Global Warming

Global warming• Global warming is caused by green house gases, which trap in

the sun’s infrared rays in the earth’s atmosphere, which in turn heat up the earth’s atmosphere.

• These green house effect warming is called as global warming. • The main gases contributing to green house effect

are : Carbon Dioxide Water Vapour Methane Nitrous OxideThe largest producers of these gases are:

• Thermal power plants- burn the fossil fuels. • Road vehicles and Industries.

History of Earth’s Climate• Earth was formed ~4.6 billion years ago• Originally very hot• Sun’s energy output was only 70% present• Liquid water was present on surface around ~4.3

billion years ago (zircon dating)• Life appeared ~3.8 billion years ago• Photosynthesis began 3.5-2.5 billion years ago

This Produced oxygen and removed carbon dioxide and methane (greenhouse gases)from atmosphere.

Earth went through periods of cooling (“Snowball Earth”) and warming

• Earth began cycles of glacial and interglacial periods ~3 million years ago

Sun

Earth’s Temperature

Solar

Energy

RadiativeCooling

Earth’s Atmospheric GasesNitrogen (N2)

Oxygen (O2)

Water (H2O)

Carbon Dioxide (CO2)

99%

Methane (CH4)

1%

Non-Greenhouse

Gases

GreenhouseGases

Annual Carbon EmissionsAnnual carbon emissionsAtmospheric CO2Atmospheric CO2 average

1955 1965 1975 1985 1995 20050

4

6

8

2

Year

Car

bon

(109 m

etric

tons

)

Winter Temperatures

10

11

12

13

14

15

16

17

1880 1900 1920 1940 1960 1980 2000

Year

Summer Temperatures

18

19

20

21

22

23

24

25

1880 1900 1920 1940 1960 1980 2000

Year

Annual Temperatures

15

16

17

18

19

20

21

22

1880 1900 1920 1940 1960 1980 2000

Year

Tem

pera

ture

(°C

)

Historic Temperatures

Consequences of Global Warming

Increase in Temperature • Ice sheets of Antarctica and Greenland is melting.• Increase in mean sea level.• It will engulf low lying countries. • Excluding the ice caps and ice sheets of the Arctic and

Antarctic, the total surface area of glaciers worldwide has decreased by 50%.

• The Himalayan glaciers, the sources of Asia's biggest rivers—Ganges, Indus, Brahmaputra, Yangtze, Mekong, Salween and Yellow—could disappear by 2035 as temperature rise.

• Approximately 2.4 billion people live in the drainage basin of the Himalayan rivers.

• India, China, Pakistan, Bangladesh, Nepal and Myanmar could experience floods followed by droughts in coming decades

1000800600400200

0-200-400-600

2003 2004 2005

Ice

Mas

s (k

m3 )

Year

Changes in Antarctica Ice Mass

Melting Glaciers – Mt. Kilimanjaro

Increase in Hurricanes?

• Two studies showed the total number of hurricanes has not changed

• However, the intensity of hurricanes has increased (more category 4 and 5 hurricanes and cyclones)

• Probably due to higher sea surface temperatures (more energy)

• Difficult to know if this trend will continue

Effects• Polar Bears

Require pack ice to live Might eventually go extinct in the wild

• Sea turtles Breed on the same islands as

their birth Could go extinct on some islands

as beaches are flooded• Other species may go extinct as rainfall patterns change throughout

the world• Effects on Humans• Introduction of some new diseases. • The bacteria are more effective and multiply much faster in warmer. • The increase in temperature has led to increase in the microbes that

cause diseases.

Drought in Africa

Lake Faguibine Lake Chad

Mitigation of Global Warming• Conservation

Reduce energy needs Recycling

• Alternate energy sources Nuclear Wind Geothermal Hydroelectric Solar Fusion?

Possible Solutions to Global WarmingConclusions

Global warming is happeningMost warming is probably the result of human activitiesAvoid deforestationAvoid usage of gases which pollutes atmosphere.