How are Hansen's Global Warming predictions panning out?

Thanks for the response. Unfortuately while there is lot of info on the Hansen predictions, I have little info on the OP's chart methodology of coming up with tempertures. Regardless, I do not want to turn this into a chase for details since the prime purpose was to measure the temperature of the PC enviornmental forum. In that case, it's lower than years past.

 

Toyota alone among the Big 3 embraced and supported the newly mandated CAFE standards. Care to change your tune?

 

I think she's referring to the American "Big 3", not the actual Big 3.

 

Timbikes, if you think you can test this better than the pros, you need to start by looking at the right data. As I understand it, Hansen's prediction was 0.24 degrees centigrade per decade for the earth's average surface temperature. So you need to look at average surface temperature data. We all know that not all parts of the atmosphere and not all parts of the surface are expected to warm at the same rate. So, you need global surface temperature data, not some other data, such as the data your link pointed to, which was somebody's posting of data labeled as lower troposphere temperatures. And you need to look at the period Hansen was discussing, which was 1984 forward, not whatever number of decades happen to show up in the dataset, as you have done.

So, whatever that data set is, it's not labeled as surface temperatures, and it doesn't match the NASA data on surface temperatures, which can be downloaded here.

Data @ NASA GISS: GISS Surface Temperature Analysis (GISTEMP)

I think that people who model climate for a living are smart enough to understand and account for things like El Nino events, or the current La Nina event. I don't have enough ego to think that a few minutes of my time doing some half-baked (ie, univariate) analysis will somehow provide a more definitive answer than theirs.

Having said that, I downloaded the GISS mean global (land+water) surface temperature data and ran my own regression. Annual observations, linear OLS regression predicting surface temperature anomaly as a function of year. From 1984 (the start year for Hansen's original model (per the realclimate article I posted earlier) to the present (2007, because there is no annual 2008 number yet), I get a trend of 0.21 degrees centigrade per decade, with a standard deviation of 0.027 degrees centigrade. Hansen's 20 year old prediction is well within two standard deviations of the mean.

(In case you wonder why I used annual data, I have to do that to get any reasonable estimate of the standard deviation in this simple analysis, as the monthly data are strongly serially correlated. The monthly data should give me roughly the same mean but (with OLS) would substantially overstate the true precision.)

(Further, the exact start point does not much matter, plus or minus a few years. If I were to start in 1988 instead of 1984 (as Hansen's model did, per the realclimate discussion noted above), the estimated slope would drop from 0.21 to 0.20 degrees centigrade per decade, which I would characterize as a negligible difference.)

For what it's worth -- and it isn't much -- I have attached the plot. Black line is the actual annual global (land and water) surface temperature anomaly (ie difference from baseline period), pink line is the linear regression fit, blue line is Hansen's predicted rate of change. (I've centered both of those straight lines on the midpoint of the data -- so I'm only testing the slopes of the straight lines, not their intercepts as well. I have to do that because the regression line will automatically be centered on the midpoint of the data unless I want to take the time to monkey around with it, which I do not.)

So, a) you can't reject Hansen's 20-year-old prediction for average global surface temperature increase based on this half-baked (ie, univariate regression) analysis, at least not if you actually look at surface temperature data and look at the period Hansen was discussing, b) by eye, the prediction looks pretty good to me, but I'm an economist so my standards are pretty low in terms of predictive accuracy, and c) the world has moved on, and there is little reason to care whether a 20-year-old prediction using methods that are crude by modern standards has or has not stood the test of time. That said, I think Hansen's work has stood the test of time so far. Again, for what that's worth. You'd be far better off reading what the actual climatologists say about it, for example, on realclimate.org.

 

Even looking at data since only 1979 is cherry picking. But why break it into segments like you did? Your first graph with the most data points is the most valuable.



Even if he is off like you say temperature is still going up. Good enough for me.

 

The country has been governed the past 8 years by a reactionary. Not a conservative. And before that, Clinton was hamstringed by a reactionary congress. The Republicans have gone beyond conservative in their move to the right. They have eroded the tax base, and continued uncontrolled spending with borrowed dollars. And ignored the scientific warnings about environmental abuse.

If the Democrats take over in the fall--and they must--lots will change, because things have to change if we are to survive. It has really become that apocalyptic. It is a question of the rational Center taking over American politics again.

 

Just this week, realclimate.org posted a nice analysis of the recent surface temperature trend after filtering out the ENSO (El Nino) variation.

RealClimate

So you don't have to eyeball the data and toss out selected years, you can see what climate scientists actually make of it in detailed modeling.

Their conclusion:

"The basic picture over the long term doesn't change. The trends over the last 30 years remain though the interannual variability is slightly reduced (as you'd expect)."

 

Just to show the pretty graph:

 

Because the graph below only includes the past 20 years as opposed to the last 55 years. Regardless, they both show clear warming trends.

Catastrophic is relative, isn't it..

 

'nuff said.

 

OK, well, let's go ahead and pick two non-consecutive time periods, and let's not require that they be a decade long. But let's actually add the numbers and do the arithmetic properly. Here are the numbers, based on the GISTEMP data as published by NASA (that I cited above, normed to an earlier period, so they are uniformly about 0.08C above the dotted blue line in the graph):

"2000s to today": 2000-2007 (last annual observation)
Average temperature anomaly: 0.516C
Midpoint of period: 2003.5

"mid 80s to early 90s": 1985-1992 (same length as interval above):
Average temperature anomaly: 0.226
Midpoint of period: 1988.5

Difference in temperature: .29C
Difference in time: 15 years
Average increase: .193C per decade

That's your choice of time periods. The only difference is that I actually added up the numbers and I did the arithmetic properly. Sensitivity check: if you did this for the last two decades available (2007 working backward), you'd get .223C per decade. Not significantly different from the .193 above, based on those selected time intervals.

As I stated earlier, that's not statistically significantly different from Hansen's projection.

I sense that maybe the basic arithmetic is not clear. Going from the decade average centered on 1990 (say), to the decade average centered on 2000, that reflects one decade of change. Not two.

So, if you just take the last two decade averages, it's .223C/decade. If instead, we take those two non-adjacent 8-year intervals, we end up with .193C/decade. That's random noise, as far as I can tell.

 

Big Oil does not control the military, so lets put the blame on who it belongs. Democrats and Republicans. If we are going to blame corporations too then lets blame not only Oil, but the entire military industrial complex, and the banks who help us borrow to pay for it.

You guys want to end our addiction to oil and stop these stupid wars? Then we need to get rid of our fiat money system. it always money creation out of thin air and lets us run these massive trade imbalances and fund our wars. Without the ability to run massive trade imbalances do you think we would still be importing 70% of our oil?