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Climate and Volcanism. By: Jared Lung. Quick Facts. Volcanoes tend to exist along the edges of tectonic plates, massive rock slabs that make up Earth's surface. About 90 percent of all volcanoes exist within the Ring of Fire along the edges of the Pacific Ocean.
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Climate and Volcanism By: Jared Lung
Quick Facts • Volcanoes tend to exist along the edges of tectonic plates, massive rock slabs that make up Earth's surface. • About 90 percent of all volcanoes exist within the Ring of Fire along the edges of the Pacific Ocean. • Volcanoes are active, meaning they show some level of activity and are likely to explode again, dormant, showing no current signs of exploding but are likely to become active at some point in the future, or extinct meaning they won’t be active again. • About 1,900 volcanoes on Earth are considered active.
Early Earth • About 4 billion years ago, planet Earth had no atmosphere and its surface was covered with erupting volcanoes. • All the water in the oceans and many of the gases that make up the atmosphere have been produced by volcanoes erupting. • The volcanoes released water vapor, carbon dioxide, and sulfur dioxide into the environment.
Climate Vs. Weather • Weather can change from minute-to-minute, hour-to-hour, day-to-day, and season-to-season. Climate, however, is the average of weather over time and space. • An easy way to remember the difference is that climate is what you expect, like a very hot summer, and weather is what you get, like a hot day with pop-up thunderstorms. • Volcanoes can have HUGE affects on the weather but typically, only the really big eruptions will have noticeable effects on the climate.
An eruption can cause warming and cooling. • An addition of carbon dioxide contributes to greenhouse warming. • An addition to sulfurous gases induces cooling, because they turn into droplets of sulfuric acid that absorb and reflect sunlight, and cut down the amount of heat that reaches the ground. • But most documented cases show a net cooling effect.
Benjamin Franklin • The first scientist to recognize the cooling pattern. • He linked the abnormal weather over Europe in 1783-84 to the great Laki eruption in Iceland, which sent volcanic gases into the stratosphere and released over 100 million tons of sulfur dioxide over just a couple of months – As much as the world’s industries release today in a year.
In May 1784, in a communication to the Literary and Philosophical Society of Manchester, England, about the haze covering the land, Franklin wrote: The cause of this universal fog is not yet ascertained. Whether it was adventitious to this Earth, and merely a smoke proceeding from the consumption by fire of some of those great burning balls or globes which we happen to meet with in our rapid course around the sun, … or whether it was the vast quantity of smoke, long continuing to issue during the summer from Hecla, Iceland, … which smoke might be spread by various winds over the northern part of the world, is yet uncertain.
Most major eruptions only cause a temperature change of a fraction of a Kelvin, which doesn’t sound like much, but over an entire year it represents a large amount of heat subtracted from the Earth’s budget. • Smaller eruptions don’t have a very big effect on the climate.
The two major variations of temperature in the atmosphere are due to the eruption of El Chichon volcano in Mexico (1982) and Pinatubo volcano in the Philippines (1991).
The change in temperature can have serious repercussions on food crops and human health. • The harsh winter that followed the eruption of Laki in 1783, played a role in the poor harvests and the famines that led up to the French Revolution. • Chinese records mention similar droughts and freezing events following major eruptions, such as Thera-Santorini in 1620 BC and Mount Etna in 44 BC.
The effect of an eruption on climate is greatest when the gas plume penetrates the stratosphere. • Unlike the lower atmosphere, the stratosphere does not have rain clouds as a mechanism to quickly wash out pollutants. Therefore, a heavy influx of aerosol pollutants will remain in the stratosphere for years until the processes of chemical reactions and atmospheric circulation can filter them out. • High-altitude winds can carry the particles and ash far distances.
Chaiten volcano captured by NASA's Terra satellite at 10:35 a.m. local time on May 3, 2008.
Can Ash Float Around the Globe? • Yes! In June of 1991 the eruptions of Mount Pinatubo in the Philippines spewed ash and gas into the atmosphere. • By July 25th the particles had spread around the world.
Because they scatter and absorb incoming sunlight, aerosol particles exert a cooling effect on the Earth’s surface. The Pinatubo eruption increased aerosol optical depth in the stratosphere by a factor of 10 to 100 times normal levels measured prior to the eruption. • “Aerosol optical depth” is a measure of how much light, airborne particles prevent from passing through a column of atmosphere. • Consequently, over the next 15 months, scientists measured a drop in the average global temperature of about 1 degree F or 0.6 degrees C.
Eruptions • A powerful ashy eruption can cause dark days, severe winds, and heavy falls of rain and mud for months. • A volcanic eruption that sends gas and dust into the atmosphere can alter the climate of the whole planet.
Volcanoes blast huge clouds into the atmosphere made up of gases and particles including sulfur dioxide, water vapor, and carbon dioxide. • In the atmosphere, water vapor and sulfur dioxide convert to tiny sulfuric acid aerosols which reflect energy coming from the sun, thereby preventing the sun's rays from heating Earth's surface.
Dark dust particles absorb sunlight, and light-colored aerosols reflect sunlight. • The amount of heat reaching the Earth is reduced and thus the surface temperatures are reduced.
The particles also affect our views of the sun and moon by scattering certain kinds of sunlight and letting other kinds through the atmosphere. • This can cause spectacular sunrises and sunsets. • The sun and moon may seem to be wrapped in halos or to glow with strange colors.
A sunset caused by the light-scattering effects of the volcanic ash thrown up into the atmosphere by the eruption of Iceland's volcano Eyjafjallajokull.
Long Term Affects • Volcanic particles can cause occurrences such as: • Global Cooling • Mass Extinctions • Ice Ages
Little Ice Ages • 1783 – Skaftar in Iceland and Mount Asama in Japan erupted. • These eruptions were followed by several very cold winters in Europe and America. • They caused unusually thick polar ice to form.
Mass Extinction One scientific theory proposes that massive volcanic eruptions produced enough gas and dust to cool global temperatures and kill off the dinosaurs.
Famous Volcanoes • Krakatoa, Mount Pinatubo, Tambora, Vesuvius, Mount Pelee, El Chichon, Laki, Eyjafjallajokull, and Mount St. Helens
Krakatoa • In 1883, Krakatoa in Indonesia erupted. • It blew dust over 80 km into the air with a force of about 100 million tons of dynamite. • The explosions were heard across the Indian Ocean and all the way in Australia, 2,400 miles away. • Produced orange and red sunsets for several years. • It panicked American firefighters into battling what they thought were raging infernos, but were actually violent sunsets caused by the Krakatoan dust.
Ash was reported over a 750,000 sq km area. • Shock of the eruption caused huge waves with breakers over 40 m high. • The dust from the eruption caused a decrease in temperature by ½ a degree centigrade worldwide. • The cooling effect lasted for about 10 years.
Mount Pinatubo • Erupted in 1991, in the Philippines. • Sulfur containing gases were spewed into the atmosphere blocking sunlight and falling back to Earth as acid rain. • The unusually cool Northern Hemisphere summer of 1992 has caused meteorologists to increase their look at the role of volcanic eruptions in world-wide weather patterns. • There was a temperature decrease of about 0.3 Kelvins.
Mount Pinatubo erupted with a tremendous force, ejecting vast amounts of ash and gas high into the atmosphere; so high that the volcano’s plume penetrated into the stratosphere. The stratosphere is the layer of atmosphere extending from about 10 km to 50 km (6-30 miles) in altitude. • Pinatubo injected about 15 million tons of sulfur dioxide into the stratosphere, where it reacted with water to form a hazy layer of aerosol particles composed primarily of sulfuric acid droplets. Over the course of the next two years strong stratospheric winds spread these aerosol particles around the globe.
The effect of the 1991 Pinatubo eruption on the Greenland Ice Sheet • The reduced air temperatures during the 1992 northern hemisphere summer had effects on the mass balance of glaciers. This is well illustrated by a diagram in the 2005 ACIA (Arctic Climate Impact Assessment) report. Unfortunately, the special background for the extraordinary low summer melting of 1992 appears not to have been recognized by the authors of the report. Consequently, the year 1992 and 2002 were erroneously presented in the ACIA report as visually demonstrating the effect on the Greenland Ice Sheet of late 20th century warming in the Arctic.
Tambora • 1815 – Located in Indonesia. • Put out over 100 million tons of sulfur dioxide. • Worldwide there was a temperature drop of close to 0.5 Kelvins. • Mt. Tambora also happened during the Dalton Minimum, increasing the cooling effects that were already occuring from low sunspot activity.
Results of Tambora • Temperatures in New England dropped an estimated 1-2 Kelvins, it snowed in July, and 1816 became known as ‘the year without a summer’. • Tambora changed the climate so much that crops in Europe and north America failed in the following years. • Tens of thousands of people were killed by the apocalyptic eruption, subsequent tsunamis and ensuing starvation and disease.
Mount Vesuvius • Rises 1,279 meters above the Bay of Naples in Italy. • The most widely known volcano on Earth and one of the most thoroughly studied. • Mount Vesuvius has experienced eight major eruptions in the last 17,000 years. • Mount Vesuvius is responsible for the destruction of the Roman cities of Herculaneum and Pompeii in AD 79. • Mount Vesuvius is regarded as one of the most dangerous volcanoes in the world because of the potential danger it poses to the population of 3,000,000 people living close to it. It is the most densely populated volcanic region in the world.
At 8:32 a.m. on May 18, 1980, a 5.1-magnitude earthquake triggered a sideways blast that swept the mountain's north face away into a cascading landslide that shot hot ash and stone out some 15 miles at speeds of at least 300 m.p.h. • At the same time, a mushroom-shaped plume of ash shot 16 miles into the air, eventually covering three states. Complete darkness blanketed Spokane, Wash., a city about 250 miles northeast of the volcano. When the ash came down it fell in the form of black rain that literally coated the residents of Washington, Idaho and parts of Montana with a fine gray powder.
The 1980 eruption of Mt. St. Helens did not have much affect on global temperatures for two reasons. • The eruption of Mount St. Helens was not very large compared to other volcanoes that did affect global temperatures in the past. • The energy emitted by this eruption went sideways, rather than vertically, therefore particles did not enter high enough into the atmosphere to reflect sunlight.
