Two new studies affirm the rapid growth in urbanization is causing significant non-climatic warming, artificially increasing the “global” trend.
Water covers approximately 362 million km² of the Earth’s surface. Land covers 148 million km² of the Earth’s surface.
As of 2003, just 0.5 million km² (0.34%) of the globe’s 510 million km² surface was urban or mostly urban. As of 2018, it was 0.7 million km² (0.42%). By 2035, 1.4 million km² (0.96%) of the Earth’s surface will be urban.
So approximately 99.8% of the Earth’s surface is not urban, and yet the majority of the temperature stations contributing to the “global” warming trend records over the last decades are located in urban areas. This would appear to have a tendency to bias the warming trends.
Urbanization adds artificial, non-climatic warmth
A new study assesses urbanization (concrete, machinery, roofs, vehicles, etc.) added 0.054°C of additional warmth to the annual temperature over the 16 years from 2003 to 2018. In summer, as much as 0.122°C was added to global temperature records over this period.
Urban areas are poised to experience rapid growth in the next two decades, almost tripling the proportion of the surface area (from 0.34% to 0.96%) during the 2003-2035 period.
This explosive expansion in global urban area is predicted to “nearly double” the growth in artificial, non-climatic warming added to the surface temperature record from densely populated areas.
Since the majority of the globe’s temperature stations are situated in urban areas, this urbanization tendency is poised to inflate temperature records well beyond that of non-urban areas.
Image Source: Shen et al., 2023
Another new study assesses the mean surface warming trend as 0.5 ± 0.20 K·decade−1 in the urban core of more than 2000 city clusters across the globe. This is “29% greater than the trend for the rural background.”
In other words, “surface warming in global cities is substantially more rapid than in rural background areas.”