Tweet

 Skriv ut utskriftsvennlig side

Pressen melder at oljesølet i Mexico-Gulfen nå er større enn fra Ixtoc 1-utblåsningen i 1979. Men hvorfor nevnes ikke at de langsiktige miljøskadene den gang var beskjedne?

Associated Press har sendt ut en melding, gjengitt i mange norske medier via NTB, om at oljeutslippet fra Deepwater Horizon nå sannsynligvis har passert utslippene fra Ixtoc 1 i 1979. Vi har nå i månedsvis lest og hørt mye om hvilken miljøkatastrofe dette er. Men hvorfor har ingen norske medier, så vidt jeg har observert, tatt seg bryet med å skrive om hva vi vet om effektene av denne tidligere oljekatastrofen i samme område?

Ixtoc 1 ga betydelige miljøskader de første par årene, men den riktinok relativt beskjedne forskningen i etterkant tyder på at etter det reparerte miljøet seg mer eller mindre selv, og de langsiktige negative effektene fremstår som ytterst beskjedne.

Det er selvsagt ikke gitt at resultatene vil bli de samme denne gangen, særlig fordi utslippene denne gangen er på dypt vann, og at de ramme ulike typer marine miljøer, men en smule relevans har vel tidligere erfaringer? La oss gå til utenlandsk presse:

Guardian 1. juni:

But although Ixtoc was a big disaster, it did not develop into the long-term catastrophe that scientists initially thought was inevitable.

“This is not to say there were no consequences. Just that the evidence is that these are not as dramatic as we feared,” says Luis Soto, a marine biologist from the National Autonomous University of Mexico. “After about two years the recuperation was well on the way.”

Wes Tunnell, now at the Texas Harte Research Institute, took samples before and after the oil arrived in Texas that showed an immediate 80% drop in the number of organisms living between the grains of sand that provide food for shore birds and crabs.

“Sampling a couple of years after the spill indicated the populations were back to normal,” he says. Six years after Ixtoc 1 exploded it was hard to find any evidence of the oil, he says. “It is rather baffling to us all. We don’t really know where it went.”

But although their message is hopeful, those who studied the Ixtoc disaster warn against assuming the gulf is automatically heading for another quick comeback.

Ixtoc 1 stood in just 50 metres (165ft) of water, while Deepwater Horizon was drilling 1,500 metres below the surface. It is also likely that the quantity of chemical dispersants being used today is significantly larger, potentially blocking the work of the oil-eating micro-organisms.

Financial Times, 1. juni

Arne Jernelov, an expert on environmental catastrophes who studied Ixtoc, says that in the case of Macondo, it is a safe bet that shrimp and squid populations will suffer, as they did in the Ixtoc case, “but so is a close-to-complete recovery within a limited number of years”.

Other scientists who studied Ixtoc concluded that the recovery of marine life was in part due to the fact that a large amount of oil evaporated, dissolved in the hot waters of the Gulf of Mexico or sunk into the seabed, forming sediment. The studies were, however, largely supported by Pemex and the Mexican government 20 years ago, so it is impossible to ascertain their independence.

The Mexican Institute of Petroleum concluded in a report after the accident that Ixtoc’s crude oil broke down due to the effect of sunlight, hot water and weather conditions. “The tar oil landing on the beaches is largely innocuous,” it said.

McClatchy 13. juni

The oil was everywhere, long black sheets of it, 15 inches thick in some places. Even if you stepped in what looked like a clean patch of sand, it quickly and gooily puddled around your feet. And Wes Tunnell, as he surveyed the mess, had only one bleak thought: “Oh, my God, this is horrible! It’s all gonna die!”

But it didn’t. Thirty-one years since the worst oil spill in North American history blanketed 150 miles of Texas beach, tourists noisily splash in the surf and turtles drag themselves into the dunes to lay eggs.

“You look around, and it’s like the spill never happened,” shrugs Tunnell, a marine biologist. “There’s a lot of perplexity in it for many of us.”  (…)

But after three months in which nothing went right, Texas had some good luck – or, to put it in a glass-half-empty way, Alabama and Mississippi had some bad luck. Hurricane Frederic, while plowing into those two states, sent tides of two-foot waves reeling into the Texas shoreline. Overnight, half the 3,900 tons of oil piled up on Texan beaches disappeared. And human cleanup efforts began putting a dent in the rest.

Even in Mexico, which had neither the resources nor the hurricanes of the United States, the oil began disappearing under a ferocious counterattack by nature. In the water, much of it evaporated; on beaches, the combined forces of pounding waves, ultraviolet light and petroleum-eating microbes broke it down. (…)

But as much as the experts marvel at the way the environment recovered from the Ixtoc spill, none of them are shrugging off the BP disaster. Some larger species with longer life spans took years to recover from the Ixtoc spill. It wasn’t until the late-1980s that the population of Kemp’s Ridley turtles, which lay a couple of hundred eggs a year, as opposed to the millions produced by shrimp, started recovering. The immediate losses from an oil spill continue to ricochet through larger species for generations.

Lignede dekning finnes i denne saken fra McClatchy 22. mai og IPS News 16. juni.

Og her er en lang liste med forskningsrapporter fra 1980-tallet (som jeg ikke har lest, men de stammer Fra Harte Resarch Institute, som er omtalt i pressedekningen ovenfor.) Denne er fra 1982, fra amerikanske Bureau of Land Management.

Twitter: @jasnoen