Increasing Atmospheric CO 2 Does Not Increase Global Net Primary Production
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Increasing Atmospheric Increasing Atmospheric CO CO 2 2 Does Not Increase Does Not Increase Global Net Primary Global Net Primary Production Production Group A15 Group A15 Corinne Benton Corinne Benton Nathan Corbin Nathan Corbin James Parker James Parker
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Increasing Atmospheric CO 2 Does Not Increase Global Net Primary Production. Group A15 Corinne Benton Nathan Corbin James Parker. Introduction. Net Primary Production: quantifies the amount of atmospheric carbon fixed by plants and accumulated as biomass (Zhao & Running 2010) - PowerPoint PPT Presentation
Transcript of Increasing Atmospheric CO 2 Does Not Increase Global Net Primary Production
Increasing Atmospheric COIncreasing Atmospheric CO2 2
Does Not Increase Global Net Does Not Increase Global Net Primary ProductionPrimary Production
Group A15Group A15
Corinne BentonCorinne Benton
Nathan CorbinNathan Corbin
James ParkerJames Parker
IntroductionIntroduction• Net Primary Production: quantifies the amount of atmospheric Net Primary Production: quantifies the amount of atmospheric
carbon fixed by plants and accumulated as biomass (Zhao & carbon fixed by plants and accumulated as biomass (Zhao & Running 2010)Running 2010)
• NPP = Photosynthesis - Respiration (Freeman 2011)NPP = Photosynthesis - Respiration (Freeman 2011)
• Could Could COCO22 increase NPP? increase NPP?
• Does Does COCO22 increase NPP in reality? increase NPP in reality?
• Temperature increases due to increased Temperature increases due to increased COCO22 levels lead to droughts levels lead to droughts
(Zhao & Running 2010)(Zhao & Running 2010)• Nitrogen is a limiting factor (Reich & Hobbie 2012)Nitrogen is a limiting factor (Reich & Hobbie 2012)• Human food supply depends on NPPHuman food supply depends on NPP
Global NPP TrendsGlobal NPP Trends• NPP had low variation with a slight NPP had low variation with a slight
decrease for past 30 years decrease for past 30 years (Running 2012)(Running 2012)– 53.6 Pg C with ~1 Pg C/year 53.6 Pg C with ~1 Pg C/year
interannual variabilityinterannual variability• Substantial Carbon increase in Substantial Carbon increase in
atmosphere over past 10 years atmosphere over past 10 years (Zhao & Running 2010)(Zhao & Running 2010)
• Losing 0.38 Pg C per decade to Losing 0.38 Pg C per decade to increasing autotrophic respirationincreasing autotrophic respiration
• Nitrogen availability limits NPP Nitrogen availability limits NPP (Reich & Hobbie 2012)(Reich & Hobbie 2012)
• NPP negatively correlates to drought NPP negatively correlates to drought (Zhao & Running 2010)(Zhao & Running 2010)
Image Credit: Reich & Hobbie 2012
Global NPP from 2000-2009Global NPP from 2000-2009
Image Credit: Zhao & Running 2010Image Credit: Zhao & Running 2010
NPP for Human UseNPP for Human Use• NPP Availability (Running 2012) NPP Availability (Running 2012)
– Inaccessible: 53% Inaccessible: 53% • RootsRoots• Preserves Preserves • Inaccessible areasInaccessible areas
– In Use: 37%In Use: 37%– Available: 10%Available: 10%
• Human population expected to grow by 40% by 2050 Human population expected to grow by 40% by 2050 (Running 2012)(Running 2012)
Image Credit: Running 2012Image Credit: Running 2012
DiscussionDiscussion• COCO22 causes higher temperatures causes higher temperatures
– Droughts are caused by higher temperaturesDroughts are caused by higher temperatures– Increase in autotrophic respiration is caused Increase in autotrophic respiration is caused
by higher temperaturesby higher temperatures• Planetary boundaries:Planetary boundaries:
– NitrogenNitrogen– PhosphorousPhosphorous– WaterWater– LandLand
• NPP limited by many other factorsNPP limited by many other factors
DiscussionDiscussion
• NPP increases linearly while human NPP increases linearly while human population increases exponentially population increases exponentially
• NPP nearing global boundariesNPP nearing global boundaries
• NPP limitations may cause global food NPP limitations may cause global food shortagesshortages
ConclusionConclusion
Increases in atmospheric COIncreases in atmospheric CO22 will have will have
little positive impact on global net primary little positive impact on global net primary productivity, which implies that human productivity, which implies that human population growth will far outpace NPP population growth will far outpace NPP growth.growth.
Works CitedWorks Cited• Maosheng Zhao and Steven W. Running, 2010. Drought-Induced
Reduction in Global Terrestrial Net Primary Production from 2000 Through 2009. Science 329 (5994), 940-943. [DOI:10.1126/science.1192666]
• Steven W. Running, 2012. A Measurable Planetary Boundary for the Biosphere. Science 337 (6101), 1458-1459. [DOI:10.1126/science.1227620]
• Peter B. Reich and Sarah E. Hobbie, 2012. Decade-long soil nitrogen constraint on the CO2 fertilization of plant biomass. Nature Climate Change doi:10.1038/nclimate1694 published online 30 Sep 2012
• Freeman, S. (2011). Biological science. (4 ed.). San Francisco: Pearson Benjamin Cummings.
