Millenial Scale For Climate Change
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Millenial Scale For Climate Change

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its all about the Millenial scale . for past climate changes nad events.

its all about the Millenial scale . for past climate changes nad events.

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Millenial Scale For Climate Change Millenial Scale For Climate Change Presentation Transcript

    • Ayesha Maqsood
    • Fareeha Aftab
    • Hira Sattar
    • Madiha Ramzan
    • Maryam Habib
    • Sundas Waheed
  • CONTENTS:
    • Introdution
    • Climate change in past years.
    • Pre-Holocene (1.5 million years)
    • Time scale its Event and Climatic conditions
    • Five Perspective of climate change
    • Evidences and records
    • Conclusion.
  • INTRODUCTION:
    • A  millennium – Latin word “ mille ” means thousand. 
    • Is a period of time equal to one thousand years.
    • The term refer to an interval of time beginning on any date.
  • Climate change:
    • The earth climate has been changed throughout history.
    • Just in the last 650,000 - seven cycles of glacial advance and retreat
    • Causes:
    • very small variations in Earth’s orbit
    • change the amount of solar energy our planet receives.
    • The current warming trend is of particular significance because most of it is very likely human-induced.
  • Pre-Holocene(1.5 M.years)
    • 15,000 BC to 5,000 BC - time of transition, and swift and extensive environmental change.
    • Planet was moving from an Ice age, towards an  interstadial(warm period).  
    • Sea levels  rose dramatically.
    • Land that was depressed by glaciers began lifting up again
    • Forests and deserts expanded.
    • and the climate gradually became more modern.
    • Warming Process lead to:
    • “ cold snaps” and “warm snaps”- Older Dryas and the  Holocene climatic optimum
    • Heavier precipitation.
    • The  Pleistocene megafauna  became extinct due to environmental and  evolutionary pressures  from the changing climate.
    • 11,700 years ago (9700 BC) is widely - end of the old age (Pleistocene, Paleolithic, Stone age, Wisconsin Ice Age), and the beginning of the modern world as we know it.
  • Some major events and climate changes:
    • 19000 BC: Last Glacial Max, Sea level Min.
    • 17000 BC: Oldest Daryas stadial , glaciation in Europe.
    • 12000-11700: Oldest Dryas stadial
    • 13000-11000: Melting of glaciar,
    • Lake Agassiz form.
    • Floods into Arctic Ocean
    • 10800: Younger Dryas begins.
    • 10000: Sea level rise, Flooding
    • End of most recent Glaciation.
  • 10 th Millennium:(9700-9000BC)
    • Lake Agassiz  reforms from glacial meltwater
    • Bering Sea : Land bridge from Siberia to North America disappears as sea level rises.
    • Younger Dryas cold period ends.  Pleistocene  ends and  Holocene  begins.
    • The Younger Dryas as stretching from 10,800 BC to 9500 BC. This cool period was possibly caused by a shutdown of the North Atlantic thermohaline circulation (Gulf Stream/Jet Stream), due to flooding from Lake Agassiz as it reformed .
    • End of the pre- Boreal  period of European climate change.
    • Temporary global chilling, as the  Gulf Stream  pulls southward, and Europe ices over (1990 Rand McNally Atlas).
    • In  Antarctica , long-term melting of the Antarctic ice sheets is commencing.
  • 9 th millennium BC 8500-800BC
    • Last glacial period ends.
    • Long term melting of Antarctic ice sheets.
    • Rising sea levels in Asia
    • Wisconsin glaciation had withdrawn completely in North America.
    • Due to glacier melting, Inland flooding occur.
  • 8 th millennnium BC 7900-3000BC
    • Lake Agassiz refills due to glacial retreat north
    • Neolithic Subpluvial begins in northern Africa.
    • Untill about 500BC, the Sahara Desert is wetter than today.
  • 7 th millennium BC 6600-6000bc
    • Kurile volcano on Russia’s Kamchatka has erupted.
    • A sudden cooling episode was occurred.
    • The Storegga Slide causing a megatsunami in the Norwegian Sea.
    • Rising sea levels from the Torres Striat, separate Australia from New Guinea.
    • Increasing desiccation of the Sahara.
    • Rising sea levels from glacial retreat flood will become the Irish Sea.
  • 6 TH MILLENNIUM BC 5600-5000BC
    • The Black Sea floods with salt water.
    • Desertification lead to the creation of Sahara Desert.
    • A global warm period begins.
  • 4 TH MILLENNIUM BC 3900-2800BC
    • Intense Aridification triggered worldwide migration to river valleys
    • Return of extremely hot and dry conditions in Sahara Desert
    • Burckle Crater is formed in Indian Ocean
  • 3 rd Millennium BC
    • Floods at Shurupak stretching as northern Kish, as far as south Uruk, associated heavy rains Nineveh.
    • Sahara becomes fully dessicated.
    • Severe Droughts in nouthern Africa , Southwestern Asia and mid-continental North America.
  • 2 nd Millennium BC 1900BC-1000BC
    • Babylonian flood…
    • Evidence of major droughts Eastern Mediterranean..
    • Sarasvati river dries up…Desertification in thar region begins
  • 1 st Millennium Bc 800-200BC
    • Sub Atlantic sea level rise.
    • Cooler and more humid climates ,and dominance of beech forest.
  • 1 st Millennium AD
    • 1 st century(year 79 AD)
    • Mount Vesuvius erupts ..
  • Pompeii and cities affected by eruption Pompeii located around base of volcano..
  • 2 nd century
    • Eruption in newzealand…
  • 6 th Century(year 535- 536)
    • Global climate abnormalities ..
    • These changes were due the ashes or dust thrown into air after impact of comet or meteorite, or after eruption of valcano..
  • 9 th century (Yr :850)
    • Severe drought exacerbated soil erosion as the result of which the central america collaps.
  • 13 th century (1250-1850)
    • Little Ice Age starts a stadial period within our interglacial warm period
  • 15 th century (1453)
    • Eruption of kuwae in pacific.
    • Environmental science developed.
  • 17 th century (1600)
    • Huaynaputina erupts in south america.
    • Effects the climate of the northern hemisphere.
    • 1601- coldest year famine in russia.
  • 18 th century (1759-1789)
    • The volcano Laki erupts.
    • Sufficient SO2 and sulphate particles- unusual cold winters in europe and western asia.
  • 19 th century (1815-1883)
    • Eruption of MT. Tembora- now indonesia.
    • Year Without Summer in N America and Europe.
    • Eruption of Krakatoa in Indonesia. The sound of the explosion is heard as far as Australia and China, the altered air waves causes strange colours on the sky and the volcanic gases reduce global temperatures during the following years. The vivid sunsets were captured in Edward Munch's The Scream
  • Temperature changes due to different forces
  • Major climatic events that occurred in last decade:
    • The summers of 1994 and 1995 broke quite some heat records e.g 24 °C recorded on south-east Greenland!
    • The Typhoon Faxai in December 2001, in the West Pacific, of over 285 km/h, gusts of 350 km/h and a central pressure of 879 mbar.
    • In the year 2005 the US were hit by two strong hurricanes : "Katrina" and "Rita" In 2010 Pakistan was hit by the largest disaster since its independence. Major floods, due to extreme monsoon rains, in the Indus valley affected more than 20 million people
  • A. The astronomical perspective
    • Brightness of the sun:
    • The climate can be influenced by solar energy caught by the Earth.
    • During the lifetime of the Earth (the past 4.5 billion years) the sun became 25% brighter .
    • Modest variation of the energy output (0.05 - 0.1%) of the sun.
    • Correlation between weather patterns and the sun spot cycle.
    • During the climax of the "little ice age" (1645-1715) there will be very little sun.
    • The rise in solar irradiance since 1750 is estimated at 0.1 - 0.5 W/m2 (0.04 - 0.2%)
  • 2. The orbit of the Earth
    • Milankovitch - study on the relation between the orbit of the Earth and its climate in the last 2 million of years.
    • The following variations occur in the orbit and orientation:
    • The eccentricity varies by 6% with a 100.000 year period. This gives rise to a 0.3% variation in solar heat flux.
    • The obliquity of the Earth varies between 21.8° and 24.4° with a period of 41.000 year.
    • The precession of the Earth's axis has a period of 25.800 year.
  • B.The geologic perspective
    • 1.Continental drift and oceanic circulation patterns
    • The positions of the continents and the resulting ocean circulation.
    • The higher amount of CO2 in the atmosphere. (maybe to a lesser extent)
    • The Earth is oscillating between an extreme greenhouse state and a totally frozen state. It evolves as follows :
    • 1. Continents gatherered around the equator. Increased rainfall on the equatoral continents leads to weathering, and a falling CO2 content.
    • 2. The albedo of the Earth rises drastically, and a run-away icehouse effect occurs. The Earths' Oceans freeze over totally, and the temperature drops to -50 °C .
    • 3. Volcanic activity, bringing CO2. Earths' temperatures raise enough, melting the ice in the equatorial regions.
    • 4. The ice melts quickly. The decreased albedo , combined with CO2 content of the atmosphere, causes the T to soar upwards to 50 °C.
    • 2. Volcanism:
    • Earth quite spectacular volcanic events have occurred. Two examples are the formation of the "Siberian traps" during the last stage of the formation of the supercontinent Pangea (-245 Myr) and the formation of the "Deccan traps" north-east of Bombay, when India was on its way to Asia (-65 Myr). In both cases 1 to 1.5 million cubic kilometers of basaltic lava was erupted in less than 1 million years
  • C. The greenhouse gases' perspective
    • The atmosphere contains greenhouse gases. Without the presence of these gases the Earth would be as cold as -18 °C in average.
    • The main greenhouse gases are:
    • Water vapour,
    • CO2
    • CH4
    • N2O
    • CFC's.
  •  
  • D.The weather patterns perspective D.The weather patterns perspective
    • 1.The location of ice caps
    • After the climax of the last "glacial" 18.000 years ago, the climate recovered.
    • The ice caps on Scandinavia and Canada were dwindling rapidly.
    • The climate in Europe in those days was about as warm as it is today.
    • E. The role of sea currents
    • 1. The Atlantic Gulf Stream (and the little ice age)
    • The Atlantic Gulf Stream has a profound influence on the climate of Europe.
    • Eastern sides of oceans in winter are much warmer than western sides of oceans
    • 2. El Niño and the southern oscillation
    • Every few years the air pressure rises in the western Pacific and drops in eastern Pacific. As a result the trade winds are weakened. Sometimes the easterly winds on the equatorial zone are replaced by western winds.
    • Sources of information on the climate change include :
  • Sources of information on the climate change include :
    • Historical documentary records,
    • Tree rings (width, density);
    • Ice cores (isotopes, melt layers, net accumulation, glaciochemistry);
    • Corals (isotopes and other geochemistry, growth rate);
    • Varved lake and marine sediments (varve thickness, sedimentology, geochemistry, biological content)
    • Banded speleothems (isotopes).
    • Microfossils records.
    • Volcanoes and Climate
    • Tree-Rings Records of Volcanic Activity
  • A list of years characterized by low tree-ring densities, with the name of the volcano eruption immediately preceding the tree-ring event indicated in parentheses
    • Sun Cycles and Climate Change
    • Conclusion