New paper finds temperature record in China contaminated by urban heat island effect

A paper published today in the Journal of Climate finds the temperature record in China was significantly influenced by the growth of urban areas around weather stations originally located in rural areas [the urban heat island effect], rather than actual planetary warming. According to the authors, "nearly half of the stations in the study area have been converted from non-urban to urban stations as a result of land cover change associated with urban expansion. We determined that both land cover change and human activity play important roles in temperature change and contribute to the observed warming, particularly in urbanized stations, where the highest amount of warming was detected. Urbanized stations showed higher...temperature trends than those of unchanged stations." The paper corroborates prior work demonstrating that half of the global warming in the US is artificial due to increased urbanization & siting issues.

The paper reminds me of the email from Phil Jones to James Hansen found in the NASA FOIA files in which Jones complains about the Chinese trying to obtain an accurate temperature record by moving their thermometers away from urban heat islands; Jones laments that the Chinese don't obtain temperature measurements from airports maximally contaminated by the urban heat island effect!

Journal of Climate 2013 ; e-View

doi: http://dx.doi.org/10.1175/JCLI-D-12-00698.1

Urbanization impact on temperature change in China with emphasis on land cover change and human activity

Yan Li,^a,b Lijuan Zhu,^c Xinyi Zhao,^a,b Shuangcheng Li,^a,b and Yan Yan^d

^a Key Laboratory for Earth Surface Processes, Ministry of Education, Peking University, Beijing, 100871, China

^b College of Urban and Environmental Sciences, Peking University, Beijing, 100871, China

^c State Key Laboratory of Satellite Ocean Environment Dynamics/Second Institute of Oceanography, State Oceanic Administration, Hangzhou, 310012, China

^d Air Force Meteorological Center, Beijing, 100843, China

Abstract

The impact of urbanization on temperature trends in China was investigated with emphasis on two aspects of urbanization, land cover change and human activity. A new station classification scheme was developed to incorporate these two aspects by utilizing land cover and energy consumption data. Observation temperature data of 274 stations and National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis temperature from 1979 to 2010 were used in conducting the observation minus reanalysis (OMR) method to detect urban influence. Results indicated that nearly half of the stations in the study area have been converted from non-urban to urban stations as a result of land cover change associated with urban expansion. We determined that both land cover change and human activity play important roles in temperature change and contribute to the observed warming, particularly in urbanized stations, where the highest amount of warming was detected. Urbanized stations showed higher OMR temperature trends than those of unchanged stations. In addition, a statistically significant positive relationship was detected between human activity and temperature trends, which suggests that the observed warming is closely related to the intensity and spatial extent of human activity. In fact, the urbanization effect is strongly affected by specific characteristics of urbanization in local and regional scales such as land cover change, human activity, and other related factors.