Download Understanding Ocean and Earth System Science through models

Understanding Ocean and Earth
System Science through models
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Understanding the contemporary Earth System Science
relies on the recruitment and formation of a generation of
young scientists with the capabilities to analyze the products
of climate and Earth System Models.
Capacity building in human and technological resources
should be an integral component of the curriculum. This
should go beyond the traditional boundaries of the scientific
disciplines taught at universities.
We target undergraduate and early graduate students from
Science, Engineering and Economics faculties in South
Africa, which provide introductory courses in Information
Technology, Computing, Applied Mathematics, Physics,
Chemistry and Earth Sciences.
AGENDA
 Lectures
 10h30-11h30 Enrico Scoccimarro
ESM crash course part 1: the physical components
 11h30-12h30 Marcello Vichi
ESM crash course part 2: the carbon cycle
 12h30-13h30 B reak
 Hands-on session
 13h30-15h00 Group A
 15h00-16h30 Group B
E S M crash cour se part
1:
the physical components
E nrico S coccimarro
Istituto Nazionale di Geofisica e Vulcanologia - INGV
Centro euro-Mediter raneo sui Cambiamenti Climatici - CMCC
B ologna, Italy
enrico.scoccimarro@ ingv.it
The euro Mediterranean
Center on Climate Change
(CMCC) mission is to
investigate and model our
climate system and its
interactions with society to
provide reliable, rigorous,
and timely scientific results to
stimulate sustainable growth,
protect the environment, and
to develop science driven
adaptation and mitigation
policies in a changing
climate.
h" p://www.cmcc.it
[email protected]
Outline
• Physics of climate: a brief introduction
• Anthropogenic impacts on the past climate
• Climate Models, future scenarios and projections
ESM crash course part 2: the carbon cycle
Outline
• Physics of climate: a brief introduction
• Anthropogenic impacts on the past climate
• Climate Models, future scenarios and projections
ESM crash course part 2: the carbon cycle
Let’s start talking about Heat !!!!!!
• Heat transfers in three ways:
• ConducAon
• RadiaAon
• ConvecAon
<- Responsible of the heat transfer from the
Sun to the Earth Planet
<- Dominates the heat transfer over the
Earth Planet
The radiation method of heat transfer
How does heat energy get
from the Sun to the Earth?
?
There are no particles
between the Sun and
the Earth so it
CANNOT travel by
conduction or by
convection.
RADIATION
The Climate Machine
Solar
Radiation
H2O
CH4
CO2
Earth
Radiation
N2
O2
The energy that drives the climate system comes from the Sun
Greenhouse gasses are mainly stored in the Troposphere
Earth Radius ?
6000 km!
Energy radiates from the
earth surface
Radia4on from the sun
warms the earth’s
surface
Energy radiates from the
atmosphere
Greenhouse gases are being
warmed by the radia4on from
earth
Without
With
greenhouse gases:
+15
-18 degrees!
Solar radiaAon
1360 W/m2 (Solar Constant)
63 x 106 W/m2
As the Sun's energy spreads through space its spectral
characteristics do not change because space contains almost
no interfering matter. However the energy flux drops
monotonically as the square of the distance from the Sun.
Thus, when the radiation reaches the outer limit of the
Earth's atmosphere, several hundred kilometers over the
Earth's surface, the radiative flux is approximately 1360 W/m2
SST - Sea Surface Temperature [oC]
The Earth is a sphere and aside from the part closest to the
sun, where the rays of sunlight are perpendicular to the
ground, its surface tilts with respect to the incoming rays of
energy with the regions furthest away aligned in parallel to
the radiation and thus receiving no energy at all
CONVECTION
ConvecAon
red= hot
blue = cold
The Atmospheric CirculaAon
The Ocean CirculaAon
The Ocean CirculaAon (OGCM results)
[latitude]
The climatological meridional heat transport
[PW]
Types of CLIMATE
Outline
• Physics of climate: a brief introduction
• Anthropogenic impacts on the past climate
• Climate Models, future scenarios and projections
ESM crash course part 2: the carbon cycle
Changes in atmospheric CO2 concentration
Keeling curve
named after Charles “Dave” Keeling
http://www.esrl.noaa.gov/gmd/ccgg/iadv/
Why “unprecedented perturbation”?
Climate Variability and Change – Fall School on "Modeling CC Impacts on Water and Crops at Different Scales”, November 5 2012 - Alghero
Why “unprecedented perturbaAon”?
Falkowski et al. (2000)
Surface Temperature evolution in the past years
Temperature change difference
(2001-2015) - (1850-1899):
+0,79
±
0,19 ! C
Climate Variability and Change – Fall School on "Modeling CC Impacts on Water and Crops at Different Scales”, November 5 2012 - Alghero
Past changes in Arctic Sea Ice extension
Past changes in the annual cycle of sea ice extent
Arctic Sea Ice Volume: time evolution since 1979
Past changes in Glaciers extension
1893
2008
Vallelunga glacier
Alpine glaciers mass evolution since 1945
Past evolution of the Sea Level High
Outline
• Physics of climate: a brief introduction
• Anthropogenic impacts on the past climate
• Climate Models, future scenarios and projections
ESM crash course part 2: the carbon cycle
SCIENTIFIC METHOD
AND CLIMATE SCIENCE
•The Oxford English Dictionary says that scientific method
is: "a method of procedure that has characterized natural
science since the 17th century, consisting in systematic
observation, measurement, and experiment, and the
formulation, testing, and modification of hypotheses.”
•This definition whould require the possibility to test our
hypothesis as many times as possible to be sure of its
statistical significance.
•In the context of climate “empirical science” is not
applicable because it would require a spare earth to
experiment on. And even if this spare earth existed it would
take many years, at least 30 but in some cases, thousands
or millions of years to test our hypotheses on it.
33
Laboratory experiments?
•This is an important consideration, because it is precisely such wholeEarth, system-scale experiments, incorporating the full complexity of
interacting processes and feedbacks, that might ideally be required to
fully verify or falsify climate change hypotheses (Schellnhuber et al.,
2004, in Chap. 1, IPCC WG1, 2007).
•That’s where
numerical climate models come for help.
Global models: a brief history
In 1904, Norwegian scientist Vilhelm
Bjerknes first argued that it should be
possible to forecast weather from
calculations based upon natural laws.
“Based upon the observations that have
been made. The initial state of the
atmosphere is represented by a number of
charts which give the distribution of 7
variables …With these chatrs …new charts
..are to be drawn wich represent the new
state of the atmosphere from hour to hour.”
However no analytic methods for
solving the physical equations
involved were known at that time, so
Bjerknes was forced to rely on graphical
methods.
35
Lewis Fry Richardson
•In 1922, Lewis Fry Richardson devised an algorithmic
scheme for weather prediction based on solving partial
differential equations.
•He set out to formulate a set of equations tha would
completely determine the behaviour of the atmosphere
given its initial state. This set later on became the well
known primitive equations:
2
1
3
4
36
Lewis Fry Richardson
•Richardson proposed a computational
strategy for the entire globe, introducing the
primal concept of discretization through the
finite differences method.
•For a forecast of 6-hour Richardson needed 6
weeks of intense labour and finally ended up with
a completely wrong solution!!!
•“Perhaps some day in the future it will be
possible to advance the computations faster
than the weather advances and at a cost less
than the saving to mankind due to the information
gained. But that is a dream”
37
The model grid
38
the problem of the resolution
Resolution 1
Resolution 2
39
I The
Hansen et al. model ( 1983)
•8° latitude by 10° longitude, 9 vertical levels up
to 10 mb. Topography and vegetation.
•The physical processes of momentum and
energy transfer among atmosphere, ocean (sea
ice) and land are solved at each grid point.
•The model also inc1udes the radiative influence
of CO2 , H20 and other gases
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Numerical climate models
•Investigation tools
•Prognostic models of the general
circulation of the ocean and
atmosphere
•Based on physical equations of
mass and energy balance
•Discretized numerical solutions at
given spatial gridpoints
General Circulation Model (global scale)
resolution: a zoom over EU
orography
2001
1990
2007
1996
42
General Circulation Model (global scale)
orography
resolution: a zoom over EU
2007
AR5
2013
now
HighResMIP within CMIP6
(6th phase of the Coupled Model Intercomparison Project that will provide climate
43
data for the next Intergovernmental Panel on Climate Change - IPCC Assessment Report)
General Circulation Model (global scale)
orography
resolution: a zoom over
the South Pacific basin
Scale of phenomena
45
Development: From Atmosphere only General CirculaAon Models (GCMs)
through fully Coupled Atmosphere – Ocean models (CGCMs) to Earth System
Models (ESMs)
AR5
Last IPCC Assessment Reports (AR4 and AR5) leverage on
Couple Model Intercomparison Projects (CMIP3 and CMIP5)
Horizontal resolution between CMIP3 (AR4) and CMIP5 (AR5) didn’t change significantly
COUPLED MODEL HIERARCHY
No dynamics
SWAMP OCEAN (no heat storage)
Downward infraRed
Sensible HF
S + Fd – Fu – H - Latent
LE =HF0
Absorbed solar Upward infraRed
SLAB/MIXED LAYER OCEAN
OCEAN GCM
Trenberth, 1992
I The phys·ca ·nterface
Sea le
igure 2 ch
sea i ·c mod
o th
h ng
tw en
s (includin , c· bon rela oo ii ld ·).
1
I
a
er
d th o
n-
FIELD EXCHANGE BETWEEN ATMOSPHERE AND OCEAN MODELS
The interpolation issue.
ORCA2 grid
ECHAM -T106 grid
Atmosphere/Ocean-Sea Ice coupled model
FIELD EXCHANGE BETWEEN ATMOSPHERE AND OCEAN MODELS
The interpolation issue.
Atmosphere/Ocean-Sea Ice coupled model
Northern Hemisphere Grids
ECHAM-T30 ORCA2
ECHAM-T106 ORCA2
An example of a CMIP5 Climate model: CMCC-CM
Atmosphere/Ocean-Sea Ice coupled model
Atmosphere
ECHAM 5
(70 km horiz. res.)
Coupler OASIS 3
(Ocean Atmosphere Sea Ice Soil )
Ocean
Sea-Ice
ORCA2 OPA 8.2
(50-200 km horiz. res.)
LIM
(Louvain-La-Neuve
sea-Ice Model )
Earth System experiments
• Climate Models are mainly used for
•process studies: to be" er understand the
relaAonship within the climate system
•aSribu4on studies: understanding the causality
between observed changes and the major natural and
anthropogenic forcings
•scenario studies: making future projecAons on the
state of the climate according to predefined scenarios
of anthropogenic usage of the Earth resources
ProjecAons
•Climate scientists never use the term prediction when
referring to future climate conditions.
•This stems from the fact that a future climate
simulation is not exactly an “initial value problem” but
mostly a “boundary value problem”
•The correct term is “projection”, because the models
are used to project into the future the climate
conditions driven by a set of predefined, time-evolving
forcing scenarios.
Future scenarios: where do they come from?
•A SCENARIO is a plausible
description of how the
future may develop,
based on a coherent and
internally consistent set of
assumptions about key
relationships and driving
forces (e.g., population,
rate of technology
change, prices).
Note that scenarios are
neither predictions nor
forecasts. (OECD, Organisation for
Economic Co-operation and Development )
http://www.ipcc.ch/ipccreports/sres
Emission scenarios: SRES in AR4 and RCPs in AR5
m o l e fraction of C H 4 in air
4000
RCP4.5
RCP8.5
A1B
HIST
3500
[CH4]
METHANE
[
ppbv
]
3000
2500
2000
1500
1000
1950
1960
1970
1980
1990
2000
2010
2020 2030
year
2040
2050
2060
2070
2080
2090
2100
m o l e fraction of C O 2 in air
1000
900
RCP4.5
RCP8.5
A1B
HIST
800
[
ppmv
]
CARBON
DIOXIDE
[CO2]
700
600
500
400
300
1950
1960
1970
1980
1990
2000
2010
2020 2030
year
2040
2050
2060
2070
2080
2090
2100
Future emission scenarios: SRES in AR4 e RCPs in AR5
m o l e fraction of C O 2 in air
1000
RCP4.5
RCP8.5
A1B
HIST
900
CO2
800
[
ppmv
]
700
600
500
400
300
1950
1960
1970
1980
1990
2000
2010
2020 2030
ye a r
2040
2050
2060
2070
2080
2090
2100
for the first 4me (AR5) Representa4ve Concentra4on Pathways (RCPs)
will include scenarios that explore approaches to climate change mi4ga4on in addi4on to the tradi4onal
„no climate policy‟ scenarios
INGV-CMCC CMIP5 IPCC Experiments: the historical run
XX sec. Ozone
XX sec. Sulfate aerosols
2d, zonal mean, monthly fields
3d, monthly fields
monthly freq.
CMCC-CM
Historical
yearly freq.
XX sec. N2O
Global value, yearly
XX sec. CH4
Global value, yearly
XX sec. CFCs
XX sec. CO2
Global value, yearly
Global value, yearly
IPCC AR5 global projections
Climate Model Data
The Coupled Model Intercomparison Project – CMIP as climate data provider to the
Intergovernmental Panel on Climate Change IPCC Reports
http://cmip-pcmdi.llnl.gov/cmip5/availability.html
IPCC AR5 global projections
CO2
2 meter Temperature
anomaly wrt 1961-1990
Mean sea level
anomaly wrt 1961-1990
Observations since 1950
compared with projections
from the previous IPCC
assessments.
Observed globally and
annually averaged CO2
concentrations in parts per
million (in ppm)
Estimated changes in the
observed globally and
annually averaged surface
temperature anomaly relative
to 1961–1990 (in °C)
Estimated changes in the
observed global annual
mean sea level (in cm)
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World Climate Research Programme
•
About ..,
Core Projects
Co-sponsored activities ...
WMO
Sitemap
mm•
Unifying Themes ..,
IOC
Grand Challenges ..,
Key Deliverables ..,
Resources ..,
CMIP Phase 6 (CMI P6)
Overview CMIP6 Experimental Design and Organization
e
W GCM
0
About WGCM
0
Members
CM IP
The overview paper o n the CMIP6 experimental desig n and organization has now been publ shedin GMO (Eyrin g et
al., 20 16) . This C M IPS overview paper presents the b ackground and rationa le for the new structure of CM IP,
prov des a detaile d descrip t io n of the CMIP Diag nostic, Evaluation and C haracterization of Klim a (DECK)
0
About CMIP
experiments and CMIP 6 historical s im ulations, andin c lu des a b riefin troduction to the 21 CMIPS-Endorsed MIP s.
0
CMIP3
A brief summary can be fou n d in the following overview presentation (CMIP6Fina1Desig n_GMD_ 160603.pdf) and
(> CMIPS
below. After a long and wide community oonsultation, a new and more federated structure has been pu tin p lace.It
0
consists of ttYee major elements:
1. a handful of common experiments, the DECK (Diagnostic, Evaluation a nd Characterizat ion of Klima) and CMIP
CMIP 6
(> Catalogue MIP s
historical s imu
la tions (185 0 - n e ar-present) that will m ain tain continuity and help docume nt basic characteristics
(> CMIPS-Endorsed P
I s
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of models across dif ferent phases of CMIP,
2. common standards , coordination, infrastructure and docum entation that will fac i tate the d istributio n of model
(> Other a c t ive MIPs
outputs and the characterizatio n of the model e nsemble , and
>
3 . a n e nsemble of CMIP- Endorsed M o del lntercomparison Projects (MIP s} that will be specific to a particular phase
of CMIP (now CMIPS) a nd that will b uild o n the DECK and CMIP h istorical s im u
la tions to address a la rge range of
specific q uestions and fill the scientific gaps of the previous CMIP phases.
0
Fo rmer MIPa
Decadal predlctJon
(> MeetJng s
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MARINERESEARCHINSTITUTE
https ://pcmdi.llnl.gov
Golden r ules for us ing climate
model data
1. Models are “models ”, not reality. Carefully cons ider the
underlying ass umptions
2. Climate models resolve climatic features. T here is no year
1998, but the climate of the 90’s .
3. Climate s cience is based on s everal realizations becaus e
climate is intrins ically variable: do not cherr y-pick one
model unless for s pecific pur pos es
4. Cons ider the s patial resolution (gr id s ize) and temporal
frequency
5. Us e like with like. Carefully read the definition of the model
variables
Outline
• Physics
of the
climate:
a brief
introduction
Due to
induced
- additional
computational costs,
Earth System Models (ESM) run with a lower horizontal resolution
compared to Coupled General Circulation Models (CGCM),
• Anthropogenic
impacts on the past climate
but the possibility to realistically represent the Carbon Cycle
within the Climate System, gives the possibility to better
Investigate
climate
changesand
under
different
• Climate Models,
future
scenarios
projections
future emission scenarios
ESM crash course part 2: the carbon cycle
QUESTIONS !!!!!
Picture by Paola Secco
[email protected]
IPCC 4th Assessment Report (AR4, 2007)
▪Global atmospheric concentraAons of carbon dioxide, methane and nitrous
oxide have increased markedly as a result of human acAviAes since 1750 and
now far exceed pre-industrial values determined from ice cores spanning
many thousands of years. The global increases in carbon dioxide
concentraAon are due primarily to fossil fuel use and land use change, while
those of methane and nitrous oxide are primarily due to agriculture (WG1
SPM)
§ Warming of the climate system is unequivocal, as is now evident from
observa5ons of increases in global average air and ocean temperatures,
widespread mel5ng of snow and ice, and rising global average sea level (WG1
SPM)
§ From new es5mates of the combined anthropogenic forcing due to
greenhouse gases, aerosols and land surface changes, it is extremely likely
that human ac5vi5es have exerted a substan5al net warming influence on
climate since 1750. (WG1-TS6.1)
IPCC 5th Assessment Report (AR5, 2013) 1/5
▪Warming of the climate system is unequivocal, and since the 1950s, many
of the observed changes are unprecedented over decades to millennia. The
atmosphere and ocean have warmed, the amounts of snow and ice have
diminished, sea level has risen, and the concentraAons of greenhouse gases
have increased.
§ Each of the last three decades has been successively warmer at the Earth’s
surface than any preceding decade since 1850. In the Northern Hemisphere,
1983–2012 was likely the warmest 30-year period of the last 1400 years.
§ Ocean warming dominates the increase in energy stored in the climate
system, accounAng for more than 90% of the energy accumulated between
1971 and 2010 (high confidence). It is virtually certain that the upper ocean
(0−700 m) warmed from 1971 to 2010, and it likely warmed between the
1870s and 1971.
IPCC 5th Assessment Report (AR5, 2013) 2/5
▪Over the last two decades, the Greenland and AntarcAc ice sheets have been
losing mass, glaciers have conAnued to shrink almost worldwide, and ArcAc
sea ice and Northern Hemisphere spring snow cover have conAnued to
decrease in extent (high confidence).
§ The rate of sea level rise since the mid-19th century has been larger than
the mean rate during the previous two millennia (high confidence). Over the
period 1901–2010, global mean sea level rose by 0.19 [0.17 to 0.21] m.
§ The atmospheric concentraAons of carbon dioxide (CO2), methane, and
nitrous oxide have increased to levels unprecedented in at least the last
800,000 years. CO2 concentraAons have increased by 40% since pre-industrial
Ames, primarily from fossil fuel emissions and secondarily from net land use
change emissions. The ocean has absorbed about 30% of the emi" ed
anthropogenic carbon dioxide, causing ocean acidificaAon.
IPCC 5th Assessment Report (AR5, 2013) 3/5
§ Human influence on the climate system is clear. This is evident from the
increasing greenhouse gas concentraAons in the atmosphere, posiAve
radiaAve forcing, observed warming, and understanding of the climate
system.
§ Climate models have improved since the AR4. Models reproduce
observed conAnental-scale surface temperature pa " erns and trends over
many decades, including the more rapid warming since the mid-20th
century and the cooling immediately following large volcanic erupAons
(very high confidence).
§ ObservaAonal and model studies of temperature change, climate
feedbacks and changes in the Earth’s energy budget together provide
confidence in the magnitude of global warming in response to past and
future forcing.
IPCC 5th Assessment Report (AR5, 2013) 4/5
▪Human influence has been detected in warming of the atmosphere and the
ocean This evidence for human influence has grown since AR4. It is extremely
likely that human influence has been the dominant cause of the observed
warming since the mid-20th century.
§ ConAnued emissions of greenhouse gases will cause further warming and
changes in all components of the climate system. LimiAng climate change will
require substanAal and sustained reducAons of greenhouse gas emissions.
§ Global surface temperature change for the end of the 21st century is likely
to exceed 1.5°C relaAve to 1850 to 1900 for all RCP scenarios except RCP2.6.
It is likely to exceed 2°C for RCP6.0 and RCP8.5, and more likely than not to
exceed 2°C for RCP4.5. Warming will conAnue beyond 2100 under all RCP
scenarios except RCP2.6. Warming will conAnue to exhibit interannual-todecadal variability and will not be regionally uniform.
IPCC 5th Assessment Report (AR5, 2013) 5/5
▪Changes in the global water cycle in response to the warming over the 21st
century will not be uniform. The contrast in precipitaAon between wet and
dry regions and between wet and dry seasons will increase, although there
may be regional excepAons.
§ The global ocean will conAnue to warm during the 21st century. Heat will
penetrate from the surface to the deep ocean and affect ocean circulaAon.
§ It is very likely that the ArcAc sea ice cover will conAnue to shrink and thin
as global mean surface temperature rises. Global glacier volume will further
decrease.
§ Global mean sea level will conAnue to rise during the 21st century. Under
all RCP scenarios the rate of sea level rise will very likely exceed that observed
during 1971–2010 due to increased ocean warming and increased loss of
mass from glaciers and ice sheets.
▪ Most aspects of climate change will persist for many centuries even if
emissions of CO2 are stopped. This represents a substanAal mulA-century
climate change commitment created by past, present and future emissions of
CO2.
The RadiaAve Balance
A Phase space view
Intergovernmental Panel on Climate Change: the 5th Assessment Report
IPCC – AR5
WG II:
Impacts, Adaptation,
and Vulnerability
WG I:
The Physical Science
Basis
WG III:
Mitigation of
Climate Change
Observed Changes in the Climate System
Key SPM Messages
19 Headlines
on less than 2 Pages
Summary for Policymakers
ca. 14,000 Words
14 Chapters
Atlas of Regional Projections
54,677 Review Comments
by 1089 Experts
2010:
259 Authors Selected
2009:
WGI Outline Approved
Observed Changes in the Climate System
WGI - IPCC 5° Assessment Report
Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are
unprecedented over decades to millennia. The atmosphere and ocean have warmed, the amounts of snow
and ice have diminished, sea level has risen, and the concentraAons of greenhouse gases have increased.
Ocean warming dominates the increase in energy stored in the climate system, accounting for
more than 90% of the energy accumulated between 1971 and 2010 (high confidence). It is virtually
certain that the upper ocean (0–700 m) warmed from 1971 to 2010.
Over the last two decades, the Greenland and Antarc4c ice sheets have been losing mass, glaciers have
conAnued to shrink almost worldwide, and Arc4c sea ice and Northern Hemisphere spring snow cover have
conAnued to decrease in extent (high confidence).
The rate of sea level rise since the mid-19th century has been larger than the mean rate during the previous
two millennia (high confidence). Over the period 1901 to 2010, global mean sea level rose by 0.19 [0.17 to
0.21] m.
The atmospheric concentra4ons of carbon dioxide, methane, and nitrous oxide have increased to levels
unprecedented in at least the last 800,000 years. Carbon dioxide concentra4ons have increased by 40% since
pre-industrial 4mes, primarily from fossil fuel emissions and secondarily from net land use change emissions.
The ocean has absorbed about 30% of the emiS ed anthropogenic carbon dioxide, causing ocean acidificaAon.
Changes in surface temperature
Figure SPM.1a
Observed globally averaged combined land and ocean surface
temperature anomaly 1850-2012
All Figures © IPCC 2013
Figure SPM.1b
Observed change in surface temperature 1901-2012
Changes in Criosphere and Oceans
Figure SPM.3
MulAple observed indicators of a changing global climate
All Figures © IPCC 2013
Climate change: detecAon and a " ribuAon
• Climate change refers to any change (mean state and/
or variability) in climate over time (sufficiently long ..
30years! ), whether due to natural variability or as a
result of human activity
• Detection of climate change is the process of
demonstrating that climate has changed in some defined
statistical sense, without providing a reason for that
change.
• Attribution of causes of climate change is the process
of establishing the most likely causes for the detected
change with some defined level of confidence (Chapter
1, AR5, IPCC WG1)
Extreme Events
• “There are a number of ways extreme climate events
can be defined, such as extreme daily temperatures,
extreme daily rainfall amounts, large areas
experiencing unusually warm monthly
temperatures, or even storm events such as
hurricanes. Extreme events can also be defined by
the impact an event has on society. That may involve
excessive loss of life, excessive economic or monetary
losses or both.” (Easterling et al. 2000)
Convection
What happens to the particles in a liquid or
a gas when you heat them?
The particles spread out
and become less dense.
This effects fluid movement.
What is a fluid?
A liquid or gas.
Fluid movement
Cooler, more dense,
fluids sink through
warmer, less dense
fluids.
In effect,
warmer liquids and gases rise up.
Cooler liquids and gases sink.