The Earths Climate System

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The Earths Climate System
Forces Acting on Climate
Climate Response
Impact
Climate Feedback
External Forcing - Incoming solar energy drives
the climate system, volcanoes modify the
climate system. Internal Forcing - Water vapor
and other gases govern how the atmosphere
reacts to solar energy, producing the
greenhouse effect that keeps the Earth
habitable.
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The Earths Climate System
Solar Energy
The Earth System
Kump, L.R., J.F. Kasting and R.G. Crane, 2004
The Earth System (2nd edition), Pearson
Education, Inc., p. 3.
Atmosphere
Hydrosphere
Biota

• Solid Earth

Heat Energy
Heat Energy
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The Earths Climate System
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The Earths Climate System
http//www.ucar.edu/communications/CCSM/overview.h
tml
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The Earths Climate System
Physical Climate Systems
Climate Change
Atmospheric Physics/Dynamics
Sun
Ocean Dynamics
Terrestrial Energy/Moisture
Human Activities
Stratospheric Chemistry/Dynamics
External Forcing
Human Forcing
Soil
CO2
Global Moisture
Land Use
Marine/ Biogeochemistry
Terrestrial Ecosystems
Volcanoes
CO2
Tropospheric Chemistry
Pollu- tants
Biogeochemical Systems
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Budgets and Cycles
The Energy Budget The movement and
transformation of energy in its various forms
within the Earth system The solar
cycle The radiation budget
http//www.cmdl.noaa.gov/infodata/faq_cat-1.html
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Budgets and Cycles
The Hydrologic Cycle The ceaseless flow of
water among terrestrial, oceanic, and
atmospheric reservoirs. (Moran Morgan,
p. 498)
http//ga.water.usgs.gov/ edu/watercycle.html
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Budgets and Cycles
The Carbon Cycle The flow of carbon among
terrestrial, oceanic, and atmospheric
reservoirs. (Moran Morgan, p. 15)
http//www.windows.ucar.edu/tour/link/earth/ clim
ate/images/carboncycle_jpg_image.html
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Budgets and Cycles
The Nitrogen Cycle The flow of nitrogen
among terrestrial, oceanic, and atmospheric
reservoirs
http//www.igbp.kva.se// uploads/NL_64.pdf
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External Forcing
Solar Energy the Earth Receives Suns energy
is emitted in all directions Intensity of the
Suns energy decreases as the square of the
distance from the Sun increases, i.e.,
Intensity a 1 / (distance )2
Sun
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External Forcing
Solar Energy the Earth Receives The Earth
intercepts only a small portion of the Suns
energy about 1.716 x 1014 kilowatts
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Sun
150 x 10
km
Earth
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External Forcing
Solar Radiation and the Earths Atmosphere
Incoming Solar Radiation 100
Total Albedo 30

6 Scattered by Air
4 Reflected from Surface
20 Reflected by Clouds
25 Direct
3 Absorbed by Clouds
16 Absorbed by Air
26 Diffuse
51 Absorbed at the Earth's Surface

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External Forcing
Radiation Energy per unit time per unit area
cal / ( s - m2 ) or watts / m2
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External Forcing
Volcanic Activity Tree-ring width vs year of
eruption - Growth index for the 24 largest
volcanoes Temperature vs year of
eruption - Composite global surface
temperature change near the time of
the five volcanoes producing the greatest
optical depths since 1880 Krakatau (1883),
Santa Maria (1902), Agung (1963), El
Chichon (1982) and Pinatubo (1991)
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Changes
Science Concepts
Temperature Change Observations Number Locat
ion
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Changes - Temperature
What do we mean by global warming? How do
we measure the temperature of the globe?
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Changes - Temperature
NASA's Goddard Institute for Space Studies
Surface Station Data Anomalies from 1951-1980
average global temperature Linear trend is
0.06C per decade - Total change for the 120
years is about 0.7C
Data from - http//data.giss.nasa.gov/ gistemp/gr
aphs/
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Changes - Temperature
Global Climate Laboratory Temperature Stations in
1900
Peterson, T.C., and R.S. Vose, 1997 An overview
of the Global Historical Climatology Network
temperature database, Bull. Amer. Meteor. Soc.,
78, 2837-2849.
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Changes - Temperature
Global Climate Laboratory Temperature Stations in
1997
Peterson, T.C., and R.S. Vose, 1997 An overview
of the Global Historical Climatology Network
temperature database, Bull. Amer. Meteor. Soc.,
78, 2837-2849.
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Changes - Temperature
NASA's Goddard Institute for Space Studies
Surface Station Data Anomalies from 1951-1980
base period 2005 Anomalies (C)
http//data.giss.nasa.gov/gistemp/ graphs/Fig.A2.p
df
http//data.giss.nasa.gov/gistemp/2005/
http//data.giss.nasa.gov/gistemp/ graphs/Fig.A3.p
df
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Changes - Temperature
Surface data Trend 0.168C
per decade Satellite lower- atmos- phe
re data Trend 0.132C per decade
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Changes - Temperature
Temperature Anomalies Satellite measured
lower-atmosphere temperature anomalies
El Nino
La Nina
Pinatubo
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Human Impacts on Climate
Adopted by American Geophysical Union Council
12/03 Human activities are increasingly altering
the Earth's climate. These effects add to natural
influences that have been present over Earth's
history. Scientific evidence strongly indicates
that natural influences cannot explain the rapid
increase in global near-surface temperatures
observed during the second half of the 20th
century. Human impacts on the climate system
include increasing concentrations of atmospheric
greenhouse gases (e.g., carbon dioxide,
chlorofluorocarbons and their substitutes,
methane, nitrous oxide, etc.), air pollution,
increasing concentrations of airborne particles,
and land alteration. A particular concern is that
atmospheric levels of carbon dioxide may be
rising faster than at any time in Earth's
history, except possibly following rare events
like impacts from large extraterrestrial
objects. 1 of 6
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Human Impacts on Climate
Adopted by American Geophysical Union Council
12/03 (Cont) Atmospheric carbon dioxide
concentrations have increased since the mid-1700s
through fossil fuel burning and changes in land
use, with more than 80 of this increase
occurring since 1900. Moreover, research
indicates that increased levels of carbon dioxide
will remain in the atmosphere for hundreds to
thousands of years. It is virtually certain that
increasing atmospheric concentrations of carbon
dioxide and other greenhouse gases will cause
global surface climate to be warmer. The
complexity of the climate system makes it
difficult to predict some aspects of
human-induced climate change exactly how fast it
will occur, exactly how much it will change, and
exactly where those changes will take place. In
contrast, scientists are confident in other
predictions. Mid-continent warming will be
greater than over the oceans, and there will be
greater warming at higher latitudes. Some polar
and glacial ice will melt, and the oceans will
warm both effects will contribute to higher sea
levels. The hydrologic cycle will change and
intensify, leading to changes in water supply as
well as flood and drought patterns. There will be
considerable regional variations in the resulting
impacts.
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Human Impacts on Climate
Adopted by American Geophysical Union Council
12/03 (Cont) Scientists' understanding of the
fundamental processes responsible for global
climate change has greatly improved during the
last decade, including better representation of
carbon, water, and other biogeochemical cycles in
climate models. Yet, model projections of future
global warming vary, because of differing
estimates of population growth, economic
activity, greenhouse gas emission rates, changes
in atmospheric particulate concentrations and
their effects, and also because of uncertainties
in climate models. Actions that decrease
emissions of some air pollutants will reduce
their climate effects in the short term. Even so,
the impacts of increasing greenhouse gas
concentrations would remain. 3 of 6
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Human Impacts on Climate
Adopted by American Geophysical Union Council
12/03 (Cont) The 1992 United Nations Framework
Convention on Climate Change states as an
objective the "...stabilization of greenhouse gas
concentrations in the atmosphere at a level that
would prevent dangerous anthropogenic
interference with the climate system." AGU
believes that no single threshold level of
greenhouse gas concentrations in the atmosphere
exists at which the beginning of dangerous
anthropogenic interference with the climate
system can be defined. Some impacts have already
occurred, and for increasing concentrations there
will be increasing impacts. The unprecedented
increases in greenhouse gas concentrations,
together with other human influences on climate
over the past century and those anticipated for
the future, constitute a real basis for
concern.

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Human Impacts on Climate
Adopted by American Geophysical Union Council
12/03 (Cont) Enhanced national and
international research and other efforts are
needed to support climate related policy
decisions. These include fundamental climate
research, improved observations and modeling,
increased computational capability, and very
importantly, education of the next generation of
climate scientists. AGU encourages scientists
worldwide to participate in climate research,
education, scientific assessments, and policy
discussions. AGU also urges that the scientific
basis for policy discussions and decision-making
be based upon objective assessment of
peer-reviewed research results. Science provides
society with information useful in dealing with
natural hazards such as earthquakes, hurricanes,
and drought, which improves our ability to
predict and prepare for their adverse effects.
While human-induced climate change is unique in
its global scale and long lifetime, AGU believes
that science should play the same role in dealing
with climate change. AGU is committed to
improving the communication of scientific
information to governments and private
organizations so that their decisions on climate
issues will be based on the best science.


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Human Impacts on Climate
Adopted by American Geophysical Union Council
12/03 (Cont) The global climate is changing and
human activities are contributing to that change.
Scientific research is required to improve our
ability to predict climate change and its impacts
on countries and regions around the globe.
Scientific research provides a basis for
mitigating the harmful effects of global climate
change through decreased human influences (e.g.,
slowing greenhouse gas emissions, improving land
management practices), technological advancement
(e.g., removing carbon from the atmosphere), and
finding ways for communities to adapt and become
resilient to extreme events. 6 of 6