Climate Change Sarah E Hobbie Dept of Ecology, Evolution & - - PowerPoint PPT Presentation

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Climate Change Sarah E Hobbie Dept of Ecology, Evolution & - - PowerPoint PPT Presentation

Dec 10, 2023 550 likes •1.1k views

Ecosystem Feedbacks to Climate Change Sarah E Hobbie Dept of Ecology, Evolution & Behavior University of Minnesota Will ecosystem responses exacerbate or moderate climate change? Atmospheric evidence of large carbon exchanges by the

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Ecosystem Feedbacks to Climate Change

Sarah E Hobbie

Dept of Ecology, Evolution & Behavior University of Minnesota

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Will ecosystem responses exacerbate

  • r moderate climate change?
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Atmospheric evidence of large carbon exchanges by the biosphere that are changing

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What is a feedback?

Driver Response

+ -

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Climate Change Feedbacks from Ecosystem Responses

Climate change

Plant growth Decomposition

CO2 Fossil fuels

  • + , -
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IPCC 2013

Negative feedbacks (moderate climate change) Positive feedbacks (exacerbate climate change)

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CO2 Plant respiration

Terrestrial Carbon Cycle

CO2 Photosynthesis Growth CO2 Soil respiration Erosion, Fire Groundwater transport Litter Roots Microbes Soil Organic Carbon

C accumulates when inputs > outputs Negative feedback

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CO2 Plant respiration

Terrestrial Carbon Cycle

CO2 Photosynthesis Growth CO2 Soil respiration Erosion, Fire Groundwater transport Litter Roots Microbes Soil Organic Carbon

C released when inputs < outputs Positive feedback

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IPCC 2013 Negative feedbacks (moderate climate change) Positive feedbacks (exacerbate climate change)

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Climate Change Feedbacks from Ecosystem Responses

Climate change

Plant growth Decomposition

CO2 Fossil fuels

  • N

+ , -

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Cedar Creek Ecosystem Science Reserve

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The NSF LTER Network

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What do plants need to grow?

CO2, light, water, soil nutrients Photosynthesis:

Conversion of CO2 to sugar using light energy

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Leaf-level response to elevated CO2

Atmospheric CO2 Net photosynthesis (µmol m-2 s-1) ambient CO2 elevated CO2 smaller increase

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BioCON: CO2, N, & diversity + temp & precip

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CO2 Plant respiration

Terrestrial Carbon Cycle

CO2 Photosynthesis Growth CO2 Soil respiration Erosion, Fire Groundwater transport Litter Roots Microbes Soil Organic Carbon

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IPCC 2013 Negative feedbacks (moderate climate change) Positive feedbacks (exacerbate climate change)

“CO2 fertilization” may moderate climate change, but only where nutrients and water are adequate

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Climate Change Feedbacks from Ecosystem Responses

Climate change

Plant growth Decomposition

+ , -

CO2 Fossil fuels

  • N
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atmosphere: 829 Pg

1 Pg=1015 g

soils: 1500-2400 Pg

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CO2 Plant respiration

Terrestrial Carbon Cycle

CO2 Photosynthesis Growth CO2 Soil respiration Erosion, Fire Groundwater transport Litter Roots Microbes Soil Organic Carbon

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Southern Boreal Forest Northern Deciduous Forest Prairie

Two sites Three temperature treatments Two rainfall treatments

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Boreal forest warming at an ecotone in danger

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Boreal Species white spruce balsam fir jack pine aspen paper birch

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Temperate Species bur oak sugar maple red maple buckthorn red oak white pine

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Photo credit: Roy Rich

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(Treatment minus control)

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Cloquet Ely

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Red maple Paper birch Red oak Balsam fir White spruce White pine

Species

Ambient Dry Ambient Dry Ambient Dry

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Red maple Paper birch Red oak Balsam fir White spruce White pine

Species

Ambient Dry Ambient Dry Ambient Dry

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Terrestrial Carbon Cycle

CO2 Growth CO2 Soil respiration Erosion, Fire Groundwater transport Litter Roots Microbes Soil Organic Carbon

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IPCC 2013 Negative feedbacks (moderate climate change) Positive feedbacks (exacerbate climate change)

Warming effects might exacerbate or moderate climate change, depending

  • n species, precipitation, …
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Climate Change Feedbacks from Ecosystem Responses

Climate change

Plant growth Decomposition

CO2 Fossil fuels

  • +
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atmosphere: 829 Pg

1 Pg=1015 g = billion tonnes

soils: 1500-2400 Pg permafrost: 1700 Pg

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Melting Permafrost, Kolyma River, Siberia

By 2040: 12% loss By 2100: 54% loss By 2300: 73% loss

(Schuur et al. 2011)

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IPCC 2013 Negative feedbacks (moderate climate change) Positive feedbacks (exacerbate climate change)

Warming effects on permafrost thaw and decomposition will exacerbate climate change

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Will ecosystem responses exacerbate

  • r moderate climate change?
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Shorter Term

Terrestrial ecosystems likely will moderate climate change

Longer Term

Moderation of climate change will decline, and terrestrial ecosystems may even exacerbate climate change

  • Plant growth response to elevated CO2 will saturate
  • Climate warming will likely be accompanied by soil drying and

drought that will limit plant growth

  • Permafrost thaw will accelerate
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Photo: Michael Yuen

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Acknowledgments

National Science Foundation Department of Energy Collaborators: Peter Reich, William Eddy, Rebecca Montgomery, Roy Rich, Artur Stefanski