Unit 8 - Carbon Cycle and Climate Change

“Climate Change is Hydrologic Change”

US Forest Service summarized the issue several years ago

Document titled

“Climate Change is Hydrologic Change”

Climate change: Known effects on hydrology

Greater snow cover in highest elevations but less at lower elevations

Earlier spring runoff

Reductions on low flows

Higher water temperature

Flooding

Drought

Projections based on three main aspects of Climate Change and hydrology

Due to warmer air temperature

Due to changes in precipitation patterns

• Lower winter precipitation at lower latitudes

• Higher precipitation at higher latitudes

Due to greater variability in precipitation from year to year

Projections of climate change: due to warmer air temperature

Decreases in snow

Faster and earlier snowmelt

Increased ET, primary productivity, water temperatures

Rising sea levels

Increased coastal erosion and saltwater intrusion

Changes in aquatic habitat and biota

• Amount, type, quality, and distribution

Change in water availability

• For recreation and cultural experiences

Lowered water quality

Decreased function and operation of existing water

• Infrastructure in coastal areas

Projections of climate change: due to changes in precipitation patterns

Lower winter precipitation at lower latitudes

• Decreased snow

• Changes in streamflow timing

• Increased risk of disturbance

  • Drought, wildfires, insects, disease

• Decreased vegetation growth

• Changes in species composition

• Reduced water supplies

• Increased water demand

• Increased GW withdrawals

• Decreases in fisheries

• Decreases in water-based tourism

Higher precipitation at higher latitudes

• Increased streamflow

• Changes in vegetation growth and species composition

• Increased soil erosion and landslides

• Increased freshwater supplies

• Increased improvements in warm water fisheries

Projections of climate change: Due to greater variability in precipitation from year to year

Increased variability in stream, lake, and riparian habitats

Increased risk for aquatic and riparian species extirpation

Increased soil erosion and landslides

Increased stream and lake sedimentation

Increased uncertainty in water supply

Increased risk to aquatic habitat and water supply infrastructure

Signs of a healthy, resilient watershed – ones that rebound after disturbance and continue to provide ecosystem services

has the capacity to:

Capture and store rainfall

Recharge ground water reservoirs

Minimize erosion losses

Protect soil quality

Sustain and regulate stream flows

Store and recycle nutrients

Support natural riparian and floodplain functions

Provide habitat for native aquatic species

Resist and recover quickly from floods, fire, insect outbreaks, and other extreme events

how do we get to a healthy watershed?

Active management for resilience and enhancing ecosystem adaptability needs to:

• Restore meadows, wetlands, and floodplains

  • To improve natural storage, reduce flood hazard, and prolong seasonal flows

• Protect and restore riparian forests

  • To moderate changes in stream temperature

• Remove migration barriers, reestablish habitat connectivity

  • To help species adapt to changing conditions

• Reduce flood and wildfire risks in vulnerable watersheds

  • To prevent erosion and maintain clean water supplies

• Improve or decommission roads

  • To reduce adverse impacts during large storms

All the Forest Service’s recommendations address water

(which has been our focus since the first class)

But they never addressed Carbon directly...

With the increasing importance of Climate Change

Future management will involve Carbon

Either directly managing for Carbon

Or a consideration of Carbon produced

And its potential impacts

Does watershed management conflict with Carbon management?

Watershed management and carbon management are not in conflict but rather are complementary.

They can work together to achieve multiple benefits, including food security, climate adaptation, and climate mitigation.

Carbon sequestration is a key component of watershed management, as it helps replenish soil organic matter, improve soil structure and stability, and reduce soil erosion.

It also enhances soil biodiversity, nutrient holding capacity, nutrient use efficiency, water holding capacity, crop yields, and profitability.

By implementing sustainable land management practices, such as afforestation and land preparation, carbon sequestration can be effectively achieved and maintained.

Primary compounds responsible for climate change

CO2 – Carbon Dioxide

• 80% (based on EPA, 2019)

CH4 – Methane

• 10%, but 25 times greater impact than CO2

Movement and Cycling - ”Carbon Cycle”

• Process in which carbon atoms continually travel from the atmosphere to the Earth and then back into the atmosphere.

  • Yellow – fluxes Units – gigatons/year

  • White – stored amounts

  • Red – human additions

Terrestrial portion

Natural Balance (without human additions)

• 120 gigatons/year in atmosphere

• due to photosynthesis

  • 60 – plant respiration

  • 60 – soil microbial respiration and decomposition

Note the importance of soil

• Hear about using plants as Carbon sink

• Should also be using soil as Carbon sink

  • 2,300 vs. 550

• Soil Health is critical

Ocean portion

Natural Balance (without human additions)

• 90 gigatons/year exchanged

Compare stored amounts

• vegetation 550 GT/yr

• soil 2,300

• atmosphere 800

• ocean surface 1,000

• deep ocean 37,000

• fossil 10,000

“Blue Carbon”

• Term for Carbon captured by oceans and coastal ecosystems

Two main carbon cycles

slow carbon cycle

fast carbon cycle

Slow Carbon Cycle –

geological time frames

10-100 million tons annually

Fast Carbon Cycle –

annually

1,000-100,000 million tons annually

in contrast of carbon cycles, human emissions give off

1,000 million tons annually

Slow carbon cycle cycles between

rocks, oceans, and the atmosphere

Complete cycle - between 100 and 200 million years

Starts with chemical weathering of rocks

• Rainfall is slightly acidic

  • pH of 5.6 for clean rain

    • 4.2 for acid rain

  • carbonic acid

• dissolves rocks, releasing C

• C carried by streams and rivers to the oceans

Slow carbon cycle in oceans

C is taken up by organisms (i.e., corals and plankton)

• forms calcium carbonate

Organisms die and remains fall to seafloor

Over time

• buildup of dead creatures

• 80% of buildup

  • sediments form limestone

• 20% of buildup - in mud

  • forms sedimentary rocks like shale

Slow carbon cycle - carbon returning back to the atmosphere

Volcanoes

tectonic plates slide over one another

• Heat forms silicate minerals

• with CO2 gas formed

erupt

CO2 gas is released

how much is released?

• normally, we think not much

• But – 130-380 million tons/yr

If the slow carbon cycle is out of balance

increase of CO2 in atmosphere

-> rise in temperature

-> increase in rainfall

-> dissolves more rock

-> moreCarbonon seafloor

-> reducedCarbonin atmosphere

-> reduced temperature

result is natural feedback process

scale of 100,000-200,000 years

fast carbon cycle is cycling of

Carbon through living organisms

1,000-100,000 million tons/year

Primary components

• Plants

• Phytoplankton

Since closely tied to plants, you can see the change annually

Fast carbon cycle - in august, peak of 

growth in the Northern Hemisphere and peak draw down of Carbon

Followed by plant death and decomposition

respiration returns Carbon to the atmosphere and the return of Carbon to prior levels

Fast carbon cycle - 

August

• growth in N Hemisphere

• (more green than Dec.)

December

• growth in S Hemisphere

• (summer down under...)

Photosynthesis

CO2 + H2O + sun’s energy = CH2O (sugar) + O2

Respiration

CH2O (sugar) + O2 = CO2 + H2O + energy released

• CO2 goes into the atmosphere

Reminder: 

1. Plants respire

2. Animals eat plants and respire

3. Death of plants and phytoplankton

4. Fire

human induced changes relative to watersheds - humans tend to cut forests

and replace with crops or pasture

which store less Carbon

also exposes soil to Carbon loss

• exacerbating the problems

human induced changes relative to watersheds - with increase in atmospheric Carbon

increased plant growth

called ”Carbon Fertilization”

models show 12-76% increase

• if levels in atmosphere double

however, other factors may be limiting

• water, light, and nutrients

human induced changes relative to watersheds - freshwater lakes and streams

Studies in Germany

pH dropped 0.3 in the last 35 years

Rate is 10 times faster than oceans

• Appears freshwater absorbs CO2 differently than oceans do

CO2 increased steadily during that time

Freshwater crustaceans (Daphnia, or water fleas) were less likely to evade predators

• Appears this is a result of changes in CO2 in water rather than pH

Managing Carbon on a Watershed

You are probably not able to:

Control fossil fuel emissions

Promote use of electric vehicles

Convert to renewable energy sources

...and a thousand other steps to manage C...

What you can do to manage carbon:

Tie-up Carbon in the landscape

• Vegetation

• Healthy Soil

• Permafrost

Reduce Carbon losses

• Erosion control

• Agricultural processes

• Reduced tillage/no tillage

• Addition of organic matter

• Use of cover crops

Erosion Control and Carbon

Some authors claim that erosion will result in a Carbon sink

Erosion leads to

• deposition of soil

• deposition of organic matter

• ...resulting in vegetative increases

• ...and thus, greater Carbon storage

Other studies have included a wider range of ecological processes

Concluded the opposite

• increased Carbon emissions

Positive feedback

Climate change produces larger rainfall events

• ...leading to more erosion

• ...leading to more Carbon emission

• ...leading to more large rainfall events

• ...and on and on...

Objective 1 – maintain or increase water yield

Seems to conflict with managing C

Increasing vegetation for C

• increased losses – Interception and Transpiration

But

• probably decrease runoff

• increase infiltration

• greater recharge (which is a form of water yield)

Wildcard are extreme events

• increase in intensity and number

• vegetation can help mitigate some impacts

• can capture some of the water (in reservoirs, etc.)

• IF you plan appropriately

Objective 2 – maintain or improve water quality

Increased soil health will aid water quality

Increased vegetation will aid water quality

• Slow down runoff

• Decrease erosion

• Increased filtering of pollutants

• Shading effects, and increased DO

Except for extreme events

• Will tend to decrease water quality

• Vegetation and soil health - mitigate

Objective 3 – regulate stream flows (timing)

Vegetation increases will have two benefits

Runoff will be reduced

• ...except for extreme events

Greater recharge potential

• aid in low stream flows

Objective 4 – control excessive soil erosion and excessive runoff

As with Objective 2, increased vegetation and improved soil health will help

Rutgers University and New Jersey Climate Adaptation Alliance - multiple actions that can be taken

1. Disconnect impervious cover

Eliminate surfaces that are not necessary

Reduce or convert impervious surfaces

Disconnect impervious surfaces from flowing directly to waterways

Rutgers University and New Jersey Climate Adaptation Alliance - multiple actions that can be taken

2. preserve and restore wetlands and marshes

Effective barriers against flash floods and sea level rise

Filter pollutants

Slow flood flows

Help to prevent erosion

Support biodiversity

Rutgers University and New Jersey Climate Adaptation Alliance - multiple actions that can be taken

3. Design green infrastructure tools to treat a higher capacity

Rain gardens

Tree trenches

• like a rain garden for trees

Stormwater planters and bioswales

Pervious (permeable) pavement

Rain barrels

Rutgers University and New Jersey Climate Adaptation Alliance - multiple actions that can be taken

4. Restore streams and their floodplains

Daylighting streams previously buried in pipes or culverts

Restoring channelized streams to natural flow patterns

Rutgers University and New Jersey Climate Adaptation Alliance - multiple actions that can be taken

5. Reestablish aquatic habitat connectivity by removing migration barriers

Convert pipe culverts to bottomless arch culverts or bridges

Replacing narrow culverts with wider openings

Increases carrying capacity during storm events

Rutgers University and New Jersey Climate Adaptation Alliance - multiple actions that can be taken

6. Maintain riparian buffers along waterways

yeah!

Rutgers University and New Jersey Climate Adaptation Alliance - multiple actions that can be taken

7. Plant tolerant native species and manage the spread of invasive species

More tolerant of inundation for a few days

Withstand warmer climates

Withstand more variable precipitation

Rutgers University and New Jersey Climate Adaptation Alliance - multiple actions that can be taken

8. set up a monitoring program

Identify key indicators and their critical levels

Water levels, fish stocks, wetland coverage, stream temps, nutrient loads, bacteria, stream flow...

Maintain good data on existing conditions and trends

• Allows managers to be more sensitive and to adapt quickly

Periodically reevaluate management practices and indicator targets

Rutgers University and New Jersey Climate Adaptation Alliance - multiple actions that can be taken

9. partner with local governments to revise land use ordinances

Assess land use, zoning, and other ordinances

Revise municipal regulations to encourage practices that enhance watershed protection

• Open space preservation

• Clustered development

• Promote natural recharge and reductions in runoff

Rutgers University and New Jersey Climate Adaptation Alliance - multiple actions that can be taken

10. Educate the public on demand management and water supply protection strategies

Reduce personal water usage

Protect groundwater

High efficiency fixtures

Native plants for lawns

• Require minimal irrigation, pesticides, and fertilizers

Redirecting downspouts to permeable surfaces