The Observer, Sunday 15th February:
A year ago, I wrote to Gordon Brown asking him to place a moratorium on new coal-fired power plants in Britain. I have asked the same of Angela Merkel, Barack Obama, Kevin Rudd and other leaders. The reason is this – coal is the single greatest threat to civilisation and all life on our planet.
The climate is nearing tipping points. Changes are beginning to appear and there is a potential for explosive changes, effects that would be irreversible, if we do not rapidly slow fossil-fuel emissions over the next few decades. As Arctic sea ice melts, the darker ocean absorbs more sunlight and speeds melting. As the tundra melts, methane, a strong greenhouse gas, is released, causing more warming. As species are exterminated by shifting climate zones, ecosystems can collapse, destroying more species.
The public, buffeted by weather fluctuations and economic turmoil, has little time to analyse decadal changes. How can people be expected to evaluate and filter out advice emanating from those pushing special interests? How can people distinguish between top-notch science and pseudo-science?
Those who lead us have no excuse – they are elected to guide, to protect the public and its best interests. They have at their disposal the best scientific organisations in the world, such as the Royal Society and the US National Academy of Sciences. Only in the past few years did the science crystallise, revealing the urgency. Our planet is in peril. If we do not change course, we’ll hand our children a situation that is out of their control. One ecological collapse will lead to another, in amplifying feedbacks.
The amount of carbon dioxide in the air has already risen to a dangerous level. The pre-industrial carbon dioxide amount was 280 parts per million (ppm). Humans, by burning coal, oil and gas, have increased this to 385 ppm; it continues to grow by about 2 ppm per year.
Earth, with its four-kilometre-deep oceans, responds only slowly to changes of carbon dioxide. So the climate will continue to change, even if we make maximum effort to slow the growth of carbon dioxide. Arctic sea ice will melt away in the summer season within the next few decades. Mountain glaciers, providing fresh water for rivers that supply hundreds of millions of people, will disappear – practically all of the glaciers could be gone within 50 years – if carbon dioxide continues to increase at current rates. Coral reefs, harbouring a quarter of ocean species, are threatened.
The greatest danger hanging over our children and grandchildren is initiation of changes that will be irreversible on any time scale that humans can imagine. If coastal ice shelves buttressing the west Antarctic ice sheet continue to disintegrate, the sheet could disgorge into the ocean, raising sea levels by several metres in a century. Such rates of sea level change have occurred many times in Earth’s history in response to global warming rates no higher than those of the past 30 years. Almost half of the world’s great cities are located on coastlines.
The most threatening change, from my perspective, is extermination of species. Several times in Earth’s history, rapid global warming occurred, apparently spurred by amplifying feedbacks. In each case, more than half of plant and animal species became extinct. New species came into being over tens and hundreds of thousands of years. But these are time scales and generations that we cannot imagine. If we drive our fellow species to extinction, we will leave a far more desolate planet for our descendants than the world we inherited from our elders.
Clearly, if we burn all fossil fuels, we will destroy the planet we know. Carbon dioxide would increase to 500 ppm or more. We would set the planet on a course to the ice-free state, with sea level 75 metres higher. Climatic disasters would occur continually. The tragedy of the situation, if we do not wake up in time, is that the changes that must be made to stabilise the atmosphere and climate make sense for other reasons. They would produce a healthier atmosphere, improved agricultural productivity, clean water and an ocean providing fish that are safe to eat. (Read more)
Tag Archives: Hansen
Nasa climate expert makes personal appeal to Obama
The Guardian, 2nd January 2008
One of the world’s top climate scientists has written a personal new year appeal to Barack and Michelle Obama, warning of the “profound disconnect” between public policy on climate change and the magnitude of the problem.
With less than three weeks to go until Obama’s inauguration, Professor James Hansen, who heads Nasa’s Goddard Institute for Space Studies, asked the recently appointed White House science adviser Professor John Holdren to pass the missive directly to the president-elect.
In it, he praises Obama’s campaign rhetoric about “a planet in peril”, but says that how the new president acts in office will be crucial. Hansen lambasts the current international approach of setting targets through “cap and trade” schemes as not up to the task. “This approach is ineffectual and not commensurate with the climate threat. It could waste another decade, locking in disastrous consequences for our planet and humanity,” the letter from Hansen and his wife, Anniek, reads.
The letter will make uncomfortable reading for officials in 10 US states whose cap and trade mechanism – the Regional Greenhouse Gas Initiative – got under way yesterday. The scheme is the first mandatory, market-based greenhouse gas reduction programme in the US.
Hansen advocates a three-pronged attack on the climate problem.
Guest Opinion: Global Warming Twenty Years Later
James Hansen on June 23, 2008
Tipping Points Near
Today, I will testify to Congress about global warming, 20 years after my June 23, 1988 testimony, which alerted the public that global warming was under way. There are striking similarities between then and now, but one big difference.
Again a wide gap has developed between what is understood about global warming by the relevant scientific community and what is known by policymakers and the public. Now, as then, frank assessment of scientific data yields conclusions that are shocking to the body politic. Now, as then, I can assert that these conclusions have a certainty exceeding 99 percent.
The difference is that now we have used up all slack in the schedule for actions needed to defuse the global warming time bomb. The next President and Congress must define a course next year in which the United States exerts leadership commensurate with our responsibility for the present dangerous situation.
Otherwise, it will become impractical to constrain atmospheric carbon dioxide, the greenhouse gas produced in burning fossil fuels, to a level that prevents the climate system from passing tipping points that lead to disastrous climate changes that spiral dynamically out of humanity’s control. Continue reading