A greening world enhances the surface-air temperature difference

Huihui Feng; Bin Zou

doi:10.1016/j.scitotenv.2018.12.210

A greening world enhances the surface-air temperature difference

Sci Total Environ. 2019 Mar 25:658:385-394. doi: 10.1016/j.scitotenv.2018.12.210. Epub 2018 Dec 15.

Authors

Huihui Feng¹, Bin Zou²

Affiliations

¹ School of Geosciences and Info-Physics, Central South University, Changsha 410083, China; Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring of Chinese Ministry of Education, Changsha 410083, China. Electronic address: hhfeng@csu.edu.cn.
² School of Geosciences and Info-Physics, Central South University, Changsha 410083, China; Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring of Chinese Ministry of Education, Changsha 410083, China. Electronic address: 210010@csu.edu.cn.

PMID: 30579196
DOI: 10.1016/j.scitotenv.2018.12.210

Abstract

The surface-air temperature difference (Ts-Ta) is a critical variable for tracking climatic and environmental change. Vegetation has unavoidably affected the temperature by altering surface properties, while the magnitude of this effect has remained unknown. This study aimed to investigate the patterns of global Ts-Ta and quantify the contribution of vegetation change. Trend analysis, correlation analysis and a trajectory-based method were adopted for the investigation. The results demonstrated that the global Ts-Ta decreased by -0.140 K from 2001 to 2016. The greening trend covered 24.46% of the land and played a profound role in changing Ts-Ta. In particular, vegetation changes resulted in -0.0022 K, -0.0092 K and - 0.0043 K of the Ts-Ta decreases at the global, greening and browning levels, respectively accounting for 11.58%, 35.38% and 20.38% of the total decrease. Physically, vegetation influenced Ts-Ta mainly by altering atmospheric properties, rather than surface properties. Specifically, the greening of the surface reduced the albedo at a rate of -0.0003/year over 20% of the global land and enhanced atmospheric water vapor by 3 × 10^-5 g/m³ over approximately 40% of the land. Meanwhile, the effect of vegetation change varied with coverage. A reduction in albedo caused by vegetation change occurred equally over different vegetated conditions, while the enhancement of atmospheric water vapor occurred mainly in sparsely (0.10 < NDVI < 0.30) and densely (0.55 < NDVI < 0.70) vegetated regions. Under these conditions, the vegetation change mainly affected Ts-Ta in sparsely vegetated regions (NDVI < 0.4). The results of this study are helpful for understanding the physical mechanism behind changes in global Ts-Ta and support climatic adaptation and environmental management.

Keywords: Climate and environment change; Contribution; Global; Surface-air temperature difference; Vegetation.