Presentation on theme: "Razakh Abdirahman Asia David April Ortega Megan Ortiz."— Presentation transcript:
Razakh Abdirahman Asia David April Ortega Megan Ortiz
Though scientists are still discovering if volcanoes cause a major shift in a global climate change, we do know the temperatures following a great eruption such as Mt. Pinatubo and Tambora, that climate changed by about 2 degrees Celsius. The aerosols put out by volcanic eruptions remain in the air for months up to a year causing a slow change in temperatures and eventually affecting the climate. These aerosols which contain, sulfur dioxide, water vapor and hydrochloric acid reflect the sun’s radiation and cause a cooling effect. These aerosols also affect the Earth’s surface albedo, causing an increase in the albedo, leading for an even greater cooling effect. A solution for geo-engineering against the problem of global warming would to recreate an artificial volcano. Releasing gases into the stratosphere would result in a cooling of the Earth’s surface since a greater amount of the sun’s radiation would be reflected back into space. Our team has explored geo-engineering options such as aerosol injections into the atmosphere, which have a greater cooling effect yet carry the greatest risk; the addition of phosphorous into the ocean that may have a long-term carbon seclusion potential than deliberately adding iron or nitrogen; Cities can also offset the heat by increasing the reflectivity of urban areas with the usage of white walls and buildings, but may only have a minimal global effect. Two other options include a plan to include ocean pipes and increases in cloud reflectivity, and adding ‘bio-char’ (charcoal added back into the soil) that has a short-term cooling effect.
Indonesia 13,000 ft before 9,348 ft elevation after Stratovolcano Caldera 3,640 ft deep VEI=7 The volcano threw sulfur dioxide gas into the stratosphere, and the aerosol layer that formed led to brilliant sunsets seen around the world for several years. Pyroclastic flows reached the sea on all sides of the peninsula and heavy tephra fall devastated croplands, causing an estimated 60,000 fatalities. The eruption of more than 150 cubic kilometers of tephra formed a 6-kilometer-wide, 1250-meter-deep caldera and produced global climatic effects. Minor lava domes and flows have been extruded on the caldera floor during the 19th and 20th centuries. Pyroclastic flowstephra falllava domes A similar phenomenon occurred in April of 1815 with the cataclysmic eruption of Tambora Volcano in Indonesia, the most powerful eruption in recorded history. Tambora's volcanic cloud lowered global temperatures by as much as 3 degrees °C. Even a year after the eruption, most of the northern hemisphere experienced sharply cooler temperatures during the summer months. In parts of Europe and in North America, 1816 was known as "the year without a summer.""the year without a summer." Volcanic Explosivity Index (VEI) is a scale that describes the size of an explosive volcanic eruption. VEI is analogous to the Richter magnitude scale for earthquakes. In the 0 to 8 scale of VEI, each interval represents an increase of a factor of ten. An eruption of VEI 4 is 10 times larger than a 3 and one hundred times larger than a 2. Key characteristics that define VEI include: Volume of ash produced Height of eruption cloud above the vent Duration of eruption
The 1815 eruption of Tambora was the largest eruption in historic time. About 150 cubic kilometers of ash were erupted (about 150 times more than the 1980 eruption of Mount St. Helens). Ash fell as far as 800 miles (1,300 km) from the volcano. In central Java and Kalimantan, 550 miles (900 km) from the eruption, one centimeter of ash fell. The Volcanic Explosivity of the eruption was 7. The eruption column reached a height of about 28 miles (44 km). The collapse of the eruption column produced numerous pyroclastic flows. As these hot pyroclastic flows reached the ocean where they caused additional explosions. During these explosions, most of the fine-fraction of the ash was removed. The eruption formed a caldera. An estimated 92,000 people were killed by the eruption. About 10,000 direct deaths were caused by bomb impacts, tephra fall, and pyroclastic flows. An estimated 82,000 were killed indirectly by the eruption by starvation, disease, and hunger.The Volcanic Explosivity The 1815 eruption of Tambora caused the "Year without a Summer." Daily minimum temperatures were abnormally low in the northern hemisphere from late spring to early autumn. Famine was widespread because of crop failures.
In the Sundra Strait, Indonesia VEI=6 Since 1927, small eruptions have been frequent and have constructed a new island, Anak Krakatau (Child of Krakatau) Earthquakes felt 5-6 years before Began with mild ash/steam for 3 months for perbuwatan Ash-leden gas columns from perbuwatan and danan Smaller eruptions intensified and culminated in the explosive eruption of August 27 th, 1883 Caused tsunami 140ft high
Philippines Thick layers of ash completely surrounds the crater and the effect of mudflows in this previously heavily forested and agricultural region can be traced as ribbons flowing downhill
The June 1991 eruption of Mount Pinatubo was global. Slightly cooler than usual temperatures recorded worldwide and the brilliant sunsets and sunrises have been attributed to this eruption that sent fine ash and gases high into the stratosphere, forming a large volcanic cloud that drifted around the world. The sulfur dioxide (SO2) in this cloud -- about 22 million tons -- combined with water to form droplets of sulfuric acid, blocking some of the sunlight from reaching the Earth and thereby cooling temperatures in some regions by as much as 0.5 degrees °C. An eruption the size of Mount Pinatubo could affect the weather for a few years. The June 1991 eruption of Mount Pinatubo
Types of Volcanoes Three types of volcanoes: Cinder- pyroclastic fragments, rock fragments, cinder cone crater, central vent- hot gases and rock Shield- mostly lava flows Composite or Stratovolcano- (most important) alternates pyroclastic flows and lava flows Radiating dikes, pyroclastic layers. Mt. St Helens Mt. Rainer Mt. Hood Mt. Fuji Mt. Pinatubo
Ice Volcanoes Mud Volcanoes Hot spot Volcanoes Three distinctions of volcanoes: Active Dormant Distinct Cont…
Volcano Hazards: Lahars- quickly moving mixtures of rock and water – looks like moving concrete Lava Flows- Streams of molten rock-magma that has come to earth’s surface Pyrcoclastic Flows- high density mixtures of hot dry rock fragments and hot gases a. vent at high speeds b. Gases- S02 (Sulfur dioxide) most important c. irritates skin and mucous membranes d. forms aerosols including H2SO4 (sulfuric acid) that can enter stratosphere Tephra
Composition of Material erupted: 63% or more silica, lava is felsic meaning that the volcano erupts violently as domes or have short stubby flows. They form stratovolcanoes. 52-63% silica, lava is of intermediate composition, they generally occur above subduction zones If the lava is less than 52% and greater than 45% silica, the lava is called mafic because it has higher levels of magnesium. They usually occur at mid ocean ridges where plates are pulling away from each other.
Gases put in the air –Mt. Pinatubo’s estimated aerosol loading is 30 (Tg). Reached an altitude of more than 30 (km) Injected gaseous sulfur dioxide into the stratosphere. The sulfur dioxide gases transformed into sulfuric acid (H2SO4/H20) aerosols. Mt. Pinatubo is estimated to have had one of the largest aerosol perturbation to the stratosphere. Gaseous components: water vapor, sulfur dioxide, and hydrochloric acid. Hydrochloric acid is dissolved quickly and rains out of the original cloud. Aerosols are produced when the sulfur dioxide is transformed into sulfuric acid; which condenses into aerosols with low saturation vapor pressure. These new aerosols increase the Earth’s Albedo by reflecting solar radiation back into space. It also can warm the stratosphere by absorbing infrared radiation. Occasional violent volcanic eruptions, such as Mt. Pinatubo, pump gases like sulfur dioxide and aerosols high into the atmosphere where they can linger for more than a year, reflecting sunlight and shading Earth’s surface. The cooling influence of this aerosol “shade” is greater than the warming influence of the volcanoes’ greenhouse gas emissions, and therefore such eruptions cannot account for the recent warming trend. Another main gas is carbon dioxide- if excess carbon dioxide gets into the soil it will kill off plants. Excess carbon dioxide is fatal to humans and animals so this affects the biosphere.
Planetary Albedo—increased by volcano-cause cooling-Volcanic emissions can change the amount of solar radiation received on Earth’s surface. Emissions of SO 2 gas react with moisture to produce extremely small droplets (aerosols) of H 2 SO 4 (sulfuric acid) which seed water droplet in clouds and increase cloud albedo. http://jack.pixe.lth.se/kfgu/KOO090_FKF075/Artiklar/P05.pdf http://jack.pixe.lth.se/kfgu/KOO090_FKF075/Artiklar/P05.pdf The aerosols affect the planetary albedo, which is how much light gets reflected back from particles in the atmosphere, mainly the stratosphere. Volcanoes emit C02 into the stratosphere There are factors in Earth’s climate system that influence how much sunlight our world reflects back to space versus how much it catches and stores in the form of heat. Any significant changes in the brightness of the land surface or in the extent of clouds and aerosols in the atmosphere affect how much sunlight Earth reflects, which, in turn, affects the climate system.
Temperature- Aerosols may enter the Earth’s stratosphere and remain there for many years until they are rained out. During this time Earth’s average temperature may drop by 2 ⁰ C or more, such as happened following the eruption of Mt. Pinatubo in 1990 or Mt. Tambora in 1815 (1816-1817 was called the “year without a summer”).
Economy—money/resources: The cost of an eruption of a volcano can be great. With the destruction of nearby crops, the cost of food production has to be increased to pay for all the damage done to the economy. Prices of goods go up and people end up spending more than they would have before the eruption. Do these alter the climate? -Yes all these effects alter the climate in one way or the other. There isn’t a one major cause to global cooling. All things in all the spheres of the earth affect one another.
According to A Climate for Change Arctic Oscillation is, “s a winter climate pattern in the Northern Hemisphere defined by difference in air pressure between mid latitude air pressure and the air pressure over the Arctic.” When low pressure predominates in the Arctic, the winds confine the extremely cold air and the Arctic Oscillation is called positive. When the pressure system weakens, allowing the cold air to slide south and warmer air to gather in the Arctic, the Arctic Oscillation is said to be negative. Up until January, most of us hadn’t heard of the Arctic Oscillation which is currently operating in the negative phase wherein the pressure system is weakening, the AO is apparently responsible for the extreme cold weather from France to Florida, where manatees and orange trees are dying in equal measure due to freezing weather. Throughout December 2009, the North Atlantic Oscillation was strongly negative, said the National Weather Service. This image shows the impact of the negative Arctic Oscillation on surface temperatures throughout the Northern Hemisphere as observed by the NASA’s Terra satellite. Cold Arctic air chilled the land surface. The AO works in two phases, in the first phase the pressure is lower over the Arctic and higher over the “middle” latitudes and the Arctic Ocean is colder. In the second phase, the negative phase, the reverse is true and the Arctic Ocean is warmer, leading to more melting ice or less ice coverage on land.