(Part of the How to Talk to a Global Warming Skeptic guide)
Objection: The surface temperature record is full of assumptions, corrections, differing equipment and station settings, changing technology, varying altitudes, and more. It is not possible to claim we know what the "global average temperature" is, much less determine any trend. The IPCC graphs only say what the scientists want them to say.
Answer: There is actually some truth to the part about the difficulties; scientists have overcome many of them in turning the hundreds of thousands of measurements taken in many different ways and over a span of more than a dozen decades into a single globally averaged trend.
But this is the nature of science -- no one said it was easy. It's taken the scientific community a long time to finally come out and say that what we have been observing for 100 years is in fact exactly what it looks like. All other possible explanations (for example, the Urban Heat Island effect) have been investigated, the data has been examined and re-examined, reviewed and re-reviewed, and the conclusion has become unassailable.
And while it is true that differing weather station locations, from proximity to lakes or rivers or elevation above sea level, probably make it impossible to arrive at a meaningful figure for global average surface temperature, that is not what we are really interested in. The investigation is focused on trends, not the absolute level. Often, as in this case, it is easier to determine how much a given property is changing than what its exact value is. If one station is near an airport at three feet above sea level and another is in a park at 3000 feet, it doesn't really matter -- they both show rising temperature, and that is the critical information.
So how do we finally know when all the reasoning is reasonable and the corrections correct? One good way is to cross check your conclusion against other completely unrelated data sets. In this case, all the other available indicators of global temperature trends unanimously agree. Go ahead, put aside the direct surface temperature measurements -- global warming is also indicated by:
- Satellite measurements of the upper and lower troposphere
- Weather balloons show very similar warming
- Borehole analysis
- Glacial melt observations
- Declining arctic sea ice
- Sea level rise
- Proxy Reconstructions
- Rising ocean temperature
All of these completely independent analyses of widely varied aspects of the climate system lead to the same conclusion: the Earth is undergoing a rapid and substantial warming trend. Looks like the folks at NASA and CRU know what they are doing after all.
The new Senate global warming deniers
20 climate experts call for aggressive U.S. action
Do as Heartland says, not as it does
Comments View as Flat
WWAGD?! Posted 5:48 am
11 Aug 2007
NASA had Y2K Bug in Temp Data
Blogger Finds Y2K Bug in NASA Climate Data
http://www.dailytech.com/Blogger+Finds+Y2K+Bug+in+NASA+Cl ... ...
"Hansen refused to provide McKintyre with the algorithm used to generate graph data, so McKintyre reverse-engineered it. The result appeared to be a Y2K bug in the handling of the raw data.
McKintyre notified the pair of the bug; Ruedy replied and acknowledged the problem as an "oversight" that would be fixed in the next data refresh.
NASA has now silently released corrected figures, and the changes are truly astounding. The warmest year on record is now 1934. 1998 (long trumpeted by the media as record-breaking) moves to second place. 1921 takes third. In fact, 5 of the 10 warmest years on record now all occur before World War II. Anthony Watts has put the new data in chart form, along with a more detailed summary of the events."
Reconstructed NASA temperature data from the horse's mouth..1934 hottest year on record.
http://data.giss.nasa.gov/gistemp/graphs/Fig.D.txt
John Bailo
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Pangolin Posted 8:00 am
11 Aug 2007
Statistics really DO matter......
Thank you jabailo for pointing out how outliers do not represent a true representation of trends. Now quit shilling for Exxon and go take a statistics course.
Your arguement:
You pull two outliers from the first half of the century and use them to attempt to discredit a theory that argues a trend towards warmer temperatures. Note that the five year mean of temperature in 1921, (.15) and in 1934, (.44) are significantly lower thant the five year means for every year after 1996, (.47, .51, .69, .79, .65, .55, .58, .66). So the mean average temperature is indeed increasing. This corresponds to trends in other data sets as the OP points out.
A trend line on a graph of the mean temperature would also show movement towards and increase in temperatures.
In fact if we discarded surface temperature readings as completely unreliable there is substantial evidence of Global Warming without them. The retreat of arctic sea ice for example.
Since you are inclinded to quote Anthony Watts, a discredited TV weatherman from my town, please refer us to his published works in peer reviewed journals. There are none. He is first and foremost a conservative shill known for telling us that the power crisis in California was due to excess internet use.
So why don't you and Anthony Watts march yourselves down to your local Junior College and take a few courses in statistics. In the meantime STFU.
Put the Carbon Back
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WWAGD?! Posted 8:17 am
11 Aug 2007
1934, A bust year for CO2
It's not just 1934 that was readjusted...but a whole series of temperatures that now reside around that time as "record years".
Yes, the temperature is "going up" but the fact that there were all these highs around 1934 and then a big drop during the 60s and 70s means that anthropogenic causes cannot be the answer!
Another point: 1934 was at the depth of the Great Depression...industry stalled...production and purchasing dwindled...trains stopped running...people couldn't buy cars...and this was a Worldwide Depression! Human CO2 production was at an all time low, and yet the temperature is the highest on record!
John Bailo
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kdnyquist Posted 8:59 am
11 Aug 2007
makes global warming seem more credible
(not commenting on the actual post, but the preceding comments)
This may sound counterintuitive, but the Y2K "bug" fix kind of was encouraging to hear. I was always a bit incredulous when I heard that seven or so of the hottest ten years this century have been in the last decade. If global warming shot up temperatures by only a degree in that time period, it seems unlikely that with such a wide range of yearly variation in average temperature (more than a few degrees) there would be so many near-record or record years so close to the end of the time period.
Global warming is subtle, it is slow, it is sneaky. The corrected stats show that better than the corrupt ones used by alarmist propagandists.
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Grevangelical Posted 11:31 am
11 Aug 2007
"New" data
If this new data is the same that is circulating in skeptic circles, then it is accurate but not global.
http://data.giss.nasa.gov/gistemp/graphs/Fig.D.txt
The data only reflects the temperatures of the lower 48 United States, to portray this information as global is either dishonest or simply poorly researched. So unless you can provide numbers from a valid source that the information you refer to is actually global, I'm not going to believe it.
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sleepkreep Posted 4:17 am
13 Nov 2007
Don't forget about global dimming
The comments above about how 1934 is the hottest year on record talks about how that was during the Great Depression and since CO2 levels (manmade) were at an all time low, manmade global warming must be busted. However, we can't forget about the global dimming effect. Visible pollutants like ash and sulfur dioxide create an effect called cloud seeding. These pollutants generate more clouds in the atmosphere. In the last 100 years we've decreased the amount of solar energy reaching the surface of the earth by 20%. This fights against the greenhouse effect and takes energy back out from greenhouse gases. The problem was getting very severe in the late eighties (the Ethiopian drought). In the 1991 the amendment to the Clean Air was enacted and visible pollutants were dramatically decreased from America. The Ethiopian drought immediately got better. It still was there however. This was caused by the clouds not being so heavy that they drop their load before reaching inland. Same concept in the 30s. The cloud cover was decreased since less fossil fuels were being burned and the greenhouse gases built up since the Industrial Revolution were able to show their true power. Since the build up of the Asian markets, cloud cover has again increased and the temperature spikes (or lack thereof) tend to reflect that. However, of course the greenhouse effect will overtake the global dimming effect as we saw in 2005 and are now seeing today. It's funny no one recognizes that if we immediately switch to clean sources like solar and wind that we would almost instantly see a very dramatic rise in temperatures since all of the sun's energy will be hitting us. Not to say we shouldn't switch though.
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waspbloke Posted 9:27 pm
13 Dec 2007
I'd be interested in your assessment of this...
http://icecap.us/images/uploads/MM.JGR07-background.pdf
I'm still digesting it.
I present it to you in the same spirit with which I recieved it - without prejudice.
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rcglinsk Posted 5:11 am
24 Mar 2008
reliable temperature measurement
Very old average temperature reports tended to be taken from once a day readings of a maximum/minimum thermometer. That's not a great method. The average score on a class' math test would only be the mean of the highest and lowest scores by lucky coincidence. Also, outliers in data sets are by definition always maximums or minimums; so that method is what statistics calls highly "biased."
The newer non-thermometer temperature measurements are far more reliable. However, the new methods have not been in use for all that long, and you can't discern any long term warming trend just from them. And there's not a scientifically principled way to negotiate any middle ground between the various methods, favoring one over others will always be a game of chance at some level. A lot of hard working people have done their best to navigate these issues, but there's no real guarantee that their best was good enough.
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