Global warming is caused by increased atmospheric CO2 from human activities like burning fossil fuels. This traps more heat and warms the planet, causing temperature and sea level rises. To mitigate global warming, we need to reduce CO2 emissions through options like renewable energy and energy efficiency, using economic considerations to choose the most cost-effective combination.

1. Global Warming
Global Warming
―
― Cause
Cause，
，Impact and Mitigation
Impact and Mitigation ―
―

2. Atmospheric CO2 Concentration
and Global mean Temperature
Atmospheric CO2 concentration and
global mean temperature increase with
the rapid increase of CO2 emission.
Cause of Global Warming
Cause of Global Warming
Fossil fuel consumption is increasing
rapidly to satisfy growing energy demand
after the Industrial Revolution, which
started at the end of the 18th century.
Fossil fuel combustion ：
C + O2 → CO2
（Carbon in （Oxide in
Fossil fuel） Atmosphere）
《Point》 Global warming is caused by anthropogenic activities.
CO2 Emission by fuel
Source: Carbon Dioxide Information Analysis Center, ORNL
Source: Carbon Dioxide Information Analysis Center, ORNL
0
1000
2000
3000
4000
5000
6000
7000
1750 1800 1850 1900 1950 2000
Year
CO
2
emissions
(MtC/yr)
Gas
Oil
Coal
275
300
325
350
375
1750 1800 1850 1900 1950 2000
Year
Atmospheric
CO
2
concentration
（ppmv）
-1
-0.5
0
0.5
1
Global
mean
temperature
change
（℃）
Historical CO2 record from the Siple Station ice core
Atmospheric CO2 record from Mauna Loa
Global mean temperature relative to the mean of 1961-1990

3. Carbon Cycle
Carbon Cycle
《Point》 Carbon（C） circulates on the Earth.
The carbon (C) circulates among
terrestrial plants, the atmosphere
and the ocean, undergoing various
reactions.
For example,
Solution
： CO2 + H2O ⇄ 2H+ + CO3
2-
Photosynthesis
： 6CO2 + 6H2O → 6O2 + C6H12O6
However, anthropogenic activities
like fossil fuel burning and
deforestation have released carbon
(C) to the atmosphere and have
increased the carbon in the
atmosphere.
Burning ： C + O2 → CO2
This carbon increase in the atmosphere
leads to the global warming.

4. Greenhouse Effect
Greenhouse Effect
《Point》 CO2（carbon dioxide） plays an important role
to keep the earth warm.
Greenhouse gases, e.g., CO2,
absorb infrared radiation,
while solar radiation passes
through gas layer.
Certain amounts of greenhouse
gases (CO2 etc) are necessary to
keep the earth warm.

5. Global Warming
Global Warming
《Point》 However, increase in atmospheric concentration
of CO2 causes global warming.
CO2 increase in the
atmosphere “thickens”
the infrared radiation
absorption layer.
The “thicker” absorption layer
keeps the earth warmer.

6. Projection of Climate Change
Projection of Climate Change
Temperature rise of 1.4 deg.C at
the lowest and 5.8 deg.C at the
highest is projected in case of no
CO2 emission reduction.
Sea level rise of 0.1m at the lowest
and 0.9m at the highest is projected
in case of no CO2 emission reduction.
Temperature Change
Sea level Change
《Point》 CO2 concentration increase causes the rises of
the global temperature and sea level.
Source: The Third Assessment Report by Intergovernmental
Panel on Climate Change(IPCC)
Source: The Third Assessment Report by Intergovernmental Panel on Climate Change(IPCC)

7. Global Warming Impacts
Global Warming Impacts
《Point》 Extraordinary weather is projected to occur
in various world regions.

8. 《Point》 CO2 emissions vary widely across countries.
CO
CO2
2 Emission
Emission
・CO2 emissions and per capita emissions are large at present for developed countries.
・CO2 emissions in developing countries are projected to increase with the population
and the economic growths.

9. Global Warming Mitigation
Global Warming Mitigation
《Point》
We have various
mitigation options to
reduce CO2 emissions.
A cost-effective
combination of the
options is required.

10. 《Point》 Economic consideration is important to
select a combination of the options.
Global Warming Mitigation Scenario
Global Warming Mitigation Scenario
Forestation
Ocean Sequestration
Renewable Energy
Nuclear Power
Fuel Switching among
Fossil Fuels
Energy Saving
0
5
10
15
20
25
2000 2010 2020 2030 2040 2050 2060 2070 2080 2090 2100
Year
CO
2
emission
and
reduction
(Gton
of
carbon
eq.)
Energy Saving
Fuel Switching among Fossil Fuels
Nuclear Power
Renewable Energy
Geological Sequestration (Depleted Gas Well)
Geological Sequestration (Aquifer)
Ocean Sequestration
Forestation
Net CO2 Emission
Geological Sequestration
(Depleted Gas Well)
Geological Sequestration
(Aquifer)
Without CO2 mitigation policy ...
The CO2 emission level is required to stabilize the double of the
pre-industrial atmospheric CO2 concentration (550 ppmv).
Effective
CO
2
reduction
by
these
technologies.