Taal (Philippines) eruption may trigger El Niño

The Taal caldera is largely filled by Lake Taal, whose 267 square kilometers surface lies only 3 meters above sea level. All historic eruptions took place from a five kilometers wide volcanic island in the northern-central part of the lake.

[Lake Taal]

When the Taal volcano near Manila (The Philippines) started erupting on January 12, 2020, ash spewed 14 kilometers into the air, coating villages in a blanket of dust and affecting nearly 460,000 people, many of whom lost access to electricity and fresh water. Despite the significant impact, the eruption so far has been tame compared to some of the biggest eruptions in history.

Climatologists think that, if the ongoing Philippine volcanic eruption does become more violent, the gases released are likely to trigger an El Niño event during the 2020-21 winter, a more intense polar vortex and considerable warming across Eurasia.

Fine ash and sulfur dioxide from eruptions will block incoming solar radiation, thus reducing heat at Earth's surface that in turn produces atmospheric warming. As a result, for a year after especially violent eruptions, temperatures can be cooler than normal across much of the planet. But in addition to the cooling, there can also be a warming in the first post-eruption winter in the northern hemisphere as surface temperatures rebounds.

Researchers took data on the scale of volcanic eruptions worldwide over the past 1,100 years taken from Greenland and Antarctica ice cores and entered this into global climate models. This then allowed them to project the impact of the Taal eruption[1].

They think there is a high likelihood (83% probability) of an El Niño-like warming event during the 2020-21 winter if the magnitude of the Taal eruption reaches a mid-range "volcanic explosive index". Such an eruption would also produce an enhanced polar vortex— a large area of low pressure and cold air surrounding the Earth's North and South poles, which in turn would drive warming across the Eurasian continent.

[1] Liu et al: Could the Recent Taal Volcano Eruption Trigger an El Niño and Lead to Eurasian Warming? in Advances in Atmospheric Sciences - 2020