From the we told you so department and The Hockey Schtick: It is all about nighttime influence on minimum temperatures, mostly due to the heat sink effect of urbanization and nearby structures and paving.
New paper finds “surprisingly, there are many US weather stations that show cooling” over the past century
A paper published today in the Journal of Climate finds, contrary to popular belief, that US “monthly maximum temperatures are not often greatly changing — perhaps surprisingly, there are many stations that show some cooling [over the past century].
In contrast, the minimum temperatures show significant warming. Overall, the Southeastern United States shows the least warming (even some cooling), and the Western United States, Northern Midwest, and New England have experienced the most warming.”
In essence, this paper is saying the weather/climate has become less extreme, with little to no change in maximum temperatures “and even some cooling” of maximum temperatures in some stations, and warming of minimum temperatures. Thus the temperature range between minimum and maximum temperatures has decreased, a less extreme, more benign climate.
According to the paper, the warming in minimum temperatures is regional, with the SE US showing “the least warming (even some cooling),” suggesting that other processes such as ocean and atmospheric oscillations are responsible, rather than a uniform warming from AGW.
Note these results are after the huge up-justments made to the US temperature data and urban heat island [UHI] artificial warming, which could account for all or most of the warming of minimum temperatures.
Trends in Extreme United States Temperatures
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From our 2012 draft paper: Acceptably placed thermometers away from common urban influences read much cooler nationwide:
A reanalysis of U.S. surface station temperatures has been performed using the recently WMO-approved Siting Classification System devised by METEO-France’s Michel Leroy. The new siting classification more accurately characterizes the quality of the location in terms of monitoring long-term spatially representative surface temperature trends. The new analysis demonstrates that reported 1979-2008 U.S. temperature trends are spuriously doubled, with 92% of that over-estimation resulting from erroneous NOAA adjustments of well-sited stations upward. The paper is the first to use the updated siting system which addresses USHCN siting issues and data adjustments.
The new improved assessment, for the years 1979 to 2008, yields a trend of +0.155C per decade from the high quality sites, a +0.248 C per decade trend for poorly sited locations, and a trend of +0.309 C per decade after NOAA adjusts the data. This issue of station siting quality is expected to be an issue with respect to the monitoring of land surface temperature throughout the Global Historical Climate Network and in the BEST network.
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Who is NCDC and why do they get to adjust historic temperature measurements downward after 100 years of these temperatures being considered accurate? Why is doing this not considered outright fraud?
That’s like investing $10,000 with a financial advisor, and finding after several years your investment had not grown and was still worth only $10,000. Then you discuss with the advisor, and his records show that you only invested $5,000. Thus he claims the current $10,000 shows that he has doubled your investment, and on that basis you should entrust him with your life savings. Save your receipts.
Nature is making a monkey out of the arrogance of man.
As a geologist I frequently look at maps upon which geochemical data is plotted. One of the more comprehensive public file data sets is the NURE data base (with other additions) for the North American land mass. One of the issues with the data is that samples were taken over different times in different areas by different people and were assayed using different analytical techniques. The result was a patchwork of say copper in soil results that were clearly related to the area sampled on a 250 000 scale map.
The map of the temperature trends shows exactly the same phenomena. Canada is different from the USA and both show different cooling/warming results to Mexico. The data presented was definitely not leveled across borders and just goes to reinforce the issue of the unreliable global surface temperature data set. The differences are rather shocking given the color bar scale a the side. Post measurement adjustments can be the only conclusion.
@richard
Great citation:
>Carbon dioxide and nitric oxide are natural thermostats,” explains James Russell of Hampton University, SABER’s principal investigator. “When the upper atmosphere (or ‘thermosphere’) heats up, these molecules try as hard as they can to shed that heat back into space.”
“The thermosphere lit up like a Christmas tree,” says Russell. “It began to glow intensely at infrared wavelengths as the thermostat effect kicked in.”
Increasing the CO2 concentration at any altitude increases the absorption of incoming IR and increases the likelihood of its being immediately re-radiated into space. Similarly that elevated number of radiators capturing surface-emitted IR provides additional opportunities to send it up or down, not only down as depicted in GHG cartoons.
Taken as a whole, more CO2 makes the planet have a higher emissivity. The top cools better. The bottom might heat more, but a higher delta T would increase the buoyancy effect and drive convection more strongly, with heat physically passing the additional CO2. Willis’ tropical convection cooling then dominates energy transport.
Thanks for bringing Russel’s observations to the discussion.
@Anthony Watts
Glad to provide something useful
@Theo Goodwin at 5:39 pm
From your map I get the impression that “no change” and “cooling” far exceed “warming.” Am I reading that correctly?
Could be 😉 are you sure you are not cool biased?
@Nick Stokes at 5:48 pm
Verity, I was curious as to the trend period in your plot? Also the data source?
Nick, GHCNv2 unadjusted – original post here: http://diggingintheclay.wordpress.com/2010/01/18/mapping-global-warming/ which also shows some plots for adjusted data. Yes know all the arguments for adjustment and accept some is necessary, but IMHO homogenisation is generally an adjustment too far (see: http://diggingintheclay.wordpress.com/2011/10/30/how-best-to-deal-with-cooling-cities/). Also produced in Google Earth version: http://diggingintheclay.wordpress.com/2010/10/06/google-earth-kml-files-spot-the-global-warming/
Also looked at GHCNV3, but can’t remember if Kevin finished that version and we kind of gave up after that because there were so many changes to adjustments at station level through the beta version that it was impossible to keep up. Some of the adjustments due to homogenisation seemed justifiable; some were physically impossible. A first differences version looking at adjustments is here: http://diggingintheclay.wordpress.com/2011/04/30/the-only-way-is-up/
@chris y at 6:57 pm
Mosher says we only need 5 stations to nail the US temperature trend. Now have a glance at Verity Jones’ map, and make your ‘pick-5′ choices for 5 stations that are dispersed across the country. My guess is that the nailed trend can vary from -5 C/century to +5 C/century.
Dead. Certain.
Yup. And that’s the same Mosh who argues for science and objectivity. Pick 5 without being subjective, and then tell me how you can be so certain that you’ve got 5 that are not artificially contaminated, properly adjusted to correct for moves, and truly representative of the country as a whole.
Roger Pielke
I believe the increase in nighttime temperature is caused by UHI. Nighttime UHI effect can be as high as 12 C. Average temperature in big cities can be 1-3 C warmer than surrounding areas. I suspect many thermometers are in urban areas. Global warming may turn out to be caused by urbanization and waste heat.