Transcript Presentation: Carbon sequestration

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Carbon sequestration
David Redfern
Hodder & Stoughton © 2016
Introduction
This presentation supports the Geographical Ideas column on mitigation and adaptation in
GEOGRAPHY REVIEW Vol. 30, No. 1, pages 9-11.
One concept introduced in this piece is carbon sequestration. This PowerPoint examines
natural and human-induced forms of sequestration and raises some associated issues.
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What is carbon sequestration?
Carbon sequestration is the process of capture and long-term storage of atmospheric carbon
dioxide. It includes the:
• process of removing carbon from the atmosphere and depositing it in a reservoir
• process of carbon capture and storage (CCS), where carbon dioxide is removed from fuel
exhaust gases, such as from power stations, before being stored in underground reservoirs,
aquifers and even ageing oil fields
• storage of carbon either by natural processes or by human activities in the oceans and their
sediments.
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Natural sequestration
Peat bogs are an important carbon store. By creating new bogs, or preserving or enhancing
existing ones, carbon can be sequestered.
Reforestation is the planting of trees on marginal crop and pasture lands to incorporate
carbon from atmospheric carbon dioxide into the biomass.
Wetland restoration Wetland soil is an important carbon sink. 14.5% of the world’s soil
carbon is found in wetlands, while only 6% of the world’s land is composed of wetlands.
Creating more wetlands would sequester more carbon.
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Enhancing natural
sequestration
Agricultural practices play an important role in enhancing natural sequestration.
Methods include:
• using cover crops such as grasses and weeds as temporary cover between planting
seasons
• concentrating livestock in small paddocks for a few days at a time so they graze lightly but
evenly. This encourages roots to grow deeper into the soil. Stock also till the soil with their
hooves, grinding old grass and manure into the soil
• covering bare paddocks with hay or dead vegetation. This protects soil from the sun and
allows the soil to hold more water and be more attractive to carbon-capturing microbes.
• restoring degraded land, which slows carbon release while returning the land to agriculture
or other use
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Human-induced
sequestration
Several methods can be used:
•
Iron fertilisation is the deposition of iron-rich dust into the waters of the oceans. This
boosts algal growth which in turn absorb more carbon dioxide.
•
Urea fertilisation is fertilising the oceans with urea, a nitrogen rich substance. This could
also encourage phytoplankton growth.
•
Carbon capture and storage (CCS) in power stations. See next slide..
•
Biochar means creating charcoal from timber which is then added to the soil.
•
Subterranean injection means injecting carbon dioxide into depleted oil and gas
reservoirs and other geological features, into the deep ocean.
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Carbon capture and storage
(CCS)
CCS can capture up to 90% of carbon dioxide emissions released by the burning of fossil fuels
in electricity generation and industrial processes. The process has three stages:
• capturing the carbon dioxide — separating carbon dioxide from other gases
• transporting the carbon dioxide by pipeline or ship to the storage location
• storing the carbon dioxide emissions securely underground in depleted oil and gas fields ,
deep saline aquifers or deep oceans.
Some carbon dioxide gas can be used to extract more oil and gas from existing reservoirs —
a similar process to fracking. Those in favour of this argue that the money raised would partly
pay for the CCS process. Those who oppose it say that this perpetuates the problem of fossilfuel burning.
Note: ocean–based CCS causes an added problem of ocean acidification.
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Climate engineering
technologies
Climate engineering technologies may also be relevant for sequestration.
Geo-engineering is the deliberate, large-scale manipulation of the planetary
environment in order to counteract human-caused climate change.
Geo-engineering technologies aim to do one of two things:
• accelerate the removal of carbon dioxide from the atmosphere (carbon dioxide removal,
CDR)
• reflect more sunlight back into space (sunlight reflection methods, SRM).
SRM technologies include placing mirrors in near-Earth space orbit, injecting tiny sunlightreflecting particles into the stratosphere and whitening low-level marine clouds by spraying
sea water into them. See the article in GEOGRAPHY REVIEW Vol. 29, No. 1 on ‘Engineering he
Earth’s climate’.
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Geotechnology: Effectiveness
v Affordability v Safety
Some of the methods mentioned in this presentation can be examined in terms of their
effectiveness, affordability and safety.
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Mitigation, adaptation and
sequestration: issues
Some interesting issues to think about regarding mitigation, adaptation and sequestration:
•
What should be the priorities for adaptation vs mitigation?
•
Equity: many of those vulnerable to climate change have contributed little to greenhouse gas
emissions. Why should they be prevented from developing in the same way Western countries
did?
•
Does delaying mitigation shift the burden from the present to the future?
•
Given that developed countries have passed through their industrial phase of development
without regard for the environment, is it now their duty to assist developing countries, or to dictate
terms in global agreements? Is this some form of climate-colonialism?
•
What is the correct scale of action for each of mitigation or adaptation?
•
Why is there so much difficulty getting politicians on board?
•
How strong is humankind’s ability (or inability) to plan on the global scale?
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This resource is part of GEOGRAPHY REVIEW, a magazine written for A-level
students by subject experts. To subscribe to the full magazine go
to: http://www.hoddereducation.co.uk/geographyreview
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