Volcanic eruptions can help mitigate global warming in the long run
the verdict
CONTESTED
contested - evenly split
refutedsupported
the weight of evidence
1 source for · 2 against
Evidence regarding the climate impacts of volcanic eruptions points in multiple directions; some studies note short-term cooling effects while others highlight specific mechanisms like water vapour forcing that can lead to warming or note that eruptions do not mitigate global warming in the long term.
Abstract Following the 15 January 2022 Hunga Tonga‐Hunga Ha'apai eruption, several trace gases measured by the Aura Microwave Limb Sounder (MLS) displayed anomalous stratospheric values. Trajectories and radiance simulations confirm that the H 2 O, SO 2 , and HCl enhancements were injected by the eruption. In comparison with those from previous eruptions, the SO 2 and HCl mass injections were unexceptional, although they reached higher altitudes. In contrast, the H 2 O injection was unprecedented in both magnitude (far exceeding any previous values in the 17‐year MLS record) and altitude (penetrating into the mesosphere). We estimate the mass of H 2 O injected into the stratosphere to be 146 ± 5 Tg, or ∼10% of the stratospheric burden. It may take several years for the H 2 O plume to dissipate. This eruption could impact climate not through surface cooling due to sulfate aerosols, but rather through surface warming due to the radiative forcing from the excess stratospheric H 2 O.
Abstract The underwater Hunga Tonga-Hunga Ha-apai volcano erupted in the early hours of 15th January 2022, and injected volcanic gases and aerosols to over 50 km altitude. Here we synthesise satellite, ground-based, in situ and radiosonde observations of the eruption to investigate the strength of the stratospheric aerosol and water vapour perturbations in the initial weeks after the eruption and we quantify the net radiative impact across the two species using offline radiative transfer modelling. We find that the Hunga Tonga-Hunga Ha-apai eruption produced the largest global perturbation of stratospheric aerosols since the Pinatubo eruption in 1991 and the largest perturbation of stratospheric water vapour observed in the satellite era. Immediately after the eruption, water vapour radiative cooling dominated the local stratospheric heating/cooling rates, while at the top-of-the-atmosphere and surface, volcanic aerosol cooling dominated the radiative forcing. However, after two weeks, due to dispersion/dilution, water vapour heating started to dominate the top-of-the-atmosphere radiative forcing, leading to a net warming of the climate system.
Abstract Estimates based on historical data place the probability of a catastrophic volcanic eruption in the next 100 years at around one in six. Large volcanic eruptions can lead to significant global cooling for 2–4 years, with potentially devastating impacts on global agriculture. In principle, the negative impacts of volcano‐induced cooling could be reduced by deliberate emission of short‐lived chemicals with high greenhouse gas intensity into the atmosphere. This article examines the physical feasibility of this concept for a wide range of short‐lived climate pollutants, using the global chemical industry for context. Deliberate emission of any known chemical species would require gigatons of material, which would have to be produced and stored far in advance of the volcanic event. The cost of this undertaking would be immense. In addition to these daunting logistical challenges, a range of other uncertainties and complications associated with this concept are discussed.
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