Ocean response to volcanic eruptions inCoupledModelIntercomparisonProject 5 simulations

Abstract

We examine the oceanic impact of large tropical volcanic eruptions as they appear in ensembles of historical simulations from eight Coupled Model Intercomparison Project Phase 5 models. These models show a response that includes lowering of global average sea surface temperature by 0.1-0.3 K, comparable to the observations. They show enhancement of Arctic ice cover in the years following major volcanic eruptions, with long-lived temperature anomalies extending to the middepth and deep ocean on decadal to centennial timescales. Regional ocean responses vary, although there is some consistent hemispheric asymmetry associated with the hemisphere in which the eruption occurs. Temperature decreases and salinity increases contribute to an increase in the density of surface water and an enhancement in the overturning circulation of the North Atlantic Ocean following these eruptions. The strength of this overturning increase varies considerably from model to model and is correlated with the background variability of overturning in each model. Any cause/effect relationship between eruptions and the phase of El Niño is weak.

The Role of Volcanic Activity in Climate and Global Change

“…It appears that the results from the CMIP5 project are largely consistent with Stenchikov et al [59,60]. Ding et al [116] The northern hemisphere anomalies of maximum and minimum ice mass (10 15 kg) for the Pinatubo ensemble.…”

“…Ding et al [116] found that all models consistently show an annual average reduction of the surface incoming solar radiation by 1 W m À2 -5 W m À2 . The global sea surface temperature decreases by 0.1 K-0.3 K. The cool SST signal penetrates in the deep ocean, decreasing temperature in the upper 1000-m layer by roughly 0.03 K. Sea ice extent and mass grow by 5%.…”

“…Ding et al [116] examined output from eight CMIP5 models to test the findings, discussed above in this section, which were based on our own simulations [59,60] from one particular model. It appears that the results from the CMIP5 project are largely consistent with Stenchikov et al [59,60].…”

Assessing the Impact of a Future Volcanic Eruption on Decadal Predictions

“…Liu et al 2016). Sea ice in the Northern hemisphere is also affected by large volcanic eruptions and SVEs can cause up to a decade of increased Arctic sea ice extent (Ding et al, 2014;Gagné et al, 2017). Gagné et al (2017) for example demonstrated that the sea ice response to SVEs is dependent on pre-eruption temperature conditions with warmer preeruption climate leading to a stronger sea ice response.…”

Reduced cooling following future volcanic eruptions

“…The negative radiative forcing induces several responses in the Earth system (Timmreck 2012;Zanchettin 2017), including expansion of sea-ice (Miller et al 2012), changes in atmospheric (Robock and Mao, 1992) and ocean circulation (Ding et al 2014), and perturbations to modes of variability (Lehner et al 2016;Maher et al 2015). These responses are partly dependent on the climate state prior to an eruption, as well as the location of the volcano and the season of Abstract Volcanic eruptions are an important influence on decadal to centennial climate variability.…”