Globally Significant CO₂ Emissions From Katla, a Subglacial Volcano in Iceland

Abstract

Abstract Volcanoes are a key natural source of CO 2 , but global estimates of volcanic CO 2 flux are predominantly based on measurements from a fraction of world's actively degassing volcanoes. We combine high‐precision airborne measurements from 2016 and 2017 with atmospheric dispersion modeling to quantify CO 2 emissions from Katla, a major subglacial volcanic caldera in Iceland that last erupted 100 years ago but has been undergoing significant unrest in recent decades. Katla's sustained CO 2 flux, 12–24 kt/d, is up to an order of magnitude greater than previous estimates of total CO 2 release from Iceland's natural sources. Katla is one of the largest volcanic sources of CO 2 on the planet, contributing up to 4% of global emissions from nonerupting volcanoes. Further measurements on subglacial volcanoes worldwide are urgently required to establish if Katla is exceptional, or if there is a significant previously unrecognized contribution to global CO 2 emissions from natural sources.