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

What is the oscillation due to? Historical CO 2 measurements 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 CO 2 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

Black line is observed temperature Orange is simulated 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

Sustainability World Early Demographic Transition World Late Demographic Transition World Warming to 2030 (~0.8˚C) warming to 2100 (~2-2.2˚C)

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

Green = with adaptation Red = without adaptation = reference line for current yields Cereal Yield Response to Warming—Temperate vs. Tropical Regions (with and without simulated adaptation) Temperate yields tend to thrive until +3˚C Tropical yields tend to decline immediately Simple adaptations extend 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 ( )

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 Greenhouse effect is getting stronger Multiple lines of evidence of warming are consistent and more certain than ever 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 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 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 Global food production likely to be adequate overall but unequal distribution harming food security in the tropics