Observational evidence for volcanic impact on sea level and the global water cycle
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Grinsted et al., Volcanic impact on sea level and the water cycle, EGU 2008 Grinsted et al., Volcanic impact on sea level and the water cycle, EGU 2008 Observational evidence Observational evidence for volcanic impact on for volcanic impact on sea level and the sea level and the global water cycle global water cycle 1. Arctic Centre, University of Lapland, Finland 1. Arctic Centre, University of Lapland, Finland 2. Thule Institute, University of Oulu, Finland 2. Thule Institute, University of Oulu, Finland 3. PSMSL, Proudman Oceanographic Laboratory, 3. PSMSL, Proudman Oceanographic Laboratory, Liverpool, UK Liverpool, UK Aslak Grinsted 1 , J. C. Moore 1,2 , S. Jevrejeva 3
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Observational evidence for volcanic impact on sea level and the global water cycle. Aslak Grinsted 1 , J. C. Moore 1,2 , S. Jevrejeva 3. 1. Arctic Centre, University of Lapland, Finland 2. Thule Institute, University of Oulu, Finland 3. PSMSL, Proudman Oceanographic Laboratory, Liverpool, UK. - PowerPoint PPT Presentation
Transcript of Observational evidence for volcanic impact on sea level and the global water cycle
Grinsted et al., Volcanic impact on sea level and the water cycle, EGU 2008Grinsted et al., Volcanic impact on sea level and the water cycle, EGU 2008
Observational evidence for Observational evidence for volcanic impact on sea level volcanic impact on sea level and the global water cycleand the global water cycle
1. Arctic Centre, University of Lapland, Finland1. Arctic Centre, University of Lapland, Finland2. Thule Institute, University of Oulu, Finland2. Thule Institute, University of Oulu, Finland
3. PSMSL, Proudman Oceanographic Laboratory, Liverpool, UK3. PSMSL, Proudman Oceanographic Laboratory, Liverpool, UK
Aslak Grinsted1, J. C. Moore1,2, S. Jevrejeva3
Grinsted et al., Volcanic impact on sea level and the water cycle, EGU 2008Grinsted et al., Volcanic impact on sea level and the water cycle, EGU 2008
OutlineOutline
• Motivation• Objectives• Data• Approach• Results• Conclusion
Grinsted et al., Volcanic impact on sea level and the water cycle, EGU 2008Grinsted et al., Volcanic impact on sea level and the water cycle, EGU 2008
Volcanoes and Climate
• Major volcanic eruptions can inject scattering aerosol into the stratosphere and thus impose a significant radiative cooling of the atmosphere.
MotivationMotivation
Grinsted et al., Volcanic impact on sea level and the water cycle, EGU 2008Grinsted et al., Volcanic impact on sea level and the water cycle, EGU 2008
Volcanoes and ClimateVolcanoes and Climate
Source: Robock (2000) Volcanic eruptions and climate. Rev. Geophys.
Grinsted et al., Volcanic impact on sea level and the water cycle, EGU 2008Grinsted et al., Volcanic impact on sea level and the water cycle, EGU 2008
Volcanoes and changes in ocean heat contentVolcanoes and changes in ocean heat content
Gleckler et al. Nature 2005
Lasting effect
From Hansen et al., 2002, JGR
Short term effect
Grinsted et al., Volcanic impact on sea level and the water cycle, EGU 2008Grinsted et al., Volcanic impact on sea level and the water cycle, EGU 2008
Models of volcanic impact on sea levelModels of volcanic impact on sea level
Major volcanic eruption▼
Cooling of the world oceans▼
Densification▼
Sea level drop
Nature, 2005
Grinsted et al., Volcanic impact on sea level and the water cycle, EGU 2008Grinsted et al., Volcanic impact on sea level and the water cycle, EGU 2008
Observational verification?Observational verification?
Nature 2005
??
Can we quantify the impact of volcanic eruptions using observations?
Grinsted et al., Volcanic impact on sea level and the water cycle, EGU 2008Grinsted et al., Volcanic impact on sea level and the water cycle, EGU 2008
Major contributors to sea level riseMajor contributors to sea level rise
Grinsted et al., Volcanic impact on sea level and the water cycle, EGU 2008Grinsted et al., Volcanic impact on sea level and the water cycle, EGU 2008
ObjectiveObjective
• Estimate the effect of volcanic eruptions on observational sea level.
Grinsted et al., Volcanic impact on sea level and the water cycle, EGU 2008Grinsted et al., Volcanic impact on sea level and the water cycle, EGU 2008
Jevrejeva et al., Jevrejeva et al., Nonlinear trends and multi-year cycle in sea level records. Nonlinear trends and multi-year cycle in sea level records. Journal of Journal of Geophysical ResearchGeophysical Research, 111, 2005JC003229, 2006, 111, 2005JC003229, 2006. . Data: Data: www.pol.ac.uk/psmsl/author_archive/jevrejeva_et_al._jgr.htmlwww.pol.ac.uk/psmsl/author_archive/jevrejeva_et_al._jgr.html
Location of 1023 tide gauges included in this study.
DataData
• RLR sea level data from PSMSL (1023 stations)• GIA corrections from Peltier (2001)• SLP corrections • 12 regions
Global sea level (GSL) reconstruction (1807-2003)Global sea level (GSL) reconstruction (1807-2003)
Grinsted et al., Volcanic impact on sea level and the water cycle, EGU 2008Grinsted et al., Volcanic impact on sea level and the water cycle, EGU 2008
Virtual station spatial stackingVirtual station spatial stacking
height = 14
wpacific
Individual tide gauge records
Regional average
Binomial tree to illustrate the ‘virtual station’ stacking method. Top-node represents the regional average, bottom nodes the tide gauge records, and rest of nodes are virtual stations.
Grinsted et al., Volcanic impact on sea level and the water cycle, EGU 2008Grinsted et al., Volcanic impact on sea level and the water cycle, EGU 2008
Jevrejeva et al., Jevrejeva et al., Nonlinear trends and multi-year cycle in sea level records. Nonlinear trends and multi-year cycle in sea level records. Journal of Journal of Geophysical ResearchGeophysical Research, 111, 2005JC003229, 2006, 111, 2005JC003229, 2006. . Data: Data: www.pol.ac.uk/psmsl/author_archive/jevrejeva_et_al._jgr.htmlwww.pol.ac.uk/psmsl/author_archive/jevrejeva_et_al._jgr.html
Global sea level (GSL) reconstruction (1807-Global sea level (GSL) reconstruction (1807-2003)2003)
Grinsted et al., Volcanic impact on sea level and the water cycle, EGU 2008Grinsted et al., Volcanic impact on sea level and the water cycle, EGU 2008
Eruptions causing the largest radiative forcing Eruptions causing the largest radiative forcing since 1890since 1890
5 largest eruptions have been modelled
to have an impact on sea
level.
We focus on these.
Grinsted et al., Volcanic impact on sea level and the water cycle, EGU 2008Grinsted et al., Volcanic impact on sea level and the water cycle, EGU 2008
ResultsResults
Sea level surrounding 5 major volcanic eruptions and the average sea level in these 5 periods. The
solid black curve shows detrended GSL (grey shows 95% confidence interval). Boxes show the median
sea level (centre line of box) of the “Before”, “Rise” and “Drop” windows. Top and bottom edges show
the 95% confidence interval of the median.
Average impact of 5 major volcanoes on detrended GSL as observed in tide gauge records (solid black curve). Coloured lines show detrended GSL around
the individual eruptions.
Grinsted et al., Volcanic impact on sea level and the water cycle, EGU 2008Grinsted et al., Volcanic impact on sea level and the water cycle, EGU 2008
How robust is the result?How robust is the result?
Average impact of 4 major volcanoes (excluding the 1902 Santa Maria eruption) on sea level. Boxes show the median sea level (centre line of box) of the “Before”, “Rise”
and “Drop” windows. Top and bottom edges show the 95% confidence interval of the
median.
Average impact of 9 major volcanoes on sea level weighted by global average
stratospheric optical depth. Boxes show the mean sea level (centre line of box) of the “Before”, “Rise” and “Drop” windows with top and bottom edges showing the 95%
confidence interval of the window mean. Thin green line shows detrended GSL, but weighted by Southern Hemisphere
stratospheric aerosol optical depth.
Grinsted et al., Volcanic impact on sea level and the water cycle, EGU 2008Grinsted et al., Volcanic impact on sea level and the water cycle, EGU 2008
Difference between modeled and observed effectDifference between modeled and observed effect
Church et al., 2005
Modeled sea level Observed sea level
Grinsted et al., 2007
Grinsted et al., Volcanic impact on sea level and the water cycle, EGU 2008Grinsted et al., Volcanic impact on sea level and the water cycle, EGU 2008
SummarySummary
• We examine the average impact on observed GSL of the 5 volcanic eruptions with the largest stratospheric aerosol loading since 1890
• We find that the initial response to a volcanic eruption is a significant rise in sea level of 9±3 mm in the first year after the eruption
• This is followed by a drop of 7±3 mm in the period 2-3 years after the eruption relative to pre-eruption sea level.
• We suggest that the mechanism is a transient disturbance of the water cycle with a delayed response of land river runoff relative to ocean evaporation and global precipitation that affects global sea level.
Grinsted et al., Volcanic impact on sea level and the water cycle, EGU 2008Grinsted et al., Volcanic impact on sea level and the water cycle, EGU 2008
ReferenceReference
Grinsted, A., J.C. Moore, and S. Jevrejeva. 2007. Observational evidence for volcanic impact on sea level and the global water cycle, PNAS, Vol, 104, nr. 50, 19730-19734,
www.pnas.org_cgi_doi_10.1073_pnas.0705825104
