Merged Recent climate observations disagreement with projections

lomiller said:
It’s not the “IPCC tend line” it’s simply the 30 year trend in the dataset. While this can vary a bit based on exactly how the trend was calculated it won’t change very much.
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How far back does this trend go? Only thirty years? Or is it based upon a 30-year running average?
 
http://nsidc.org/arcticseaicenews/

NSIDC scientists expect to see the minimum ice extent for the year in the next few weeks. While this year's minimum ice extent will probably not reach the record low of 2007, it remains well below normal: average ice extent for August 2009 was the third-lowest in the satellite record. Ice extent has now fallen below the 2005 minimum, previously the third-lowest extent in the satellite record.
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Doesn't this settle a bet between a couple of posters here?
 
I understand what you mean..the physics didn't quit then either...the volcano acted to reduce the net uptake of energy by the planet by blocking some solar?
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You got it

Reducing one forcing - incoming energy -offset the other trapping energy in the system.

The atmosphere/geo-system will hunt for an equilibrium for centuries into the future and the more C02 we pump in - the longer it will take to get new equilibrium.

The train is left the station and the only way to get it back is to actively reduce C02 to pre industrial levels...:boggled:

Even then the lag in response might mean things like methane release might overwhelm our efforts.....the engineering would would be massive.

It would be far better if we could figure out a way to enhance the biological carbon sinks we already have AND get quickly to carbon neutral.....

don't be holding your breath about that happening.....:garfield:

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High ice loss in the Beaufort Sea and Siberian Arctic
This August, the Beaufort Sea lost more ice than in either 2007 or 2008. In other regions of the Arctic, ice loss rates were about the same as in August 2007, except in the central Arctic, where more ice was lost in 2007. These year-to-year differences in regional ice loss rates reflect variations in surface wind and temperature patterns that affect the ice motion and melt.
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Likely reflects the warm Pacific current encroaching further - the retreat of the ice pack in the Beaufort is astonishing - fishing rules have to be re-written and new species are moving in...
 
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Wangler said:
How far back does this trend go? Only thirty years? Or is it based upon a 30-year running average?
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A trend line is a linear best fit to the data, in this case the past 30 years. 30 year running average would be a smoothed plot of that same data, there are better smoothing techniques available then a simple running average. A linear approximation is the simplest and therefore preferred explanation for the data.

The fact that 8 of the last 9 years fall above that trend could suggest that warming has accelerated, but to my knowledge they are not significant enough to constitute proof. The years that were above trend were probably a consequence of El Nino, as soon as we hit a La Nina in 2008 global temperatures were right back in line with the 30 year trend.
 
Sure, Ben. But summing them for 30 year norms,we get 1 climatic data point.

We were discussing climate, right? Not weather?
 
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That is not ONE data point. If it were, there could be no trend. It is MILLIONS of sensor readings averaged over decades.

One data point would be if I read my thermometer at 3:15 PM on June 2nd in 1980, and that was all the data I had...
 
lomiller said:
the 30 year norm is a trend line...
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Sounds...trendy.. ..

wait...that would take a succession of 30 year numbers like a decade apart. So you guys are hunting around for global warming, basically in weather?
 
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mhaze said:
Sounds...trendy.. ..

wait...that would take a succession of 30 year numbers like a decade apart. So you guys are hunting around for global warming, basically in weather?
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No, aren't we talking about a 30 year average, like thus (for example):

point 1: average of 1951-1980
point 2: average of 1952-1981
point 3: average of 1953-1982
...
...
 
Wangler said:
No, aren't we talking about a 30 year average, like thus (for example):

point 1: average of 1951-1980
point 2: average of 1952-1981
point 3: average of 1953-1982
...
...
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Hey, I accept that. But not this looking within the last 30 years for climatic wisdom.

You have generated three data points.
 
mhaze said:
Hey, I accept that. But not this looking within the last 30 years for climatic wisdom.

You have generated three data points.
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I know, but I meant it as a continuing series, which will produce a smoothed graph of annual data that will be useful for discerning trends in climate.

Right?
 
Wangler said:
I know, but I meant it as a continuing series, which will produce a smoothed graph of annual data that will be useful for discerning trends in climate.

Right?
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Yes. Although some would disapprove of the dilution of facts by the smoothing, but it is the established definition of climate as opposed to weather.
 
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mhaze said:
Yes. Although some would disapprove of the dilution of facts by the smoothing, but it is the established definition of climate as opposed to weather.
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So what you do is average over the smallest interval that makes sense, so you can have your cake and eat it too.

Where does the 30-year number come from?

I hear "30 years is climate" and "less than 30 years is weather"....

but who decides? What is the basis? Anyone have a reference?
 
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Wangler said:
I know, but I meant it as a continuing series, which will produce a smoothed graph of annual data that will be useful for discerning trends in climate.

Right?
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The point of differentiating weather and climate is that weather is subject to short term chaotic effects and can therefore show significant random natural variation around the attractor (normal expected value). Since these are randomly distributed around the attractor the longer the period you look at the smaller their impact.

If you want to find out what the attractor is doing you need to look at a long enough time period for any trend to show up against the background noise. As a rule of thumb this means looking at a period of 20-30 years, but larger movements can be seen in shorter periods.

What mhaze really really wants to do is look at shorter trend and draw conclusions from it. If one looks at the last 10 years you get a warming trend of ~0.05 deg/dec, but the error bars are +/-0.3 deg. This time period simply cannot tell you if the long term trend of ~0.2 deg/dec has stopped, the natural variation is still to large.
 
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