Citizen Action Monitor

Climate scientist Jim Hansen highlights selected global impacts of climate change

Yet to come is the danger of locking in sea level rise of 6 to 9 meters within decades, not centuries.

No 1964 Posted by fw, May 25, 2017

Dr. James Hansen

“In the Mediterranean, in the Middle East, summers are now hot enough that it’s uncomfortable to work outdoors. More than half of the jobs are either agriculture or construction. And we notice an impact on the productivity. Also, it has an impact on conflicts and violence…. it’s empirical observation that as the temperature gets hotter in the summer, the interpersonal conflicts have increased at 4% per standard deviation. And the intergroup violence by an even larger amount…. it took many centuries for the sea level to rise several meters – but once they [researchers] put in this process of cliff failure and hydro fracturing of the ice, then their time constant becomes several decades instead of several centuries. So, it’s hard to say exactly how long it will take sea level to rise if CO2 keeps increasing.”Jim Hansen

On March 8, 2017, Dr, James Hansen, in a kind of climate change 101 address, a sweeping spectrum of climate change, talked for 50 minutes about what young people will have to do to take charge of the mess they will inherit from the boomers. His talk, titled, Global Climate Change: How Can Young People Take Charge of Their Future? was the keynote address of Williams College’s “Confronting Climate Change” year of inquiry.

Hansen, Adjunct Professor at Columbia University’s Earth Institute, where he directs the Program on Climate Science, Awareness and Solutions, is best known for his testimony on climate change to congressional committees in the 1980s that helped raise broad awareness of the global warming issue.

In Part 1 of this series, Hansen first outlined the global climate crisis, explaining why the crisis, although urgent, has largely been ignored, why there’s a need for a rapid reduction of CO2 emissions, and why a technically feasible solution is not even being proposed by Washington. Secondly, he briefly explained why the failure to act is a potential injustice to young people, to people living in southern regions of the globe, and to other species.

In Part 2, Hansen, without going into detail, briefly highlights more of “the frigging mess” boomers are leaving young people — this time in terms of the severe global impacts of a climate out of control. This 7:19-minute video segment begins at about the 5:41-minute mark of the full 72-minute embedded video, ends at the 13:00-minute mark. My transcript includes subheadings, text highlighting, and some, but not all, of Hansen’s slides.

Alternatively, the full video, without a transcript, is accessible by clicking on the following You Tube linked title.

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Climate Expert Jim Hansen explains the Climate Crisis, James Hansen address at Williams College, You Tube, May 20, 2017 (72 minutes)

TRANSCRIPT

[Highlighting Global Impacts of Climate Change]

I just wanted to say that I’ll say something now about the North to South injustice.

If we look at the climate of a given region, it varies from year to year just because of natural variability, the dynamics of the atmosphere and ocean. But if you go back to the middle of last century, the anomalies about the average formed a nice symmetric bell curve.

But now, as the planet is getting warmer, that bell curve is shifting toward higher temperatures, and the units are standard deviations of the climate that existed 50 years ago.

Extreme warm events over the northern hemisphere are now occurring more than 10% of the time

The extreme warm events over northern hemisphere land that occurred only a tenth of a percent at the time are now occurring more than 10 percent of the time. People should notice that summers are becoming warmer, even though some of them are still cold relative to 50 years ago.

But this shift depends upon your location and the season. In the United States the shift is about one standard deviation. If you’re perceptive, and you’re old enough, you should notice that summers are tending to be warmer than they were some decades ago. But the winters are not as noticeably affected because the natural variability is larger.

In the subtropics, every summer is hotter than it was 50 years ago  

On the other hand, if you go to the subtropics, like the Mediterranean Region in the Middle East, there the shift in the summer is more than two standard deviations; so every summer is hotter than it was 50 years ago. In the tropics, that’s true and it’s all seasons. The Horn of Africa, where they’re now having an extreme drought in high temperatures, is an example.

Extreme heat lowers productivity, increases conflicts and violence, causes drought

And that has a noticeable effect. In the Mediterranean, in the Middle East, summers are now hot enough that it’s uncomfortable to work outdoors. More than half of the jobs are either agriculture or construction. And we notice an impact on the productivity. Also, it has an impact on conflicts and violence. It’s just an appearance, not a physical law, but it’s empirical observation that as the temperature gets hotter in the summer, the interpersonal conflicts have increased at 4% per standard deviation. And the intergroup violence by an even larger amount. And all places, all regions, as the planet gets warmer, those regions that tend to be dry, the subtropics, and when it is dry we tend to get more extreme heat and drought.

Higher temperature = more evaporation = more floods = more forest and wild fires

But the higher temperature also causes more evaporation from the ocean. So the times and places where the rain comes down will tend to be heavier, so you tend to get more floods. And we see this statistically, the fires – it’s one of the reasons that we see an increase in the forest fires, the wild fires.

More 100-year floods, more severe tornadoes, hurricanes and other extreme weather events

Also, we see the hundred-year flood is now occurring more often that once every century. And those storms that are driven by the latent heat in the water vapor – that means thunderstorms, tornadoes, tropical storms have the potential to be stronger, as the atmosphere holds more water vapor – because that’s the fuel for the storm. For example, this hurricane Sandy, as it came up the east coast, the ocean was 3°C warmer than normal. It was able to stay a hurricane all the way up to New York City, which it would not have without that extra warming. And that did have a number of effects, which have still not been recovered from, in fact.

Spread of insect carrying diseases related to shifting climate zones to higher latitudes and altitudes

And the shifting of zones is also allowing these disease vectors to move to higher latitudes, and to higher altitudes in the tropics.

Biggest change yet to come – Sea level is beginning to rise faster

But the biggest effect of climate change is going to be the effect of sea level rise. Sea level is beginning to rise faster. The rate now, several times larger than a century ago, is still moderate in a sense – three or four millimeters a day is about 13 or 14 inches in a century. So that’s a little more than a nuisance. But with the shape of this curve, it’s very likely that we will get much higher rates, particularly if the temperature of the earth continues to increase, as we know from the earth’s history.

Sea levels on earth were once 6 to 9 meters higher than they are now, even though the temperature then was less than 2°C warmer

The last time the earth was warmer than the current interglacial period was during the Eemian, which was 120 thousand years ago. Sea level then reached six to nine meters higher than now, and yet the temperature was less than 2°C warmer than pre-industrial.

We are in danger of locking in sea level rise of 6 to 9 meters

The temperature now has risen already a little more than 1°C relative to pre-industrial. We are in danger of locking in sea level rise of that amount. You can argue about how long it will take to get multi-meter sea level rise. We presented a paper in which we argue it would be — if we stay on high emissions – that it would be between 50 and 150 years when you get multi-meter sea level rise.

Adding in effects of cliff failure and ice fracturing, the time constant is now decades, not centuries

They’ve [researchers] realized that ice sheets are not rocks. Their models had suggested – well, it took many centuries for the sea level to rise several meters – but once they put in this process of cliff failure and hydro fracturing of the ice, then their time constant becomes several decades instead of several centuries. So, it’s hard to say exactly how long it will take sea level to rise if CO2 keeps increasing.

Add to your worries the coastline location of most large cities of the world

The problem is that most of the large cities in the world are located on coastlines. I think you’re going to have to worry about that.

END OF PART 2

SEE ALSO

As Trump Ignores Climate Change, Seas Threaten to Swallow Alaskan Villages by John Light, Moyers & Company, May 23, 2017 — The rapidly warming Arctic means that dozens of villages inhabited by Alaskan native peoples need to relocate — but the money isn’t there.

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