PACC 2011 Moscow, 7 9 November, Volcanic eruptions and climate of the Earth: volcanism as an analog of geoingineering

Transcription

1 PACC 2011 Moscow, 7 9 November, 2011 Volcanic eruptions and climate of the Earth: volcanism as an analog of geoingineering Irena Borzenkova, Elena Zhiltsova State Hydrological Institute, Second Line, 23, St.Petersburg, , Russia, irena_borzen@mail.ru

2 Content Introduction Types of the volcanic eruptions; Products of the eruptions and stratospheric aerosol; Radiation and climate Impact of volcanic eruptions; Conclusion

3 Introduction Benjamin Franklin was a first who pay attention to the possible climatic effects of the volcanic eruptions; The first comprehensive effort to quantify the atmospheric effects of volcanic eruptions was made by H.Lamb (1970) who compiled the Dust Veil Index (DVI) using historical evidence of atmospheric optima phenomena, and temperature and radiation records;

4 Introduction (continied) Russian academician M.I. Budyko (1974) was first who proposed a way to regulate present climate state by introducing the fine aerosol sulfate particles into the lower stratosphere (13 18 km), which could slightly decrease a value of the meteorological solar constant and reduce the tropospheric temperature by a needed amount of degrees; The important role of aerosols in the regulation of solar radiation incoming to the ground has been confirmed in the IPCC Assessment Reports; Last time M.Budyko s ideas were continued studying in investigations by Yu. Israel (1983, 2005) and Yu.Israel et al. (2005, 2007 etc).

5 C. Hammer and his colleagues (1980) proposed a new method for estimating the contents of volcanic sulfur-acid aerosol in the stratosphere by using ice cores data from the Greenland and the Antarctic ice sheets. The greater part of volcanic gases injected into the stratosphere is assumed to consist of sulfates being oxidized in the atmosphere before falling down with precipitation; Information about past volcanism shows that in a few years after eruptions ice layers contain higher concentrations of dissolved admixtures. The indicator of their availability could be a higher electrolytic conductivity or excess sulfate in the ice layers.

6 Types of volcanic eruptions There are two main types of volcanic eruptions: effusive and explosive ones; All types of the explosive eruptions are accompanied by outbursts of volcanic dust and blowouts of different gases into the atmosphere. At the effusive eruptions, fluid lava outflows with rather small emissions of the gases. Climatic effect is observed after the explosive type eruptions with the Dust Veil Index more than 4.

7 An eruption of the Strombolian type produces a small amount of microcrystalline matter. The height of the column of ejected material is small, and it falls out in the beginning of the eruption. The area covered with the erupted material is small enough; During an eruption of the Volcanian type (the socalled sharp Strombolian eruption), a large amount of small dispersion particles is emitted; the column of erupted matter can reach and even penetrate the tropopause. An example of this type of eruption is that of the Agung volcano, 1963;

8 With an eruption of the Plinian and the Ultraplinian types the column of erupted substance can reach 30 km and more. A large amount of erupted matter rises at a considerable height and scatters over a vast area. The total volume of ejected substance ranges from 0.1 to 50 km3. The Taupo eruption (about 186 AD) is an example of the Ultraplinian type of eruption, when the total volume of ejected substance was 24 km3, 80 percent of which deposited at the distance of 200 km; The Ignimbrite type of eruption is similar to the Plinian one but in this case a lava stream develops converting later into ignimbrite or tufflava. These eruptions produce up to 1000 km3 of matter being a significant source of atmospheric dust. The eruptions of this type were those of the Tambora volcano,1815, the Krakatoa,1883, and the Katmai,1912

9 All types of the explosive eruptions are accompanied by ejections of volcanic dust, water vapor (H 2 O), carbon dioxide (CO 2 ), carbon monoxide (CO), sulfurcontaining gases (SO 2, H 2 S, CS 2 ), and chlorinefluorine compounds (HCl, HF) into the atmosphere. Having high temperatures, these gases penetrate into the lower stratosphere where the sulfurcontaining gases form fine-dispersive layer of fine drops of sulfuric acid; During powerful and catastrophic eruptions amount of gaseous substances and the aerosol particles increases by 2-3 orders and larger; The aerosol is spread around the globe and increases the planetary albedo and produces the negative radiation forcing.

10 Impact on the climate and solar radiation This fine-dispersive layer creates a peculiar screen for coming solar radiation, so that a part of it is absorbed, and some part is reflected back toward the space; After major volcanic eruptions an increased concentration of the stratosphere aerosol layer decreases the absorption of solar radiation on the Earth s surface by more than 10-15%. At the same time scattered radiation increases; After strong and catastrophic eruptions the global air temperature mean can decrease by several tenths of a degree during the following three to five years.

11 S (%) Direct solar radiation changes after eruptions Krakatau (1883), Mon-Pelé (1902) and Katmai (Novaputra) (1912) Krakatau Кракатау S (%) Mon-Pelé Мон-Пеле, Суфриер, Санта-Мария Katmai S (%) 120 Катмай

12 After major volcanic eruptions an increased concentration of the stratosphere aerosol layer decreases the absorption of solar radiation on the Earth s surface by more than 15%. At the same time scattered radiation increases; The surface air temperature change over the terrestrial globe has a complicated mosaic character after volcanic eruptions.

13 Year 1259/ / Powerful and strong eruptions over the last 1000 years Volcano, region Unknown eruptions Height of injection, km >50 Kuwae, Vanuatu > 30 Huaynaputina, Peru Quantity (amount) of material Volume of the gaseous substance more than Tambora eruption Total sulfate deposition was 93 kg SO4/km2 in Antarctica and 23 kg SO4/km2 in Greenland > 30 About more than 70 Mt H 2 SO > 122 Mt of SO Laki, Iceland > 20 2, and about 95 Mt 1784 from this into lower stratosphere Mt of gaseous substances Tambora, Total sulfate deposition was 59 >50 Indonesia kg/km2 in Antarctica and 50 kg/km2 in Gteenland 1883 Krakatau > Mt of gaseous substances By 0.5 C 1912 Katmai, Alaska Mt of sulfide aerosols By C 1963 Agung, Indonesia 20 >16 Mt of sulfide aerosols By C El Chichon, Mexico Pinatubo, the Phillippines Mt of sulfide aerosols By 0.3 C > Mt of sulfide gases, 20 Mt of SO 2 By C Decrease in global temperature and other consequences Global temperature fall by several degrees Celsius The frost ring in dendroclimatical records from the different regions in the Northern and Southern hemisphere Catastrophic social and economic consequences for countries of the South America Almost complete absence of the direct radiation during five months By 3-4 C, the year without the direct solar radiation

14 The combined picture of the anomalies of the mean annual temperature (blue) for the extratropical part of the Northern Hemisphere obtained by using by tree-ring data and the sulphate concentration (pink) from site Dronning Maud Land (East Antarctica) over the last 2000 years.

15 The number of the explosive volcanic eruptions in the different latitudinal zone of the Northern and Southern hemisphere over the last 2000 years (yellow color) and during the Little Ice Ages (blue color) only Number of eruptions ю.ш Latitude с.ш.

16 Radiation effect estimates obtained after the 1991 eruption of volcano Pinatubo based on the general atmosphere circulation models show that radiation cooling resulting from volcano discharge has almost fully compensated for a global temperature increase due to greenhouse gases effect.

17 Conclusion Climate impact of explosive type volcano eruptions is determined by the height of volcanic gas column, sulfur content, latitudinal position of the volcano, and climatic conditions during the eruption; With no major volcanic eruptions of explosive type the upper troposphere-stratosphere background aerosol determining radiation income to the Earth s surface experiences relatively slight variations. These variations cannot noticeably affect the surface air temperature due to ocean thermal inertia; The surface air temperature can change during 2 to 5 years after individual even powerful volcanic eruptions, however no considerable change occurs in the sign of global temperature trend.

18 A prolonged global temperature impact results from a series of volcanic eruptions when an elevated level of sulfate aerosol concentration stays in the stratosphere for 10 to 15 years and more; As a result, the incoming solar radiation and surface air temperature decrease for a long period of time. These effects took place in , , and AD; These episodes were accompanied with global temperature cooling periods that appeared to be a part of a long cooling epoch between AD known as the Little Ice Age.

19 The Medieval Warm as an analog of present of 1930s warming The Medieval Warm Anomalies (MWA) between AD considered as an analogue of the 1930s warming when according to radiation stations data for the extra tropical zone (30 60 N) the incoming solar radiation was maximum. At this time only weak explosive type volcanic activities took place. After the powerful eruptions of Mt. Pelee (1902) and Mt. Katmai (1912) there were no considerable explosive type eruptions until the mid-1940s.

20 Volcanism as an analog of the geoingineering A rapid response of surface air temperature to relatively small changes in aerosol concentration in the upper troposphere and stratosphere is indicative of the possibility of control over the global climate by injecting aerosol of different type directly into these layers of the atmosphere (Budyko, 1974; Israel, 1983, 2005; Israel et al., 2007)

21 References Borzenkova I.I Climate change over the Cenozoic. St.Petersburg, Gidrometeoizdat, 246 p. (in Russian); Borzenkova I.I. and Brook S.A About influence of the volcanic eruptions on the climatic changes in the Lateglacial- Holocene. Proc. of the State Hydrological Institute (Trudy of the State Hydrological Institute), vol. 347, p (in Russian); Budyko M. I., 1974 Climate Change, Gidrometeoizdat, Leningrad, [in Russian]; Izrael Yu. A., I. I. Borzenkova, and D. A. Severov, The Role of Stratospheric Aerosols in the Maintenance of the Present-Day Climate, 2007, Meteorologiya and Hydrologiya, N1, 2007 (in Russian and in English); Борзенкова и др Ледниковые керны и дендрохронологические записи как источники информации об изменениях климата в историческое время. Лёд и снег, 2, с Борзенкова и др Изменение климата внетропической зоны северного полушария за последние 1000 лет: анализ данных и возможных причин. В кн: The Problems of the ecological monitoring and the modeling of the ecosystem, v.24, Moscow, Planet, 2012.