Transcript The Latest Scientific Assessment of Climate Change and its

The Latest Scientific
Assessment of Climate
Change and its Impacts on
World Food Security—the
IPCC Reports
William E. Easterling
Penn State University
The Facts
Fact 1: The Greenhouse
Effect is real
Without the Greenhouse
Effect, the Earth’s
surface temperature
averages ~30˚C colder
NATURAL GREENHOUSE EFFECT
Fact 2—the chemistry of the
global atmosphere is changing
ENHANCED GREENHOUSE EFFECT
Historical CO2 measurements
What is the
oscillation
due to?
Began in 1958
Prehistoric Greenhouse Gas Measurements
Recent rise of atmospheric greenhouse gas concentrations is
unprecedented in last 10,000 yrs—ice cores suggest even the last
650,000 yrs
IPCC-SPM, 2007
Fact 3—human activity is the
source of the rise in
greenhouse gas concentrations
Fact 4—Ipso facto from the previous
two facts: radiative forcing of the
atmosphere is increasing
Growth in fossil fuel emissions highly
correlated with growth in atmospheric CO2
Total radiative
forcing—a
measure of the
stengthening of
the greenhouse
effect—has
increased by 20%
(~+1.5Wm-2) over
the past decade.
Several lines of evidence
have converged giving high
confidence that the Earth’s
climate is changing………
UK going Mediterranean in 2003
Katrina fueled by
warm Gulf water
Research has narrowed the
attribution of observed
warming to human
activity…….
General Circulation
Models (GCMs) take
into account the full
three-dimensional
structure of the
atmosphere and ocean
Orange is simulated
temperature
Black line is observed temperature
Blue is simulated
temperature
Rate and amount of warming is dependent on the political,
social and economic factors that govern emissions
Range of warming is ~1-4˚C
by 2100
Warming to 2030 (~0.8˚C)
Sustainability
World
warming to 2100
(~2-2.2˚C)
Early Demographic
Transition World
Late Demographic
Transition World
+
+
-
-
-
White areas are where less than 2/3 of models
agree; stippled areas are where more than 9/10
of models agree
Effects on Global Food
Security
Temperate yields tend to
thrive until +3˚C
Cereal Yield Response to
Warming—Temperate vs.
Tropical Regions
Tropical yields tend to
decline immediately
(with and without
simulated adaptation)
Red = without adaptation
Green = with adaptation
Simple adaptations extend
= reference line
for current yields temperate crops to +4-5 ˚C
but tropical yields only to
+2-3˚C
One of the earliest effects
of climate change is likely
to be the range of crop
pests and diseases
Simulated spread of soybean
rust into the U.S. with
Hurricane Ivan was scary
accurate!
Pan and Yang,
2004 Science
What happens when
conventional adaptive
measures are
exhausted?—will
biotechnology be the
answer?
Global Area of Transgenic Crops:
Industrial and Developing Countries
(1996- 2000)
40
Million hectares
35
30
Industrial
countries
Developing
countries
25
20
15
10
5
0
1995 1996 1997 1998 1999 2000
Biofuels as Adaptation and
Mitigation: Does energy
have to compete with
food?
Availability of Currently Unused
Arable Land for Food and/or
Bioenergy Crops (est. by FAO)
Summary

Greenhouse effect is getting stronger

Multiple lines of evidence of warming are consistent and
more certain than ever

Models are making the case that most of the warming is
attributable to GHG emissions

Warming by end of century could be equal to 60-80% of
the warming since the last ice age until now

Global food production likely to be adequate overall but
unequal distribution harming food security in the tropics