Climate: Monsoon Climate


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A description of the causes and effects of the Monsoonal Climate system, how it will be affected by climate change and a case study of Bangladesh.

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Climate: Monsoon Climate

  1. 1. Monsoon climate<br />A monsoon is a large scale reversal in wind direction which occurs seasonally across SE Asia and is associated with distinct dry and wet seasons.<br />
  2. 2. How is it caused?<br />Movement of the ITCZ<br /> The point of max insolation alters throughout the year and the ITCZ migrates accordingly; north in June (dragging low pressure over India) and south in December (dragging high pressure over central Asia). <br />
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  4. 4. How is it caused?<br />Differential heating<br />Summer: Intense heating of land mass. Oceans take longer to warm. This generates pressure differences leading to SW winds (Em and Tm air masses).<br />Winter: Land cools rapidly. Ocean retains warmth. Pressure change is reversed and winds move from NE(Tcand Pc from desert).<br />
  5. 5. How is it caused?<br />Summer: SW Monsoon<br />Winter: NE Monsoon<br />ITCZ dragged North<br />Low pressure over India<br />Land warmer than seas<br />Coriolis deflects northerly winds to the East<br />Heavy rains move North along west and east coasts<br />East rains deflected west due to Himalayas <br />ITCZ dragged South<br />High pressure over C.Asia<br />Land cools rapidly<br />Coriolis deflects southerly winds to the West<br />Dry air dries further as it moves over Tibetan Plateau<br />Air warms as it descends to the Indian plains<br /><br />
  6. 6. How is it caused?<br />Pattern of rainfall in summer monsoon is altered by topography. Western Ghats create rain shadow in central India. Himalayas have same effect for central Asia.<br />Some areas of SE India and Sri Lanka receive rainfall in Winter as winds pass over Bay of Bengal and gain moisture<br />
  7. 7. Arrival and retreat of the monsoon rain<br />There is a stepped progression and recession of the monsoon rains as they cross India.<br />Sri Lanka usually has monsoon rainfall in early May whereas in Pakistan it is July.<br />In winter, the retreat begins in September but will not reach Southern India until November<br />
  8. 8. Monsoons and climate change<br />The key question lies with the ability of the affected nations to cope with the changes – India, Pakistan, Bangladesh, Myanmar<br />
  9. 9. Half of global population rely on annual monsoon to bring water for agriculture<br />Variations of timing and intensity will affect billions of people<br />Frequency has increased (10%) since 1950s, severe rains have doubled<br />Impacts of heavy rains – flash floods and landslides – if these intensify the agriculture suffers<br />End of 21stC temps up 3C – some areas get more rain, others suffer drought<br />Increases in cholera, hepatitis, malaria<br />
  10. 10. Bangladesh<br />Temperature up 1.5-2.0C by 2050<br />Annual increase in precipitation of 10-15% by 2050<br />More frequent and severe cyclones – why?<br />Increased river discharge – why?<br />Sea level rise of 3mm per year (world average is 2mm) and 1m by 2050 (15% loss of land)<br />
  11. 11. 13-30m people displaced<br />Rice crop yield down 30%<br />Mass migration to NE.India leading to?<br />Coral reefs damaged<br />Loss of Sundarban Islands – unique ecosystem (mangroves) biggest carbon sink in region, supports Bengal Tiger, Indian Python, Estuarine Crocodile<br />
  12. 12. Responses to climate change<br />No carbon emission restrictions – based on comparative levels and popn (4th globally)<br />Investment in drought/flood resistant crops<br />Increase photovoltaic production to 1 gigawatt per year. 4 companies in the photovoltaic business have set up in 'Fab City', a proposed semiconductor-making hub outside Hyderabad<br />
  13. 13. Integrated Coastal Zone Planning – restoration of coral reefs and mangrove planting<br />National Cyclone Risk Mitigation Programme<br />Coastal zone mapping of topography to identify areas at high risk<br />Construction of shelters and early warning systems<br />Rajiv Ghandi plan to connect 79 million rural home to electricity – why?<br />India’s Solar Mission - decentralised power including large scale and domestic generation<br />