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Climate change

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Re: Climate change

Postby Mad Howler » Thu Jan 31, 2013 10:24 pm

Mad Howler wrote:
green union terrace chair wrote:Kurt, I especially appreciate your attention to the importance of sample size. Two dumb comments I equally hate to hear:
  • When it's an unusually warm winter day:
    -- "OMG, GLOBAL WARMING!!! :shock: "
  • When it's a particularly cold winter day:
    -- "LOL, GLOBAL WARMING :lol: "
A single data point does not an argument make.


Kw's OP was January 13th so I do not understand your point. Although, I think I have an idea where this thread might be heading.


green union terrace chair,
Sorry, I seem to have miss fired there. I need to read more carefully or stick to a thread dedicated to drunk posting, although I don't think this would work out well either so I will work on reading more carefully.
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Re: Climate change

Postby Mad Howler » Thu Jan 31, 2013 10:43 pm

Kurt_w,
Thank you so much, this thread and the effort you choose to share is so much more than a master class on the subject. While this story may be a souce of mundane everyday irritation to you, your care in presentation is an "innovative" example of clarity to me. Thank you for quickly cutting through the clutter.

Best,
MH
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Re: Climate change

Postby rabble » Thu Jan 31, 2013 10:56 pm

Sandi wrote:
rabble wrote:
Sandi wrote:Well I an naturally skeptical.

It seems more like "selectively skeptical" to me. You're very skeptical of those theories you've always disliked. No matter how much evidence is put before you, you're not buying it.

But of the sources for your refuting evidence, not so much. You really seem to trust those guys.

Totally wrong. I trust no one except my mother, and not always her.

I'm really glad you cleared that up because I couldn't figure that out from your other posts. You presented those graphs and papers as if they knew what they were talking about.
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Re: Climate change

Postby DCB » Thu Jan 31, 2013 11:12 pm

Sandi wrote:
rabble wrote:
But of the sources for your refuting evidence, not so much. You really seem to trust those guys.


Totally wrong. I trust no one except my mother, and not always her.

I see. You were just posting those fraudulent Sargasso Sea temperature graphs just for kicks! It doesn't mean anything! Science is just an existential quagmire!

Here's another global warming fun graph:
Image
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Re: Climate change

Postby Sandi » Fri Feb 01, 2013 1:24 am

DCB wrote:I see. You were just posting those fraudulent Sargasso Sea temperature graphs just for kicks! It doesn't mean anything! Science is just an existential quagmire!


Get a grip on life.

I admit that it isn't a big enough sample. That doesn't make it fraudulent, it makes it a smaller sample than desired, and can introduce variance from true global temperatures.
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Re: Climate change

Postby rabble » Fri Feb 01, 2013 9:05 am

Sandi wrote:
DCB wrote:I see. You were just posting those fraudulent Sargasso Sea temperature graphs just for kicks! It doesn't mean anything! Science is just an existential quagmire!


Get a grip on life.

I admit that it isn't a big enough sample. That doesn't make it fraudulent, it makes it a smaller sample than desired, and can introduce variance from true global temperatures.

Wow. I take it all back. You're totally skeptical of that data.
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Re: Climate change

Postby DCB » Fri Feb 01, 2013 1:54 pm

Sandi wrote:I admit that it isn't a big enough sample. That doesn't make it fraudulent, it makes it a smaller sample than desired, and can introduce variance from true global temperatures.

What's fraudulent is taking the paper out of context to make a claim it doesn't support.

Of course there is a lot of regional variation in temperatures, nobody would argue otherwise. That's why real scientists don't use a single site to determine a global temperature. And real scientists have demonstrated, convincingly, that global temperatures have risen.
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Re: Climate change

Postby HawkHead » Fri Feb 01, 2013 2:20 pm

Sandi wrote:
DCB wrote:I see. You were just posting those fraudulent Sargasso Sea temperature graphs just for kicks! It doesn't mean anything! Science is just an existential quagmire!


Get a grip on life.

I admit that it isn't a big enough sample. That doesn't make it fraudulent, it makes it a smaller sample than desired, and can introduce variance from true global temperatures.


Let me get this right. You are now admitting that the study you are using to "disprove" the other study "isn't a big enough sample" and "can introduce variance from true global temperatures"

Who needs are enema?
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Re: Climate change

Postby kurt_w » Fri Feb 01, 2013 2:46 pm

DCB wrote:
Sandi wrote:I admit that it isn't a big enough sample. That doesn't make it fraudulent, it makes it a smaller sample than desired, and can introduce variance from true global temperatures.

What's fraudulent is taking the paper out of context to make a claim it doesn't support.

Of course there is a lot of regional variation in temperatures, nobody would argue otherwise. That's why real scientists don't use a single site to determine a global temperature. And real scientists have demonstrated, convincingly, that global temperatures have risen.


The other problem was the "2006" point that the Junior Robinson inserted in that graph. It's much lower than the actual 2006 sea surface temperature at that site, and no one knows why he plotted it where he did:

Image

It always leaves me scratching my head when I see someone citing the Robinsons' OISM "paper". There are much more sophisticated (if still misleading) contrarian websites out there. Why even bother citing something that was only published in an obscure crank medical journal?

In 2010 and 2012, Art Robinson was the GOP/Tea Party candidate for a congressional seat in Oregon. (He lost by 20 points this time around). At one point in the campaign he was interviewed by Rachel Maddow. She asked Robinson about some of the wackier things he'd written in his newsletter over the years (AIDS is a government conspiracy, we should spray low-level radioactive waste over America because something called "radiation hormesis" makes small doses of radiation beneficial, etc. ad nauseam). Basically, Robinson is quite the crackpot.
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Re: Climate change

Postby rabble » Fri Feb 01, 2013 2:52 pm

Sandi wrote: Well there are no polar bears. If you look at the chart below you will see that they all had to die out in the Roman Warm Period and the Medieval Warm Periods. Just kidding of course.

Image

Kurt, did you analyze this one and I missed it? If you're busy no problem. I'll see if I can dig up anything on it this weekend. Cause I'm a little skeptical.
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Re: Climate change

Postby kurt_w » Fri Feb 01, 2013 3:28 pm

rabble wrote:Kurt, did you analyze this one and I missed it? If you're busy no problem. I'll see if I can dig up anything on it this weekend. Cause I'm a little skeptical.


Oh, jeez. Yeah, I know exactly what's going on there, but demonstrating it is a bit of a pain. I figured it would be sufficient to debunk one of the figures that Sandi posted, and we wouldn't have to look at all of them. But since you ask, I will oblige.

You'll be unsurprised to learn that the graph is partly wrong and partly misleading. I'll post something about it shortly.
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Re: Climate change

Postby kurt_w » Fri Feb 01, 2013 4:03 pm

So here's the deal with that Greenland temperature graph that Sandi posted.

It's probably originally sourced back to work by one prominent climate contrarian, Don Easterbrook. But it's been reprinted by lots of people in different versions over the years, and so figuring out the exact provenance is difficult.

The raw data, though, are taken from the GISP2 ice core, which was drilled near the summit of the Greenland ice sheet. The raw data are archived at the National Climate Data Center here.

To prove that I have correctly identified the source for Sandy's figure, here are the GISP2 data (red line) superimposed on the figure itself:

Image

The match is virtually perfect. But there's one problem: the most recent (latest) point on the graph falls at 1905, when it should be 1855. Whoever made that graph didn't realize that a convention with most geosciences paleodata is to use the term "Before Present" to refer to "years before 1950", not "years before whatever year this paper was published". So Easterbrook or whoever copied his work mistakenly thought the final data point in the graph is 50 years later than it actually is.

Here's the corrected version:

Image

Of course, showing a graph that ends in 1855 doesn't really help us understand anthropogenic global warming that only really took off in the 1970s. Fortunately, a team of scientists led by Jason Box has a new paper that reports the surface temperatures in the center of the Greenland ice sheet -- more or less the same area where GISP2 was drilled -- from 1840 to 2011. From that, we can see that temperatures there have risen approximately 1.3 C from 1855 to 2011. We can superimpose that on Easterbrook's graph to compare current temperatures to the past:

Image

So temperatures in the interior of Greenland now are approaching the warmest levels of the past 2500 years. If warming continues at the rate of the past three decades, by 2050 Greenland will be warmer than it's been since the last (Eemian) interglacial, around 120,000 years ago.

The other point, of course, is that polar bears don't actually live at GISP2. It's at about 10,000 feet above sea level ... which is why they chose to drill the core there.
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Re: Climate change

Postby kurt_w » Tue Mar 26, 2013 9:27 pm

I thought it would be interesting to look at "local" climate change rather than "global" climate change.

So I went to the US Historical Climatology Network and downloaded the past century's temperature data for the four USHCN stations surrounding Madison (Brodhead, Darlington, Watertown, and Portage). Madison itself doesn't qualify as a USHCN station, probably because of its history of urbanization.

I took the average of those four stations to represent Madison's climate. I also calculated the long-term trend (using a LOESS function) and the two-sigma envelope around that trend. That envelope gives an idea of the year-to-year random variability -- 19 out of 20 years should fall within that envelope.

Unfortunately the USHCN data don't yet include 2012 yet, but I was able to track down a preliminary version of the station data for Watertown and Portage, and in recent years the average of those two has been virtually identical to the average of all four stations, so I think it's a fair comparison. I showed 2012 on the graph, but didn't use it in any of the calculations that follow.

Here are the results:

Image
Fig 1. Thin red line is annual temperature; thick red line is long-term trend; dashed lines are two-sigma envelope. Red dot at upper right is preliminary figure for 2012.

Next, I compared this to the output from a global climate model simulation of the 20th century. The model was the National Center for Atmospheric Research's Community Climate System Model (NCAR CCSM). Here is the comparison of the model results for south-central Wisconsin to the actual weather station data:

Image
Fig 2. Same as previous, but blue lines represent climate model output.

Note that the model's temperature trend has matched the observed temperature trend pretty well over the past few decades. Since 1970, the model shows a bit less warming than actually occurred -- actually, about 50% less.

On the other hand, the model seems to underestimate how much random year-to-year variation in temperature there is. The standard deviation of the detrended residuals from the model is about half of the value from the actual weather station data.

So, model-Wisconsin has a bit less warming than real-Wisconsin, and also a bit less random year-to-year variation.

The next figure adds in a typical projection of 21st century temperatures for the Madison area, from the same NCAR CCSM model. It's based on the IPCC's "A1B" emissions scenario, a scenario that assumes that CO2 emissions keep growing for a while before stabilizing in the middle of the century. It's considered a "middle-of-the-road" emissions scenario.

Because (as we saw above) the model seems to be underestimating the random year-to-year variability in temperature, I scaled up the variability to match that of the observed data from the 20th century. This doesn't affect the long-term trend at all -- I didn't change that -- but it gives a more realistic view of how "noisy" the temperatures are likely to be in any given time period.

Image
Fig 3. Same as previous, but with expanded variance for model output; green lines represent IPCC A1B scenario projection.

Oops! Houston, we have a problem. The temperatures seem to have gone off the top of the graph. Here's a re-scaled version:

Image
Fig 4. Same as previous, with addition of line representing 2012 temperature.

For comparison, I added in a line at the "2012 temperature" level. As you can see, by sometime around 2050 what was formerly considered a fairly hot year in Wisconsin (actually, the hottest on record...[1]) will be normal, or actually cooler than normal.

So. Two questions that I'd ask myself:

How much does average temperature really matter?
Any change in water availability is probably much more important ... but it's also much harder to predict how this will change. In general, a warmer climate means more evaporation and a drier landscape. But whether precipitation increases by 10% or decreases by 10% will matter a lot. Unfortunately, I don't think there's much agreement on this.

The statistics of "extreme" weather also matter a lot. A slight increase (or decrease) in the frequency of droughts, floods, tornadoes, etc. could cost (or save) the state a lot. Again, though, I don't think this kind of thing can be predicted reliably at the regional scale we're looking at here.

Do I really believe this?
I wouldn't put too much weight in the predictions of global climate models. I think they're still a bit too primitive and limited to make reliable predictions, and the uncertainty in the emissions scenario is very large. We could end up burning much more fossil fuel than expected, or much less.

That said, I think this is an interesting exercise. The real-Wisconsin in 2050 or 2100 might be hotter or cooler than the model-Wisconsin, but without any way to judge which of those is more likely, I'd go with this model as a rough approximation of what to expect.

There are other ways of studying past climate change that don't rely on models. Even if no one had ever programmed a numerical climate model, we would expect the global temperature to increase just due to the fact that we know we're increasing the CO2 concentration of the atmosphere, and we know that CO2 absorbs infrared radiation. You don't need a model to tell you that a planet whose atmosphere resists the loss of heat to space will warm up.

---------------------
[1] As I understand it, 2012 was the warmest year on record for the continental US, and from my calculations it also set a new record for the south-central Wisconsin area. According to the Wisconsin State Climatologist's Office, for the state as a whole 2012 was tied for second-warmest on record.
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Re: Climate change

Postby kurt_w » Tue Mar 26, 2013 9:33 pm

The tl;dr version for anyone who is curious about the previous post but disinclined to read it all:

By sometime around 2050, "normal" temperatures in Madison will be as hot (or hotter, actually) as they were in the record-breaking year of 2012.

Probably.

This may not seem all that striking now, in what's been a cold and gray March. But if you think back to 2012, it's pretty radical to think of that year as being colder than normal.
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Re: Climate change

Postby bdog » Wed Mar 27, 2013 6:07 am

kurt_w wrote:The tl;dr version

I think that's the better way to go if you're trying to change people's minds. Even better, appeal to people's common sense. You can throw all the graphs and stats you want me at me - shit I don't have time to research it all to see if their methods / conclusions are correct.

But show me the output from an electric car vs. gas in a closed environment (kind of like that commercial where the computers, coffee makers, etc. are gas powered) and I will agree - that's f'd up.

Heck even 2050 is too far away, too theoretical for most people to consider it with a sense of urgency.
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