The greenhouse effect and global warming

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The greenhouse effect and global warming

• What are they?
• The causes, effects, impacts and responses

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Key Idea only the one

• Environmental abuse has serious consequences. Its
  causes need to be tackled to ensure a more
  sustainable future.
• But there are still 3 sections to study ..

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Section 3 part 1

• Causes of global warming and climate change
  deforestation use of fossil fuels air
  pollution agricultural change CFCs.
• Consequences rising sea levels more hazards
  ecosystem changes new employment opportunities
  changing settlement patterns health and well
  being.
• A case study of the threats posed by global
  warming and climate change to one country (eg
  Bangladesh, the Maldives).

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Please visit

• http//news.bbc.co.uk/1/shared/spl/hi/sci_nat/04/c
  limate_change/html/greenhouse.stm
• I tried downloading it but it wouldnt
• I am aware some of you cannot access BBC sites
  but those who can it is worth a look I
• In the meanwhile ..

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THE NATURAL GREENHOUSE EFFECT

• The atmosphere has a number of gases, often in
  tiny amounts, which trap the heat given out by
  the Earth.
• To make sure that the Earth's temperature remains
  constant, the balance of these gases in the
  atmosphere must not be upset.

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The GREENHOUSE GASES are very important and are
mainly

• water vapouroccurs naturally in the atmosphere.
• carbon dioxideproduced naturally when people and
  animals breathe. Plants and trees absorb carbon
  dioxide to live. Volcanoes also produce this gas.
  Carbon dioxide is not the same as carbon monoxide
  
• methanecomes from cattle as they digest their
  food. The gas also comes from fields where rice
  is grown in paddy fields.
• nitrous oxidewhen plants die and rot, nitrous
  oxide is produced.
• ozoneoccurs naturally in the atmosphere.

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THE ENHANCED GREENHOUSE EFFECT

• Because there are more and more greenhouse gases
  in the atmosphere, more heat is trapped which
  makes the Earth warmer. This is known as global
  warming.
• A lot of scientists agree that man's activities
  are making the natural greenhouse effect
  stronger. If we carry on polluting the atmosphere
  with greenhouse gases, it will have very
  dangerous effects on the Earth.

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What are the causes of rises in Greenhouse gases
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THE ENHANCED GREENHOUSE EFFECT

• Some of the activities of man also produce
  greenhouse gases. These gases keep increasing in
  the atmosphere. The balance of the greenhouse
  gases changes and this has effects on the whole
  of the planet.
• Burning fossil fuels - coal, oil and natural gas
  - releases carbon dioxide into the atmosphere.
  Cutting down and burning trees also produces a
  lot of carbon dioxide.
• A group of greenhouse gases called the
  chlorofluorocarbons, - which are usually called
  CFCs, because the other word is much too long! -
  have been used in aerosols, such as hairspray
  cans, fridges and in making foam plastics. They
  are found in small amounts in the atmosphere.
  They are dangerous greenhouse gases because small
  amounts can trap large amounts of heat.

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Some greenhouse gases
Methane is x 30 more effective than CO2 Where
does methane come from? (3 places)
X 300 more effect on global warming than CO2
Man-made sources of nitrous oxide include nylon
and nitric acid production, the use of
fertilisers in agriculture, cars with catalytic
converters and the burning of organic matter.
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CO2 and temperature rise
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Two ways of looking at causes
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• The effects

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Global Warming some effects

• Since 1970, rise in Decrease in
• Global surface temperatures Snow extent
• Tropospheric temperatures Arctic sea ice
• (air closest to ground level)
• Global Sea Surface Temperatures Glaciers
• Global sea level Cold temperatures
• Water vapor
• Rainfall intensity
• Precipitation
• Hurricane intensity
• Drought
• Extreme high temperatures
• Heat waves

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Global mean temperatures are rising faster with
time
Warmest 12 years 1998,2005,2003,2002,2004,2006,20
01,1997,1995,1999,1990,2000
Period Rate Years ?/decade
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Global mean temperatures are rising faster with
time
Period Rate Years ?/decade
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Global mean temperatures are rising faster with
time
Period Rate Years ?/decade
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Land surface temperatures are rising faster than
SSTs
Sea Surface T Land
Annual anomalies of global average SST and land
surface air temperature
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Land precipitation is changing significantly over
broad areas
Smoothed annual anomalies for precipitation ()
over land from 1900 to 2005 other regions are
dominated by variability.
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Regions of disproportionate changes in heavy
(95th) and very heavy (99th) precipitation
Proportion of heavy rainfalls increasing in most
land areas
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Projected Patterns of Precipitation
Change 2090-2100
Precipitation increases very likely in high
latitudes Decreases likely in most subtropical
land regions This continues the observed patterns
in recent trends
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Sea level is rising from ocean expansion and
melting glaciers

• Since 1993
• Global sea level has risen 41 mm (1.6 inches)
• 60 from expansion as ocean temperatures rise,
• 40 from melting glaciers
• Steve Nerem

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Evidence for reality of climate change
Glaciers melting
Muir Glacier, Alaska
1909 Toboggan Glacier Alaska 2000
1900 2003 Alpine glacier, Austria
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Global mean temperatures are rising faster with
time
Period Rate Years ?/decade
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The impacts
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Impacts on living things

• If the sea-levels are rising then what might
  the effects be? And on people and the ecosystems?
• If there are more climatic hazards what might
  they be? What is the impact? Where might be
  affected the most?
• Changes in rainfall what might be the effects
  on the earth? On the human welfare?
• Rises in temperature what would be the effects?
  What are the impacts on the different groups?
  That is the sea as well? Warming seas with more
  CO2 in ( that is an acid by the way)?

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Impacts on living things

• Ecosystem changes
• which would be most affected?
• What would be the impacts on the world as a
  whole?
• On people?
• On ecosystem populations?
• Agricultural production all bad or maybe some
  good?

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One of the impacts is on human health why?
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Case study Bangladesh
Notice all the rivers that come down from the
Himalayas when is there the highest flow in
these?
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75 of Bangladesh is at or below just 10 metres
in height.
Before we go further, what do you know about
Bangladesh?
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Projected climate change impacts

• Many of the projected impacts of climate change
  will reinforce the baseline environmental,
  socio-economic and demographic stresses already
  faced by Bangladesh. Climate change is likely to
  result in
• i. Increased flooding, both in terms of extent
  and frequency, associated with sea level rise,
  greater monsoon precipitation and increased
  glacial melt
• ii. Increased vulnerability to cyclone and storm
  surges
• iii. Increased moisture stress during dry periods
  leading to increased drought
• iv. Increased salinity intrusion
• v. Greater temperature extremes

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So what are the issues?

• The ice caps in the Himalayas are melting so the
  spring flood carrying sediments to re-enrich the
  soils are slowly reducing.
• The storms seem to be becoming more intense
• The sea level is rising due to snow melt and
  thermal expansion.
• The mangrove swamps, the Sundarbans, are the
  largest in the world, will disappear is the sea
  levels rise by a mere 45cm.
• Without mangroves to protect the coastal behind
  them, much land will be washed away in storms,
  leaving millions homeless.

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So what are the issues?

• More salt water infiltration is likely, which
  will make more of the land that is still above
  sea level, useless for growing rice, so putting
  more pressure on more to people to migrate.
• Saltwater from the Bay of Bengal already
  penetrates 100 kilometres inland during the dry
  season , and climate change is likely to
  exacerbate this.
• Pressure from an increasing population (rising at
  2 pa) and rising demand for groundwater further
  reduces the availability of freshwater supplies
  for domestic and industrial purposes
• If sea levels rises up to one metre this century,
  Bangladesh could lose up to 15 per cent of its
  landmass and up to 30 million Bangladeshis could
  become climate refugees .
• In these areas, agriculture, industry,
  infrastructure, livelihoods, marine resources,
  forestry and biodiversity, human health, and
  utility services will all suffer. Such a scenario
  could lead to a decline in GDP of between 27 and
  57 per cent . ( It is currently US 700)
• Given the high population density (954 per sq km)
  of the country as a whole, this could lead to
  mass climate emigration where could they go?