Just some days before I came out to join Greenpeace’s Arctic Sunrise on August 4, headlines from a NOAA (National Oceanographic and Atmospheric Administration) press conference said that ‘the vast majority of the oil from the BP spill has either evaporated or been burned, skimmed, recovered from the wellhead or dispersed’. This, the Federal report boasted, was a ‘direct result of the robust federal response efforts’.

However, as reported in the journal Nature other scientists were, to say the least, sceptical. James Cowan, an oceanographer at Louisiana State University said "in my mind it's scientifically indefensible". It appears that neither the report nor its supporting data mention the scale of the uncertainties, and there are scant details about how the numbers were calculated. Other scientists questioned the timing of the report which was released at the same time that BP announced that it had succeeded in capping the well.

The beginning of this spill was characterised by claims and counter-claims – and now as the well is capped and the in-depth work starts to assess the impacts of this spill we are confronted again by claims and counter-claims. Who are we to believe?

Science is certainly not the final arbiter of truth, but we all rely on science as in some ways able to give some kind of balanced assessment. But in the case of the politically and economically powerful vested interests of the oil industry issues of ‘balance’ ‘truth’ ‘openness’ and ‘honesty’ all come way down the priority list when compared to ‘profit’ ‘getting back to business’ ‘satisfying shareholders’.

And today, August 17, clearly outraged by media reports suggesting that 75% of oil had “gone”, the Georgia Sea Grant Program issued a report of their calculations. Contrary to the upbeat NOAA findings this report says that many independent scientists interpret the data differently with some suggesting that less than 10% is gone, leaving 90% in the ecosystem. This report, from a group of university based oceanographic experts, criticised media reports that “gone” meant no longer a threat. But it is difficult to blame the media when this is the spin put on the report as at a White House press conference announcing the calculations Jane Lubchenco, administrator of NOAA said “At least 50% of the oil that was released is now completely gone from the system.”

By contrast the Georgia Sea Grant group believes that most of the dissolved and dispersed oil are still present and not necessarily harmless. They point out that the degradation of crude oil by marine organisms mostly entails the less toxic parts of the crude oil (the so-called short-chain hydrocarbons) not the most toxic elements such as polycyclic aromatic hydrocarbons (PAHs). In fact the most toxic components of crude oil are the least likely to be naturally broken down.

This group of scientists agree that about 4.9 million barrels of oil had gushed from the wellhead between the rig explosion on April 20 and the final capping of the well on July 15 2010, but they estimate that between 70 and 79% remains.

In a further serious questioning of so-called scientific balance, it has emerged that independent scientists who have been working on the Gulf coast for years have had samples taken from them and been denied access to sample areas by BP or the government's National Resource Damage Assessment (NRSA) process. One researcher, Linda Hooper-Bui is an ecosystem biologist at Louisiana State University wrote that if she were to submit data to the NRDA she would have to sign a confidentiality agreement that lacks an end date. Exactly when she or her students would be able to publish any results would be determined by the Department of Justice. If she was to accept research funding directly from BP or from one of their contractors, she would have to sign a contract that includes a three-year no publication clause.

But if she agreed to work then she would have funds and virtually unlimited access to study sites and more research support. Fortunately for us all, this scientist says that the price of the secrecy involved with participating in NRDA or conducting research under the auspices of BP is too high.

It is against this background that Greenpeace is providing the logistical support for independent scientists to do their work and to publish their findings freely. We must not let the truth suffer in this high stakes game with the environment. It is up to all of us to challenge the corporate and political fossil fuel powers that would have it differently.