Download Change - UNDP Climate Change Adaptation

C LIMATE C HANGE : T HE SCIENCE
UNDP-GEF CBA Workshop
June 30 2009
Michael A. Taylor
Climate Studies Group, Mona
Department of Physics
University of the West Indies, Mona
1
QUIZ #1
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Context
Why Change?
How Change?
More Change?
We Change?

Weather, climate, climate variability, climate
change – all these terms are sometimes
confusing.
A.
Yes
B.
No
C.
Not really, but remind me anyway
about them.
W EATHER AND C LIMATE
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
Why Change?
Weather

Day to day (short term) changes in meteorological parameters –
rainfall, temperatures, pressure, etc.

Often perceived in terms of extreme events: heat waves,
downpours, cold spells .
How Change?
More Change?
We Change?

Climate

Commonly defined as the “average weather”. Mean and
variability of weather over a periods of time ranging from
months to thousand/millions of years.

That concerning the status of the entire Earth system,
(atmosphere, land, oceans, snow, ice and living things) which
serve as the global background condition for determining
weather patterns (IPCC 2007)
VARIABILITY AND C HANGE
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Why Change?
How Change?
More Change?
We Change?
Regular
Long Term
Irregular
Trendy
VARIABILITY AND C HANGE
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
In any climate timeseries multiple timescales of variation exist.
Why Change?

Climate Variability - Regular, Irregular, Long Term
How Change?

Timescales that are ‘short term’ – seasonal, annual,
interannual (every few years), even decadal. – ENSO, AMO,
PDV

Good harbinger for climate change impacts.
More Change?
We Change?

Climate Change – Trendy


Distinct changes in measures of climate lasting for a long
period of time e.g. major changes in temperature, rainfall,
snow, or wind patterns lasting for decades or longer.
Variability and Change and Weather Extremes interrelated.
Will examine climate change.
QUIZ #2
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Why Change?

Possible contributors to Climate Change include:
How Change?
More Change?
We Change?
A.
Changes in the earth’s orbit
B.
Volcanic eruptions
C.
Burning of fossil fuels
D.
All of the above
C LIMATE
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Why Change?
How Change?
More Change?
We Change?
CAN CHANGE DUE TO ...
Natural
Variations
Volcanic Eruptions
Human Activity
•Changes in the
earth’s orbit
•Alter aerosols in the
atmosphere (block sunlight) …
not long term effect.
•Changing land cover
(reflective properties of
earth).
•Alter carbon dioxide
concentrations (CO2)
•Altering aerosol
concentrations.
•Alter aerosols in the
atmosphere (block sunlight) …
not long term effect.
•Post Industrial Revolution
(~1750). Burning of fossil
fuels and biomass has
altered the composition of
the atmosphere primarily
through the addition of
greenhouse gases.
•Changes in solar
intensity
•Preindustrialized
era e.g. Ice Ag
•Alter carbon dioxide
concentrations (CO2)
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Why Change?
How Change?
G REENHOUSE
GASES ?
Purpose: Glass house to
keep plants warm during
winter.
How works?
More Change?
•Sun’s rays hit the glass
We Change?
•Some rays immediately
reflected
•Some pass through glass
and reach plants. Inside
gets hot.
•Heat cannot escape due
to glass.
•Glass very important!!!
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Why Change?
How Change?
G REENHOUSE
GASES ?
Atmosphere around earth is
like the glass!!!
How works?
More Change?
• Solar radiation hits
atmosphere
We Change?
•30% reflected. 70% reaches
the earth
•Earth warms and gives off
heat.
•Certain gases in atmosphere
prevent most of heat
escaping. E.g. CO2, methane,
H2O, ozone, nitrous oxide
Called greenhouse gases!!!
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G REENHOUSE
GASES ?
Context
Why Change?
How Change?
More Change?
We Change?
Greenhouse effect is not a
bad thing = warm
(habitable) earth!!
Problem
Since the Industrial
Revolution humans have
added a significant amount
of greenhouse gases in the
atmosphere by burning fossil
fuels, cutting down forests
and other activities.
G REENHOUSE
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GASES ?
Context
Why Change?
How Change?
More Change?
We Change?
CO2
CH4
A 36% Increase from pre-industrial times.
Almost all of the increase is due to human
activities (IPCC, 2007) .
Now 148% above pre-industrial
levels. (IPCC, 2007) .
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G REENHOUSE
GASES ?
Context
Why Change?
How Change?
More Change?
We Change?
Radiative
Forcing
How the energy
balance of the
earthatmosphere
system is altered
by factors that
affect climate.
G REENHOUSE
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GASES ?
Context
Why Change?
How Change?
More Change?
We Change?
IPCC (2007)
It is extremely unlikely (<5%) that the global pattern of
warming during the past half century can be explained
without external forcing, and very unlikely that it is due
to known natural external causes alone.
QUIZ #3
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Why Change?
How Change?
More Change?
We Change?

Which of the following changes has been
observed in the last century:
A.
Warmer temperatures
B.
More rain
C.
Less rain
D.
All of the above
E.
None of the above
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G LOBAL WARMING
Context
Why Change?
How Change?
More Change?
We Change?
Global warming is an average increase in temperatures near the Earth’s
surface and in the lowest layer of the atmosphere.
G LOBAL WARMING
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Why Change?
How Change?
More Change?
We Change?
IPCC:
Global warming is unequivocal!
There is a greater than 90 percent chance that most of the warming
we have experienced since the 1950s is due to the increase in
greenhouse gas emissions from human activities.
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T EMPERATURES
Context
Why Change?
How Change?
More Change?
We Change?
• Global mean surface temperatures
continue to rise.
• Earth is 0.75 degrees warmer
than in 1860.
• 11 of the last 12 years rank among
the 12 warmest years on record
since 1850.
• 7 of 8 warmest years on record
have occurred since 2001.
• In last 30 years, the rate of
warming across the globe has been
approximately 3 x greater than the
rate over the last 100 years.
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T EMPERATURES
Context
Why Change?
How Change?
More Change?
We Change?
• The warming trend is seen in
both daily maximum (day time)
and minimum (night time)
temperatures.
•Minimum temperatures
increasing at a faster rate than
maximum temperatures.
•Land areas have tended to
warm faster than ocean areas.
•‘Winter’ months have warmed
faster than summer months.
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S EA L EVEL R ISE
Context
Why Change?
How Change?
More Change?
We Change?
Primary factors driving current
sea level rise include:
•the expansion of ocean
water caused by warmer
ocean temperatures
•melting of mountain
glaciers and small ice caps
•(to a lesser extent)
melting of the Greenland
Ice Sheet and the
Antarctic Ice Sheet
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S EA L EVEL R ISE
Context
IPCC (2007)
Why Change?
How Change?
More Change?
We Change?
•Most of the Pacific and Atlantic
basins are experiencing average to
above-average sea level rise.
•the rate of observed sea level rise
increased from the mid 19th to
the mid 20th century. During the
20th century, sea level rose at an
average rate of 4.8 to 8.8 inches
per century (1.2-2.2 mm/year)
• Satellite measurements estimate
that sea level has been rising at a
rate of 9 to 15 inches per century
(2.4-3.8 mm/yr) since 1993.
R AINFALL
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Why Change?
How Change?
More Change?
We Change?
Rainfall patterns changing.
IPCC (2007)
•Significant changes in
amount, intensity, frequency
and type of precipitation.
•Trends vary widely by region
and over time.
•Precipitation strongly
modulated by variability e.g.
ENSO.
•Globally there has been no
statistically significant overall
trend in precipitation over the
past century.
R AINFALL
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Why Change?
How Change?
More Change?
We Change?
Rainfall patterns changing.
IPCC (2007)
•Precipitation has generally
increased over land north of
30°N from 1900-2005, but has
mostly declined over the
tropics since the 1970s.
•Wetter in eastern North and
South America, northern
Europe and northern and
central Asia, but drier in the
Sahel, southern Africa, the
Mediterranean and southern
Asia.
•More precipitation now falls
as rain rather than snow in
northern regions.
R AINFALL
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Why Change?
How Change?
More Change?
We Change?
Proportion of heavy rainfall is
increasing over many land
areas
IPCC (2007)
•There has been an increase in the
number of heavy precipitation
events over many areas during the
past century, as well as an increase
since the 1970s in the prevalence
of droughts — especially in the
tropics and subtropics.
•The long-term record emphasizes
that patterns of precipitation vary
from year to year, and even
prolonged multi-year droughts are
usually punctuated by a year of
heavy rains; for instance as El Niño
influences are felt.
E XTREME E VENTS
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IPCC (2007)
Why Change?
•Since 1950, the number of heat waves
has increased and widespread increases
have occurred in the numbers of warm
nights.
How Change?
More Change?
•The extent of regions affected by
droughts has increased as precipitation
over land has marginally decreased .
We Change?
•Tropical storm and hurricane
frequencies vary considerably from
year to year, but evidence suggests
substantial increases in intensity
and duration since the 1970s.
• Generally, numbers of heavy daily
precipitation events that lead to flooding
have increased, but not everywhere.
•In the extratropics, variations in tracks
and intensity of storms reflect variations
in major features of the atmospheric
circulation, such as the North Atlantic
Oscillation.
C ARIBBEAN E XAMPLE
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Why Change?
Study done at UWI and
NCDC
How Change?
More Change?
•Tmax, Tmin, rainfall station
data. 1950-2000
We Change?
Peterson, T. C., M. A. Taylor, et al., 2002:
Recent changes in climate extremes in
the Caribbean region, J. Geophys. Res.,
107(D21)
•Looking if climate extremes
have changed in Caribbean in
recent history.
C ARIBBEAN E XAMPLE
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Why Change?
How Change?
More Change?
We Change?
•Frequency of Hot days and
hot nights increasing (nights >
days)
•Frequency of cool days and
nights decreasing
• Trendlines significant at 1% level
•Frequency of cool days and nights decreasing
•True for rest of world.
QUIZ #4
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Why Change?

A climate model is:
How Change?
More Change?
A.
A tool to help us determine future
climates
B.
A person hired by IBM to show their
product
C.
A person hired by Mac to show their
product
We Change?
C LIMATE M ODELS
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COMPUTER MODELS
Why Change?
•A set of physics based
equations to describe
processes of atmosphere.
How Change?
More Change?
We Change?
•Prescribed boundary and
initial conditions.
•Start with real time and
simulate into future (most
times to end of century).
•Can produce projections of
rainfall, temperature, wind,
pressure, cloud cover, humidity
and a suite of other variables
for a day, month, or a year in
the future.
C LIMATE M ODELS
Context
Why Change?
How Change?
More Change?
We Change?
General Circulation Models (GCMs)
Regional Climate Models (RCMs)
•Horizontal resolution: 250-600 km
•10-20 vertical layers in the
atmosphere
•As many as 30 ocean layers
•Use outputs from GCM as
boundary conditions
•Horizontal resolution: 25-50 km
•Small islands can be resolved.
E MISSION S CENARIOS
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Why Change?
How Change?
•To generate projections with
More Change?
the climate models we have to
We Change?
make up stories about how the
world will evolve in the future.
SCENARIOS = STORYLINES
E MISSION S CENARIOS
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Why Change?
How Change?
More Change?
We Change?
Most common: IPCC Special
Report of Emissions Scenarios
(SRES)
•Storylines depend on what
population growth, energy use,
economic development and
technology could look like in the
future.
•A and B families are created to
represent different storylines
with similar attributes.
•Storylines give us estimate of
future greenhouse gas
concentrations.
E MISSION S CENARIOS
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Why Change?
How Change?
More Change?
We Change?
A2 (High Emissions)
•Continuously increasing
population
•Regionally oriented
economic development
•Technological change
more fragmented
A1B (Intermediate Emissions)
•Global population peaks
in mid-century and
declines thereafter
•Rapid economic growth
•Balance across fossil and
non-fossil energy sources
None involves the stabilization
of concentrations of
greenhouse gases!!
B1 (Low Emissions)
•Population peaks mid-century and
declines thereafter
•Rapid change towards a service and
information economy
•Introduction of clean and efficient
technologies
P ROJECTIONS
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Why Change?
How Change?
More Change?
We Change?
Models
+
Scenarios
=
Future Climate
Projection: A potential future evolution of a quantity or set of quantities. Not
the same as a Prediction since projections involve some assumptions about the
future –and are therefore open to a great deal of uncertainty.
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T EMPERATURES
Context
Why Change?
How Change?
Emission Scenarios
More Change?
We Change?
Commitment
No increase in greenhouse
gas concentrations from
2000
T EMPERATURES
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Why Change?
Near-term warming projections are
little affected by different scenario
assumptions. By 2030 change lies in
narrow range of 0.64°C to 0.69°C .
How Change?
More Change?
We Change?
End of century
Commitment = 0.6 degrees
Best-Worst: 1.5 – 5 degrees
T EMPERATURES
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Why Change?
Geographic patterns show greatest
temperature increases at high
northern latitudes and over land, with
less warming over the southern
oceans and North Atlantic.
How Change?
More Change?
We Change?
Global mean surface
temperatures
End of century (A18 medium emissions
scenario)
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R AINFALL
Context
Why Change?
How Change?
More Change?
We Change?
Regional changes (+/-) of up to 20% in
average rainfall
Generally, robust large-scale patterns:
precipitation generally increases in
the tropical precipitation maxima,
decreases in the subtropics and
increases at high latitudes as a
consequence of a general
intensification of the global
hydrological cycle.
But…
Model projections for extremes of precipitation show larger ranges in
amplitude and geographical locations than for temperature.
The response of some major modes of climate variability such as ENSO differs
from model to model.
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Why Change?
How Change?
More Change?
We Change?
S EA L EVEL R ISE
•Sea level will continue
to rise in the 21st
century because of
thermal expansion and
loss of land ice.
•Sea level rise was not
geographically uniform
in the past and will not
be in the future.
•Projected warming due to emission of greenhouse gases during the 21st
century will continue to contribute to sea level rise for many centuries.
•Sea level rise due to thermal expansion and loss of mass from ice sheets
would continue for centuries even if radiative forcing were to be stabilised.
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Why Change?
How Change?
More Change?
We Change?
E XTREMES
•Type, frequency and intensity of extreme
events are expected to change as Earth’s
climate changes.
•Changes could occur even with relatively
small mean climate changes.
•Changes in some types of extreme events
have already been observed .
Other…
Heat waves become more frequent and longer lasting in a future warmer climate.
Increased summer dryness and winter wetness in most parts of the northern
middle and high latitudes
Precipitation tends concentrated into more intense events, with longer periods of
dry in between .
Evidence from modelling studies that future tropical cyclones could become more
severe, with greater wind speeds and more intense precipitation.
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C ARIBBEAN E XAMPLE
Context
Why Change?
How Change?
More Change?
We Change?
End of century temperature change (PRECIS RCM)
•Irrespective of scenario Caribbean expected to warm
•Warming between 1and 5 degrees.
•Warming greater under A2 scenario
•Warming consistent with projections for other parts of the globe
C ARIBBEAN E XAMPLE
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Why Change?
How Change?
More Change?
We Change?
End of century % rainfall change (PRECIS RCM)
•For both scenarios Caribbean is in general drier.
•Up to 30% drier.
•Drying more severe under A2 scenario
•Far north Caribbean however could be wetter
QUIZ #5
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Why Change?

In light of all this, should we be concerned?
How Change?
More Change?
We Change?
A.
Yes
B.
Absolutely yes
C.
Yeah Man!
D.
This is a rhetorical question, right?
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C ONFIDENCE
Context
In light of everything, should we change how we operate?
Why Change?
Perhaps depends on how confident we are about the projected changes.
How Change?
More Change?
We Change?
Confidence in the models comes from the following:
1. Model fundamentals are based on established physical laws, such as
conservation of mass, energy and momentum, along with a wealth of
observations.
2. Models ably simulate important aspects of the current climate. Reasonable skill
in representing important features of the general circulation across shorter time
scales, and aspects of seasonal and interannual variability.
3. Models ably reproduce features of past climates and climate changes.
4. Over several decades models have consistently provided a robust and
unambiguous picture of significant climate warming in response to increasing
greenhouse gases.
C ONFIDENCE
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Why Change?
How Change?
More Change?
We Change?
So…
Though models still show significant errors (mainly due to
important small-scale processes not being represented
explicitly in models) there is considerable confidence
that they are able to provide credible quantitative
estimates of future climate change, particularly at
larger scales.
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Why Change?
How Change?
More Change?
We Change?
I MPACT
WILL BE WIDELY
F ELT...
C ARIBBEAN
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EXAMPLE
Context
Dengue
Why Change?
How Change?
Time Series of Reported Cases In the Caribbean
More Change?
10000
9000
We Change?
Reported Cases (RC)
8000
7000
Caribbean problem!
6000
5000
4000
3000
2000
1000
0
2004
2002
2000
1998
1996
1994
1992
1990
1988
1986
1984
1982
1980
Year
C ARIBBEAN
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EXAMPLE
Context
More Change?
We Change?
32
Rainfall
Dengue Cases
Average Temperature
1200
31
1000
30
800
29
600
28
400
27
200
26
0
25
0
1996
20
1997
40
1998
60
2000
1999
80
2001
Year
Hot  Wet  Dengue
2002
100
2003
Average tempertaure (C)
How Change?
1400
Rainfall (mm)
Reported dengue
Why Change?
Time series graph of rainfall, dengue cases & average temperature
(4-Week periods in Trinidad & Tobago)
C ARIBBEAN
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EXAMPLE
CARRIBEAN REPORTED CASES AND RATE OF
Why Change?
CHANGE (1980-2004)
10000
Annual Totals
Rate of change
8000
More Change?
We Change?
Reported Cases/Rate of Change
How Change?
6000
4000
2000
0
1980
1985
1990
1995
2000
-2000
-4000
-6000
Year
Linkage to El Niño
Due to rainfall and temperature changes
2005
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C ARIBBEAN
EXAMPLE
Context
Why Change?
How Change?
More Change?
We Change?
Estimated that a future 2 degree rise in
temperature will cause an increase in
incidence of dengue in the Caribbean
region.
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S UMMARY
Context
Why Change?
How Change?
More Change?
We Change?
Why the Change?
Greenhouse gas forcing has very likely caused most of
the observed global warming over the last 50 years.
How has the Change been manifested to date?
Global mean surface temperatures continue to rise.
Eleven of the last 12 years rank among the 12 warmest
years on record since 1850.
Other changes in precipitation patterns, sea levels
and extreme events have also been observed.
Will there be More Change in the future?
Even if concentrations of radiative forcing agents were to be
stabilised, further committed warming and related climate
changes would be expected to occur.
S UMMARY
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Should We Change our mode of operating?
Why Change?
How Change?
More Change?
We Change?
We live in a climate sensitive world. This
makes us vulnerable to climate variability and
change. It would be foolish to continue to
operate as normal. We must begin to consider
appropriate actions to enable quality lifestyles
in the future.
QUIZ #6
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Why Change?

Is this the end of this talk?
How Change?
More Change?
We Change?
A.
Yes
B.
Yes
C.
Yes
D.
No, let’s start it all again
END
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Why Change?
How Change?
More Change?
We Change?
Thank You