How Tambora Stole Summer:Global consequences of the eruption

Dr. Nicholas KlingamanSenior Research Fellow

NCAS-Climate, Univ. of Reading

Co-author of ”The Year Without Summer:

The Volcano That Darkened the World and Changed History”

• Initial eruption just before sunset on 5 April.

• Mistaken for cannonfire by lieutenant-governor of Java, Thomas Stamford Raffles.

• Troops dispatched and rescue boats launched from bases across Java.

The eruption

• Light rain of ash shortly after dawn the following day.

• Explosions die away in the following days, but rain of ash continues.

The eruption

• Main eruption began during the evening of 10 April.

• Pyroclastic flows running down the mountain heat the air above.

• Whirlwinds caused by pressure vacuum destroy all vegetation.

• Village of Tambora vanishes in a flood of pumice stone.

• Within 24 hours, ash cloud expands to the size of Australia.

Satellite image of caldera formedby 1815 eruption of Tambora.Source: NASA

The eruption

• Tsunamis 15 feet high caused by collison of pyroclastic flows with sea around Tambora.

• Tsunami reaches Java about six hours after the eruption began.

• Fields of pumice stone several miles wide, driven west by prevailing winds and currents.

• Some found by ships in the open Indian Ocean up to three years later, believed to be from underwater volcanoes.

Pumice stone formed by an underwater volcanoSource: Sunnyskyz.com

The eruption• Eruption lasts about 48 hours, but ash continues to fall for a week.

• Ash depths of 40 inches reported 20 miles away• Ash depths of 10 inches reported 100 miles away

• Nearly all of the native population in the vicinity (~12,000) killed by eruption.

• Tens of thousands more killed due to poisoned crops.• Deadliest eruption in recorded history.

Devastation caused bythe eruption of Pamandayanin Indonesia.  Source: demisindonesia.blogspot.com

The eruption

• One of the four strongest eruptions of the past 10,000 years.• Volcanic Explosivity Index – similar to the Richter scale for

earthquakes, in that each point on the scale is a factor of 10 in terms of intensity.

Stratospheric aerosol veil• Eruption ejected approximately 55

million tons of sulfur dioxide to a height of 32 km (20 miles).

• Sulfur dioxide combined with hydroxide gas to form more than 100 million tons of sulfuric acid.SO2 + H2O2 = H2SO4

• Height of the eruption is critical for climate consequences.

• Strong stratospheric winds dispersed the sulfuric acid veil, circumnavigating the equator in about two weeks.

Satellite image of eruption plumefrom Eyjafjallajokull.Source: volcano.oregonstate.edu

Stratospheric aerosol veil

• Stratospheric winds are primarily zonal, so veil took 2-3 months to reach the poles and completely cover the globe.

• Reflected approximately 0.5% of the incoming solar radiation.

• Imperceptible to the human eye.

Chichester Canal by J. M. Turner (1827)

• Likely caused dramatic sunsets in the autumn of 1815 and 1815-16.Impact on artists?

• Reports of coloured snow in the winter of 1815-16.

Stratospheric aerosol veil

• Latitude of a volcanic eruption determines the region directly affected by the aerosol veil.

• Volcanoes directly influence the climate only poleward of their latitude.

• Lower stratospheric circulation extends from the equator to the pole in each hemisphere.

• The return circulation is in the troposphere.

Schematic of the general circulation in the troposphere and stratosphere from the

summer hemisphere (left) to winter hemisphere (right).

Source: World Meteorological Organization

Climate consequences

• Global cooling from Tambora of approximately 1ºC. Reduction in global precipitation of approximately 3.4%.

• 1816 second coldest year since 1400 (only 1601 was colder).• Land cools much more than oceans, as well as more quickly.• Cooling does not necessarily scale with amount of sulfuric acid.

Temperature anomalies from HadGEM2-ES model simulations forced with Tambora-like volcanic aerosols.

Source: Kandlbauer et al. (2013, JGR Atmospheres)

Climate consequences

Model simulated sea‐level pressure anomalies in November 1815 – April 1816.Source: Shindell et al. (2003, J. Climate)

• Volcanic eruptions often induce a positive phase of the Arctic Oscillation in winter.

• Strong polar vortex and highly zonal flow

• Aerosol veil heats lower stratosphere in the tropics, but cannot do so in the perpetually dark wintertime polar latitudes.

• Increased equator to pole temperature difference.

Climate consequences

Model simulated sea‐level pressure anomalies in November 1815 – April 1816.Source: Shindell et al. (2003, J. Climate)

• Warm winter of 1815-16 in New England as jet stream confined to the north.

”Our own Winters are …Comfortably Moderated since the Land has been Peopled ... Our Snows are not so Deep, and Long ... And our Winds blow not such Rasours, as in the Days of our Fathers when the Hands of Good Men would Freeze unto the Bread upon their Tables.” -- Cotton Mather

• Sequence of snow and rainstorms in continental Europe, including some with colored snow.

Climate consequences

• After a mild winter and spring, the summer of 1816 was 2-3ºC cooler across western Europe and eastern North America.

• Aerosol veil cooled surface temperatures in the tropics more than the poles, reducing the temperature difference.

Model simulated surface temperature anomalies in 

June – August 1816.Source: Shindell et al. 

(2003, J. Climate)

• May saw six inches of snow in New York and Quebec, with ice in the St. Lawrence River.

Climate consequences

Warm and humidair for the East Coast

Most storms staynorth of Europe

Cold, dryArctic air

Conveyor beltof storms to Europe

Typical summer jet streamJet stream in “summer” of 1816

• Frosts in New England and Ohio Valley in every month of 1816.

• Drought in the eastern US lasts through autumn and into winter.

• Many farmers sold their land and moved west to the Ohio Valley, including the family of the young Joseph Smith.

• Religious revivals intensify (“Second Great Awakening”) as many were convinced God was punishing them.

Effects in the United States

Effects in the United States

• Repeated incursions of Arctic cold fronts across Quebec, New England and the mid-Atlantic states.

”The ground was covered with snow, and the temperature of the weather during the day more like that of March than May. Rarely has vegetation been more backward at this season of the year than it is now in this city.” – Albany, New York, 14 May

“[Farmers are] ploughing up and replanting the corn. The temperature of the weather with us is very fluctuating-–the evenings and the mornings generally so cold as to render a fire quite agreeable.” – Norfolk, Virginia, 16 May

”The season continues extremely unfavorable to Agriculture. Masses of snow still lie in the fields, and very little wheat has yet been sown in this district.” – Quebec, May

Effects in the United States• In early June, a strong cold front swept across the US Midwest,

southern Canada and New England.• Trailed by several Arctic high pressure systems.• Ridge over the Atlantic, combined with an early-season

hurricane, provided warm air and moisture.

Synoptic charts for 5‐6 June, drawn 

based on station data 

shown.Source: 

Chenoweth (2009)

Effects in the United States• 5 June: Boston reaches 86ºF reports of ”hot and sultry

weather” in Montreal; Salem, Mass. hits 92ºF.• Overnight minimum of 72ºF in Albany, NY; 15ºF above normal.• Steady rain overnight throughout New England.• Strong NW gales reported by Royal Navy ships on Lake Erie.

Synoptic charts for 5‐6 June, drawn 

based on station data 

shown.Source: 

Chenoweth (2009)

Effects in the United States• Front passes across New England on 6 June.• Maximum of 30ºF in Quebec City on 6 June. Steady snow with

accumulations up to 10 inches.• 7 June: Montreal reports a ”frost [of] sharp ice as thick as a

dollar [coin], which as injured tender as well as hardy plants.”

Synoptic charts for 7‐8 June, drawn 

based on station data 

shown.Source: 

Chenoweth (2009)

Effects in the United States• Shift from mild southeasterlies to gale-force northwesterlies

across New England.• 6 June: Snow and occasional hail throughout New England;

accumulations of up to four inches.• Temperatures drop from 90ºF on 5 June to 35ºF on 6 June.

Synoptic charts for 7‐8 June, drawn 

based on station data 

shown.Source: 

Chenoweth (2009)

Contemporary explanations• No contemporary connection between

Tambora and the disrupted climate. Very few reports of the eruption itself!

• Benjamin Franklin postulated a link between volcanoes and temperatures after the eruption of Laki in 1783.

• Contemporary explanations included:• God• Deforestation• Icebergs• Sunspots• Earthquakes• Changes in the magnetic field

Source: space.com

Impacts elsewhere• Model simulations show cooling

of mean temperatures across the globe.

• Contemporary reports of heavy rainfall and incidence of water-borne disease in southern China and southern India.

• Southward shift in monsoons due to land cooling more than ocean?

• Disrupted jet in summer 1816 led to mild conditions in eastern Europe and western US.

Average (top) temperature and (bottom) precipitation anomalies for 1816‐20, from model simulations.  Source: Kandlbauer et 

al. (2013, J. Geophys. Res.)

Epilogue• No connection between Tambora and the Year Without a

Summer for nearly 150 years.

• Scientists disagreed overwhether volcanic aerosolclouds produced net warming or cooling.

• Few volcanoes to observeand few observations taken.

• Disagreements finallyresolved after observationsof response to nucleartests in 1950s and 1960s.

The picture can't be displayed.

Nuclear explosion.  Source: Wikipedia

Conclusions

• The Year Without a Summer is a powerful example of natural climate change.

• Our climate system is finely balanced: a 0.5% reduction in incoming solar radiation was enough to cool global temperatures by 1ºC and severely disrupt the trans-Atlantic jet stream.

• By 1818, most of the sulfuric acid veil had dissipated and temperatures had returned to near normal.

• Human activity is adding more greenhouse gases to the atmosphere every year – anthropogenic warming will soon be greater than was Tambora’s cooling. Our influence on the climate system will not fade as quickly as Tambora’s did!