Climate forcing by the volcanic eruption of Mount Pinatubo

Douglass, D. H.; Knox, Robert

doi:10.1029/2004gl022119

Cited by 36 publications

(72 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Studies [Soden et al, 2002;Lindzen and Giannitis, 1998;Douglass and Knox, 2005] have attempted to use observations [Christy et al, 2000] of the global mean temperature response to constrain sensitivity (usually after removing the ENSO signal [e.g., Santer et al, 2001]). In our analysis, conducted using our EBM ensemble in conjunction with the MSU Channel 2 data [Christy et al, 2000], we have allowed the baseline climate, background trend and ENSO signals to adjust to each EBM.…”

mentioning

confidence: 99%

Constraining climate forecasts: The role of prior assumptions

Frame

Booth

Kettleborough

et al. 2005

Geophysical Research Letters

152

167

View full text Add to dashboard Cite

[1] Any attempt to estimate climate sensitivity using observations requires a set of models or model-versions that simultaneously predict both climate sensitivity and some observable quantity(-ies) given a range of values of unknown climate system properties, represented by choices of parameters, subsystems or even entire models. The choices researchers make with respect to these unknown properties play a crucial role in conditioning their climate forecasts. We show that any probabilistic estimate of climate sensitivity, and hence of the risk that a given greenhouse gas stabilisation level might result in a ''dangerous'' equilibrium warming, is critically dependent on subjective prior assumptions of the investigators, not simply on constraints provided by actual climate observations. This apparent arbitrariness can be resolved by focussing on the intended purpose of the forecast: while uncertainty in long-term equilibrium warming remains high, an objectively determined 10 -90% (5 -95%) range of uncertainty in climate sensitivity that is relevant to forecasts of 21st century transient warming under nearly all current emission scenarios is 1.4-4.1°C with a median of 2.4°C, in good agreement with the ''traditional'' range. [2] Climate sensitivity, or equilibrium warming due to a doubling of carbon dioxide (CO 2 ), is a key determinant of climate change [Intergovernmental Panel on Climate Change (IPCC), Morgan and Keith, 1995]. Studies [Andronova and Schlesinger, 2000;Forest et al., 2002;Knutti et al., 2002;Gregory et al., 2002;Murphy et al., 2004;Stainforth et al., 2005] attempting to constrain climate sensitivity by comparing models with recent observations report a wide range of distributions. Here we show that much of this variation arises from different prior assumptions regarding climate sensitivity before any physical or observational constraints are applied, suggesting fundamental reasons why a universal consensus on longterm equilibrium warming consistent with any given stabilisation level for greenhouse gases may prove impossible to achieve.[3] We demonstrate our point with a simple global energy balance model (EBM) and diffusive ocean [Hansen et al., 1985], although the reasoning applies to any model in which atmospheric feedbacks scale linearly with surface warming and in which effective oceanic heat capacity is approximately constant under 20th century climate forcing. The diamonds in Figures 1a and 1b show the average warming trend caused by greenhouse gas increase over the 20th century (vertical axis) as a function of effective heat capacity of the troposphere-land-ocean system (horizontal) and the climate sensitivity S (colours) for a range of different settings of model parameters. The black contour encloses the region consistent (at the 5% level) with observations of 20th century greenhouse warming and the effective heat capacity.[4] We isolate the greenhouse warming signal using a pattern-based attribution analysis [Stott and Kettleborough, 2002] allowing for uncertainty in both greenhouse and oth...

show abstract

mentioning

confidence: 99%

Constraining climate forecasts: The role of prior assumptions

Frame

Booth

Kettleborough

et al. 2005

Geophysical Research Letters

152

167

View full text Add to dashboard Cite

show abstract

“…Large-magnitude eruptions that inject SO 2 directly into the stratosphere therefore typically have more prolonged and widespread (global or hemispheric) impacts than small-magnitude eruptions that typically inject SO 2 into the troposphere only. The June 1991 eruption of Mount Pinatubo was a large-magnitude eruption, with a volcanic explosivity index (VEI, as defined in Newhall and Self, 1982) of 6, that had a significant impact on the stratospheric aerosol layer and hence climate (Bluth et al, 1992;Sato et al, 1993;Ammann et al, 2003): global aerosol optical depth (AOD) (in the visible) was enhanced, reaching up to 0.15, causing a surface cooling of up to 0.5 • C (Douglass and Knox, 2005;Wunderlich and Mitchell, 2017). In addition, stratospheric halogens (bromine and chlorine, which are present at elevated post-industrial concentrations in the stratosphere as a consequence of past anthropogenic chlorofluorocarbon (CFC) emissions) became activated through reactions on the volcanic aerosol, causing substantial depletion of stratospheric ozone and larger polar ozone holes Solomon et al, 1996;Tilmes et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

Model simulations of the chemical and aerosol microphysical evolution of the Sarychev Peak 2009 eruption cloud compared to in situ and satellite observations

Lurton

Jégou²,

Berthet³

et al. 2018

Atmos. Chem. Phys.

View full text Add to dashboard Cite

Abstract. Volcanic eruptions impact climate through the injection of sulfur dioxide (SO2), which is oxidized to form sulfuric acid aerosol particles that can enhance the stratospheric aerosol optical depth (SAOD). Besides large-magnitude eruptions, moderate-magnitude eruptions such as Kasatochi in 2008 and Sarychev Peak in 2009 can have a significant impact on stratospheric aerosol and hence climate. However, uncertainties remain in quantifying the atmospheric and climatic impacts of the 2009 Sarychev Peak eruption due to limitations in previous model representations of volcanic aerosol microphysics and particle size, whilst biases have been identified in satellite estimates of post-eruption SAOD. In addition, the 2009 Sarychev Peak eruption co-injected hydrogen chloride (HCl) alongside SO2, whose potential stratospheric chemistry impacts have not been investigated to date. We present a study of the stratospheric SO2–particle–HCl processing and impacts following Sarychev Peak eruption, using the Community Earth System Model version 1.0 (CESM1) Whole Atmosphere Community Climate Model (WACCM) – Community Aerosol and Radiation Model for Atmospheres (CARMA) sectional aerosol microphysics model (with no a priori assumption on particle size). The Sarychev Peak 2009 eruption injected 0.9 Tg of SO2 into the upper troposphere and lower stratosphere (UTLS), enhancing the aerosol load in the Northern Hemisphere. The post-eruption evolution of the volcanic SO2 in space and time are well reproduced by the model when compared to Infrared Atmospheric Sounding Interferometer (IASI) satellite data. Co-injection of 27 Gg HCl causes a lengthening of the SO2 lifetime and a slight delay in the formation of aerosols, and acts to enhance the destruction of stratospheric ozone and mono-nitrogen oxides (NOx) compared to the simulation with volcanic SO2 only. We therefore highlight the need to account for volcanic halogen chemistry when simulating the impact of eruptions such as Sarychev on stratospheric chemistry. The model-simulated evolution of effective radius (reff) reflects new particle formation followed by particle growth that enhances reff to reach up to 0.2 µm on zonal average. Comparisons of the model-simulated particle number and size distributions to balloon-borne in situ stratospheric observations over Kiruna, Sweden, in August and September 2009, and over Laramie, USA, in June and November 2009 show good agreement and quantitatively confirm the post-eruption particle enhancement. We show that the model-simulated SAOD is consistent with that derived from the Optical Spectrograph and InfraRed Imager System (OSIRIS) when both the saturation bias of OSIRIS and the fact that extinction profiles may terminate well above the tropopause are taken into account. Previous modelling studies (involving assumptions on particle size) that reported agreement with (biased) post-eruption estimates of SAOD derived from OSIRIS likely underestimated the climate impact of the 2009 Sarychev Peak eruption.

show abstract

“…There are two critical unknowns whose values have had to be assumed in these applications, namely the intrinsic relaxation time for surface temperature anomalies and the effective eddy diffusion constant at the top of the thermocline. In a series of earlier publications [Douglass and Knox, 2005a, 2005c] (a revised version of Douglass and Knox [2005a] incorporating the two subsequent papers is available at http://arXiv.org/abs/physics/ 0509166), to be called DKa, DKb, and DKc, we applied a model of the type considered by Wigley and Schlesinger [1985] and Lindzen [1994] and determined, by analysis of the temperature data, a relaxation time much shorter (months instead of years) than those assumed in the complex models.…”

Section: Introductionmentioning

confidence: 99%

Thermocline flux exchange during the Pinatubo event

Douglass

Knox

Pearson

et al. 2006

Geophysical Research Letters

View full text Add to dashboard Cite

[1] We analyze the temperature anomaly of the Pinatubo eruption using an exact mathematical solution of a standard energy balance model that includes coupling between the mixed layer and the thermocline. Our solution yields a short response time t = 4.4 months and a small climate sensitivity l = 0.22 C/(W/m 2 ), implying short-term negative feedback. Also, our analysis determines a value of the effective eddy diffusion constant k = 2 Â 10 À6 m 2 /s that is much smaller than that assumed in many climate models. We find for this model that the heat flux to the thermocline reverses sign and integrates to zero for any forcing of finite duration. This effect should be observable in any future Pinatubotype event. Citation:

show abstract

Climate forcing by the volcanic eruption of Mount Pinatubo

Cited by 36 publications

References 14 publications

Constraining climate forecasts: The role of prior assumptions

Constraining climate forecasts: The role of prior assumptions

Model simulations of the chemical and aerosol microphysical evolution of the Sarychev Peak 2009 eruption cloud compared to in situ and satellite observations

Thermocline flux exchange during the Pinatubo event

Contact Info

Product

Resources

About