(Host) A top government scientist told a federal court that the world has about 10 years to slow the production of greenhouse gases before the planet’s climate is dramatically altered.
Climate expert James Hansen was a lead witness for the state of Vermont.
The state is in court defending new rules that would limit greenhouse gas emissions from cars and trucks.
VPR’s John Dillon has more:
(Dillon) The federal courtroom seemed more like a university lecture hall as physicist James Hansen led the court through the science of global climate change.
But instead of students hunched over tiny desks, there were lawyers – rows and rows of lawyers – with documents and legal briefs piled high in cardboard boxes.
Hansen is a well known scientist who directs NASA’s Goddard Institute of Space Studies in New York City. He became interested in changes to the Earth’s climate and atmosphere after studying the atmosphere on Venus. His job at NASA includes simulating global climate change using high speed computers.
Hansen came to Vermont as an expert witness. The auto industry has sued the state to block new rules that require a 30% reduction in greenhouse gas pollution from cars and light trucks. Hansen said he testified on his own time, and as a private citizen.
(Hansen) “Obviously this is a very important case. If this were to be won it could influence efficiency standards in the whole country and eventually the world. And vehicles are a large fraction of CO2 emissions.”
(Dillon) In court, Hansen told Judge William Sessions that humans have pumped so much greenhouse gas into the atmosphere that it’s now forcing a steady rise in planetary temperature.
He said the levels of carbon dioxide- as measured by air bubbles trapped in ancient ice cores – are now the highest in at least 700,000 years.
He said rising CO2 levels lead to rising temperatures which in turn will melt polar ice sheets. The resulting flooding, Hansen told the court, will inundate areas where about 1 billion people now live.
Hansen said the greenhouse gas rules adopted by Vermont and 11 other states won’t by themselves stop global warming. But he said the world has about 10 years left to reduce greenhouse gas emissions before catastrophic climate change may be unstoppable. He said Vermont’s auto emissions rules are a worthwhile first step.
(Hansen) “We’re going to have to do a lot of other things too. But this is a very important one. Because if we don’t get vehicles under control, they have the potential to cause huge problems just by themselves. We’re going to have to find other ways to power vehicles in the long run.”
(Dillon) But the auto industry says the state’s rules will have an insignificant impact on world climate. Andrew Clubok is a lead lawyer for the car companies.
(Clubok) “And the problem is that if we spend time and billions of dollars, tens of billions of jobs and 200,000 jobs of people going to work, trying to feed their families. We sacrifice all those people now for what we know will not have anything more than a microscopic impact. That’s a big mistake. What we should be doing is focusing on good science, finding the right solution, and addressing the problem sensibly.”
(Dillon) Clubok also sought to discredit Hansen’s projection that the polar ice sheets will melt rapidly as the earth warms. He said that Hansen’s estimates are not supported by the Intergovernmental Panel on Climate Change, an international body of scientists.
But Hansen stood by his testimony. He said recent research using satellites show the Antarctic ice sheet is melting faster than anticipated.
The trial is expected to finish early next week.
For VPR News, I’m John Dillon in Burlington.