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Global warming forecast ... from 1981

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Global warming forecast ... from 1981

Postby kurt_w » Tue Apr 03, 2012 8:13 am

Way back in 1981, NASA scientist James Hansen published a paper in Science with the title Climate Impact of Increasing Atmospheric Carbon Dioxide. In the paper, Hansen and his colleagues made various projections of global climate through 2100.

How are those projections looking so far? Pretty accurate -- except that they tended to underestimate the rate of warming. The red and pink lines are actual, observed temperatures so far; the gray graph behind them is the projections from the 1981 paper:

Image

More here. Continuing on this trend would lead to temperatures in 2100 that are warmer than anything in tens of millions of years, before the evolution of humans.
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Re: Global warming forecast ... from 1981

Postby snoqueen » Tue Apr 03, 2012 10:00 am

Our March this year has contained a series of days at least 30 degrees warmer than usual, maybe more. Think what 30 degrees warmer than usual would mean in July.
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Re: Global warming forecast ... from 1981

Postby gargantua » Tue Apr 03, 2012 11:13 am

snoqueen wrote:Our March this year has contained a series of days at least 30 degrees warmer than usual, maybe more. Think what 30 degrees warmer than usual would mean in July.


Someone has. During one of the 80 degree forecasts back in March, Gary Cannalte commented that an equivalent event in July would have high temperatures over 120 degrees.

The other thing that struck me was that all of the meteorologists are so puzzled by it. Maybe things have changed since, but during the hot spell they admitted they had no idea why it was so warm for so long.
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Re: Global warming forecast ... from 1981

Postby ArturoBandini » Tue Apr 03, 2012 12:55 pm

gargantua wrote:The other thing that struck me was that all of the meteorologists are so puzzled by it. Maybe things have changed since, but during the hot spell they admitted they had no idea why it was so warm for so long.
Climate != Weather.
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Re: Global warming forecast ... from 1981

Postby ArturoBandini » Tue Apr 03, 2012 12:58 pm

snoqueen wrote:Our March this year has contained a series of days at least 30 degrees warmer than usual, maybe more. Think what 30 degrees warmer than usual would mean in July.

I'm not sure it makes sense to apply a direct linear translation temperatures like that. There are almost certainly some environmental feedbacks (perhaps water phase equilibria) that would make the difference between 50F and 80F qualitatively different than 90F/120F. Make sense?
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Re: Global warming forecast ... from 1981

Postby Meade » Tue Apr 03, 2012 1:04 pm

snoqueen wrote:Our March this year has contained a series of days at least 30 degrees warmer than usual, maybe more. Think what 30 degrees warmer than usual would mean in July.

But if this July turns out to be 30 degrees cooler than normal, you will abandon your belief in anthropogenic global warming, right?
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Re: Global warming forecast ... from 1981

Postby kurt_w » Tue Apr 03, 2012 1:05 pm

ArturoBandini wrote:
snoqueen wrote:Our March this year has contained a series of days at least 30 degrees warmer than usual, maybe more. Think what 30 degrees warmer than usual would mean in July.

I'm not sure it makes sense to apply a direct linear translation temperatures like that. There are almost certainly some environmental feedbacks (perhaps water phase equilibria) that would make the difference between 50F and 80F qualitatively different than 90F/120F. Make sense?


I thought about that, mentally waffled about it for a while, and then decided that I didn't know what to say.

I've worked in literally 120+ heat in the Middle East, on a civil engineering project. Was it more different from 90 F than the difference between 55F and 85F? Hard to say.

All else being equal, I dislike hot and would prefer to err on the side of cold.
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Re: Global warming forecast ... from 1981

Postby kurt_w » Tue Apr 03, 2012 1:07 pm

Meade wrote:
snoqueen wrote:Our March this year has contained a series of days at least 30 degrees warmer than usual, maybe more. Think what 30 degrees warmer than usual would mean in July.

But if this July turns out to be 30 degrees cooler than normal, you will abandon your belief in anthropogenic global warming, right?


If snoqueen had said that the warm weather in March was the reason to accept the idea of anthropogenic global warming, then you'd have a point.
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Re: Global warming forecast ... from 1981

Postby ArturoBandini » Tue Apr 03, 2012 1:23 pm

kurt_w wrote:I thought about that, mentally waffled about it for a while, and then decided that I didn't know what to say.

I've worked in literally 120+ heat in the Middle East, on a civil engineering project. Was it more different from 90 F than the difference between 55F and 85F? Hard to say.

All else being equal, I dislike hot and would prefer to err on the side of cold.
I suppose what I'm saying is that a 30 degree anomaly seems more believable for a given geographic area when it happens during a transition period from high-to-low temperature (or vice versa) than at a time when peak high or low temperatures are expected. It's more of a shifting of the arrival of the high temperatures (80 degrees were going to arrive here sooner or later) than a wholly new temperature regime.

I'm not really sure if this makes that much sense either, after reading over it again myself. From a geometrical standpoint, the solar influx is based solely on the latitude and time-of-year and thus shouldn't really change over decades (or millenia). But there are lots of other complicating factors - surface water, clouds, vegetation, snow cover, land-use factors and more. It's not a simple problem.
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Re: Global warming forecast ... from 1981

Postby Meade » Tue Apr 03, 2012 1:27 pm

kurt_w wrote:If snoqueen had said that the warm weather in March was the reason to accept the idea of anthropogenic global warming, then you'd have a point.

And what would my point be? She ordered us to "[t]hink what 30 degrees warmer than usual would mean in July." I asked her a hypothetical question.
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Re: Global warming forecast ... from 1981

Postby ArturoBandini » Tue Apr 03, 2012 1:31 pm

Meade wrote:
kurt_w wrote:If snoqueen had said that the warm weather in March was the reason to accept the idea of anthropogenic global warming, then you'd have a point.

And what would my point be? She ordered us to "[t]hink what 30 degrees warmer than usual would mean in July." I asked her a hypothetical question.
It was a rhetorical question, dumbass. The point was implicit.
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Re: Global warming forecast ... from 1981

Postby snoqueen » Tue Apr 03, 2012 5:31 pm

My use of the imperative was rhetorical, and those who choose not to play are as always welcome to think instead about whatever they find more compelling.

NOAA's capsule forecast for this past La Nina winter in Wisconsin was pretty far off:

http://www.crh.noaa.gov/arx/?n=winter201112outlook

Click some of the links for more historical data.
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Re: Global warming forecast ... from 1981

Postby ArturoBandini » Tue Apr 03, 2012 5:43 pm

snoqueen wrote:My use of the imperative was rhetorical, and those who choose not to play are as always welcome to think instead about whatever they find more compelling.
I meant that Meade's question was rhetorical. I kinda regret making that post anyway, since I don't really like to do name-calling.
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Re: Global warming forecast ... from 1981

Postby snoqueen » Tue Apr 03, 2012 7:39 pm

Don't feel too bad. You aren't the first to get baited and you likely won't be the last.

It doesn't change Kurt's graph.
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Re: Global warming forecast ... from 1981

Postby acereraser » Tue Apr 03, 2012 9:07 pm

I am no climatologist, but one thought occurred to me when we were breaking the temp. records a few weeks ago. It was very nearly as warm about a hundred years ago. Again, I am no expert, but it seems to me that we are enjoying a hundred-year warm spell, in much the same way we suffered through hundred-year flood conditions a few years ago. So, yeah, I think it's weather fluctuation, not climate change.
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