The heat is on

March 26 | Kuensel
By Ugyen Penjore and Phub Dem

Aum Zam is a deeply religious woman. The sight of the house crow attacking other birds’ nest at her locality, in Olakha, pains her. She blames the change in temperature in Thimphu.

“The small crow (Indian crow or house crow) belongs to the hot plains.

We see a lot in Phuentsholing,” she says. “Thimphu has become a lot warmer. The birds are adapting easily.”

Whether Thimphu is becoming warmer or the invasive bird is adapting well, will need a study, but experts with the National Centre for Hydrology and Meteorology (NCHM) say the temperature had been on the rise.

An analysis on date of 21 years, from 1996-2017 over Bhutan from 15 weather stations, revealed an increasing trend, according to a scientific report launched on Friday in Thimphu.

However, it is the projection that is more concerning.

The report, Analysis of Historical Climate and Climate Projection for Bhutan, projects an increase of about of 0.8 degree celsius to 1.6 degree between 2021 and 2050 and about 1.6 degree celsius to 2.8 degree Celsius towards the end of the century (2070-2099).

Overall the climate projection of surface temperature under the RCP4.5 scenario with certain policies framed to address green house gas consultation -indicated an increase in about 0.8 degree celsius – 2.8 degree celsius between 2021 and 2100.

The Intergovernmental panel on climate change (IPCC) projects an increase of about 4.8 degree celsius in global mean surface temperature by the end of the century.

The independent study is one of the three technical studies implemented by NCHM under the Pillar I of Strategic Program for Climate Resilience (SPCR) of the GNHC that describes possible future climate changes over Bhutan.

Deputy executive engineer, Tshencho Dorji, one of the two authors of the study, said the report provides valuable information to planners, stakeholders and decision makers, as it provides a glimpse of where our climate is heading.

For instance, the reports states that the country as a whole is expected to experience an increase in temperature with a larger increase projected in the high lands.

“A more significant rise in temperature is projected in highlands where our glaciers are definitely going to be affected. So planners should question if they are still going to depend on hydropower? Should we diversify our economy?”

The formation of supra-glacial lake due to the accelerated retreat of the glaciers with increasing temperature is considered the most significant impact of climate change in Bhutan.

The yak herding elders’ observation of warming over the past 15 years concurs with climate research data.

In a 2018 study published in Mountain Research and Development, Bhutanese highlanders reported observing an increase in temperature, glacial retreat, and ascension of the snow line.

They noted that weather events like flash flood have become increasingly unpredictable and severe. Yak herders also linked the declining health of yak and shift in timing of the migration to the increase in temperature. “Due to warming and availability of glacial melt-water, the yak herders can remain on the summer pastures longer than before,” it was reported.

Rainfall

The mean annual rainfall over Bhutan is likely to increase in the future. Under the RCP 4.5 scenarios, the annual rainfall over Bhutan indicates an increase of about 10-30 percent on mean annual scale.

Tshencho Dorji said that the average annual rainfall at the moment is 1,350mm and the country experiences disasters such as floods and landslides. The projected increase of 10 -30 percent will have unimaginable impact on the country.

He, however, explained that the average annual rainfall of the country will not experience continuous 10-30% rainfall throughout the year, but there will be an increase in extremes. “The 10 percent increase in rainfall could be in a week or a month alone and rest of the year could be dry,” he said.

The study reported that the country is already experiencing prolonged and extreme drought which increase the risk of loss of biodiversity, forest fire, reduction of crop yield and agricultural productivity.

Unseasonal and heavy rainfall triggering floods and flash floods are a recurring phenomenon in Bhutan. “Changes in precipitation pattern are impacting the availability of water for drinking and energy production with cycles of flooding during monsoons and drying streams during other seasons.” The report also indicates drier winter and wetter summer with projections of increasing rainfall during the summer months and decreased rainfall in winter, particularly in the northwestern region of Bhutan.

While many expect more rainfall in summer, Tshencho Dorji explained that in such conditions, while the average rainfall remains same, one month of the summer could experience most of the rainfall and the rest could be drier. “The centre can only provide data and recommend concerned authority to be prepared,” he said.

Should we be worried?

Tshencho Dorji said the centre or climate science rule does not allow recommending sectors to take certain actions. “What is clear is the need of reliable information. If the temperature is increasing, it will affect crops. Planners could use the data to think of a different variety of crops.”

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