Eastern Nepal more sensitive to climate change: Study

Kathmandu, May 10: A recent study has found that the eastern part of Nepal is more sensitive to climatic changes and is warming faster than the central and western parts. 

The study titled “Recent Warming and its Risk Assessment on Ecological and Societal Implications in Nepal,” published a month ago, analysed temperature data from 76 meteorological stations across Nepal from 1970 to 2016 to understand the warming trends and their ecological and societal implications.

The study found that the eastern part is warming faster than the central and western parts, showing an increased climatic sensitivity across the Khumbu and the warming trend has been observed in all physiographic regions. 

The lower hills experienced higher warming trends than the upper hills and mountains, said lead researcher Dr. Yam Prasad Dhital, Associate Professor at College of Water Resources and Architectural Engineering, Shihezi University in China. 

Higher warming trends were observed in the winter season than in other seasons in all regions except the Terai. The study also found that higher-warming regions experienced higher ecological impacts, such as changes in water resources and phenology. The Lower Hills, Upper Hills, and Mountains were hit harder than the Terai and Siwaliks in the current global warming scenario, Dr. Dhital said.

The gradual rise in temperature in the mountainous region has attracted the interest of the scientific community. However, there is a lack of recent data on the east-west and south-north temperature gradients in Nepal and their implications for ecology and society. The study used a hybrid analytical approach, including integrated statistical and theoretical tools, to detect the warming trend and its ecological and societal implications across the country.

The warming trend has been observed in all physiographic regions along an altitude gradient, with the Terai, Siwaliks, Lower Hills, and Upper Hills experiencing 0.15, 0.26, 0.68, and 0.57 Degrees Celsius per decade, respectively. The lower hills experienced higher warming trends than the upper hills and mountains, indicating that higher elevations experienced lesser degrees of warming than the lower elevations in the mountainous regions, according to the research.

Based on the warming trends in different physiographic regions, the study found a similar pattern of ecological impacts, where higher warming regions experienced higher ecological impacts, such as changes in water resources and phenology, Dr. Dhital said.

Climate Change is adversely affecting the temperatures and temperature variations globally. The IPCC’s Sixth 

Assessment Report reveals that human activities are the main culprit behind global warming. Due to the continuous increase of greenhouse gases (GHG), the temperature has been rising, leading to severe consequences for the environment, socio-economic systems, and human life. Mountain areas, especially snow-and-glacier-dominated regions, are highly vulnerable to the impact of climate change, he said.

Nepal is a sensitive zone in the context of climate change in South Asia due to its fragile ecological system, rugged physical structure, and steep slopes, where glaciers are retreating rapidly in the Himalayas, and the equilibrium line altitude (ELA) has been shifting upward. In the High Himalaya region, formation, growth, and likely outburst of glacial lakes are phenomena directly related to climate change and deglaciation. Consequently, some signs of negative impacts on river hydrology, agriculture, natural biodiversity, livelihoods, and human health have been observed in recent years, Dr. Dhital said.

In recent years, agriculture shifting has also been observed in the High Mountains. Furthermore, risk factors have increased due to the increased number of pests and invasive species in the Middle Mountains, including some parts of the High Mountains. Distinct warming patterns have been reported in Nepal, and the increasing trend in minimum temperature was negligible compared to maximum temperature in almost all parts of the country.

However, the trends of climatic warming along east-west and south-north altitudinal gradients and their ecological impacts across the different physiographic regions of Nepal have not been comprehensively explored yet to address this key issue, the study said.

The study provides cause-and-effect relationships between warming trends and adverse ecological impacts in different physiographic regions from a lower elevation to the High Mountains of Nepal.  

As high as the average 0.4 Degrees Celsius per decade warming trend of Nepal’s temperature observed annually in this study is unusually high, alarming the nation’s climate policy makers.

The contrast of warming across the south-north gradients of the country further suggests that region-specific adaptation strategies are needed to tackle climate change, Dr. Dhital said. Both seasonal and annual trends of temperature warming indicate the importance of micro-level evaluation of ecological and societal responses to climate change in Nepal. The national adaptation programme should be more focused on ecosystem management, he suggested.