1 / 28

Land-atmosphere interaction (1): Vegetation feedback & global warming

Land-atmosphere interaction (1): Vegetation feedback & global warming. John Banghoff Junior, Atmospheric Science. What is the Carbon Cycle?. Carbon Cycle Video. http:// www.youtube.com/watch?feature=player_detailpage&v=U3SZKJVKRxQ. How does that relate to global warming and vegetation?.

lee
Download Presentation

Land-atmosphere interaction (1): Vegetation feedback & global warming

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Land-atmosphere interaction (1): Vegetation feedback & global warming John Banghoff Junior, Atmospheric Science

  2. What is the Carbon Cycle?

  3. Carbon Cycle Video • http://www.youtube.com/watch?feature=player_detailpage&v=U3SZKJVKRxQ

  4. How does that relate to global warming and vegetation? • Concentration of CO2 is increasing in the atmosphere. This leads to global warming. • Plants take in CO2 during photosynthesis so they can help compensate for some of the increased CO2 – to a certain extent.

  5. Carbon Sinks or Stores

  6. Carbon-Vegetation Feeback • For 50 years, ecosystems have been absorbing 25-30% of anthropogenic carbon dioxide emissions (a majority in forest biomass and soils) • More CO2 leads to more plant growth, which leads to more CO2 uptake. • Warming temperatures lengthen growing season, thus lengthening CO2absorbtion.

  7. The Big Question: HOW LONG CAN THESE CARBON SINKS KEEP UP WITH ANTHROPOGENIC PRODUCTION OF CO2?

  8. Cox et al. 2000 • Investigation of climate simulations which take into account the effect of climate change on the carbon cycle feedback. • Three different simulations: • Fixed vegetation (standard simulation) • Interactive CO2 and dynamic vegetation (doesn’t include adjustment for climate change) • Fully coupled climate/carbon-cycle

  9. SUCCESS!!!!! The figure shows the anomaly in the growth rate of atmospheric CO 2 versus the Nino3 index, taken from our pre-industrial control simulation (crosses) and the Mauna Loa observations (triangles). USED TO TEST THE ACCURACY OF MODELING OF ENSO TO DETERMINE VALIDITY OF FULLY COUPLED MODEL.

  10. Land becomes a source by 2050 (approximately). • By 2100, land and ocean cancel each other out so emissions supply all of increased carbon concentration. Absence of climate forcing factors

  11. Too high – no aerosol cooling. • Note increased temperature and CO2 concentration with fully coupled model. the fully coupled simulation with interactive CO2 and dynamic vegetation (red lines), a standard GCM climate change simulation with prescribed (IS92a) CO2 concentration and fixed vegetation (dot-dashed lines) and the simulation which neglects direct CO2-induced climate change (blue lines).

  12. Note reduction of terrestrial carbon after 2050 as a result of climate driven loss of soil carbon. vegetation carbon soil carbon global land area (continuous lines) and South America alone (dashed lines).

  13. Scary Stats from Coupled Model • Increase in CO2 concentration is 250 ppm higher (980 ppm) than the standard simulation. This equates to an 8 K increase from 1860-2100. • Model with fixed vegetation has 5.5 K increase. Model without climate change has 4 K increase.

  14. Reichstein et al. 2013 • Discusses how terrestrial carbon sinks might actually be made less effective by extreme climate events. • Looks at forests, croplands, and grasslands. • Discusses extreme events that affect each of the aforementioned land coverage regions.

  15. What affects Carbon Sinks? • Increased research that climate extremes can lead to a decrease in carbon stocks. • Examples include severe storms or periods of drought. • How extreme is enough to alter the ecosystem?

  16. Extreme Climatic Events • “an episode or occurrence in which a statistically rare or unusual climatic period alters ecosystem structure and/or functions well outside the bounds of what is considered typical or normal variability” • Examples might include a combined heat wave and drought or a drought followed by heavy precipitation.

  17. Processes and feedbacks triggered by extreme climate events. M Reichstein et al. Nature 500, 287-295 (2013) doi:10.1038/nature12350

  18. Types of Effects • Concurrent Source – An event that puts CO2 into the atmosphere when it occurs. Ex: Fire • Concurrent Sink – An event that takes in CO2 or keeps it out of the atmosphere. Ex: Photosynthesis • Delayed Source – An event that eventually leads to increased CO2concentration. Ex: Plant death • Delayed Sink – An event that eventually leads to CO2storage. Ex: Sedimentation

  19. Overview of how carbon flows may be triggered, or greatly altered, by extreme events. Gross Primary Productivity (GPP): the rate at which photosynthesis or chemosynthesis occurs. M Reichstein et al. Nature 500, 287-295 (2013) doi:10.1038/nature12350

  20. Forests

  21. Grasslands

  22. Croplands • Highly influenced by human intervention. • Type of crop, amount of harvesting, time left bare. • Therefore, hardest to simulate and account for impacts on carbon dioxide store.

  23. Global impact of extreme events on the carbon cycle. Extreme Temps Water Scarcity M Reichstein et al. Nature 500, 287-295 (2013) doi:10.1038/nature12350

  24. Uncertainty Remains • Climate extremes seem to be occurring more frequently, but how frequent are they? • What effect do they have on the carbon-cycle and how do they contribute to feedbacks? • Further research must be done to investigate extreme climate events and how each part of the carbon cycle is contributing to feedbacks. • We must further improve weather forecasting and climate modeling to improve accuracy.

  25. Uncertainty Remains • Carbon Cycle is still only partially understood. • How ocean, land, and vegetation sinks function is still not fully grasped. • Rate of CO2 increase depends on when the land will become a source instead of a sink. • Models don’t account for human impacts in deforestation or afforestation which can alter timing and functionality of sinks.

  26. Let’s Dive Into the Models a Little Bit More Hasting Ng will have more in our next presentation investigating further the climate models and how they handle carbon-cycle feedbacks – specifically the role of ocean and land carbon sinks.

  27. Questions, Comments, Concerns??

More Related