12 agriculture and climate


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12 agriculture and climate

  1. 1. Climate Change and Agriculture <ul><li>Effects of agriculture on climate change </li></ul><ul><li>Effects of climate change on agriculture </li></ul>
  2. 2. <ul><li>Most of the effects of agriculture on climate change revolve around greenhouse gases. </li></ul><ul><li>- CO 2 </li></ul><ul><li>- CH 4 </li></ul><ul><li>- N 2 O </li></ul><ul><li>There are also albedo effects. </li></ul>Climate Change and Agriculture C O O O N N C H H H H
  3. 3. <ul><li>Land clearing is the leading source of agricultural CO 2 . </li></ul>Agriculture and CO 2
  4. 4. <ul><li>Forests are much more efficient carbon sinks than farmland. </li></ul><ul><li>Farms waste “carbon space” vertically and horizontally. </li></ul>Agriculture and CO 2
  5. 5. <ul><li>Agriculture also creates soil disturbance and increased rates of organic decomposition – both result in CO 2 release. </li></ul>Agriculture and CO 2
  6. 6. <ul><li>Soil erosion resulting from agriculture further reduces the land’s ability to uptake carbon. </li></ul>Agriculture and CO 2
  7. 7. Agriculture and CO 2 <ul><li>Forest area in the United States between 1620 and 1920 AD. </li></ul>
  8. 8. Agriculture and CO 2
  9. 9. Agriculture and CO 2 <ul><li>Brazil contains 30% of the world’s rainforest. </li></ul><ul><li>That is almost 13 Long Islands a year! </li></ul>
  10. 10. Agriculture and CO 2
  11. 11. <ul><li>Borneo losing 5000 square miles a year (3.6 Long Islands). </li></ul><ul><li>Why? … </li></ul>Agriculture and CO 2
  12. 12. <ul><li>China - high demand for wood (housing, flooring, furniture). </li></ul><ul><li>Forest is replaced with Palm plantations (palm oil a key ingredient in detergent, soaps, cosmetics, foods, etc. ). </li></ul>Agriculture and CO 2
  13. 13. <ul><li>“ Slash and burn” agriculture creates CO 2 as part of the deforestation process. </li></ul>Agriculture and CO 2
  14. 14. <ul><li>Methane is a byproduct of many agricultural activities. </li></ul><ul><li>Current concentration in the atmosphere is 1700 parts per billion – preindustrial concentration was less than half of that (700 ppb). </li></ul><ul><li>21 times more effective greenhouse gas than CO 2 . </li></ul>Agriculture and CH 4
  15. 15. Agriculture and CH 4 <ul><li>Main agricultural sources are rice paddies, livestock, and termite mounds. </li></ul><ul><li>Landfills, swamps, biomass burning also significant sources. </li></ul>
  16. 16. <ul><li>Bacteria need oxygen just like we do. In environments where O 2 is not available, bacterial will use CO 2 as an oxygen source (CO 2 in, CH 4 out) - anaerobic respiration. </li></ul><ul><li>Standing water with lots of organic matter will quickly turn anaerobic. </li></ul>Agriculture and CH 4
  17. 17. <ul><li>Typical rice paddy is submerged at least 4 months a year. </li></ul>Agriculture and CH 4 <ul><li>Rice agriculture contributes 50-100 million tons of CH 4 per year to the atmosphere – this is the largest anthropogenic source. </li></ul>
  18. 18. <ul><li>What to do about it? </li></ul><ul><li>Experimenting with varieties that don’t require as much water, and denser-growing varieties (more rice per paddy). </li></ul><ul><li>Using specific fertilizers can also make a difference. </li></ul>Agriculture and CH 4
  19. 19. Agriculture and CH 4 <ul><li>Livestock (cows in particular) are the next major agricultural source of methane. </li></ul><ul><li>100 million tons per year. </li></ul><ul><li>Comes from bacteria living in the animals’ stomachs and intestines. </li></ul>
  20. 20. Agriculture and CH 4
  21. 21. Agriculture and CH 4 <ul><li>Decomposition of cow and chicken manure accounts for another 25 million tons of methane. </li></ul><ul><li>Some of this gets collected in slurry tanks (“biogas”) and is used as fuel. </li></ul>
  22. 22. Agriculture and CH 4 <ul><li>Deforestation in the tropics leaves a lot of dead wood that is quickly colonized by termites. </li></ul>
  23. 23. Agriculture and CH 4 <ul><li>Natural methane sources: </li></ul>
  24. 24. Agriculture and CH 4 <ul><li>Anthropogenic methane sources: </li></ul><ul><li>Energy- and ruminant-related methane dominate. </li></ul>
  25. 25. Agriculture and N 2 O <ul><li>Nitrous oxide – “laughing gas.” </li></ul><ul><li>Relatively low concentrations (300 ppb now , 275 ppb pre-industrial). </li></ul><ul><li>310 times more effective greenhouse has than CO 2 . </li></ul><ul><li>Similar to anaerobic methane production, bacteria in low/zero-oxygen environments convert nitrite (NO 3 ) to nitrogen gas (N 2 ) and nitrous oxide (N 2 O). </li></ul>
  26. 26. Agriculture and N 2 O <ul><li>The use of man-made fertilizers rich in nitrogen compounds contributes to N 2 O production in soils. </li></ul><ul><li>2-4 million tons of N 2 O from this source per year. </li></ul><ul><li>Widespread use of animal manure as fertilizer can release substantial amounts. </li></ul>
  27. 27. Agriculture and Climate <ul><li>But when did all of this really start? </li></ul>
  28. 28. Agriculture and Climate <ul><li>Recently been speculated that humans may have been influencing climate for much longer than previously thought. </li></ul>
  29. 29. Agriculture and Climate
  30. 30. Agriculture and Climate <ul><li>When human population decreased, CO 2 levels decreased. </li></ul>