This document provides information about climate change and global warming. It defines climate change as a significant and lasting change in weather patterns over decades or longer. It discusses the difference between weather and climate. It then explains the various factors that determine Earth's climate, including both internal dynamics and external forcings such as volcanic eruptions, solar variations, and human activities. Specifically, it discusses how human emissions of greenhouse gases like carbon dioxide, methane, nitrous oxide, and halocarbons from activities like burning fossil fuels and deforestation are the dominant cause of recent global warming. The document summarizes observed and projected impacts of climate change, such as increasing global temperatures, rising sea levels, and more extreme weather events.

1. Climate change
&
Global warming
Puskar Suwal
@ Khec, Nepal

2. What is Climate Change?
• Climate change is a significant and lasting
change in the statistical distribution of weather
patterns over periods ranging from decades to
millions of years.

3. Weather vs. Climate
 Weather is the specific condition of the atmosphere
at a particular place and time and is measured in
terms of things such as wind, temperature, humidity,
atmospheric pressure, cloudiness and precipitation.
 Climate, on the other hand, is the average pattern of
weather for a particular region, usually taken over a
30 year time period. Climate elements can include
precipitation, temperature, humidity, wind velocity,
fog, frost, hailstorms, and other measures of weather.

4. What factors determine Earth’s Climate?
Influence of its own internal dynamics
(Internal forcing)
Changes in external factors that affect climate
(External forcing).

5. Internal forcing mechanisms are natural
processes within the climate system itself (e.g.,
the meridional overturning circulation).
External forcing include natural phenomena such
as volcanic eruptions and solar variations, as well
as human induced changes in atmospheric
composition.

6.  Volcanic eruptions contain huge amounts of volcanic gas,
aerosol droplets, and ash.
 Most of it is removed within several days to weeks -- and
has little impact on climate change.
 But volcanic gases like sulfur dioxide and carbondioxide
takes time to remove.

7.  Solar variation is the
change in the amount
of radiation emitted by
the sun and its spectral
distribution over years
to millennia.

8. Energy from Sun
 The range of electromagnetic energy emitted by the
sun is known as the solar spectrum, and lies mainly
in three regions: ultraviolet, visible, and infrared.
 While the sun does emit ultraviolet radiation, the
majority of solar energy comes in the form of "light"
and "heat," in the visible and infrared regions of the
electromagnetic spectrum.

10. Solar radiation in atmosphere
 The atmosphere may seem to be completely
transparent to solar radiation, but in fact there are
dynamic interactions occurring constantly that result
in a complex and delicately balanced system crucial
to the continuation of present life forms on Earth.
 two resulting phenomena that are crucial to the
maintenance of life on Earth:
1. The atmosphere acts as a filter, absorbing and reflecting
portions of electromagnetic spectrum, such as the UV
region, that are harmful to humans and other life forms.
2. The atmosphere provides a natural “Greenhouse effect”
maintaining the temperatures and climates in which life
forms on Earth have evolved to survive.

11.  In red  solar radiation spectrum at the top of the atmosphere
 In Blue  solar radiation spectrum at the sea level

12. Solar Radiation Absorption, Balance,
and the Natural Greenhouse Effect
 For every 100 units of solar radiation falling on the
Earth and its atmosphere, 25 units are reflected by
the atmosphere, and 25 units are absorbed by the
atmosphere. The remaining 50 units fall on the
surface of the Earth. Of these 50 units, 5 units are
reflected by the surface of the Earth, and 45 units are
absorbed.
 Approximately 30% of the incident energy is reflected
by the atmosphere and the surface of the earth.
 The atmosphere absorbs approximately 25% of the
radiation, and the earth's surface absorbs 45%.

15. The phenomenon is responsible for keeping
the temperature of the Earth a full 33° C
warmer than it would be otherwise.
The reason the Earth’s surface is this warm is
the presence of greenhouse gases, which act
as a partial blanket for the longwave radiation
coming from the surface. This blanketing is
known as the natural greenhouse effect.

16. Greenhouse gas
Water vapor (H2O)
Carbondioxide (CO2)
Methane (CH4)
Ozone (O3)
Nitrous oxide (N2O)
sulfur hexafluoride (SF6)
hydrofluorocarbons (HFCs)
perfluorocarbons (PFCs)
chlorofluorocarbons (CFCs)
Major GHG
Two abundant
constituents of the
atmosphere – nitrogen
and oxygen – have no
such effect

17. GHG Formula Contribution
Water vapor H2O 36-72%
Carbondioxide CO2 9-26%
Methane CH4 4-9%
Ozone O3 3-7%
GHG Preindustrial
level
Current level Increase since
1750
CO2 280ppm 388ppm 108ppm
CH4 700ppb 1745ppb 1045ppb
N2O 270ppb 314ppb 44ppb
CFC-12 0 533ppt 533ppt

18. Contribution of human activities on
climate change
 Human activities results in emissions of four principal
GHGs:
1. CO2
2. CH4
3. N2O
4. Halocarbons (group of gases containing fluorine, chlorine and
bromine)
 These gases accumulate in the atmosphere, causing
concentrations to increase with time.

19. CO2
 CO2 has increased from fossil fuel use in
transportation, building heating and cooling and the
manufacture of cement and other goods.
 Deforestation

20.  In terms of temperature, the move from the pre-
industrial CO2 concentration to today's level (i.e. from
280 ppm to 380 ppm) has resulted in a 0.5° C direct
increase in the mean global temperature.
 Looking into the future, models used by the IPCC
predict that CO2 concentrations will rise to between
500 ppm and 1000 ppm in 2100.
 It is estimated that between 1990 and 2100,
temperatures will actually increase by between 1.4° C
and 5.8° C.

21. CH4
 Agriculture and livestock farming are two of the principal human
activities that produce methane.
 Another important factor in the emission of methane is the
burning of vegetation
 leakage of this gas from coal, defective natural gas extraction
systems

22. Halocarbons
 Best known – CFC
 Accused of being the principal cause of a possible
depletion of stratospheric ozone, they also act as
greenhouse gases in the troposphere.
 Because they are man-made, there were barely
present at all in the atmosphere until 1950.
 Since that time, they have been used extensively in
refrigeration systems

23. N2O
 N2O is emitted by use of fertilizer and fossil fuel
burning.
 Natural process in soils and the oceans also release
N2O.

25.  Water vapor has very small direct influence of human
activities. (human activities also influence CH4 undergoes
chemical destruction in the stratosphere, producing a small
amount of water vapor.
 Ozone is continually produced and destroyed in the
atmosphere by chemical reactions. In the troposphere,
human activities have increased ozone through the release
of gases such as CO, HC and Nox, which chemically react
to produce ozone. Halocarbons released by human activities
destroy ozone in the stratosphere.

27. US GHG Emission Flow Chart
Source: World Resource Institute

28. country % of global total
annual emission
Tones of GHG per
capita
China 17% 5.8
United States 16% 24.1
European Union 11% 10.6
Nepal 0.09%

29. Impacts
global temperature
 Instrumental observations over the past 157 years
show that temperatures at the surface have risen
globally.
 Expressed as a global average, surface temperatures
have increased by about 0.740
C over the past
hundred years (between 1906 – 2005).
 For the last 50 years, the linear warming trend has
been 0.13 °C [0.10 to 0.16 °C] per decade according
to AR4

31. The values in the table
above are anomalies
from the 1901–2000
global mean of
13.9°C. For instance,
the +0.55°C anomaly
in 2007 added to the
1901–2000 mean of
13.9°C gives a global
average temperature
of 14.45 °C (58.00 °F)
for 2007.
year Global mean temperature
(0C anomaly from 1901-
2000)
2005 0.6183
2010 0.6171
1998 0.5984
2003 0.5832
2002 0.5762
2006 0.5623
2009 0.5591
2007 0.5509
2004 0.5441
2001 0.5188
2008 0.4842
1997 0.4799
1999 0.4210
1995 0.4097
2000 0.3899

32. Snow and Ice is Decreasing
 Ice sheet and glaciers are melting due to increasing
global temperature.

33.  Greenland ice sheet is melting because of these rising
temperatures.
 Previously, NASA had estimated that Greenland’s ice sheet
would melt a meter every year. Now, it could be as much as a
meter every month.
 In just the past 15 years, over 105 million acres of ice has
melted and emptied into the oceans.

34.  Annual average Arctic sea ice extent shrunk by 2.7 %
per decade, decreases in summer 7.4 %
Sept. 21,
1979
Sept. 16,
2007
Sea Ice
Concentration (%)0 15
100

37. Sea level rising
 Global average sea level rose at an average rate of
around 1.7 ±.3mm per year over 1950 to 2009 and at
a satellite-measured average rate of about 3.3
±.4mm per year from 1993 to 2009.
 Over the last 100 years, the global sea level has
risen by about 10 to 25 cm.
 Cause: a) thermal expansion
b) ice sheet / glacier melting

38. 2 - 4C warming by ~2100
 0.18 - 0.59 meter rise in sea level
2 - 4C warming by ~2100
 0.18 - 0.59 meter rise in sea level

39.  Projected impacts
 Major cities like Los Angeles, London, and Tokyo will
be flooded as sea level rises.
 Already inhabitants of islands of Vanuatu have had to
evacuate due to the rising water and some are
already underwater.
 Sea level rise could also displace many shore-based
populations: for example it is estimated that a sea level rise
of just 200 mm could create 740,000 homeless people in
Nigeria. Maldives, Tuvalu, and other low-lying countries are
among the areas that are at the highest level of risk.
 The UN's environmental panel has warned that, at current
rates, sea level would be high enough to make the Maldives
uninhabitable by 2100.

40. Changes in extreme events
Heat waves
Droughts
Floods
Hurricanes

41. Extreme Heat Wave
Summer 2003
Europe
Heat waves are increasing

44. North Atlantic hurricanes have increased with SSTs
SST
(1944-2005)
Marked increase
after 1994
Duration and
strength of
hurricanes
has increased
about 50%
over the last
30 years

46.  http://www.dartmouth.edu/~floods/Archives/GlobalFlo
ods1985-2006.gif

47. Regions of disproportionate changes in heavy
(95th
) and very heavy (99th
) precipitation
Proportion of heavy rainfalls: increasing in
most land areas

48. Smoothed annual anomalies for precipitation (%) over land from
1900 to 2005; other regions are dominated by variability.
Land precipitation is changing significantly over broad areas
Increases
Decreases

49. If emission of the GHGs are reduced, how
quickly do their concentration in the atmosphere
decrease?
GHG Life time at atm (Yrs)
CO2 50 - 1000+
CH4 10 +/- 3
N2O 120
CFC 45-100
HCF
C
1-18
PFC 1000
HFC 1-270
CO2
CH4

50. Projections of Future Changes in
Climate
For the next two decades a warming of about
0.2°C per decade is projected.
Even if the concentrations of all greenhouse
gases and aerosols had been kept constant at
year 2000 levels, a further warming of about
0.1°C per decade would be expected.

51. Projections of Future Changes in Climate
Best estimate
for low
scenario (B1)
is 1.8°C (likely
range is 1.1°C
to 2.9°C), and
for high
scenario
(A1FI) is 4.0°C
(likely range is
2.4°C to
6.4°C).

52. Projected warming
in 21st century
expected to be
greatest over land
and at most high
northern latitudes
and least over the
Southern Ocean
and parts of the
North Atlantic
Ocean
Projections of Future Changes in Climate

53. Projections of Future Changes in Climate
Precipitation increases very likely in high latitudes
Decreases likely in most subtropical land regions

54. Projected impacts of climate change (Stern report, 2006)
1°C 2°C 5°C4°C3°C
Sea level rise
threatens major cities
Falling crop yields in many areas, particularly
developing regions
FoodFood
WaterWater
EcosystemsEcosystems
Global temperature change (relative to pre-industrial)
0°C
Falling yields in many
developed regions
Rising number of species face extinction
Significant decreases in water
availability in many areas, including
Mediterranean and Southern Africa
Small mountain glaciers
disappear – water
supplies threatened in
several areas
Extensive Damage
to Coral Reefs
ExtremeExtreme
WeatherWeather
EventsEvents
Rising intensity of storms, forest fires, droughts, flooding and heat waves
Possible rising yields in
some high latitude regions

55. Global Warming
Solutions
Prevention Cleanup
Cut fossil fuel use (especially coal)
Shift from coal to natural gas
Improve energy efficiency
Shift to renewable energy resources
Transfer energy efficiency and
renewable energy technologies to
developing countries
Reduce deforestation
Use more sustainable agriculture
Limit urban sprawl
Reduce poverty
Slow population growth
Store (sequester) CO2 by
planting trees
Sequester CO2 in the deep ocean
Repair leaky natural gas pipelines
and facilities
Remove CO2 from smokestack
and vehicle emissions
Solutions to Global Warming

56. CC Impacts the poorest the most!