Humans may go the way of the dinosaur if we don't get a hold of global air pollution.

That is according to American environmental activists Barbara Ettinger and husband Sven Huseby, who were in Bermuda to show their documentary film 'A Sea Change: A World Without Fish'.

The film, by Niijii Films, shown at the Bermuda Institute for Ocean Sciences (BIOS) was about rising acidity levels in the world's oceans and its impact on human health.

"The problem is the rate that the oceans are becoming acidic," Mr. Huseby said. "The oceans have become 30 percent more acidic in the last 200 years."

He said microscopic ocean creatures, particularly calcifying organisms, zoo plankton and shelled organisms are fighting a harder fight because of the increasing acidity.

"As the oceans become increasingly acidic, it is more challenging for them to find the calcium carbonate they need to build their shells," he said. "The problem is the worst for the infant forms of these animals.

"These organisms need time to evolve and adapt to the changes in the ocean."

And if you think the fortune of some microscopic animal has nothing to do with your life, think again.

Fish depend on these critters for survival. And one billion people in the world depend on fish as their main source of protein.

No fish, no food for more than one sixth of the world's population.

"The world may be on the brink of a catastrophic extinction period not experienced in over 60 million years," said Mr. Huseby, a retired highschool teacher from Germantown, New York.

"We are experiencing a phenomenon that has never been known during the time of man.

"People forget that whatever killed the dinosaurs 65 million years ago, also killed 70 percent of the other species in the world at that time."

He said the increasing acidity was the direct result of the decision people made during the Industrial Revolution, 200 years ago, to fuel modern life with the combustion of fossil fuels.

"When we combust oil, natural gas or gasoline we are putting carbon dioxide (CO2) into the air and every day thirty percent of that, or 22 million tons, is absorbed by the ocean.

"That CO2 combines with water to form carbonic acid. We all know carbonic acid which is the same as the bubbles we see in any carbonated beverage.

"Because the amounts of CO2 we are putting into the atmosphere are so great, we are actually changing the chemistry of the ocean."

Ms Ettinger and Mr. Huseby decided to make the movie, after reading Elizabeth Kolbert's article 'The Darkening Sea' in The New Yorker.

The article discussed the research of oceanographer Victoria Fabry, an oceanographer who studies tiny marine organisms, called pterapods. As part of her research, she noted that increased CO2 in the water caused the pterapod shells to dissolve.

"It is important that you understand that we are not scientists," said Mr. Huseby. "We are not marine biologists. We are just people who want to make the world aware of a growing threat."

Ms Ettinger said despite increasing education about environmental pollution and global warming, the amount of carbon dioxide being released into the world hasn't decreased at all.

"It is within our power to lessen the amount of CO2 emissions we are putting into the atmosphere," she said. "That means it is within our power to slow down the rate of change.

"Then, maybe different species would have a chance to adapt and not be at risk of extinction."

Mr. Huseby said ordinary people could do their part in cutting down on emissions.

"One of the people in our film says 'perhaps we can slow down the rate in such a way that we will have a moment in which we can learn to live on this planet without destroying it'."

'A Sea Change' is one of the first documentaries about ocean acidification.

"Ocean acidification is such a newly-known phenomenon," said Mr. Huseby. "It has only been seven or eight years that scientists have become aware of it."

The couple have spent the last nine months travelling all over the United States showing their film, and talking about ocean acidification to anyone who will listen.

It seems they have met with some success getting the word out there.

The National Oceanic and Atmospheric Administration (NOAA) purchased 2,400 copies of 'A Sea Change' to include in a new magazine they are publishing called 'Oceanography'. It will be attached to the backflap.

The Husebys also appeared on a segment of the Martha Stewart Show which is viewed by millions of people.

The film has collected several awards including Best Green Film, at the Kosovo International Documentary Film Festival; Grand Prize, Feature Documentary, at the Fica International Environmental Film Festival; and the Dumosa Award for Best Coastal Film, at the Cottonwood Environmental Film Festival, among many other awards.

"NOAA has told us that we have made a difference in Washington DC," said Ms Ettinger. "Many people of influence have seen the film and now know what ocean acidification is, and are beginning to take notice."

The film has aired several times on Planet Green, a station owned by the Discovery Channel.

And now the Husebys plan to take their battle across the ocean.

They will soon be off to Copenhagen, Denmark, to show the film at the Conference of the Parties 15 (COP15) meeting, the precursor to the renegotiation of the Kyoto Treaty 1997 which committed industrialised nations to reducing emissions of greenhouse gases, principally CO2, by 5.2 percent below their 1990 levels over the following decade.

The agreement needed to be ratified by countries who were responsible for more than half of the world's carbon emissions. In March 2001, then president George W. Bush refused to sign it.

"My hope and dream as we look forward to getting beyond Kyoto that expires in 2012, is that the US and China will come to an agreement about how they together can provide leadership, and move things forward," said Ms Ettinger. "If they fail, we all fail."

Ms Ettinger has been a filmmaker for 20 years. She previously produced a film called 'Two Square Miles' (2006) that aired on PBS in the United States.

This film was about a small community in upstate New York trying to dissuade the St. Lawrence Cement Company (SLC) from building North America's largest coal fire cement plant one mile from a local hospital.

"This was a six-year-battle," said Ms Ettinger. "It was one of the few environmental victories in that political era."

She said in the Hudson River Valley area of New York State where they live, more people were becoming more environmentally aware.

"They are living more conscious of their carbon footprint," said Ms Ettinger. "They are looking at ways of driving less and driving less with smaller cars or hybrid cars. A lot of people are also looking at insulation to cut down on house heating costs."

She said that soon the United States would be passed by China in terms of total CO2 output.

"But China is now doing some extraordinary new developments that could move them away from their tremendous dependence on coal," she said. "They are building a 3,000 megawatt solar facility in Mongolia.

"They have over 200 companies working on better batteries for electric vehicles. They would like to see themselves as the worlds major supplier of electric cars by 2030."

For more information about the film go to their website at www.aseachange.net