Transcript US National Academy of Sciences - Climate Science Program

Recent Observed and Projected Future Climate
Trends for the Midwest:
Agricultural Impacts
Eugene S. Takle
Director, Climate Science Initiative
Professor of Atmospheric Science
Department of Geological and Atmospheric Sciences
Professor of Agricultural Meteorology
Department of Agronomy
Iowa State University
Ames, Iowa 50011
[email protected]
Climate Change and Its Impacts on Food Production and Biofuels
Ames, Iowa
2 March 2010
“I hear so many
conflicting views on
climate change,
I don’t know what or
who to believe”
Soybean producer from NE Iowa
US National Academy of Sciences
 Established on 3 March 1863 by Abraham
Lincoln
 Act of Incorporation: to "investigate, examine,
experiment, and report upon any subject of
science or art" whenever called upon to do so
by any department of the government
 June 2001: National Academy of Sciences
Committee on the Science of Climate Change
concludes that human-induced global warming
is a serious issue
[http://www.nasonline.org/site/DocServer/speech2002.pdf?docID=121]
http://www.nasonline.org/
US National Academy of Sciences
 "Human activities ... are modifying the concentration
of atmospheric constituents ... that absorb or scatter
radiant energy. ... [M]ost of the observed warming
over the last 50 years is likely to have been due to
the increase in greenhouse gas concentrations” (NAS,
2001: p. 21)
 "The IPCC's conclusion that most of the observed
warming of the last 50 years is likely to have been
due to the increase in greenhouse gas concentrations
accurately reflects the current thinking of the
scientific community on this issue” (NAS, 2001: p. 3)
National Academy of Sciences Committee on the Science of Climate Change,
2001: Climate Change Science: An Analysis of Some Key Questions.
National Academy Press, Washington, DC.
A critical examination of climate modeling as a
basis for assessing climate change
 Morning session:
 The scientific basis underpinning climate change
projections for the 21st century
 Recent trends in Midwest climate relating to
agriculture and farmer adaptations
 Afternoon sessions:
 Limitations of climate models (Arritt)
 Recent mild summers: What’s going on? (Anderson)
 Emerging climate forecasting techniques
(applications maybe you hadn’t thought
about)(Gutowski)
Presenters collectively have over 50 years of global and
regional climate modeling research experience
In science, the
prevailing theory is
the one that explains
the balance of
evidence
What is the evidence?
Global Mean Surface Temperature
http://www.ncdc.noaa.gov/img/climate/research/2008/ann/global-jan-dec-error-bar-pg.gif
Global Mean Surface Temperature
http://www.ncdc.noaa.gov/img/climate/research/2008/ann/global-jan-dec-error-bar-pg.gif
Global Mean Surface Temperature
http://www.ncdc.noaa.gov/img/climate/research/2008/ann/global-jan-dec-error-bar-pg.gif
NASA
http://data.giss.nasa.gov/gistemp/graphs/
Source: IPCC, 2001: Climate Change 2001: The Scientific Basis
Source: IPCC, 2001: Climate Change 2001: The Scientific Basis
Temperature Trends in Upper and Lower
Atmosphere
Upper
Atmosphere
(Stratosphere)
Lower
Atmosphere
(Troposphere)
“One of the clearest trends in the
United States observational record
is an increasing frequency and
intensity of heavy precipitation
events… Over the last century
there was a 50% increase in the
frequency of days with
precipitation over 101.6 mm (four
inches) in the upper midwestern
U.S.; this trend is statistically
significant “
Karl, T. R., J. M. Melillo, and T. C. Peterson, (eds.), 2009:
Global Climate Change Impacts in the United States.
Cambridge University Press, 2009, 196pp.
Arctic Sea-Ice Decline
Decline in Greenland Ice Mass
Equivalent to about 5 ft of
ice over the state of Iowa
each year
Tropical Atlantic Ocean
Hurricane Power Dissipation Index (PDI)
Sea-surface temperature
V
V
V
Emanual, Kerry, 2005: Increasing destructiveness of tropical cyclones
over the past 30 years. Nature, 436, 686-688.
Ocean Heat Content
1oC rise in top 3 m of global
ocean is equivalent to a 1oC
rise in entire atmosphere
Where is this extra
heat coming from?
Possible
mechanisms:
• More solar radiation
• Less reflection from clouds
• Less reflection from Earth’s
surface
• More energy trapped and
recycled by ozone and
greenhouse gases
Earth’s Energy Balance:
Incoming solar = outgoing infrared
radiation
But rapid changes in atmosphere and
ocean temperatures and loss of land
and sea ice indicate an imbalance
?
Earth’s Energy Balance:
Incoming solar = outgoing infrared
radiation
But rapid changes in atmosphere and
ocean temperatures and loss of land
and sea ice indicate an imbalance
?
?
?
0.1
%
*Other solar cycles have periods of 22,000, 41,000, and 100,000
Forcing Factors in the Global Climate
More trapped
(recycled) heat
More cloud &
land reflection
See Arritt for details
this afternoon
Karl, T. R., J. M. Melillo, and T. C. Peterson, (eds.), 2009: Global Climate Change Impacts in the United States. Cambridge University Press, 2009, 196pp.
Increasing
greenhouse gases
increases heating
of the Earth
Increased Greenhouse Gases
=> Global Heating
Karl, T. R., J. M. Melillo, and T. C. Peterson, (eds.), 2009: Global Climate Change Impacts in the United States. Cambridge University Press, 2009.
Global Carbon Emissions (Gt)
Actual emissions are exceeding worst
case scenarios projected in 1990
Warming of the Lower
and Upper Atmosphere
Produced by Natural
and Human Causes
Karl, T. R., J. M. Melillo, and T. C. Peterson, (eds.), 2009:
Global Climate Change Impacts in the United States.
Cambridge University Press, 2009, 196pp.
Warming of the Lower
and Upper Atmosphere
Produced by Natural
and Human Causes
Note that greenhouse gases
have a unique temperature
signature, with strong
warming in the upper
troposphere, cooling in the
lower stratosphere and strong
warming over the North Pole.
No other warming factors
have this signature.
Karl, T. R., J. M. Melillo, and T. C. Peterson, (eds.), 2009:
Global Climate Change Impacts in the United States.
Cambridge University Press, 2009, 196pp.
Global Mean Surface Temperature
http://www.ncdc.noaa.gov/img/climate/research/2008/ann/global-jan-dec-error-bar-pg.gif
Attribution studies: See
Anderson this afternoon
for applications to the
Midwest
Source: Jerry Meehl, National Center for Atmospheric Research
The balance of
evidence for the
magnitude and
distribution of
warming is explained
by increases in
atmospheric
greenhouse gases
Energy intensive
Balanced fuel sources
More environmentally friendly
If current emission trends
continue, global temperature rise
will exceed worst case scenarios
projected in 2007
FI =fossil intensive
IPCC Fourth Assessment Report Summary for Policy Makers
IPCC 2007
7.2oF
DecemberJanuaryFebruary
Temperature
Change
6.3oF
A1B Emission
Scenario
2080-2099
minus1980-1999
IPCC 2007
June-JulyAugust
Temperature
Change
4.5oF
5.4oF
A1B Emission
Scenario
2080-2099
minus1980-1999
June-JulyAugust
Temperature
Change
4.5oF
5.4oF
Not the direction
of current trends
(see Anderson
this afternoon)
A1B Emission
Scenario
2080-2099
minus1980-1999
IPCC 2007
Low confidence in model projection of summer
precipitation. See Arritt presentation this afternoon
IPCC 2007
IPCC 2007
Karl, T. R., J. M. Melillo, and T. C. Peterson, (eds.), 2009: Global Climate Change Impacts in the United States. Cambridge University Press, 2009, 196pp.
Karl, T. R., J. M. Melillo, and T. C. Peterson, (eds.), 2009: Global Climate Change Impacts in the United States. Cambridge University Press, 2009, 196pp.
Low confidence:
See Arritt this
afternoon
Emerging techniques for
improvement: See Gutowski this
afternoon
Karl, T. R., J. M. Melillo, and T. C. Peterson, (eds.), 2009: Global Climate Change Impacts in the United States. Cambridge University Press, 2009, 196pp.
Trend of increase
in occurrence of
heavy precipitation
over the 20th C is
consistent with
increasing GHG
concentrations.
Frequency of
intense
precipitation
events is likely to
increase in the
future.
Karl, T. R., J. M. Melillo, and T. C. Peterson, (eds.), 2009:
Global Climate Change Impacts in the United States.
Cambridge University Press, 2009, 196pp.
The planet is
committed to a
warming over the
next 50 years
regardless of
political decisions
Adaptation
Necessary
Adaptation
Necessary
Mitigation
Possible
Karl, T. R., J. M. Melillo, and T. C. Peterson,
(eds.), 2009: Global Climate Change Impacts in
the United States. Cambridge University Press,
2009, 196pp.
The planet is
committed to a
warming over the
next 50 years
regardless of
political decisions
Adaptation
Necessary
Farmers install
more drainage tile
Adaptation
Necessary
Mitigation
Possible
Karl, T. R., J. M. Melillo, and T. C. Peterson,
(eds.), 2009: Global Climate Change Impacts in
the United States. Cambridge University Press,
2009, 196pp.
The planet is
committed to a
warming over the
next 50 years
regardless of
political decisions
Adaptation
Necessary
Adaptation
Necessary
Mitigation
Possible
Karl, T. R., J. M. Melillo, and T. C. Peterson,
(eds.), 2009: Global Climate Change
Impacts in the United States. Cambridge
University Press, 2009, 196pp.
The planet is
committed to a
warming over the
next 50 years
regardless of
political decisions
Adaptation
Necessary
Farmers plant earlier,
choose longer season
hybrids
Adaptation
Necessary
Mitigation
Possible
Karl, T. R., J. M. Melillo, and T. C. Peterson,
(eds.), 2009: Global Climate Change
Impacts in the United States. Cambridge
University Press, 2009, 196pp.
Observed Summer (JJA) Daily Maximum Temperature
Changes (K), 1976-2000
Adapted from
Folland et al.
[2001]
Observed Summer (JJA) Daily Maximum Temperature
Changes (K), 1976-2000
See
Anderson
presentation
this afternoon
Adapted from
Folland et al.
[2001]
Des Moines Airport Data
1983: 13
1988: 10
2009: 0
Des Moines Airport Data
1983: 13
1988: 10
6 days ≥ 100oF in the last 20 years
2009: 0
State-Wide Average Data
State-Wide Average Data
Totals above 40”
Cedar Rapids Data
Cedar Rapids Data
Relationship of Streamflow
to Precipitation in Current
and Future Climates
D. Herzmann, Iowa Environmental Mesonet
State-Wide Average Data
Projected Changes* for the
Climate of the Midwest
Temperature




Longer frost-free period (high)
Higher average winter temperatures (high)
Fewer extreme cold temperatures in winter (high)
Fewer extreme high temperatures in summer in short
term but more in long term (medium)
 Higher nighttime temperatures both summer and
winter (high)
 More freeze-thaw cycles (high)
 Increased temperature variability (high)
Follows trend of last 25 years and projected by models
No current trend but model suggestion or current trend but model inconclusive
*Estimated from IPCC reports
Projected Changes* for the
Climate of the Midwest
Precipitation
 More (~10%) precipitation annually (medium)
 Change in “seasonality”: Most of the increase will come in the
first half of the year (wetter springs, drier summers) (high)
 More water-logging of soils (medium)
 More variability of summer precipitation (high)
 More intense rain events and hence more runoff (high)
 Higher episodic streamflow (medium)
 Longer periods without rain (medium)
 Higher absolute humidity (high)
 Stronger storm systems (medium)
 More winter soil moisture recharge (medium)
 Snowfall increases (late winter) in short term but
decreases in the long run (medium)
Follows trend of last 25 years and projected by models
No current trend but model suggestion or current trend but model inconclusive
*Estimated from IPCC reports
Projected Changes* for the
Climate of the Midwest
Other






Reduced wind speeds (high)
Reduced solar radiation (medium)
Increased tropospheric ozone (high)
Accelerated loss of soil carbon (high)
Phenological stages are shortened (high)
Weeds grow more rapidly under elevated atmospheric
CO2 (high)
 Weeds migrate northward and are less sensitive to
herbicides (high)
 Plants have increased water used efficiency (high)
Follows trend of last 25 years and projected by models
No current trend but model suggestion or current trend but model inconclusive
*Estimated from IPCC and CCSP reports
Iowa Agricultural Producers’ Adaptations
to Climate Change
 Longer growing season: plant earlier, plant longer season
hybrids, harvest later
 Wetter springs: larger machinery enables planting in smaller
weather windows
 More summer precipitation: higher planting densities for
higher yields
 Wetter springs and summers: more subsurface drainage tile
is being installed, closer spacing, sloped surfaces
 Fewer extreme heat events: higher planting densities, fewer
pollination failures
 Higher humidity: more spraying for pathogens favored by
moist conditions
 Drier autumns: delay harvest to take advantage of natural
dry-down conditions
HIGHER YIELDS!!
Is it genetics or climate? See
Anderson this afternoon
Will These Agriculturally Favorable Midwest
Climate Trends Continue?
Caution: These are my speculations!!
 In the short-term (next 5-10 years) climatic conditions will
be dominated by natural variability from base conditions of
the past 20 years (not long-term averages)
 If we continue to have high spring and summer rainfall and
soil moisture, we likely will continue to have lower chances
of extended periods of extreme heat
 If we continue to have high spring and summer rainfall and
soil moisture, we likely will continue to have pathogens
favored by high humidities
 In the longer term (>50 years), hot summers, milder
winters, and higher variability of precipitation will become
more dominant
 Failure to limit global carbon emissions will accelerate trends
toward less favorable agricultural climate for Iowa
Suitability
Index for
Rainfed
Agriculture
IPCC 2007
Summary
 There is no scientifically defensible explanation for
atmospheric warming, increase in ocean heat content,
and loss of ocean and land ice over the last 40 year
other than increase of anthropogenic greenhouse
gases
 Some recent climate trends in the Midwest that have
been favorable to agriculture likely will continue in the
next few years
 Climate challenges to agriculture will intensify toward
mid-century
 Global and regional climate models have much to
offer for understanding future Midwest and global
agricultural production: Agriculture needs future
climate information at regional scales.
 The afternoon climate model session will be led by
world experts in seasonal climate forecast models,
future climate extremes, and attribution studies.
For More Information
 National academies of science joint statement (May
2009): G8+5 Academies’ joint statement: Climate
change and the transformation of energy
technologies for a low carbon future.
[http://www.nationalacademies.org/includes/G8+5energy-climate09.pdf]
 North American Regional Climate Change
Assessment Program: http://www.narccap.ucar.edu/
 For current activities on the ISU campus, regionally
and nationally relating to climate change see the
Climate Science Initiative website:
http://climate.agron.iastate.edu/
 Contact me directly: [email protected]