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China is warming fastest where the cities are, not where the models predicted – classic UHI

The biggest changes in temperature (“divergence” in dark red brown Fig 6) occurred where the most people lived (blue dots). In the 60 years to 2010 China was reported to have warmed by 0.79 ± 0.10 °C. However Scafetta et al calculate at most, China could have experienced a real warming of only 0.46 ± 0.13 °C.

Somehow the combined might and supercomputers at NOAA, NASA, Hadley and the Bureau of Met experts all missed this.

It’s another third of a degree gone from the Glorious CO2 Narrative. Just like that.

China, Scafetta 2019, UHI, Urban Heat Island Effect. Graph.

Fig. 6. Map of the divergence (ΔTMin − ΔTMax) between the warmings registered by the minimum and maximum temperature records (CRU TS4) between 1945 and 1954 and 2005–2014. The cyan dots indicate the 200 most populated cities in China according to the Free World City Database. (White regions over India and the ocean indicate missing data).

Is there a  more perfect nation to study the Urban Heat Island effect than China?

The worlds most populous nation has made a blistering transformation in two decades. As recently as 1995 the population was 75% rural. Now it’s approaching 60% urban. Shenzhen, which is near Hong Kong, grew from 3000 people in 1950 to more than 10 million in 2010. Around Beijing, thousands of towns have been built in a networked carpet, each a mere 2km apart (zoom in on Google satellite view). The stations in these areas are effectively not rural anymore.

Prof Nicola Scafetta and Shenghui Ouyang wondered how this massive growth affected the temperatures. They discovered the regions that warmed the fastest were also the largest population centers. Proving the warming might be “man-made” but nearly half the warming is due to heated concrete and all the assorted infrastructure and industry around thermometers. That part is not CO2.

There would be more CO2 produced from those population centres too, but we all know that given five minutes CO2 will split for Tahiti or Siberia, or anywhere. In any case, Scaffeta et al compared what the top greenhouse models driven by CO2 predicted. And lo, the models were totally  wrong. The CMIP5 set projected that CO2 would warm all of China roughly equally.

The research duo looked at the minima, the maxima, the seasonal and monthly patterns, and in pretty much every case, the warmth follows the same pattern we’d expect if it was caused by human industry. The minimums rose more than the maximums. The biggest warming effect comes in the coolest part of the day and in the coolest half of the year —  and it’s a toss up whether China has even warmed at all since 1940. The nights are hotter, but the days are colder than they used to be — inasmuch as anyone has any idea at all what the temperature would really have been.


The Climate models (CMIP5) have barely any ability to predict future maxima and minima…

China, Scafetta 2019, UHI, Urban Heat Island Effect. Graph.

Fig. 5. (Left) Tmax and (Right) Tmin. The maps show the 2005–2014 mean value minus 1945–1954 mean value. (top) Temperature observations (CRU TS4) and (bottom) full CMIP5 GCM mean ensemble simulation. The maps are centered over China. The hatching represents areas where the signal is smaller than one standard deviation of natural variability (e.g. the value is nearly zero).

 Compare the models to the measurements:

And notice how hot China was in the daytime in 1940? I don’t see how that can last.

China, Scafetta 2019, UHI, Urban Heat Island Effect. Graph.

:Fig. 9. [A] CRU TS4 Tmax and Tmin near-surface annual average temperature records. [B] CMIP5 maximum, mean and minimum near-surface annual ensemble average temperature records. Region [112°–120°E:32°–40°N]. The red segments indicate the mean values, T1 and T2, in the 1945–1954 and 2005–2014 decades.

Presumably China in the 1940’s will start cooling soon like most other places in the world have.

The population doubled, doubled, and doubled again

Beijing that increased from 1.7 million in 1950 to 18.4 million in 2015. It grew by about 11 times in 65 years.


China, Scafetta 2019, UHI, Urban Heat Island Effect. Graph.

ig. 12. [A] Population density in China (2000). Mapping prepared by Beijing City Lab (http://longy.jimdo.com). [B] Urban agglomeration population increase in China from 1950 to 1990, from 1990 to 2015 and the projected population increase between 2015 and 2035. Data from United Nations 2018.

Thanks to Nicola Scafetta. See also posts on Tallblokes and Paul Homewood’s site Notalotofpeopleknowthat.


Nicola Scafetta, Shenghui Ouyang: Detection of UHI bias in China climate network using Tmin and Tmax surface temperature divergence. Global and Planetary Change, Volume 181, October 2019, 102989. https://doi.org/10.1016/j.gloplacha.2019.102989
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