil—but that would burn profits, too. So the company likely will be forced to import natural gas from overseas, an expensive process that involves chilling it to turn it into a liquid, then shipping it thousands of miles.

Some experts are shaking their heads.

"They're in trouble," says Robert Toronyi, a retired Chevron engineer who now serves as chief operating officer for Quantum Reservoir Impact, a Houston-based consulting firm. He says the project is so challenging that it will be hard for Chevron to turn much of a profit.

Expectations that "peak oil" would be beneficial because the scarcity of energy would reduce carbon emissions seem clearly misguided from this example. The scarcer that ready-to-access oil becomes, the greater the incentive to expend energy to get energy. The consequence is a lower net return on energy invested and a greater impact on emissions for every barrel of oil consumed.

The essential points were made in a paper by Alex Farrell and A.R. Brandt in 2006 (cited the other day by Climate Progress). There were two basic propositions:

[T]he oil transition is not a shift from abundance to scarcity: fossil fuel resources abound. Rather, the oil transition is a shift from high quality resources to lower quality resources that have increased risks of environmental damage, as well as other risks.

[T]he oil transition brings more long-term environmental concerns than long-term economic or security threats because tradeoffs have strong potential to be resolved by accepting increased environmental damage in order to avoid economic or security risks. The global petroleum industry has begun to recognize this interaction, but strategies to deal with them have not yet emerged.

6/5/11

Solar Sags

247 Wall Street is a good source to keep up with the the doings of the solar sector. Here's a snippet from a recent report:

While some of these solar players are not changing their forecasts on shipments, all have seen gross margin declines since last year, and the capacity expansion that is taking place this year will only make matters worse for margins. Capacity is expected to grow by 9,500 megawatts in 2011, to a worldwide total of 41,500 megawatts, while global demand for solar panels is forecast for around 28,000 megawatts.. . .

The second weight on share prices is a fuller understanding of just how much many of the solar makers depend on European sales, particularly Germany, Italy, and Spain. With that understanding comes the realization that both Italy and Spain are suffering from bigger problems than continuing solar subsidies, and that German sales will not be robust as before.

Electropolis: US Atlantic Seaboard At Night

From NASA Earth Observatory, May 22, 2011

Agricultural Policies: Bill Clinton Recants on the Washington Consensus

From Democracy Now and Haitian journalist Kim Ives, an interview with Bill Clinton in 2010 in which he laments the role his administration played in forcing down rice tariffs in Haiti--a step that, according to Democracy Now, "wiped out Haitian rice farming and seriously damaged Haiti's ability to be self-sufficient."

At a donors conference the month before the interview, Clinton said the following:

Since 1981, the United States has followed a policy, until the last year or so when we started rethinking it, that we rich countries that produce a lot of food should sell it to poor countries and relieve them of the burden of producing their own food, so . . . they can leap directly into the industrial era. It has not worked. It may have been good for some of my farmers in Arkansas, but it has not worked. It was a mistake. It was a mistake that I was a party to. I am not pointing the finger at anybody. I did that. . . .

Clinton subsequently said that Robert Zoellick, the head of the World Bank, also saw the folly of the agricultural policies foisted on poor nations in the name of free trade: "it’s failed everywhere it’s been tried. And you just can’t take the food chain out of production. And it also undermines a lot of the culture, the fabric of life, the sense of self-determination. And I have been involved for several years in agricultural products, principally in Rwanda, Malawi, other places in Africa, and now increasingly in Latin America, and I see this. . . .[W]e made this devil’s bargain on rice. And it wasn’t the right thing to do. We should have continued to work to help them be self-sufficient in agriculture."

Al-Qaeda Threat to Energy Infrastructure

From CNN:

The Department of Homeland Security and the FBI have warned police across the United States that al Qaeda has a "continuing interest" in attacking oil and natural gas targets, a department spokesman said Friday.

The warning issued Thursday came as a result of information seized during the May 2 raid that killed Osama bin Laden in Pakistan, a U.S. official said.

"We are not aware of indications of any specific or imminent terrorist attack plotting against the oil and natural gas sector overseas or in the United States," Homeland Security spokesman Matthew Chandler said.

"However, in 2010 there was continuing interest by members of al Qaeda in targeting oil tankers and commercial oil infrastructure at sea."

It is "unclear if any further planning has been conducted" since the middle of last year, Chandler said.

CNN obtained a copy of a DHS/FBI intelligence bulletin that says al Qaeda has been interested in "targeting unspecified oil tankers abroad" as a means to "draw the West into an extreme economic crisis" by disrupting a significant portion of the oil supply for several years.

The advisory says al Qaeda wanted to target oil tankers in the Indian and Atlantic oceans, as well as the Arabian Sea, but the terrorist group "was opposed to targeting tankers in coastal areas with large Muslim populations."

The warning says al Qaeda "believed an effective method for sinking oil tankers was to hijack them and then detonate explosives from the inside." The group thought it would be more difficult to stage an attack from outside a ship, as it could "require several explosive charges since tankers are divided internally into multiple watertight sections." . . .

More on the same subject in an essay by Daveed Gartenstein-Ross at Foreign Policy, which traces the evolution of al-Qaeda's attitudes: 

The threat that keeps counterterrorism officials up at night is a massive strike on Saudi oil installations, taking advantage of the limited number of production hubs to knock a significant amount of oil off the world market. The kingdom relies on its Abqaiq facility to process two-thirds of its crude oil, and on two primary terminals (Ras Tanura and Ras al-Ju'aymah) to export its oil to the world. The economic impact of a successful attack on one of these targets would be tremendous: Gal Luft and Anne Korin of the Institute for the Analysis of Global Security estimate that, if a terrorist cell hijacked a plane and crashed it into either the Abqaiq or Ras Tanura facilities in a 9/11-style attack, it could "take up to 50% of Saudi oil off the market for at least six months and with it most of the world's spare capacity, sending oil prices through the ceiling."

Former CIA case officer Robert Baer agrees, writing his 2004 book Sleeping with the Devil, "A single jumbo jet with a suicide bomber at the controls, hijacked during takeoff from Dubai and crashed into the heart of Ras Tanura, would be enough to bring the world's oil-addicted economies to their knees, America's along with them." . . .

Bin Laden didn't always see attacks on oil as a part of his fight against the United States. When he first declared war against America in 1996, he specified that oil was not one of al Qaeda's targets because the resource was "a large economical power essential for the soon to be established Islamic state." In other words, when al Qaeda's ultimate goal of re-establishing the caliphate was satisfied, bin Laden thought the new state would benefit economically and strategically from its control over a significant portion of the world's oil supply -- and for that reason, al Qaeda would not jeopardize that future wealth by targeting oil infrastructure.

One early indication of a shift in jihadist thinking on attacking oil facilities was Rashid al-Anzi's The Laws of Targeting Petroleum-Related Interests and a Review of the Laws Pertaining to the Economic Jihad, a treatise posted online in March 2004. Anzi, a noted jihadist thinker, called the widespread availability of oil the factor that "enabled America to dominate the world," and explained how attacks on the oil supply could harm the jihadists' foes. He claimed that rising oil prices hurt industrialized countries more than others, and that they were particularly devastating to the United States, the world's largest consumer.. . .

Recognizing their shared vulnerability, the United States and Saudi Arabia embarked on an unprecedented expansion of their security cooperation beginning in 2008. The two countries are developing an elite security force tasked with protecting this infrastructure from attack. It will eventually have at least 35,000 members, the Associated Press reports.. . .

5/23/11