El Nino intensifies cold spell in northern Vietnam: expert

Both northern and central Vietnam are undergoing intense cold weather.

Since Jan. 20, cold air has swept down from the north, leaving mountainous regions with temperatures of 0 degrees Celsius or lower, resulting in ice and frost.

The mercury in the plains has dropped to 7-10 degrees at night, and around 15 degrees during the day.

According to the National Center for Hydro-Meteorological Forecasting, this intense cold spell is expected to last until Jan. 25.

Nguyen Ngoc Huy, an expert in meteorology, hydrology, and climate change, said in years with El Nino, as with this year, sudden cold spells usually occur during winter when temperatures drop sharply, making it colder than the average of the same period in previous years.

El Nino is a natural climate pattern that occurs when the Pacific Ocean near the equator gets warmer than usual, affecting the weather around the world, causing unusual and often extreme weather events around the globe, such as heavy rains and flooding in some areas, and droughts in others.

Huy said that these sudden cold spells were unpredictable and randomly occur when cold cores form in Siberia (Russia) and move southwards.

The ongoing cold wave is intense, yet the wind levels are weak, and therefore it affects only the north and central regions, not the south.

At the same time, he noted that due to El Nino, which make temperatures higher than the multi-year average by 1.5 – 2 degrees Celsius, and global warming, Ho Chi Minh City and other southern localities have not experienced any cold spells this past year.

In a study published in 2017 by Nature, the world’s leading multidisciplinary science journal, researchers Xin Geng, Wenjun Zhang, Malte F. Stuecker and Fei-Fei Jin said that large-scale cold spell can be attributed to the El Niño event in the tropical Pacific.

“Our analysis reveals that all super El Niño winters (1982/83, 1997/98, and 2015/16) were accompanied by a rapid sub-seasonal North Atlantic Oscillation (NAO)/Arctic Oscillation (AO) phase reversal from a positive to a negative state during early January, which was largely caused by the interaction of these super El Nino events with the subtropical jet annual cycle.

The NAO/AO phase transition leads to a rapidly strengthened Siberian High, which favors southward intrusions of cold air to East Asia and thus causes severe local cooling,” they said.

Extreme and unusual weather is increasingly evident worldwide, with deeper cold spells and more severe summer temperatures.

The Intergovernmental Panel on Climate Change reports that the average global temperature is rising.

Vietnam follows this trend but at a faster pace of 38%, according to temperature difference data from 2006-2015 compared to the preceding 20 years.

According to research conducted by GEMMES Vietnam, a joint project between the Vietnamese government and the Agence Française de Développement, the French international development agency, if nothing is done to fight climate change, temperatures could rise by as much as 6 degrees Celsius in Vietnam in the worst-case scenario.

Researchers from GEMMES utilized the most recent data from the World Climate Research Program to simulate Vietnam’s climate across various climate policy frameworks. In the scenario where greenhouse gas emissions persist at their current global rate without any intervention, a 6-degree rise is projected.

Conversely, if the commitments of the Paris Climate Agreement are adhered to, Vietnam is expected to experience a moderate temperature rise of 1.3 degrees Celsius.