Impact of Deforestation on Land–Atmosphere Coupling Strength and Climate in Southeast Asia

Merja H Tölle

doi:10.3390/su12156140

Abstract

Southeast Asia (SEA) is a deforestation hotspot. A thorough understanding of the accompanying biogeophysical consequences is crucial for sustainable future development of the region’s ecosystem functions and society. In this study, data from ERA-Interim driven simulations conducted with the state-of-the-art regional climate model COSMO-CLM (CCLM; version 4.8.17) at 14 km horizontal resolution are analyzed over SEA for the period from 1990 to 2004, and during El Niño–Southern Oscillation (ENSO) events for November to March. A simulation with large-scale deforested land cover is compared to a simulation with no land cover change. In order to attribute the differences due to deforestation to feedback mechanisms, the coupling strength concept is applied based on Pearson correlation coefficients. The correlations were calculated based on 10-day means between the latent heat flux and maximum temperature, the latent and sensible heat flux, and the latent heat flux and planetary boundary layer height. The results show that the coupling strength between land and atmosphere increased for all correlations due to deforestation. This implies a strong impact of the land on the atmosphere after deforestation. Differences in environmental conditions due to deforestation are most effective during La Niña years. The strength of La Nina events on the region is reduced as the impact of deforestation on the atmosphere with drier and warmer conditions superimpose this effect. The correlation strength also intensified and shifted towards stronger coupling during El Niño events for both Control and Grass simulations. However, El Niño years have the potential to become even warmer and drier than during usual conditions without deforestation. This could favor an increase in the formation of tropical cyclones. Whether deforestation will lead to a permanent transition to agricultural production increases in this region cannot be concluded. Rather, the impact of deforestation will be an additional threat besides global warming in the next decades due to the increase in the occurrence of multiple extreme events. This may change the type and severity of upcoming impacts and the vulnerability and sustainability of our society.

Highlights

Ongoing climate change is a global problem [1]
In order to analyze changes in land–atmosphere coupling due to deforestation and during El Niño–Southern Oscillation (ENSO) phases, data were taken from simulation experiments for Southeast Asia (SEA) with the state-of-the-art regional climate model COSMO-CLM
The spatial distribution of Pearson correlation coefficients over Southeast Asia is shown in Figure 3 for the period from 1990 to 2004 for November to March

Summary

Introduction

Ongoing climate change is a global problem [1]. Anthropogenic changes in atmospheric gaseous components and land-use changes are the main drivers leading to climate change [2]. Deforestation modifies the land surface properties, resulting in alterations to surface fluxes such as moisture, heat, and momentum, which directly affect the temperature and the atmospheric boundary layer [11,12] These effects are known as biogeophysical impacts acting on local and regional scales. The state of the land surface and land–atmosphere feedback could potentially modulate and Sustainability 2020, 12, 6140 amplify extreme climatic events in SEA, and more importantly, during ENSO events The strength of this coupling might determine the impact the land cover change in the Southeast Asian region. The coincidence metric concentrates on the bivariate dependence structure of two variables, and is insensitive to biases in the means or variances We use this approach to quantify the change in the land–atmosphere coupling due to deforestation, and during ENSO events.

Study Region

Model Data

Land–Atmosphere Coupling

Coupling Change during La Niña

Coupling Change Due to Deforestation