On a day marking the 20th anniversary of the notorious Exxon Valdez oil spill, environmentalists urged lawmakers to reinstate a ban on new offshore drilling for oil and gas in vast expanses of the outer continental shelf—the land that extends off of North America's coasts under relatively shallow waters.

These areas were largely off-limits to energy exploration from 1990 through last year, when former President George W. Bush lifted an executive order prohibiting oil and gas extraction and Congress let lapse a legislative moratorium on drilling there.

Since the bans ended, leasing has begun anew off the coast of Alaska, with some three million acres (one million hectares) in the Chukchi Sea now let. In all, some 70 million acres (28 million hectares) around Alaska are now available for fossil-fuel exploration and industrial development.

With that much territory in play, wildlife conservationists and some policymakers fear a repeat of the Exxon Valdez accident, the largest tanker spill in the U.S. and one of the most environmentally deleterious in history. Oil washed up on 1,200 miles (1,900 kilometers) of Alaskan shoreline, killing countless sea creatures and disrupting commercial fishing and the lives of thousands of locals. The region still has not completely recovered, with toxic oil still turning up when people or animals dig pits on some beaches. Despite some $2 billion spent on cleanup, only about 8 percent of the oil was recovered and removed from the environment, Jeff Short testified during a House hearing today. Short is the Pacific science director since 2008 for Oceana, a Washington, D.C.–based ocean conservation organization.

Short knows a bit about Alaska, having lived there for 37 years. He also knows about oil spills, having studied them for 31 years as an environmental chemist for the National Oceanic & Atmospheric Administration (NOAA) in Juneau. (He retired from the agency last year.)

ScientificAmerican.com spoke with Short yesterday about the potential effects of expanded oil and gas production off Alaska's coasts—and whether it holds the answers to our energy woes.

[An edited transcript of the interview follows.]

What do you hope to gain by testifying in Washington today?

My overall hope is that the government will reinstate a moratorium on offshore oil and gas exploitation, consider terminating leases in the Chukchi and Beaufort Seas, and not offer up Bristol Bay in the Bering Sea as well. We at Oceana think this is a really bad idea. We're encouraged by recent pronouncements by the new secretary of the interior, Ken Salazar, and the Obama administration in general about increasing conservation and alternative energy sources, each of which could quickly preclude any need for drilling in our continental shelf.

Why do you think further oil and gas activity should not occur in Alaskan waters?

I don't think it is widely appreciated that the Bering Sea and the Chukchi Sea are among the most biologically productive seas in the world. They are particularly bad places to add industry. Beyond basic productivity, though, we really know very little about how the basic food web of these ecosystems works, or even to a large extent what life forms are there—we're at a very primitive state of understanding. Plus, the region is already undergoing profound change due to global warming and increasing ocean acidification.

How much oil is in these areas of Alaska's outer continental shelf?
The U.S. Minerals Management Service (MMS) estimates there are 22 billion barrels of recoverable reserves in the Beaufort and Chukchi seas. If even a portion were exploited, it would be far more than what is currently produced in the state of Alaska. If the total 22 billion barrels were somehow recovered and produced—which is an almost negligible likelihood—it would be enough oil to supply all the U.S.'s [current level of consumption] for three years. It's really more like six months once you get down to what they're likely to recover, though. As far as world consumption is concerned, that goes down to a week or so. So drilling off of Alaska is not something that's going to save us as far as energy security and supply goes. It's just one more quick fix.

How close to becoming a reality is this expansion of offshore oil and gas drilling?
If the new leases and others go forward, it would be an enormous expansion of current offshore drilling off of Alaska. But there are several hurdles for the projects to overcome, so it is hard to estimate the likelihood of these oil fields being exploited. The biggest obstacle is the absence of existing infrastructure in the region. Projects will rely on tapping into the Trans-Alaska Pipeline and its tributaries. Oil companies would need to see a single large consolidated oil deposit to really provide the economic incentive to build further access. If that happens, it would allow exploration and production of smaller satellite fields around the main field.

The MMS calculates a 40 percent and a 26 percent chance of a "large" spill in the Chukchi and Beaufort seas, respectively. What are those figures based on and what do they mean?
The MMS looks at the safety record for these sorts of operations, and then tries to apply considerations for the significantly more adverse conditions in the Arctic. If you do the math right, that is, if you combine those figures together, you see that it's more likely than not that at least one large oil spill will occur. By "large," the MMS doesn't mean as big as the Exxon Valdez [which spilled almost 260,000 barrels], but more on the order of 4,000 barrels or so. That would still make one heck of a mess.

When you say "adverse conditions in the Arctic," what do you mean?
Well, for four months of the year, for starters, there is continuous darkness—that doesn't help. These oil platforms would also be operating in broken sea ice conditions, as well, and we don't have very much experience in dealing with that. Engineers would bury pipelines beneath the seabed to be below most instances of ice scour [which is when icebergs gouge the seabed], but it's infeasible to bury them deep enough to be totally safe.

The situation is very analogous to the Exxon Valdez—all sorts of estimates were made to try and figure out the likelihood of a spill in the region. But there are three things you can never factor in: complacency; the inexorable drive [by operators] to minimize costs at the expense of safety; and plain old human error, all of which played a role in the Exxon Valdez accident. We see the same thing starting up again in Prince William Sound as there's talk about lessening [post-incident] measures since there hasn't been a significant spill in some time. Some people are asking if we really need dual tugboats to escort these oil tankers, for example.

How could the existing outer continental shelf leases in Alaska leases be terminated?
There's a legal precedent for undoing them in Alaska with Kachemak Bay in the 1970s. After the leases were let, the biological value of the area was so highly prized that the state decided to buy the leased lands back. Today, Kachemak Bay is one of the most biologically productive stretches of water in the state.

What are your other major concerns about the future health of the Arctic?
As a civilization, we're playing with fire in the Arctic—the loss of sea ice in the last two years risks engaging feedback loops that could put runaway global warming beyond our control. As sea ice melts in the summertime, a reflective surface, the ice, is transformed into an absorptive, watery one. So the waters heat up, which in turn heat up the landmasses, melting the permafrost and setting the stage for massive methane and carbon dioxide release from frozen biomass, accelerating [climatic warming causing more] sea ice melting, and so on.

These are the kind of things that keep me up at night. I have a 12-year-old kid and I despair thinking of what kind of planet he will be dealing with when he's my age. It is just crazy to me why we are considering doing this in Alaska when we may set in motion events that we will never be able to stop.