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(Science Daily)   You think you have Java problems now? By 2080, arabica could be extinct in the wild, commercial production severely reduced by changes in rainfall and temperature   (sciencedaily.com) divider line 55
    More: Scary, extinct in the wild, temperatures, Java, music production, botanic gardens, South Sudan, seedlings, genetic diversity  
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1389 clicks; posted to Geek » on 14 Jan 2013 at 7:44 AM (1 year ago)   |  Favorite    |   share:  Share on Twitter share via Email Share on Facebook   more»



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2013-01-14 11:48:49 PM  

TheGreatGazoo: History of Corn
Also, bananas were supposed to be extinct by 2013.


You do know that we've already all but lost a major variety of banana, right?
 
2013-01-15 07:17:05 AM  

SVenus: Damnhippyfreak: So we know you are very much aware that a short term period (relative to variability) can be misleading. You contend that this is similar to what James Hansen used (supposedly only 8 years) in past congressional testimony. This is not the case, as his testimony and the papers it was based on used a longer period of time than that and did not solely rely on some sort of simple linear regression or simple correlation.

Perhaps you can interpret this for us then:

From
http://www1.ncdc.noaa.gov/pub/data/cmb/bams-sotc/2008/chapter2.pdf

Do global temperature trends over the last decade falsify climate predictions?

Near-zero
and even negative trends are common for intervals of a decade or
less in the simulations, due to the
model's internal climate variability.
The simulations rule out (at the
95% level) zero trends for intervals
of 15 yr or more, suggesting that
an observed absence of warming of
this duration is needed to create
a discrepancy with the expected
present-day warming rate.

The latest Met Office model newly proposed as seen in the screen grab above predicts a slight warming over the next three or four years. This would put the warming trend at within or nearly within a zero trend line bracket for considerably more than 15 years.

I interpret the above statement, still available on the NOAA website, as saying that, from a statistical standpoint, modeling has trouble with a zero trend that's longer than 15 years, essentially ruling it out. I don't think it's just James Hansen's testimony in 1988 alone that addresses this issue. If it's been shown the deep Pacific can store up heat over 30 years and then disgorge that as a super El Nino with a new baseline trend, great. Love the theory. Can't wait for the science part of that (i.e., hard data).

Again, not a modeling or numbers guy -- so if someone says "hey, it's 25 years, we can model 25 years and still have very little change in the temps and still make the existing GCM work" I can't argu ...


The statement you quote does not take into account any formal statistical significance test, so it's irrelevant whether warming is large or small. What they're saying is that almost all 15-year linear trends (95%+) in their model runs exhibited warming larger than zero using simulation conditions relevant to the recent period (as far as we know at least), therefore trends of zero or lower in real-world equivalent datasets would indicate that our current trajectory is very likely outside the bounds of the model ensemble projection. However, all the major global surface temperature datasets do exhibit greater than zero warming over the last 15 years, and every 15-year period since the early 60s.

That's not to say their model ensemble is correct. There are numerous things it could be getting wrong, such as the strength of low-resolution internal "unforced" variability, or the forcing history - the impact of past and current aerosol emissions in particular is highly uncertain, or the sensitivity of the model. Reading the text, it appears in making this determination they used a model named HadCM3, which has a short-term sensitivity at the upper-end of climate models currently in use. A model with sensitivity closer to average might have a higher likelihood of low trends. However, this particular 15-year trend test does not currently rule out the ensemble (according to the test outlined in the report) since they only state that 15-year linear trends should be greater than zero, which they are.
 
2013-01-15 08:24:19 AM  
It always amuses me when people try to cite science they don't even have a basic understanding of.
 
2013-01-15 08:31:49 AM  

Lee Jackson Beauregard: TheGreatGazoo: History of Corn
Also, bananas were supposed to be extinct by 2013.

You do know that we've already all but lost a major variety of banana, right?


Yes, billions of people worldwide mourn the loss of that banana variety.
 
2013-01-15 09:11:22 AM  

dillengest: The statement you quote does not take into account any formal statistical significance test


Aaand this is where I get off the math train.
 
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