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Global Warming: It

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Global Warming: It s Later Than We Think But It s Not Too Late Anthony J. Broccoli Director, Center for Environmental Prediction Department of Environmental ... – PowerPoint PPT presentation

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Title: Global Warming: It


1
Global Warming Its Later Than We ThinkBut Its
Not Too Late
  • Anthony J. Broccoli
  • Director, Center for Environmental
    PredictionDepartment of Environmental Sciences
  • Rutgers University
  • Pulse of the Planet Lecture SeriesLiberty
    Science Center, Jersey City, NJJanuary 26, 2008

2
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Temperatures in the New York City area in the
past 30 days have beena) more than 2F below
normalb) within 1F of normalc) about 3F above
normald) more than 6F above normal
4
Temperatures in the New York City area in the
past 30 days have beena) more than 2F below
normalb) within 1F of normalc) about 3F above
normald) more than 6F above normal
5
Source NOAA Climate Prediction Center
6
Source NOAA Climate Prediction Center
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11
The unequivocal detection of the enhanced
greenhouse effectfrom observations is not likely
for a decade or more. Climate Change The IPCC
Scientific Assessment (1990)
The balance of evidence suggests a discernible
human influence on global climate. Climate
Change 1995 The Second Assessment of the
Intergovernmental Panel on Climate Change (IPCC)
Most of the observed warming over the last 50
years is likely to have been due to the increase
in greenhouse gas concentrations. Climate Change
2000 The Third Assessment Report of the IPCC
Most of the observed increase in globally
averaged temperaturessince the mid-20th century
is very likely due to theobserved increase in
anthropogenic greenhouse gas concentrations. Clim
ate Change 2007 The Fourth Assessment Report of
the IPCC
12
The IPCCs conclusion that the observed warming
is very likely due to increasing greenhouse gases
an that further warming is on the way is based
ona) laboratory measurementsb) results from
computer modelsc) climate observations d) all
of the above
13
The IPCCs conclusion that the observed warming
is very likely due to increasing greenhouse gases
an that further warming is on the way is based
ona) laboratory measurementsb) results from
computer modelsc) climate observations d) all
of the above
14
What Are Climate Models?
15
It is extremely unlikely that global climate
change of the past fifty years can be explained
without external forcing.
Blue Natural Pink Natural Human-induced
16
Projections of Future Climate
Variations among colored lines represents
uncertainty due to uncertainty in future
emissions.
17
Simulating Future Climate Change
Source NOAA Geophysical Fluid Dynamics Laboratory
18
Potential Climate Change Impacts
19
Global Impacts of Climate Change
Report by IPCC Working Group II on Impacts,
Adaptation and Vulnerability was released on 6
April 2007. Some of the highlights from this
report
  • There will be some winners, but more losers
  • Densely populated coastal regions will face
    increased pressures from sea level rise and more
    extreme weather
  • Poor communities and stressed ecosystems will
    suffer most, as they are already living on the
    edge
  • 60 of worlds species are already responding to
    change

20
Global Impacts of Climate Change
Report by IPCC Working Group II on Impacts,
Adaptation and Vulnerability was released on 6
April 2007. Some of the highlights from this
report
  • There will be some winners, but more losers
  • Densely populated coastal regions will face
    increased pressures from sea level rise and more
    extreme weather
  • Poor communities and stressed ecosystems will
    suffer most, as they are already living on the
    edge
  • 60 of worlds species are already responding to
    change

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Sea Level Trends in New Jersey
Atlantic City, NJ
Source National Oceanic and Atmospheric
Administration
NJ sea level rise global sea level rise
other effects 0.4 m/century 0.16
m/century 0.24 m/century
23
Why is global sea level rising?a) the density
of the ocean is decreasingb) sea ice is melting
rapidlyc) mountain glaciers are meltingd) the
Greenland and Antarctic ice sheets are melting
24
Why is global sea level rising?a) the density
of the ocean is decreasingb) sea ice is melting
rapidlyc) mountain glaciers are meltingd) the
Greenland and Antarctic ice sheets are melting
25
Why Is Global Sea Level Rising?
  • Thermal expansion
  • Warmer water is less dense than colder water.
  • Melting of glaciers and ice caps
  • Water released by the melting of ice on land
    adds to the volume of the oceans.
  • Melting and calving of Greenland and Antarctic
    ice sheets
  • Depends on the ice sheet dynamics (how the ice
    flows).

26
Why Is Global Sea Level Rising?
  • Thermal expansion
  • Warmer water is less dense than colder water.
  • Melting of glaciers and ice caps
  • Water released by the melting of ice on land
    adds to the volume of the oceans.
  • Melting and calving of Greenland and Antarctic
    ice sheets
  • Depends on the ice sheet dynamics (how the ice
    flows).

27
Why Is Global Sea Level Rising?
  • Thermal expansion
  • Warmer water is less dense than colder water.
  • Melting of glaciers and ice caps
  • Water released by the melting of ice on land
    adds to the volume of the oceans.
  • Melting and calving of Greenland and Antarctic
    ice sheets
  • Depends on ice sheet dynamics (how the ice
    flows).

28
Effects of Sea Level Rise on the Coastal
Environment
Land area susceptible to inundation
Land area susceptible to coastal flooding (30-yr
flood)
Source M. D. Beevers, U.S. Climate Change
Science Program Workshop, Nov. 2005
29
Ash Wednesday Storm
Harvey Cedars, March 1962
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3 of 7 largest floodssince 2004
32
Warmer? MorePrecipitation
Warmer? MoreEvaporation
33
there is an increased chance of intense
precipitation and flooding due to the greater
water-holding capacity of a warmer atmosphere.
This has already been observed and is projected
to continue because in a warmer world,
precipitation is concentrated into more intense
events IPCC Fourth Assessment, 2007
34
IPCC It is very likely that hot extremes, heat
waves, and heavy precipitation events will
continue to become more frequent.
Changes in number of days with heat waves from
UCS Northeast Climate Impacts Assessment
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Future Emissions Scenarios
Some scenarios showdecreased emissionsin latter
half of 21stcentury
Even with aggressivereductions in emissions,CO2
would rise to 2xpreindustrial levels
All scenarios showincreasing emissionsduring
next severaldecades
38
More Warming in the Pipeline
Future emissions
Additional zero-emission warming (aka
commitment)
Warming to date
39
Psychological Barriers?
  • Climate change is not the result of malevolence.
  • Climate change does not violate our moral
    sensibilities (i.e., cultural taboos).
  • Climate change is perceived as a future rather
    than an immediate threat.
  • Climate change proceeds gradually.

Source Daniel Gilbert, Harvard University, Los
Angeles Times, July 2006
40
What actions would you favor for reducing the
threat of climate change?a) increase energy
efficiencyb) capture and sequester CO2 from
fossil fuel burningc) increase nuclear power
generationd) build more wind turbines and solar
power systems
41
What actions would you favor for reducing the
threat of climate change?a) increase energy
efficiencyb) capture and sequester CO2 from
fossil fuel burningc) increase nuclear power
generationd) build more wind turbines and solar
power systems
42
Wedges
Billion of Tons of Carbon Emitted per Year
14
14 GtC/y
Currently projected path
Seven wedges
O
Historical emissions
7 GtC/y
7
Flat path
1.9 ?
0
2106
2056
2006
1956
Source S. Pacala and R. Socolow, Princeton Univ.
43
15 Different Technologies Already in the
Marketplace at Industrial Scale
Coal to Gas
44
The Global Warming Dilemma(J. Mahlman, In
Solutions for an Environment in Peril,
2002) There are no quick policy fixes,
nationally or globally. If we don't begin to
chip away at the problem soon, it is very likely
that serious consequences will be wired in for
the world of our great-grandchildren and for
their great-grandchildren.... The long time
scales and robustness of the problem almost
guarantees that our descendants in the 22nd
century will, with historical perspective, see
that we were actually confronted with a major
planet-scale stewardship/ management
problem. They will most assuredly note how we
responded, or how we did not respond to the
problem.
45
The climate is changing
46
Why Is Global Sea Level Rising?
  • Melting Glaciers and Ice Caps
  • Water released by the melting of ice on land adds
    to the volume of the oceans.

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Global Warming and the Hydrologic Cycle
  • The downward flux of radiative energy (i.e.,
    sunlight and infrared radiation) at the surface
    is balanced by evaporation and sensible heating
    of the atmosphere.
  • If the downward flux of energy increases, then
    evaporation will increase.
  • On a global basis, evaporation and precipitation
    must balance.
  • Thus as the earth warms, both evaporation and
    precipitation will increase.

49
Warmer? MorePrecipitation
Warmer? MoreEvaporation
50
Detection Attribution
Projection
51
Rahmstorf, Stefan, et al., 2007 Recent climate
observations compared to projections.
Science.Published online 2 February 2007,
10.1126/science.1136843 Dashed lines and gray
shading are 2001 TAR projections. Colored lines
are observations. While CO2 is increasing as
projected, temperature is increasing a little
more than all the scenarios. Sea level closely
follows the upper gray dashed line, the upper
limit referred to by IPCC as including land-ice
uncertainty. Note that the rate of rise for the
last 20 years of the reconstructed sea level is
25 faster than the rate of rise in any 20 year
period in the preceding 115 years.
52
Global mean sea level changes
53
  • Changes in Heat Index
  • The heat index combines the effects of
    temperature and humidity to estimate human
    comfort.
  • Results are from simulations with three global
    climate models with two emissions scenarios,
    representing the low and high ends of the IPCC
    range.
  • Under the high emissions scenario, Tri-State
    summers at the end of the 21st century are
    projected to be similar to those in Savannah,
    Georgia today.

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55
Simulated Changes in Precipitation
Relative changes in precipitation () for the
period 20902099, relative to 19801999.
Stippled areas are where more than 90 of the
models agree in the sign of the change.
Increased frequency of heavy precipitation events
over most areas Very likely
More areas affected by drought Likely
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