Global Consequences Of Land Use

1. Global Consequences Of Land Use Written by: Jonathan A. Foley Jacob Hoelscher Atmospheric Science Major

2. Land Use Activities • Clearing Forests, Practicing Subsistence Agriculture, Intensifying Farm Production, and Expanding Urban Centers are changing the worlds landscapes in pervasive ways. • The outcome is generally the same around the world. Natural resources are acquired at the expense of degrading environmental conditions.

3. Since 1850, 35% of anthropogenic CO2 emissions resulted from land use. • Irrigation, Fertilization, and Modification of habitats.

4. Dilemma • Land use is essential for humanity for food, fiber, shelter, and freshwater. • Yet we are degrading the ecosystem that we depend on. • Are we altering the environment enough to undermine ecosystem services, human welfare, and the long term sustainability of human societies?

5. Food Production • Land used for agriculture occupies 40% of the land surface. • During the past 40 years there has been a 700% increase of fertilizer use and 70% increase of irrigated cropland.

6. Consequences • Degradation of Water Supply due to fertilizers. • Salinization of Irrigated Land: Worldwide loss of 1.5 million hectares, $11 billion in lost production. • 40% of global croplands are experiencing soil erosion, reduced fertility, or overgrazing.

8. Freshwater Resources • Disruption of the surface water balance. • Global Withdrawals total 3900 km3/yr ~ about 10% of the global renewable resource. • Only half of which is returned to the watershed.

9. Regional Climate and Air Quality • Land use alters the effects of net radiation. • Large scale clearing of tropical forests create a warmer, drier climate. • Clearing of temperate and boreal forest cools the climate through an increased albedo.

10. Infectious Disease • Tropical Deforestation coincides with an upsurge of malaria. • 75% of human diseases have links to wildlife or animals.

12. Confronting the Effects of Land Use • Will require tradeoffs between human needs and the maintenance of the environment. • Increasing agricultural production per unit land area, per unit fertilizer input, and per unit water consumed, as well as increasing soil organic matter.

14. The Importance of Land –Cover Change in Simulating Future Climates • Written by: Johannes Feddema, Keith Oleson, GordanBonan, Linda Mearns, Lawrence Buja, Gerald Meehl, and Warren Washington.

15. Anthropogenic Impact • As mentioned before land cover conversion of mid latitude areas may have decreased temperatures by 1-2 degrees Celsius. • Whereas tropical deforestation may lead to an increase of the same increment of temperature in the effected region.

16. Biogeochemical and Biogeophysical • Biogeochemical- affect climate by altering the rate of biogeochemical cycles, changing the composition of the atmosphere. • Biogeophysical – affect the physical parameters the determine the absorption and disposition of energy at the surface.

17. Parallel Climate Model • Simulation of the combined land cover and atmospheric forcing's for the IPCC and SRES scenarios. • To simulate they used land cover projections and natural vegetation data.

18. Present Day Land Cover

19. Change of Previous Slide Land Cover Types

20. Temperature Change Based on Models

21. Changes in DTR

22. So, what do we do? • Humans choices about future land use can have a significant impact on the climate. • If we continue to destroy tropical rainforest there will be a weakening of the Hadley Circulation, which would have adverse affects for much of the Earth. • We must go back to a more natural state of land use while still being able to produce an acceptable amount of goods for the population.

24. Questions???????