A presentation made by Keith Cressman, FAO Senior Locust Forecasting Officer, at the WMO/FAO International Conference of Adaptation to Climate Change and Food Security in West Asia and North Africa (Kuwait City, 13-16 Nov 2011). The presentation gives an overview of Desert Locust population dynamics, climatological effects and adaptation strategies. The Desert Locust is probably the oldest and most feared migratory pest in the world, plaguing farmers in Africa and Asia since Phaoronic times. Under optimal conditions, locusts increase rapidly and form swarms. A single swarm, larger than Paris or Cairo, can contain billions of insects, migrate across continents, and eat enough food for 2,500 people in one day. During plagues, vulnerable households can find themselves in debt, limited national resources are rapidly depleted and food security can be at risk in affected countries. It can take several years and hundreds of millions of dollars to bring a plague to an end. Changes in the climate during the remainder of this century will affect Desert Locust habitats, breeding, migration and plague dynamics in West Asia and North Africa (WANA). Although it is widely acknowledged that WANA will become warmer, there are differing views about changes in precipitation under the various climate change scenarios. General trends may contain hidden variations within the regions and countries. Certain areas will become more prone to extreme events such as flooding and droughts. Regular assessment of climate change impacts is a component of the locust early warning system operated by the Food and Agriculture Organization (FAO) of the United Nations to monitor the global situation and alert locust-affected countries and international donors. The latest scientific evidence is reviewed to postulate potential effects on the Desert Locust. It is probably reasonable to assume that this ancient pest, which is particularly well suited for survival under difficult conditions in arid areas and has successfully endured previous changes in the climate, will adapt to climate changes in the foreseeable future.

6. 0 2 6 12 16 months

9. 50
40
30
20
10
0
1860 70 80 90 1900 10 20 30 40 50 60 70 80 90 2000 10

10. Mauritania Niger
Mali
Sudan
solitarious gregarious

16. frontline
secondary
invasion
www.fao.org/ag/locusts

17. Africa is warmer than100 years ago
+4˚C
2-4˚C increase by 2050s
+3˚C
greatest warming along Sahara edge (0.5˚C/decade)
+2˚C
warming increases the spatial variability of rainfall
substantial and sustained decline in rainfall (Sahel)
decrease: Sahel (Mar-Aug), Sahara (Dec-May) -0.25-0
increase: Sahel (Jun-Aug), Sahara (Sep-Feb) 0-0.25
0.25-0.5
Sahara will turn green like 12,000 years ago
mm/day
increase in the intensity of high rainfall events IPCC3

18. Habitat
the Sahara is in retreat in the past 15 years (satellite imagery)
Predictions
rainfall under climate change scenarios in the Sahara varies and lacks consensus
half the models follow a wetter trend, half follow a drier
high uncertainty over Sahara due to few stations & poor quality data
regional models + satellite + stations may offer more precise estimates

19. Ice Age Holocene
Present
(cold, dry) (warm, wet)
desert
forest
18,000 years ago 8,000 4,500 500 5

22. L
L H H
IPCC AR4

24. 0˚

26. Keith Cressman
Senior Locust Forecasting Officer
Rome, Italy
keith.cressman@fao.org
www.fao.org/ag/locusts