The effects of volcanic eruptions on hurricane statistics are examined using two long simulations from the Community Earth System Model (CESM) Last Millennium Ensemble (LME). The first is an unforced control simulation, wherein all boundary conditions were held constant at their 850 CE values (LMEcontrol). The second is a “fully forced” simulation with time evolving radiative changes from volcanic, solar, and land use changes from 850 CE through present (LMEforced). Large tropical volcanic eruptions produce the greatest change in radiative forcing during this time period, which comprise the focus of this study. The Weather Research and Forecasting (WRF) model is used to dynamically downscale 150 control years of LMEcontrol and an additional 84 years of LMEforced for all mid-latitude volcanic eruptions between 1100 and 1850 CE. This time period was selected based on computational considerations. For each eruption, 2 years are dynamically downscaled. 23 of these volcanic eruptions are in the Northern Hemisphere and 19 are in the Southern Hemisphere. The effectiveness of the downscaling methodology is examined by applying the same downscaling approach to historical ERA-I reanalysis data and comparing the downscaled storm tracks and intensities to the International Best Track Archive for Climate Stewardship (IBTrACS) database. Hurricane statistics are then computed from both the downscaled control and downscaled forced LME simulations. Results suggest moderate effects on hurricanes from the average of all northern hemisphere eruptions, with the largest effects being from the volcanoes with the most aerosol forcing. More specifically, reductions in hurricane frequency, intensity, and lifetime following northern hemisphere eruptions are apparent. Strong evidence is also shown for correlation between eruption strength and changes in these diagnostics. The aggregate effect from both northern and southern hemisphere eruptions is minor. While reductions in frequency, intensity, and lifetime from northern hemisphere eruptions occur, the opposite effect is observed from southern hemisphere eruptions.
more »
« less
Minor impacts of major volcanic eruptions on hurricanes in dynamically-downscaled last millennium simulations
The effects of volcanic eruptions on hurricane statistics are examined using two long simulations from the Community Earth System Model (CESM) Last Millennium Ensemble (LME). The first is an unforced control simulation, wherein all boundary conditions were held constant at their 850 CE values (LMEcontrol). The second is a “fully forced” simulation with time evolving radiative changes from volcanic, solar, and land use changes from 850 CE through present (LMEforced). Large tropical volcanic eruptions produce the greatest change in radiative forcing during this time period, which comprise the focus of this study. The Weather Research and Forecasting (WRF) model is used to dynamically downscale 150 control years of LMEcontroland an additional 84 years of LMEforcedfor all mid-latitude volcanic eruptions between 1100 and 1850 CE. This time period was selected based on computational considerations. For each eruption, 2 years are dynamically downscaled. 23 of these volcanic eruptions are in the Northern Hemisphere and 19 are in the Southern Hemisphere. The effectiveness of the downscaling methodology is examined by applying the same downscaling approach to historical ERA-I reanalysis data and comparing the downscaled storm tracks and intensities to the International Best Track Archive for Climate Stewardship (IBTrACS) database. Hurricane statistics are then computed from both the downscaled control and downscaled forced LME simulations. Results suggest moderate effects on hurricanes from the average of all northern hemisphere eruptions, with the largest effects being from the volcanoes with the most aerosol forcing. More specifically, reductions in hurricane frequency, intensity, and lifetime following northern hemisphere eruptions are apparent. Strong evidence is also shown for correlation between eruption strength and changes in these diagnostics. The aggregate effect from both northern and southern hemisphere eruptions is minor. While reductions in frequency, intensity, and lifetime from northern hemisphere eruptions occur, the opposite effect is observed from southern hemisphere eruptions.
more » « less- NSF-PAR ID:
- 10369386
- Publisher / Repository:
- Springer Science + Business Media
- Date Published:
- Journal Name:
- Climate Dynamics
- Volume:
- 59
- Issue:
- 5-6
- ISSN:
- 0930-7575
- Page Range / eLocation ID:
- p. 1597-1615
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
more » « less
Abstract Large volcanic eruptions drive significant climate perturbations through major anomalies in radiative fluxes and the resulting widespread cooling of the surface and upper ocean. Recent studies suggest that these eruptions also drive important variability in air‐sea carbon and oxygen fluxes. By simulating the Earth system using two initial‐condition large ensembles, with and without the aerosol forcing associated with the Mt. Pinatubo eruption in June 1991, we isolate the impact of this volcanic event on physical and biogeochemical properties of the ocean. The Mt. Pinatubo eruption forced significant anomalies in surface fluxes and the ocean interior inventories of heat, oxygen, and carbon. Pinatubo‐driven changes persist for multiple years in the upper ocean and permanently modify the ocean's heat, oxygen, and carbon inventories. Positive anomalies in oxygen concentrations emerge immediately post‐eruption and penetrate into the deep ocean. In contrast, carbon anomalies intensify in the upper ocean over several years post‐eruption, and are largely confined to the upper 150 m. In the tropics and northern high latitudes, the change in oxygen is dominated by surface cooling and subsequent ventilation to mid‐depths, while the carbon anomaly is associated with solubility changes and eruption‐generated El Niño—Southern Oscillation variability. We do not find significant impact of Pinatubo on oxygen or carbon fluxes in the Southern Ocean; but this may be due to Southern Hemisphere aerosol forcing being underestimated in Community Earth System Model 1 simulations.
-
Abstract. The injection of sulfur into the stratosphere by volcanic eruptions is thedominant driver of natural climate variability oninterannual to multidecadal timescales. Based on a set of continuous sulfateand sulfur records from a suite of ice cores from Greenland and Antarctica,the HolVol v.1.0 database includes estimates of the magnitudes andapproximate source latitudes of major volcanic stratospheric sulfurinjection (VSSI) events for the Holocene (from 9500 BCE or 11 500 years BP to1900 CE), constituting an extension of the previous record by 7000 years.The database incorporates new-generation ice-core aerosol records with asub-annual temporal resolution and a demonstrated sub-decadal dating accuracyand precision. By tightly aligning and stacking the ice-core records on theWD2014 chronology from Antarctica, we resolve long-standing inconsistenciesin the dating of ancient volcanic eruptions that arise from biased (i.e.,dated too old) ice-core chronologies over the Holocene for Greenland. Wereconstruct a total of 850 volcanic eruptions with injections in excess of 1 teragram of sulfur (Tg S); of these eruptions, 329 (39 %) are located in the low latitudes with bipolarsulfate deposition, 426 (50 %) are located in the Northern Hemisphere extratropics (NHET) and 88 (10 %) are located in the Southern Hemisphere extratropics (SHET). The spatial distribution of the reconstructed eruption locationsis in agreement with prior reconstructions for the past 2500 years. Intotal, these eruptions injected 7410 Tg S into thestratosphere: 70 % from tropical eruptions and 25 % from NHextratropical eruptions. A long-term latitudinally and monthly resolvedstratospheric aerosol optical depth (SAOD) time series is reconstructed fromthe HolVol VSSI estimates, representing the first Holocene-scalereconstruction constrained by Greenland and Antarctica ice cores. These newlong-term reconstructions of past VSSI and SAOD variability confirm evidencefrom regional volcanic eruption chronologies (e.g., from Iceland) in showingthat the Early Holocene (9500–7000 BCE) experienced a higher number ofvolcanic eruptions (+16 %) and cumulative VSSI (+86 %) compared withthe past 2500 years. This increase coincides with the rapid retreat of icesheets during deglaciation, providing context for potential future increasesin volcanic activity in regions under projected glacier melting in the 21stcentury. The reconstructed VSSI and SAOD data are available at https://doi.org/10.1594/PANGAEA.928646 (Sigl et al., 2021).more » « less
-
null (Ed.)Abstract. Volcanic eruptions are a key source of climatic variability, andreconstructing their past impact can improve our understanding of theoperation of the climate system and increase the accuracy of future climateprojections. Two annually resolved and independently dated palaeoarchives –tree rings and polar ice cores – can be used in tandem to assess thetiming, strength and climatic impact of volcanic eruptions over the past∼ 2500 years. The quantification of post-volcanic climateresponses, however, has at times been hampered by differences betweensimulated and observed temperature responses that raised questions regardingthe robustness of the chronologies of both archives. While manychronological mismatches have been resolved, the precise timing and climaticimpact of two major sulfate-emitting volcanic eruptions during the 1450s CE, including the largest atmospheric sulfate-loading event in the last 700 years, have not been constrained. Here we explore this issue through acombination of tephrochronological evidence and high-resolution ice-corechemistry measurements from a Greenland ice core, the TUNU2013 record. We identify tephra from the historically dated 1477 CE eruption of theIcelandic Veiðivötn–Bárðarbunga volcanic system in directassociation with a notable sulfate peak in TUNU2013 attributed to thisevent, confirming that this peak can be used as a reliable and precisetime marker. Using seasonal cycles in several chemical elements and 1477 CEas a fixed chronological point shows that ages of 1453 CE and 1458 CE can beattributed, with high precision, to the start of two other notablesulfate peaks. This confirms the accuracy of a recent Greenland ice-corechronology over the middle to late 15th century and corroborates thefindings of recent volcanic reconstructions from Greenland and Antarctica.Overall, this implies that large-scale Northern Hemisphere climatic coolingaffecting tree-ring growth in 1453 CE was caused by a Northern Hemispherevolcanic eruption in 1452 or early 1453 CE, and then a Southern Hemisphereeruption, previously assumed to have triggered the cooling, occurred laterin 1457 or 1458 CE. The direct attribution of the 1477 CE sulfate peak to the eruption ofVeiðivötn, one of the most explosive from Iceland in the last 1200 years, also provides the opportunity to assess the eruption's climaticimpact. A tree-ring-based reconstruction of Northern Hemisphere summertemperatures shows a cooling in the aftermath of the eruption of −0.35 ∘C relative to a 1961–1990 CE reference period and−0.1 ∘C relative to the 30-year period around the event, as well as arelatively weak and spatially incoherent climatic response in comparison tothe less explosive but longer-lasting Icelandic Eldgjá 939 CE and Laki1783 CE eruptions. In addition, the Veiðivötn 1477 CE eruptionoccurred around the inception of the Little Ice Age and could be used as achronostratigraphic marker to constrain the phasing and spatial variabilityof climate changes over this transition if it can be traced in moreregional palaeoclimatic archives.more » « less
-
Uncertainty about the influence of anthropogenic radiative forcing on the position and strength of convective rainfall in the Intertropical Convergence Zone (ITCZ) inhibits our ability to project future tropical hydroclimate change in a warmer world. Paleoclimatic and modeling data inform on the timescales and mechanisms of ITCZ variability; yet a comprehensive, long-term perspective remains elusive. Here, we quantify the evolution of neotropical hydroclimate over the preindustrial past millennium (850 to 1850 CE) using a synthesis of 48 paleo-records, accounting for uncertainties in paleo-archive age models. We show that an interhemispheric pattern of precipitation antiphasing occurred on multicentury timescales in response to changes in natural radiative forcing. The conventionally defined “Little Ice Age” (1450 to 1850 CE) was marked by a clear shift toward wetter conditions in the southern neotropics and a less distinct and spatiotemporally complex transition toward drier conditions in the northern neotropics. This pattern of hydroclimatic change is consistent with results from climate model simulations indicating that a relative cooling of the Northern Hemisphere caused a southward shift in the thermal equator across the Atlantic basin and a southerly displacement of the ITCZ in the tropical Americas, with volcanic forcing as the principal driver. These findings are at odds with proxy-based reconstructions of ITCZ behavior in the western Pacific basin, where changes in ITCZ width and intensity, rather than mean position, appear to have driven hydroclimate transitions over the last millennium. This reinforces the idea that ITCZ responses to external forcing are region specific, complicating projections of the tropical precipitation response to global warming.more » « less
