Impacts of forestation and deforestation on local temperature across the globe

Abstract

Changing forest cover is a key driver of local climate change worldwide, as it affects both albedo and evapotranspiration (ET). Deforestation and forestation are predicted to have opposing influences on surface albedo and ET rates, and thus impact local surface temperatures differently. Relationships between forest change, albedo, ET, and local temperatures may further vary regionally, as the strengths of warming by albedo effects and cooling by ET effects vary with latitude. Despite these important relationships, the magnitude of forest cover effects on local surface temperature across the globe remains unclear. Using recently-released global forest change data, we first show that forestation and deforestation have pervasive and opposite effects on LST, ET and albedo worldwide. Deforestation from 2000 to 2010 caused consistent warming of 0.38 ± 0.02 (mean ± SE) and 0.16 ± 0.01°C in tropical and temperate regions respectively, while forestation caused cooling in those regions of -0.18 ± 0.02 and -0.19 ± 0.02°C. Tropical forests were particularly sensitive to the climate effects of forest change, with forest cover losses of ~50% associated with increased LST of 1.08 ± 0.25°C, whereas similar forest cover gains decreased LST by -1.11 ± 0.26°C. Secondly, based on a new structural equation model, we show that these changes on LST were largely mediated by changes in albedo and ET. Finally, based on this model, we show that predicted forest changes in Brazil associated with a business-as-usual land use scenario through 2050 may increase LST up to 1.45°C. Our results contribute to a better understanding of the mechanistic inter-relationships between forest change and changes in albedo, ET and LST, and provide additional evidence that forestation has the potential to reverse deforestation impacts on local climate, especially in tropical and temperate regions.

Quantifying the Actual Impacts of Forest Cover Change on Surface Temperature in Guangdong, China

“…A variety of satellite-based datasets describing forest cover and climate variables as well as their changes have been developed and applied in site-based pairs and individual time-based statistical modeling methods [15,16]. Forest change can significantly affect surface temperature, and the area, magnitude, and direction of any changes vary significantly from local to global scales [7,17,18]. Some studies have found the inconsistent warming or cooling effects of forest change on temperature [7,[19][20][21].…”

“…This approach has been refined in order to quantify the potential effects of the hypothetical land use change (i.e., no change between land cover types) and the effects of the actual change (i.e., land cover change minus local no-change in two time periods) on surface temperature [15]. Sampling scales for the change estimation, such as moving window size, circle area, or even larger sizes, have been utilized [18,24,26]. In actuality, the conversion from forest to other types between different years would have different impacts on both the sign and magnitude of the surface temperature [17,27].…”

“…These types of global land cover maps are typically characterized by low accuracy, particularly in regions with heterogeneous land cover [29]. Forest or land cover changes extracted from high-resolution satellite data, such as the historical Landsat archive, have also been adopted for assessing the impacts of these changes on surface temperature [18,30]. Even though applications of long-term Landsat data on a large scale can be difficult due to data matching issues with observations from other sources (e.g., modeling and in-situ observations) [18], high-resolution maps developed with Landsat are still recommended to assess the impacts of forest change on temperature [27,31].…”

Beyond diversity loss and climate change: Impacts of Amazon deforestation on infectious diseases and public health

“…The Amazon rainforest plays a pivotal role in regulating Earth's climate (Bonan 2008, Malhi et al 2008. In this sense, Amazon deforestation leads to regional and global average temperature rise (Baker & Spracklen 2019, Cohn et al 2019, Prevedello et al 2019, and changes in the Amazon biome are associated with an increase in the frequency of extreme weather events, such as droughts, altered rain patterns, heat waves, cold waves, and severe storms (Nepstad et al 2008, Sena et al 2014, Wu et al 2016, Stoy 2018, Leite-Filho et al 2019. Deforestation also facilitates forest fires, since degraded areas are naturally more susceptible to combustion.…”

“…In addition to reducing deforestation, it is necessary to recuperate degraded areas. Reforestation, afforestation, and restoration of forest environments help mitigate climate change through carbon sequestration, and social, ecological and economic benefits are obtained through the recovery of degraded forest areas (Bonan 2008, Brancalion et al 2019, Bustamante et al 2019, Prevedello et al 2019. However, the carbon and biodiversity benefits of preventing Amazonian deforestation are much greater than those of forest recovery, both per hectare and per unit cost, making avoiding deforestation the current priority in the Amazon region (Fearnside 2017b).…”