CLIMATE CHANGE
&
GLOBAL WARMING
Lecture-1
Causes and Implications
Dr. Paul
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Causes and Implications
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The term climate change is often used interchangeably with the term global
warming, but according to the National Academy of Sciences, "the phrase
'climate change' is growing in preferred use to 'global warming' because it
helps convey that there are [other] changes in addition to rising
temperatures."
Climate change refers to any significant change in measures of climate
(such as temperature, precipitation, or wind) lasting for an extended period
(decades or longer).
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Climate change may result from:
1. natural factors, such as changes in the sun's intensity or slow
changes in the Earth's orbit around the sun;
2. natural processes within the climate system (e.g. changes in ocean
circulation);
3. human activities that change the atmosphere's composition (e.g.
through burning fossil fuels) and the land surface (e.g. deforestation,
reforestation, urbanization, desertification, etc.)
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Global warming is an average increase in the temperature of the
atmosphere near the Earth's surface and in the troposphere, which can
contribute to changes in global climate patterns.
Global warming can occur from a variety of causes, both natural and human
induced.
In common usage, "global warming" often refers to the warming that can
occur as a result of increased emissions of greenhouse gases from human
activities.
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What is the Greenhouse Effect?
• Energy from the sun drives the earth’s weather and climate, and heats the
earth’s surface;
• In turn, the earth radiates energy back into space;
• Some atmospheric gases (water vapor, carbon dioxide, and other gases)
trap some of the outgoing energy, retaining heat somewhat like the glass
panels of a greenhouse;
• These gases are therefore known as greenhouse gases;
• The greenhouse effect is the rise in temperature on Earth as certain gases
in the atmosphere trap energy.
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Six main gases considered to be contributing to global climate change are
carbon dioxide (CO2), methane (CH4) (which is 20 times as potent a
greenhouse gas as carbon dioxide) and nitrous oxide (N2O), plus three
fluorinated industrial gases: hydrofluorocarbons (HFCs),
perfluorocarbons (PFCs) and sulphur hexafluoride (SF6). Water vapor is
also considered a greenhouse gas.
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Many of these greenhouse gases are actually life-enabling, for without them,
heat would escape back into space and the Earth’s average temperature
would be a lot colder.
However, if the greenhouse effect becomes stronger, then more heat gets
trapped than needed, and the Earth might become less habitable for
humans, plants and animals.
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GLOBAL WARMING – Implications !!!
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global warming will lead to the following situations ………..
• Rapid global heating according to a US National Academy of Science
• Ozone loss aggravated by global warming;
• Warming of the oceans leads to increased green house gasses;
• Oceanic changes observed that may aggravate the situation;
• A vicious circle whereby each problem will exacerbate other problems which
will feedback into each other;
• Massive extinction of species will aggravate the environmental crisis;
• Sudden collapse of biological and ecological systems may occur, but will have
a very slow recovery;
• While effective measures can decrease global warming and other problems the
World community has repeatedly failed to establish cooperation.
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Natural systems are vulnerable to climate change and some
will be irreversibly damaged
Loss of biodiversity
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Some Threatened Systems
• Endorheic lakes: e.g. Caspian, Aral seas
• Tropical glaciers and related water flows
http://video.google.com/videoplay?docid=3928187439892473367&q=global+warming+glaciers&total=116&start=0&num=10&so=0&type=search&plindex=0
• Coral Reefs (1% of ocean area, 30% of ma
rine species)
http://video.google.com/videoplay?docid=6209601119636354557&q=global+warm
ing+coral+reef&total=25&start=0&num=10&so=0&type=search&plindex=0
• Mangroves- e.g. Sundarbans, last habitat o
f Royal Bengal Tiger
• Endangered species
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a body of water from which there is no o
utflow of water by rivers, only by evapora
tion. That makes the Caspian Sea the lar
gest "lake" on Earth.
CASPIAN SEA
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The Aral Sea, in 2003, had shrunk to well under half of the area it had covered fift
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y years before.
Many human systems are sensitive to climate
change and some are vulnerable
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Human Systems
Sensitive Systems
Water resources
Agriculture, forestry, fisheries
Human settlements
Industry, energy, financial services
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•
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Vulnerabilities
Food and water security
Incomes and livelihoods
Human health
Infrastructure
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Projected changes in climate extremes could
have major consequences
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Changes in extreme events
(temperature)
•
Higher maximum temperatures, more hot days and heat waves over nearly
all land areas (Very likely)
•
Increased death and serious illness in older age groups and urban poor
•
Increased heat stress in livestock and wildlife
•
Shift in tourist destinations
•
Increased risk of damage to a number of crops
•
Increased electric cooling demand and reduced energy supply reliability
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Increased summer drying over most mid-latitude continental interiors and
associated risk of drought (Likely)
Decreased crop yields
Increased damage to building foundations caused by ground shrinkage
Decreased water resource quantity and quality
Increased risk of forest fire
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Forest fire
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Changes in extreme events
(hydrological)
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More intense precipitation
events (Very likely, over m
any areas)
• Increased flood, landslide, avalanche, and mudslide damage
• Increased soil erosion
• Increased pressure on government and private insurance systems and disaster
relief
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avalanche
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Land slide
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Mud slide
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Soil erosion
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FLOOD
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The year 2005 was the warmest year in over a century, according to NASA
scientists studying temperature data from around the world
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global map of 2005 average temperatures shows areas that have warmed the most
in red, to the areas that have cooled (in blue). Note that the Arctic has warmed
significantly. These temperatures are from Dec. 2004 through Nov. 2005.
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Extreme Weather Patterns
the warming of the climate will lead to more extreme weather patterns such as:
• More hurricanes and drought;
• Longer spells of dry heat or intense rain (depending on where in the world);
• Scientists have pointed out that Northern Europe could be severely affected
if climate change continues
• In South Asia, the Himalayan glaciers could retreat causing water scarcity
in the long run.
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Warning!!!!!!
“Recent scientific assessments indicate that, as the global temperatures
continue to warm due to climate change, the number and intensity of
extreme events might increase.”
July 2003
(The WMO limits the definition of extreme events to high temperatures, low temperatures and high
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rainfall amounts and droughts.)
Warming Winds, Rising Tides: Unstable Weather
significant weather and climate events for the globe included:
• severe drought in parts of southern Africa and the Greater Horn of
Africa,
•
extreme monsoon-related rainfall in western India including a 24-hour
rainfall total of 37.1 inches in Mumbai,
• the worst drought in decades in the Amazon River basin,
• severe drought in large parts of western Europe, and a record warm year
in Australia."
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Super-storms
world’s oceans are approaching 27 degrees C or warmer during the summer.
This increases the odds of major storms.
• When water reaches such temperatures, more of it evaporates, priming
hurricane or cyclone formation.
• Once born, a hurricane needs only warm water to build and maintain its
strength and intensity.
Furthermore, “as emissions of greenhouse gases continue to trap more and more
of the sun’s energy, that energy has to be dissipated, resulting in stronger storms,
more intense precipitation and higher winds.”
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Structure of a tropical cyclone
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Cyclone Catarina, a rare South Atlantic tropical cyclone viewed from the
International Space Station on March 26, 2004
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Tropical cyclones form when the energy released by the condensation of
moisture in rising air causes a positive feedback loop over warm ocean waters.
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The aftermath of Hurricane Katrina in Gulfport, Mississippi. Katrina
was the costliest tropical cyclone in United States history.
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few case reports:
1. In 1998, Hurricane Mitch killed nearly 20,000 people in Central America
2. more than 4,000 people died during disastrous flooding in China
3. Bangladesh suffered some of its worst floods ever the following year, as
did Venezuela.
4. Europe was hit with record floods in 2002, and then a record heat wave in
2003.
5. Brazil was struck by the first-ever recorded hurricane in the South Atlantic
2004 March.
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