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Introduction to Climate ChangeIntroduction to Climate Change

Dr. A.K.M. Saiful IslamBangladesh University of Engineering and Technology

Training Course of Small Scale Water Resources Project (SSWRP-II)

Copy right @ Dr. A.K.M. Saiful Islam, IWFM, BUET

Climate Systems

• The complicated system consisting of various components, including the dynamics and composition of the atmosphere, the ocean, the ice and snow cover, the land surface and its features, the many mutual interactions between them, and the large variety of physical, chemical and biological processes taking place in and among these components.

• Climate refers to the state of the climate system as a whole, including a statistical description of its variations.

Atmosphere

– 78% nitrogen, 21% oxygen, and 1% other gases.– Carbon dioxide accounts for just 0.03 - 0.04%. – Water vapor 0 to 2%

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Components of Climate System

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Green house gases

CO2 and some other minor gases

1. Absorb some of the thermal radiation leaving the surface of the earth.

2. Emit radiation from much higher and colder levels out to space.

These radiatively active gases are known as greenhouse gases.

– They act as a partial blanket for the thermal radiation from the surface which enables it to be substantially warmer than it would otherwise be, analogous to the effect of a greenhouse.

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Green house effect

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Green house effect

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Human induced climate variation Perturbations of the atmospheric composition – the

enhanced greenhouse effect

Effect of aerosols:

– direct effect (scattering of incoming solar radiation)– indirect effect (affecting the radiative properties of clouds)

Land-use change (agriculture, deforestation, reforestation, afforestation, urbanisation, traffic, …)

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Increasing trends of CO2

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Human induced changes of green house gases

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Global temperature and Greenhouse gases

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Temperature variation past 1,000 years

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Increase of Temperature past 140 year

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Trends of increase of Temperature

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Predicted changes of Temperature

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Trends of Precipitations

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Trends of Seal Surface temperature

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Sea Level Rise

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Impacts of climate change

Human Health impacts

Ecosystem Impacts

Agriculture Impacts

Water Resources Impacts

Market Impacts

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Human Health impacts Expansion of the areas of potential transmission of

malaria and dengue fever (medium-to-high confidence); roughly 300 million more people at risk of malaria

Increased heat-related deaths and illness, affecting particularly the elderly, sick, and those without access to air conditioning

Increased risks to human life, risk of infectious disease epidemics and many other health risks where floods, droughts or storms increase in frequency and/or intensity

Decreased winter deaths in some temperate regions

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Ecosystem Impacts Coral death from exposure to 3-4 ºC higher seasonal maximum sea-

surface temperatures for 6 months or more

Substantial reduction in glacier and ice-cap volume; tropical glaciers particularly vulnerable to elimination

Loss of unique vegetation systems and their endemic species (e.g. vegetation of Cape region of South Africa and some cloud forests)

Extensive reduction in Arctic summer sea-ice extent with benefits for shipping but adverse effects on sea-ice dependent animals (e.g. polar bears, seals, walrus)

Coastal wetland loss from sea level rise (up to 10% globally for 20 cm rise, higher percentages in some areas)

Increased disturbances of ecosystems by fire and insect pests

Increase net primary productivity of many mid- and high-latitude forests

Extinction of some critically-endangered and endangered species

Copy right @ Dr. A.K.M. Saiful Islam, IWFM, BUET

Agriculture Impacts General decrease in cereal crop yields in mid-latitudes

Decreased crop yields in areas of increased drought

Food prices increase relative to projections that exclude climate change

Decreased cereal crop yields in most tropical and subtropical regions

Increased heat stress in livestock and crop damage from heat waves

Decreased frost damage for some crops

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Water Resources Impacts Decreased water quantity and quality in some areas of

increased drought

Increased flood damage due to more intense precipitation events

Decreased water supply in many water stressed countries (half-billion people in central Asia, southern Africa, and countries surrounding the Mediterranean affected)

Increased water supply in some other water stressed countries (e.g. parts of Asia)

Copy right @ Dr. A.K.M. Saiful Islam, IWFM, BUET

Market Impacts Net market sector losses most regions and for global

aggregate

Increased insurance prices and reduced insurance availability in response to increased frequency and intensity of some extreme climate events

Decreased energy demand for heating buildings in winter and increased energy demand for cooling buildings in summer

Net market sector losses in many developing countries

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Climate change and Bangladesh The country is located in the Bengal Basin, a low-lying

very flat delta. About 80 per cent of Bangladesh is floodplains with very low mean elevation above the sea level.

Differences in the elevation between adjoining ridge tops and depression centers range from

– less than 1 meter on tidal floodplains, – 1 to 3 meters on the main river and estuarine floodplains, and – up to 5 to 6 meters in the Sylhet Basin in the north-east. – Only in the extreme north-west land elevations exceed 30 meters

above the mean sea level.

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Climate change and Bangladesh The flat topography makes a significant part of

Bangladesh vulnerable to sea level change. The active delta and dynamic morphology complicates the reliable estimation of vulnerability of tidal floodplains to sea level rise.

The net sea level rise would result in

– Inundation of coastal land

– Reduced drainage and hence prolonged flooding due to high backwater.

– Higher precipitation within GBM basin would result in greater flood magnitude and frequency.

Copy right @ Dr. A.K.M. Saiful Islam, IWFM, BUET

Emission of CO2 ->who is responsible?

Per capita emissions of CO2 is less than 0.2 ton annually in Bangladesh, compared to 1.6 tons in the developing countries