Science

Why I must speak out on climate change: James Hansen at TED2012

Posted by: Ben Lillie

Photo: James Duncan Davidson

Drawn into controversy

Wearing his wide-brimmed hat, climate scientist James Hansen starts his TEDTalk by asking, “What do I know that would cause me, a reticent midwestern scientist, to get arrested in front of the White House, protesting?”

Hansen studied under professor James Van Allen, who told him about observations of Venus — there was intense microwave radiation — because it’s hot, and it was kept that way by a thick C02 atmosphere. He was fortunate enough to join NASA and send an instrument to Venus. But while it was in transit, he became involved in calculating what would be the effect of the greenhouse effect here on Earth.

It turns out the atmosphere was changing before our eyes and, “A planet changing before our eyes is more important, it affects and changes our lives.” The greenhouse effect has been understood for a century. Infrared radiation is absorbed by a layer of gas, working like a blanket to keep heat in.

He worked with other scientists and eventually published an article in Science in 1981. They made several predictions in that paper: There would be shifting climate zones, rising sea levels, an opening of the northwest passage, and other effects. All of these have happened or are underway.

That paper was reported on the front page of the NY Times, and led to him testifying to congress. He told them it would produce varied effects, heat waves and droughts, but also (because warmer atmosphere holds more water vapor) more extreme rainfall, stronger storms and greater flooding.

All the global warming ‘hoopla’ became too much, and was distracting him from doing science. In addition, he was upset that the White House had altered his testimony, so he decided to leave communication to others.

The future draws him back in

The problem with not speaking was that he had two grandchildren. He realized he did not want them to say, “Opah understood what was happening, but he didn’t make it clear.”

So he was drawn more and more into the urgency.

Adding carbon to the air is like throwing a blanket on the bed. “More energy is coming in than is going out, until Earth is warm enough to raiate to space as much energy as it recieves from the Sun.” The key quantity is the imbalance, so they did the measurements. It turns out that continents to depths of tens of meters were getting warmer, and the Earth is gaining energy from heat. That amount of energy is equivalent to dropping 400,000 Hrioshima bombs every day, over a year, and there is as much in the pipeline as has already occurred.

If we want to restore energy balance and prevent further warming, we need to reduce the carbon levels from 391 parts per million to 350.

The arguments against

Deniers contend that it’s the sun driving this change. But Hansen notes the biggest change occurred during the low point of the solar cycle — meaning that the effect from the sun is dwarfed by the warming effect.

There are remarkable records in the Earth of what has come before, and we’ve studied them extensively. There is a high correlation between the overall temperature, carbon levels, and sea level. The temperature slightly leads carbon changes by a couple centuries. Deniers like to use that to trick the public. But these are amplifying feedbacks, even through it’s instigated by small effect, a cycle is set up that feed in on itself: More sun in the summer means that ice sheets melt, which means a darker planet, which means more warming. These amplifying feedbacks account for almost entire paleoclimate changes.

The same amplifying feedbacks must occur today. Ice sheets will melt, carbon and methane will be releaseed. “We can’t say exactly how fast these effects will happen, but it is certain they will occur. Unless we stop the warming.”

The view of the future

Hansen presents data showing that Greenland and Antarctica are both losing mass, and that methane is bubbling from the permafrost. That does not bode well. Historically, even at today’s level of carbon, the sea level was 15 meters higher than it is now. We will get least one meter of that this century.

We will have started a process that is out of humanity’s control. There will be no stable shoreline, and the economic implications of that are devastating — not to mention the spectacular loss of speices. It’s possible that 20-50% of all species could be extinct by end of century if we stay on fossil fuels.

Changes have already started. The Texas, Moscow, Oklahoma and other heat waves in recent memory were all exceptional events. There is clear evidence that these were caused by global warming.

Intergenerational injustice

Hansen’s grandson Jake is super-enthusiastic, “He thinks he can protect his 2 and a half day old little sister. It would be immoral to leave these people with a climate system spiraling out of control.”

The tragedy is that we can solve this. It could be addressed by collecting a fee for carbon emissions, distributed to all residents. That would stimulate the economy and innovation, and would not enlarge the government. Instead of doing this, we are subsidizing fossil fuels by $400-500 billion per year worldwide.

This, says Hansen, is a planetary emergency, just as important as an asteroid on its way. “But we dither, taking no action to divert the asteroid, even though the longer we wait, the more difficult and expensive it becomes.”

“Now you know some of what I know that is sounding me to sound this alarm. Clearly I haven’t gotten this message across. I need your help. We owe it to our children and grandchildren.”