ENVS10011 Lecture Notes - Lecture 9: Global Warming Potential, Ozone Depletion, Soil Carbon
17 May 2018
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WEEK 9: CARBON AND CLIMATE CHANGE MITIGATION
Cropping + Grazing
• Involves photosynthesis + respiration, mineralisation
• Ruminant animals: nitrous oxide, methane (strong GHG) + decay of organic matter,
also eat plants
• Issue: photosynthesis doesn’t equal respiration + mineralisation + methane
Methane from animal production:
• Global warming potential
o Shorter lifetime in atmosphere (8-12 years)
o Concentrations: increased 260% (ppb) in 2016 since pre-1750
• Ruminants (cows, sheep), Non-Ruminants (pigs, horse, poultry) + effluent ponds
Nitrous Oxide (cropping + animal production)
• Comes from side reactions of nitrogen cycle
• Atmospheric concentrations:
o Pre-industrial (270ppb) to current (328ppb) – rise of 0.25% per year
• Amounts to 10% of global GHG (90% from agriculture)
• Australia: (2.5% national emissions – 76% from agriculture)
• Long residence time in atmosphere: causes ozone depletion in stratosphere, stays
forever in troposphere
Carbon Assessment Methods
• Began on a national level, when c.c became an issue
• Australia: used fullCAM model, made by CSIRO
• Types:
o GAF (Greenhouse Accounting Frameworks): simple inventory tools, used for
land use
o Farm System Models
o Forest Growth Models
Measurement of Carbon Pools
• Debris + belowground biomass: low accuracy, time consuming + involves destruction
of environments
• Allometrics: measuring one base object to determine others using formula
o Used for aboveground biomass
• Soil carbon: easy to measure, however slow rate of change
• More than is visible
o Storage in forest biomass + soil
o Storage in forest products: paper, furniture, construction
o Displacement: use of biofuels to replace fossil fuels
o Substitution: use of wood products that replace fossil fuel intensive products
(concrete, steel, aluminium, plastic)
Managing Environments for Carbon Sequestration/Storage
Tree Carbon Change:
• Drivers influencing carbon uptake:
o Environmental factors (hard to control/predict) Light, water availability, temp,
atmospheric CO2 + nutrients
• Drivers influencing tree carbon loss:
o Water availability, temp, nutrients
