Section 5 Climate Change slides
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Section 5 Climate Change slides Presentation Transcript

  • 1. Climate Change Carbon Sequestration Links between CO2 and climate change were forecast • more than 100 years ago (Arrhenius). Given little attention because of several uncertainties, • especially instrumented measurements of atmospheric CO2. Scientists thought the oceans would simply absorb • any excess CO2. Measurements have since eliminated that • uncertainty. Soil 7170 Pre-class Review Notes
  • 2. Atmospheric CO2 concentration (ppmv) 380 370 360 350 340 330 320 310 1958 1962 1966 1970 1974 1978 1982 1986 1990 1994 1998 2002 Monthly atmospheric CO2 concentration as monitored at the Mauna Loa Observatory (Data from http://cdiac.esd.ornl.gov/)
  • 3. Intergovernmental Panel on Climate Change, 2001. [Online] Available at http://www.ipcc.ch/pub/spm22- 01.pdf Last accessed 1-Oct- 2002.
  • 4. Climate Change Carbon Sequestration • Carbon in SOM is recognized as a means to mitigate the increase in atmospheric CO2 that has been caused by burning fossil fuel • Plants utilize CO2 and H2O to produce carbohydrates, the basic organic building block, which converts atmospheric CO2 into an organic form • When the plants die, the organic material remains in organic form until the soil micro-organisms use them for energy, during the decomposition, CO2 is released back into the atmosphere • By increasing the level of soil organic matter, we keep or “sequester” carbon in organic form which reduces the amount of CO2 in the atmosphere Soil 7170 Pre-class Review Notes
  • 5. Notes Carbon storage values in the boreal region reach a maximum of 1,250 metric tons of carbon per hectare. Carbon storage values greater than 1,000 metric tons of carbon per hectare account for 2 percent of the area falling in the greater than 300 metric tons per hectare class. Carbon storage values are not shown for Greenland and Antarctica, where limited data were available. Sources: 1. Food and Agriculture Organization of the United Nations (FAO). 1995, Digital Soil Map of the World (DSMW) and Derived Soil Properties. Version 3.5. CD-ROM. 2. Batjes, N.H.. 1996. quot;Total Carbon and Nitrogen in the Soils of the Worldquot;. European Journal of Soil Science 47: Available On-line at: Source Link.
  • 6. Units are in Gigatonnes (GT) or billions of tonnes CO2 and the carbon cycle (Schimel et al. 1995)
  • 7. Pacific Marine Environmental Laboratory, National Oceanic and Atmospheric Administration. [Online] http://www.pmel.noaa.gov/co2/gcc.html Accessed: 25 Nov 2005
  • 8. Climate Change Carbon Sequestration • Farmers can receive payment for implementing specific practices to increase soil organic matter • The increase in soil organic C is meant to offset the release of CO2 by industry • Industry is paying for a “carbon credit” • If the land is tilled, the soil organic carbon can be quickly released by to the atmosphere as CO2 • This is not a permanent solution to solve increasing atmospheric CO2 because C storage capacity of soil is limited Soil 7170 Pre-class Review Notes
  • 9. Climate Change Potential Climate Change Impacts on Agriculture As weather patterns change over time in western • Canada, we will need to continue to adapt our crop choices and practices. The impacts of climate change on agriculture will be • reflected through the response of crops, livestock, soils, weeds, insects and diseases to the elements of climate to which they are most sensitive Can we anticipate the response of various crops to • these changes so that we can improve our crop outcomes in the future? Soil 7170 Pre-class Review Notes
  • 10. Climate Change Potential Climate Change Impacts on Agriculture • How will future weather affect the yield and quality of western Canadian crops? • Effects on individual plant organs • Effects on plants • Effects on field • Indirect Effects • Weeds • Pathogens • Insects • Soil temperature Soil 7170 Pre-class Review Notes
  • 11. Climate Change Potential Climate Change Impacts on Agriculture Plant Processes Affected by the Environment • • Photosynthesis • Respiration • Partitioning • Development rate Soil 7170 Pre-class Review Notes
  • 12. Photosynthesis and Respiration. From Mathews et al. 2000 Biochemistry 3rd Edition, Addison-Wesley-Longman
  • 13. Wheat yield versus atmospheric CO2. Amthor, 2001, as reported in Pritchard and Amthor 2005 Crops and environmental change. Food Products Press
  • 14. Photosynthesis and Elevated CO2 • Increased biomass production • C3 > C4 • Enhanced biomass production more apparent in dry conditions, especially for C4 crops Samarakoon and Gifford, 1995. J Biogeog. 22: 193.
  • 15. • Yield and Elevated CO2 • % increase in yield of 9 soybean varieties grown in CO2-enriched air compared to ambient air. Ziska et al, 2001, as reported in Pritchard and Amthor 2005 Crops and environmental change. Food Products Press
  • 16. • Photosynthesis and Elevated CO2 • When exposed for long periods to high CO2, the increased biomass response is reduced (individual leaves) • “acclimation” Bunce, 1995. J Biogeog. 22: 341.
  • 17. • Photosynthesis and Elevated Temp • The optimum temperature for photosynthesis is generally higher for C4 plants. Adapted from Stone, 2001, as reported in Pritchard and Amthor 2005 Crops and environmental change. Food Products Press
  • 18. • Elevated Temp and CO2 • Winter wheat biomass production declines with rising temp for either ambient or elevated CO2 Batts et al. 1998. J. Agric. Sci. 130: 17-27.
  • 19. Climate Change Potential Climate Change Impacts on Agriculture Respiration and Elevated CO2 • It is unclear if respiration is directly affected by atmospheric CO2 levels • If plants respond to increased CO2 by producing more biomass, then the plant will increase the amount of growth respiration Soil 7170 Pre-class Review Notes
  • 20. Climate Change Potential Climate Change Impacts on Agriculture Partitioning and Elevated CO2 • Most plants grown under elevated CO2 have greater root/shoot ratios, especially in nitrogen- limited conditions. • The tendency is for harvest index to increase with elevated CO2. Soil 7170 Pre-class Review Notes
  • 21. % change in root/shoot ratio for crops in CO2-enriched atmosphere (264 observations). Data from Rogers et al, 1996 as reported in Pritchard and Amthor 2005 Crops and environmental change. Food Products Press
  • 22. Climate Change Potential Climate Change Impacts on Agriculture Partitioning and Elevated Temperature • Warmer temperatures can spur photosynthesis rates and production of assimilates which takes place in the leaves • Since the shoots are closer to the source of assimilates than the roots, this will advantage the shoot tissue Soil 7170 Pre-class Review Notes
  • 23. Temp & CO2 Effects on Root Partitioning Root biomass (% of 10 total plant biomass) Root Biomass (% of total plant biomass) increases with 8 increasing CO2 but decreases with 6 increasing air temperature. 4 2 Data from Batts et al, 1998. J. Agr. Sci. 130: 0 17-27. Warm Average Cool Normal Elevated Temperature CO2
  • 24. Climate Change Potential Climate Change Impacts on Agriculture Mineral Nutrition and Elevated CO2 • Elevated CO2 improves growth and yield but decreases nutrient concentrations as plants are unable to acquire enough nutrients to keep pace with more C from higher photosynthesis • However, soil warming generally increases nutrient uptake capacity of plant roots and may mitigate the dilution impact of high CO2 to some extent Soil 7170 Pre-class Review Notes
  • 25. Barley Grown at Different Root Zone Temperature 3 b b b b a a 2 5C 10 C 15 C 1 0 Water Use Water Use Efficiency (Liters) (grams per liter) Root growth responds positively to increased soil temperature within the range experienced in western Canada. Data from Sharratt, 1991, Agron. J. 83: 237-239.
  • 26. Climate Change Potential Climate Change Impacts on Agriculture Bunce, 1995. J Biogeog. 22: 341-347. Eastern USA field trial • No yield increase at increased CO2 levels in the field for alfalfa and orchard grass even though CO2 assimilation rates of individual leaves were higher (only 2 reps) • Leaf nitrogen content decreased in crops grown at elevated CO2 level • Weed yield was 2 to 4 times higher in both crops with elevated CO2!! Soil 7170 Pre-class Review Notes
  • 27. Bunce, 1995. J Biogeog. 22: 341.
  • 28. Climate Change Potential Climate Change Impacts on Agriculture Yield Components and Elevated Temperture • Elevated temperature increases the growth rate but decreases the time from flowering to maturity, especially in determinate species • Net effect of increased temperature is expected to reduce individual grain size Soil 7170 Pre-class Review Notes
  • 29. Climate Change Potential Climate Change Impacts on Agriculture Impacts on Pests From ‘Agriculture and Climate Change’ November 2005, National Farmers Union http://www.nfuonline.com Soil 7170 Pre-class Review Notes
  • 30. Climate Change Potential Climate Change Impacts on Agriculture Effects of Elevated CO2 • Increased biomass in C3 plants (although perhaps not as much as first suggested) • Increased WUE in most plants • Increased root/shoot biomass ratio • Decreased mineral content in the biomass • Increased weed growth Soil 7170 Pre-class Review Notes
  • 31. Climate Change Potential Climate Change Impacts on Agriculture Elevated Temperature • Reduced biomass production • Shift towards the optimum temperature for photosynthesis in C4 plants • Increased root growth and water (nutrient) uptake • Reduced filling period and lower grain yields from increased rate of maturity • Increased pest pressure Soil 7170 Pre-class Review Notes
  • 32. Government of Canada, Climate Change Impacts and Adaptation Directorate. 2004. Climate Change Impacts and Adaptation: A Canadian Perspective. [Online] http://adaptation.nrcan.gc.ca/perspective_e.asp, last accessed 18 Sep 04
  • 33. Climate Change Potential Climate Change Impacts on Agriculture Feedbacks Example 1: Higher WUE-higher plant productivity • Will the lower amount of water needed to produce each unit of biomass be offset by larger plants with bigger leaves such that plant water use does not change or perhaps even increases? Example 2: Higher WUE and lower ET • Higher WUE will reduce ET, decrease latent heat and increase sensible heat (i.e. warmer temperatures in the canopy). Will the warmer temperature cause higher evaporative demand? Soil 7170 Pre-class Review Notes
  • 34. Climate Change Potential Climate Change Impacts on Agriculture Western Canada Longer growing season will facilitate northward • expansion of agriculture (which may be limited by lack of suitable soil) Potential increased variety of crops suitable for • production Warmer temperatures will hasten crop maturity, • potentially reduce yields Soil 7170 Pre-class Review Notes
  • 35. Climate Change Potential Climate Change Impacts on Agriculture Western Canada For perennial grasses and forages, which maintain • an actively growing ground cover through the entire growing season, an increase in temperature will increase potential evapotranspiration Unless there is a corresponding increase in • precipitation, perennial crops may also suffer yield declines. Soil 7170 Pre-class Review Notes
  • 36. Climate Change Potential Climate Change Impacts on Agriculture Western Canada • Increased temperatures may facilitate the expansion of warm-season weed species to more northerly latitudes • Insect pests, fungal and bacterial pathogens of importance to agricultural production are sensitive to climate change through the direct effects of changes of temperature and moisture on the pest or pathogen, on host susceptibility and on the host- parasite inter-relation. Soil 7170 Pre-class Review Notes