Ian Bradford: Are the Global Temperature Estimates Used in the IPCC Reports Contaminated by Urban Warming Biases?

To obtain an average temperature of the Earth, weather stations are set up in many locations.  A hundred and fifty years ago, there were only small towns. Roads were not sealed and buildings were in the main made of wood. There were no airports, no cars, no huge industries, and a smaller number of people.  Temperature reading devices-mainly thermometers were set up in these towns so that those reading them did not have far to travel.

Things are very different now. Roads are sealed, high concrete buildings dominate our cities, and air conditioning units are fixed to most buildings. Cities are full of vehicles, as well as people.  There are often airports nearby. Many small businesses also occupy places in cities. All these things contribute to making our cities very warm places, especially in summer. In fact, most of the time, the temperature in a city is higher than the temperature in the surrounding countryside.  This is known as the Urban Heat Island effect.

The above is a typical profile for temperature. It shows the city temperature about 4 deg C  higher than the rural temperature.

Scientist Oke produced a formula for the warming which is connected to the population.

He said:  UHI  =   0.73 log₁₀ pop    (pop is the population.)   So in a town of 1000 people the extra temperature is  2.2deg C.  In a city of population 1 million the extra temperature is 4.4 deg C.  

Now since most temperature measuring devices are in cities for convenience this extra heat must be corrected for. But is it?

The Siting Problem

In the USA a team of volunteers under Anthony Watts began an effort to look at siting issues with over a thousand stations. They found issues with a high percentage of them. All of the siting issues identified introduced a warming bias.

The bottom right shows the white temperature box near a drum for burning rubbish. That’s bad enough. Look at the graph top right. It shows a steady but small increase in temperature then a huge jump. This is because a sealed asphalt tennis court was built right next door. The huge amount of heat coming off this surface caused the sudden increase in temperature. In this example the sudden increase, and the reason is obvious. The temperature device needed to be shifted. But often there is just a steady increase of temperature shown because the city expands out through and past the temperature device. No thought is given about a correction for the urban heat island effect as the city expands.

Not too long ago the Heartland Institute conducted a study of the placement of temperature stations in the USA. They found that 96% of climate data is corrupted. These are NOAA official temperature stations. The Heartland Institute report was compiled by satellite plus actual visits to the stations. Their research showed that 96% of the stations are corrupted by localised effects of urbanisation producing heat bias because of their close proximity to machinery, asphalt, and other heat producing, heat trapping and heat accentuating objects.

A new study published in the scientifically peer reviewed journal Climate, by 37 researchers from 18 countries suggests that current estimates of global warming are contaminated by urban warming biases. The study also suggests that the solar activity estimates considered in the most recent IPCC reports on climate change underestimated the role of the sun in global warming since the 19^th Century.        

Urban areas account for less than 4% of the global land surface. Many of the weather stations used for calculating global temperatures are located in urban areas. For this reason many scientists are concerned that the current global warming estimates may have been contaminated by urban heat island effects. In their latest report, the IPCC estimated that urban warming accounted for only about 10% of global warming . However, this new study suggests that urban warming might account for up to 40% of the warming since 1850.

In the study two different temperature estimates were considered: a rural-urban blend (that matches almost exactly with most current estimates), and a rural only estimate.

The rural and urban blend indicates a warming of 0.89 deg C per century since 1850, while the rural only indicates 0.55 deg C per century.  This contradicts a common assumption that current thermometer-based global temperature indices are relatively unaffected by urban warming biases.        

When the authors analysed the temperature data only using the IPCC’s solar dataset they could not explain any of the warming since the mid 20^th century. That is they replicated the IPCC’s finding that global warming is mostly human caused. However, when the authors repeated the analysis using a different estimate of solar activity- one often used by the scientific  community, they found that most of the warming and cooling trends of the rural data could actually be explained in terms of changing solar activity.  The study found that the IPCC’s chosen estimate for solar activity appeared to have ruled out a substantial role for the sun in observed warming. So since the 1850’s the IPCC has downplayed a possible large role for the sun.

The review by the 37 scientists concluded that it was not scientifically valid for the IPCC to rule out the possibility that global warming might be mostly natural.

Many people accept human-made climate change because the internet is flooded with climate change and global warming propaganda. There are many fake charts and fake high temperatures. For example, on June 28^th 2019 a high temperature was reported from France of 46 deg C but when this was checked with the weather station it was found the actual temperature was 43 deg C.  Germany claimed 41.2 deg C on July 5^th 2019 but the actual temperature was 39 deg C. The UK claimed 40.3 deg C on July 19^th 2022 but the actual temperature was 37.9 deg C.

If you are told such and such was the hottest day on record then I would advise checking it if you have the means. Just remember that a heat wave in the UK or the USA is not an indication of global warming. These are localised events and are weather events. They would need to continue for some years and be worldwide, before they could be called climate change.

Ian Bradford, a science graduate, is a former teacher, lawyer, farmer and keen sportsman, who is writing a book about the fraud of anthropogenic climate change.