Yangyel Lhaden
As the world is headed to a warmer climate with rising temperatures due to global warming, Bhutan is also experiencing warmer winters.
After the drop at 14.1°C in 2018, the average temperature during October, November, and December (OND) has steadily increased by an average of 0.3°C.
This trend aligns with findings from the Climate Change Projection Report (CCPR) 2024, which forecasts a rise in both maximum and minimum temperatures across Bhutan in the coming decades. The report attributes these changes to increased greenhouse gas emissions and presents varied warming scenarios under different emission pathways such as moderate and high emissions
The report emphasises that pre-existing vulnerabilities will complicate efforts to adapt to these changes. Key sectors such as agriculture, hydropower, water supply, and construction—each crucial to Bhutan’s economy—are at risk from climate change.
The Paris Agreement, adopted in 2015, aims to limit global warming to well below two degree Celsius below pre-industrial levels and pursues efforts to limit the temperature increase to 1.5°C. Scientists warn that warming beyond two degree Celsius could lead to irreversible changes.
Bhutan, a carbon-negative country committed to remaining carbon neutral and playing no role in global emissions, is already feeling the brunt of climate change.
Last year was the warmest year on record after an extended streak of exceptionally high monthly global mean temperatures, according to the World Meteorological Organisation.
In Thimphu, the average temperature during OND dropped to 9.5°C in 2000 and 2018. Since then, the OND average temperature has been steadily increasing by 0.4°C. A National Centre for Hydrology and Meteorology (NCHM) official said that a cold bias has been observed since the station moved from Simtokha to Babesa in 2017 but it aligns with the warming trend.
The official also said that no clear trend emerged regarding the early or late onset of winter over the past five years and some winters have been colder or warmer influenced by varying climate drivers. “Each year is influenced by different Sea Surface Temperature patterns in the Pacific and Indian Oceans. However, the decreasing monthly average temperature has remained consistent.”
Since the Covid-19 pandemic, low-lying areas of Thimphu have not experienced snowfall in winter. “ These areas are receiving less snowfall, as seen in recent years,” the official said. “This trend is likely to continue even under a warming scenario. However, high-altitude areas of Thimphu continue to receive annual snowfall.”
Winter precipitation, primarily from the Western Disturbance, is a key source of moisture for snowfall. Bhutan generally experiences drier winters with less precipitation. “No major changes have been observed in winter precipitation over the years,” the official said.
The official said that winter precipitation and snowfall were vital water sources for soil recharge, glacier feeding, and biodiversity. “While snowfall in low-lying areas can be replaced with increased precipitation, snowfall in the mountains and high-altitude areas is essential for snow cover and glaciers.”
Climate change is expected to increase monsoon rains, and winter precipitation is also projected to rise. However, the official noted, “While there could be a slight decrease in snowfall due to warming, the increase in projected winter precipitation and interannual variability could still bring snowfall. Therefore, it is difficult to predict definitively whether snowfall will increase or decrease at this stage.”
According to the CCPR 2024 report, precipitation is expected to decrease in the medium term but increase in the long term. This increase, however, comes with challenges. Northern, western, north-western, and south-western Bhutan are likely to experience higher precipitation, raising the risk of floods.
In contrast, eastern and southeastern areas may experience reduced rainfall, which could lead to seasonal droughts or water scarcity.
In the near to mid-term, accelerated glacial melt will enhance water availability in river basins but also increase the risk of Glacial Lake Outburst Floods. In the long term, however, reduced glacial runoff could increase the risk of seasonal droughts, particularly in areas where rainfall is expected to decrease.
The Wangchhu basin is likely to be particularly affected by this reduced glacial runoff.
Densely populated areas are expected to face higher temperatures and increased rainfall, affecting agriculture and infrastructure. Major rice-producing regions in the east may face water shortages, while areas in the west, south, and north could experience floods.
By 2040, climate projections suggest that rainfall distribution will vary from the baseline, with northern, western, central, and south-western dzongkhags likely to experience increased precipitation.
Wangdue, Gasa, Punakha, Bumthang, and Thimphu are expected to see the highest increases, while eastern and south-eastern districts may receive less rainfall.
By 2060, precipitation is expected to rise across the country, with the most significant increases in the northern, western, central, and south-western dzongkhags. However, eastern and south-eastern dzongkhags may continue to receive less rainfall, leading to potential water scarcity.
By the end of the century, all dzongkhags are projected to see an increase of at least 56 millimetre in total annual precipitation compared to the baseline, with the most significant increases expected in Punakha, Gasa, Thimphu, Paro, Bumthang, and Wangdue.
This would also result in a minimum 2°C increase in minimum temperatures, even during winter months.