kottke.org posts about James Hansen

Climate change: we're past the point of no returnAug 10 2015

In Rolling Stone, Eric Holthaus writes that as far as climate change is concerned, we are already past the point of no return. The things climate scientists have warned against are already beginning to happen...and faster than predicted.

Hansen's new study also shows how complicated and unpredictable climate change can be. Even as global ocean temperatures rise to their highest levels in recorded history, some parts of the ocean, near where ice is melting exceptionally fast, are actually cooling, slowing ocean circulation currents and sending weather patterns into a frenzy. Sure enough, a persistently cold patch of ocean is starting to show up just south of Greenland, exactly where previous experimental predictions of a sudden surge of freshwater from melting ice expected it to be. Michael Mann, another prominent climate scientist, recently said of the unexpectedly sudden Atlantic slowdown, "This is yet another example of where observations suggest that climate model predictions may be too conservative when it comes to the pace at which certain aspects of climate change are proceeding."

Since storm systems and jet streams in the United States and Europe partially draw their energy from the difference in ocean temperatures, the implication of one patch of ocean cooling while the rest of the ocean warms is profound. Storms will get stronger, and sea-level rise will accelerate. Scientists like Hansen only expect extreme weather to get worse in the years to come, though Mann said it was still "unclear" whether recent severe winters on the East Coast are connected to the phenomenon.

You might also like to read Adam Sobel's reaction to this piece. As I wrote in reaction to James Hansen's recent paper: "That's the thing about nonlinear systems like the Earth's climate: things happen gradually, then suddenly."

Update: A group of climate scientists at Climate Feedback analyzed Holthaus' piece at his request for accuracy.

While the information within the article is mostly accurate, the main issue for scientists is the article's framing of the information. More specifically, the article implicitly attributes many weather events to human-induced climate change, while the influence of human activity on these events is not always supported by science, or is at the frontier of scientific knowledge and still debated.

Sea level may rise much faster than previously predictedJul 21 2015

James Hansen, NASA's former top climate scientist, is joined by 16 other leading climate scientists in a paper with some alarming conclusions. The gist is that the glaciers in Antartica and Greenland are melting so much faster than previously predicted that the global sea level will rise more than 10 feet in as little as 50 years, rendering many coastal cities uninhabitable. From Eric Holthaus in Slate:

The study -- written by James Hansen, NASA's former lead climate scientist, and 16 co-authors, many of whom are considered among the top in their fields -- concludes that glaciers in Greenland and Antarctica will melt 10 times faster than previous consensus estimates, resulting in sea level rise of at least 10 feet in as little as 50 years. The study, which has not yet been peer reviewed, brings new importance to a feedback loop in the ocean near Antarctica that results in cooler freshwater from melting glaciers forcing warmer, saltier water underneath the ice sheets, speeding up the melting rate. Hansen, who is known for being alarmist and also right, acknowledges that his study implies change far beyond previous consensus estimates. In a conference call with reporters, he said he hoped the new findings would be "substantially more persuasive than anything previously published." I certainly find them to be.

That's the thing about nonlinear systems like the Earth's climate: things happen gradually, then suddenly. This is much more terrifying to me than the Pacific Northwest earthquake. BTW, as a reminder, here's what NYC and the surrounding area looks like with 10 more feet of water. Goodbye JFK Airport.

Update: The paper is now available online.

Update: In the New Yorker, Elizabeth Kolbert provides a bit more explanation and context about Hansen's paper.

What the new paper does is look back at a previous relatively warm period, known as the Eemian, or, even less melodically, as Marine Isotope Stage 5e, which took place before the last ice age, about a hundred and twenty thousand years ago. During the Eemian, average global temperatures seem to have been only about one degree Celsius above today's, but sea levels were several metres higher. The explanation for this, the new paper suggests, is that melt from Antarctica is a non-linear process. Its rate accelerates as fresh water spills off the ice sheet, producing a sort of "lid" that keeps heat locked in the ocean and helps to melt more ice from below. From this, the authors conclude that "rapid sea level rise may begin sooner than is generally assumed," and also that a temperature increase of two degrees Celsius would put the world well beyond "danger."

"We conclude that the 2°C global warming 'guardrail,' affirmed in the Copenhagen Accord, does not provide safety, as such warming would likely yield sea level rise of several metres along with numerous other severely disruptive consequences for human society and ecosystems," Hansen and his colleagues wrote.

Photo of a massive Arctic cycloneAug 09 2012

Where have I seen this before, a massive long-lasting Arctic storm that looks a lot like a hurricane? Oh right, The Day After Tomorrow.

Arctic Storm

The storm had an unusually low central pressure area. Paul A. Newman, chief scientist for Atmospheric Sciences at NASA's Goddard Space Flight Center in Greenbelt, Md., estimates that there have only been about eight storms of similar strength during the month of August in the last 34 years of satellite records. "It's an uncommon event, especially because it's occurring in the summer. Polar lows are more usual in the winter," Newman said.

Arctic storms such as this one can have a large impact on the sea ice, causing it to melt rapidly through many mechanisms, such as tearing off large swaths of ice and pushing them to warmer sites, churning the ice and making it slushier, or lifting warmer waters from the depths of the Arctic Ocean.

I love The Day After Tomorrow. I know it's a cheeseball disaster movie (which is pretty much why I love it) but it's also looking more than a little prescient. Well, as prescient as a cheeseball disaster movie can be anyway. In the Washington Post the other day, prominent climatologist James Hansen wrote that human-driven climate change is responsible for an increase in extreme weather.

My projections about increasing global temperature have been proved true. But I failed to fully explore how quickly that average rise would drive an increase in extreme weather.

In a new analysis of the past six decades of global temperatures, which will be published Monday, my colleagues and I have revealed a stunning increase in the frequency of extremely hot summers, with deeply troubling ramifications for not only our future but also for our present.

This is not a climate model or a prediction but actual observations of weather events and temperatures that have happened. Our analysis shows that it is no longer enough to say that global warming will increase the likelihood of extreme weather and to repeat the caveat that no individual weather event can be directly linked to climate change. To the contrary, our analysis shows that, for the extreme hot weather of the recent past, there is virtually no explanation other than climate change.

In many ways, the phrase "global warming" is grossly misleading. "Oh," we think, "it's gonna be a couple degrees warmer in NYC in 20 years than it is now." But the Earth's climate is a chaotic non-linear system, which means that a sudden shift of a degree or two -- and when you're talking about something as big as the Earth, a degree over several decades is sudden -- pushes things out of balance here and there in unpredictable ways. So it's not just that it's getting hotter, it's that you've got droughts in places where you didn't have them before, severe floods in other places, unusually hot summers, and even places that are cooler than normal, all of which disrupts the animal and plant life that won't be able to acclimate to the new reality fast enough.

But pretty Arctic cyclone though, right?

Climatologist James Hansen: we're almost too late re: climate changeJun 24 2009

Climatologist James Hansen, who is the director of NASA's Goddard Institute for Space Studies and the creator of one of the first climate models that predicted global warming, is convinced that the problem of climate change caused by humans is much more dire than is generally thought (subscribers only link; abstract).

Hansen has now concluded, partly on the basis of his latest modeling efforts and partly on the basis of observations made by other scientists, that the threat of global warming is far greater than even he had suspected. Carbon dioxide isn't just approaching dangerous levels; it is already there. Unless immediate action is taken-including the shutdown of all the world's coal plants within the next two decades-the planet will be committed to climate change on a scale society won't be able to cope with. "This particular problem has become an emergency," Hansen said.

Hansen is so adamant about this belief that he has begun participating in protests around the globe, an unusual level of activism for such a respected and high-ranking government official. The last sentence of the piece reads:

He said he was thinking of attending another demonstration soon, in West Virginia coal country.

Elizabeth Kolbert, the author of the piece above, reports that Hansen not only attended that demonstration but got arrested.

Tags related to James Hansen:
global warming science Eric Holthaus

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