Global Volcanic Uptick And The Potential Implications: New Study Shows How Historical Eruptions Triggered Global Cooling

Global Volcanic Uptick

News of volcanoes popping off/threatening to pop off are doing the mainstream rounds this week, and while it makes for good ‘clicks’ I am not yet seeing anything overly concerning–over localized hazards that is, in Iceland most notably.

Residents of Iceland’s southwestern town of Grindavik have briefly been allowed back to their homes to collect belongings due to a hush in seismicity. Despite the reprieve however, a volcanic eruption is still expected, warn officials.

Pedrag, a native Serb who has lived in Iceland for many years, was one of those who fled the town with his wife.

“If you talk to Icelandic people who have lived there all their lives, they say they have never felt something like that”.

Another resident, Gisli Gunnarsson, said he feared he might never see his home again and called the situation “grim”.

Volcanologists say that a 15km-long (9 mile) river of magma running under the Reykjanes Peninsula is very active. Latest updates could indicate a smaller impending eruption than was previously thought, but one that would still put the town in real danger.

The river runs under Iceland as well as part of the Atlantic Ocean, and the impact of an eruption on the country –and further afield with regard to aviation and potential cooling– will depend on where exactly the magma breaches the surface.

One of Iceland’s most extensive eruptions occurred in 1783 when a flood of lava lasted for eight months. This produced extensive sulphur clouds which hung over Northern Europe for six months and caused an estimated cooling of 1.3C for the following two years.

Dr Ilyinskaya, who is in regular contact with geologists on the ground, said: “It looked concerning back on Friday and Saturday that we could have something of that scale … That is not the situation that is likely at the moment.”

Dr Bill McGuire, professor emeritus of Geophysical & Climate Hazards, UCL, said: “Grindavik is very close to the position of the new fracture, and its survival is far from assured. Everything depends upon where magma eventually reaches the surface, but the situation doesn’t look good for the residents of the town.”

Despite initial concerns of a much wider eruption now receding, officials are continuing to monitor the situation on a “minute by minute” basis things could change quickly.

The area had remained dormant to volcanic activity for 800 years before a 2021 eruption.

Thor Thordason, professor of volcanology at the University of Iceland, said that the magma is now less than 800m (2,600ft) below the surface and that an eruption appeared imminent.

“Unfortunately, the most likely eruption side appears to be within the boundary of the town of Grindavik,” he pointed out.

Other than Reykjanes volcano in southwest Iceland, we also see Italy’s Mount Etna establishing a new eruptive phase, as well as sizable eruptions at Sabancaya (Peru), Popocatépetl (Central Mexico), Klyuchevskoy (Kamchatka/Russia) and Sakurajima (Japan).

Again though, nothing overly concerning — not yet anyway.

Erupting volcanoes (red), and volcanoes with a warning/minor activity (orange) [].

Volcanic eruptions are one of the key climatic forcings that will drive Earth into its next bout of global cooling.

They have been shown to increase in both number and explosivity during bouts of prolonged low solar activity. This is thought to be tied to an influx of cosmic rays (CRs) penetrating and exciting silica-rich magma.

During solar minimums the sun’s magnetic field weakens and the outward pressure of the solar wind decreases . Ths allows more CRs to enter the inner solar system, including our own planet’s atmosphere, agitating magma and sending volcanoes a-popping.

New Study Shows How Historical Eruptions Triggered Global Cooling

A new international study led by Scotland’s University of St Andrews reveals historical high latitude volcanic eruptions caused dramatic global cooling.

“High sensitivity of summer temperatures to stratospheric sulfur loading from volcanoes in the Northern Hemisphere” is led by the School of Earth and Environmental Sciences at St Andrews with international colleagues from Switzerland and the United States, and was published in the Proceedings of the National Academy of Sciences (PNAS) on November 6.

Unusually cold decades of the past, such as the 540s, 1450s, and 1600s, are associated with large volcanic eruptions, resulting in volcanic sulfate particles reflecting incoming sunlight. However, the source of the volcanic eruptions and the amount of sulfate they injected into the upper atmosphere has been unknown.

To address this, the international team of researchers, led by Dr. Andrea Burke, studied sulfur isotopes in ice cores from Greenland and Antarctica. The isotopes provided a fingerprint of the fraction of the sulfate that reached the stratosphere.

The results, correlated with tree-ring data, reveal that the largest historical cooling periods were due to volcanic eruptions at high latitudes. It also show that the amount of sulfate injected into the stratosphere by these eruption events may have been around half that previously estimated, suggesting that summer temperatures may be highly sensitive to high latitude volcanic eruptions.

Volcanic events of the 530s (Left, A–E), mid-1450s (Middle, F–J), and 1600s (Right, K–O). (A, F, and K) NH summer temperature anomaly relative to the three-year mean prior to the eruption reconstructed from tree-rings (B, G, and L) Concentration of sulfur (ppb) in the Tunu2013 ice core from Greenland (blue) and the B40 ice core from Antarctica (pink). The line is from continuous measurement on the ice core , and squares are from the discrete concentrations made on the isotope samples. (C, H, and M) δ34S of sulfate and (D, I, and N) Δ33S of sulfate from ice core samples from Tunu2013(blue) and B40 (pink). Measured values are represented by x’s (Tunu2013) or +’s (B40). For samples with more than 65% volcanic sulfate, estimates of the isotopic composition of the volcanic sulfate from isotope mass balance are also plotted in blue circles (Tunu2013) or pink triangles (B40). (E, J, and O) Continuous S concentration (ppb) from Tunu2013 ice core as in (B, G, and L), with the filled blue area as the estimate of the fraction of the sulfate coming from the stratosphere based on isotope mass balance The dashed line represents 1σ uncertainty on the fraction of stratospheric sulfate as estimated from Monte Carlo simulations. Credit: Proceedings of the National Academy of Sciences (2023). DOI: 10.1073/pnas.2221810120

“Our data show that when Earth’s climate gets altered, other parts of the climate system can kick in to strongly amplify this initial change,” said Dr. Burke.

“High latitudes feel these amplified climate changes particularly strongly.”

You can read the study for yourself, here.

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