Disentangling the trend in the warming of urban areas into global and local factors

Abstract

Large cities account for a significant share of national population and wealth, and exert high pressure on local and regional resources, exacerbating socioenvironmental risks. The replacement of natural landscapes with higher heat capacity materials because of urbanization and anthropogenic waste heat are some of the factors contributing to local climate change caused by the urban heat island (UHI) effect. Because of synergistic effects, local climate change can exacerbate the impacts of global warming in cities. Disentangling the contributions to warming in cities from global and local drivers can help to understand their relative importance and guide local adaptation policies. The canopy UHI intensity is commonly approximated by the difference between temperatures within cities and the surrounding areas. We present a complementary approach that applies the concept of common trends to extract the global contributions to observed warming in cities and to obtain a residual warming trend caused by local and regional factors. Once the effects of global drivers are removed, common features appear in cities' temperatures in the eastern part of the United States. Most cities experienced higher warming than that attributable to global climate change, and some shared a period of rapid warming during urban sprawl in the mid-20th century in the United States.

Surface warming in global cities is substantially more rapid than in rural background areas

“…More importantly, LST and SAT characterize distinct and complementary components of urban warming, and LST is still useful for various applications such as weather forecasting and prediction as it provides a lower boundary condition to the atmosphere. We admit possible uncertainties induced by the deficiencies of satellite LST and reanalysis SAT data, such as the data error, potential urbanization signals and natural oscillations of these two data sources 11,36 . Nevertheless, a closer analysis suggests such impacts should be minimal and may not induce a large bias on the major findings (refer to Supplementary Note 3).…”

“…Some studies have examined the equal-rate assumption by isolating the urban warming signal from surface air temperature (SAT) data, i.e., by directly separating contributions of urbanization from other forcing factors based on linear or non-linear models 11,12 . This approach has been applied to China where rapid urbanization has occurred in the past decades and where the density of weather station network is high 13 .…”

Anthropogenic influence on extremes and risk hotspots

“…The synergy between global and local (due to UHI) climate change in cities can exacerbate socioeconomic losses and contribute to more severe heat waves and precipitation events 50 , 51 , 67 , 68 . Given the socioeconomic importance of these findings, it would be valuable to extend the proposed methodology to study the attribution of extreme events at the city scale and to evaluate the relative contribution of UHI effects 69 . The results presented here provide further support for adopting strategies to reduce the UHI effect, as they can be low-cost risk reduction instruments for large shares of global population and GDP with increasing risks from climate change.…”

Daya Serap Ruang Terbuka Hijau Perkotaan terhadap Emisi Sektor Transportasi.

“…Penelitian menunjukkan adanya kenaikan suhu dan penurunan kelembapan relatif di wilayah perkotaan sehingga mengakibatkan peningkatan stress (S. Kumar D et all, 2022). Beberapa dampak perubahan iklim di daerah perkotaan yang sudah terjadi yaitu peningkatan kejadian iklim/cuaca ekstrim seperti badai, angin kencang dan hujan lebat (F. Estrada and P. Perron, 2021) Peningkatan konsentrasi GRK sebagai penyebab utama perubahan iklim global telah disadari oleh dunia sehingga komitmen dunia dlam rangka penanggulangan iklim dicanangkan melalui berbagai inisiatif misalnya melalui pertemuan tingkat dunia guna menghasilkan dokumen persetujuan misalnya Paris Agreement sebagai landasan negara-negara dunia untuk bertindak bersama mengurangi emisi karbon (P. Dargusch, and G. Hil, 2022). Indonesia telah meratifikasi Paris dan berkomitmen mengurangi emisi GRK dalam beberapa dekade ke depan (M.A.…”