Recent changes in heatwaves and maximum temperatures over a complex terrain in the Himalayas

Area of Science:

• Environmental Science
• Climate Science
• Remote Sensing

Background:

• Assessing the distinct impacts of global warming and forest cover change on regional temperatures is challenging, especially in complex mountainous terrains.
• Understanding these impacts is crucial for predicting heat stress and climate change effects in vulnerable regions.

Purpose of the Study:

• To estimate regional and local heat stress responses to global climate change and forest cover loss in the Himalayas.
• To segregate the temperature impacts of global warming from local forest cover changes using a high-resolution dataset.

Main Methods:

• Utilized a satellite-based, high-resolution land-surface temperature dataset for the Himalayas (2003-2019).
• Developed a regional multiple linear regression model to differentiate temperature responses.
• Analyzed trends in heatwaves, heat days, and annual maximum/mean surface temperatures.

Main Results:

• Observed large-scale decreasing trends in heatwave frequency and surface temperatures, with localized increases in urban/high-elevation areas.
• Deforestation led to steeper declines in surface temperatures compared to areas with intact forest cover.
• The model estimated a regional decrease of ~2.0 °C in annual maximum temperature, modulated by urbanization, forest cover, and elevation.

Conclusions:

• Forest clearing amplifies anthropogenic climate change effects in the Himalayas.
• Deforestation exerts a local cooling effect that interacts with broader climate change trends.
• Findings highlight the complex interplay between land cover change and global warming in mountainous regions.