Environmental Science: Geoengineering Risks and Proposals
Evaluating climate intervention ideas, benefits, uncertainties, and ethics
Environmental Science: Geoengineering Risks and Proposals
Evaluating climate intervention ideas, benefits, uncertainties, and ethics
Environmental Science - Grade 9-12
- 1
Define geoengineering in the context of climate change. Then name one example of solar radiation management and one example of carbon dioxide removal.
Separate methods that reflect sunlight from methods that remove carbon dioxide from the air.
Geoengineering is the deliberate large-scale intervention in Earth systems to reduce climate change or its impacts. Stratospheric aerosol injection is an example of solar radiation management, and direct air capture is an example of carbon dioxide removal. - 2
A proposal suggests adding reflective particles to the stratosphere to reduce incoming solar energy. Explain one possible climate benefit and two possible risks of this proposal.
A possible benefit is that reflecting more sunlight could temporarily lower global average temperatures. Possible risks include changes in rainfall patterns and damage to the ozone layer, along with the problem that this method does not reduce ocean acidification because carbon dioxide would remain in the atmosphere. - 3
Compare solar radiation management and carbon dioxide removal. Which approach addresses the root cause of ocean acidification, and why?
Ocean acidification is caused mainly by dissolved carbon dioxide forming carbonic acid in seawater.
Carbon dioxide removal addresses the root cause of ocean acidification because it lowers the amount of carbon dioxide in the atmosphere, which can reduce the amount absorbed by the ocean. Solar radiation management may cool the planet, but it does not remove carbon dioxide. - 4
A direct air capture facility removes 1,000 metric tons of carbon dioxide per year. A city emits 2,500,000 metric tons of carbon dioxide per year. What percent of the city's annual emissions would this facility remove? Show your calculation.
Use percent = part divided by whole multiplied by 100.
The facility would remove 0.04% of the city's annual emissions. The calculation is 1,000 divided by 2,500,000, multiplied by 100, which equals 0.04%. - 5
Explain the term termination shock in relation to solar radiation management. Why would this risk matter for ecosystems and human societies?
Termination shock is the rapid warming that could occur if solar radiation management were suddenly stopped while greenhouse gas levels remained high. This risk matters because ecosystems, agriculture, infrastructure, and human health may not be able to adapt quickly to a sudden temperature increase. - 6
Some scientists have proposed ocean iron fertilization to increase phytoplankton growth and carbon storage. Describe how it is supposed to work and identify two environmental uncertainties or risks.
Think about how adding a nutrient can affect many parts of an ecosystem, not just carbon uptake.
Ocean iron fertilization is supposed to work by adding iron to parts of the ocean where iron limits phytoplankton growth, causing more photosynthesis and possible carbon dioxide uptake. Risks include harmful algal blooms, disruption of marine food webs, low-oxygen zones, and uncertainty about how much carbon would actually be stored long term. - 7
A country suffering from extreme heat wants to test stratospheric aerosol injection, but neighboring countries worry about changes to monsoon rainfall. Explain why geoengineering decisions raise issues of environmental justice and international governance.
Geoengineering decisions raise environmental justice issues because the benefits and harms may not be shared equally, and vulnerable communities could face risks without having a voice in the decision. They raise international governance issues because one country's intervention could affect weather, water supplies, agriculture, and health in other countries. - 8
Look at a hypothetical climate graph where greenhouse gas emissions keep rising, solar radiation management begins in 2040, and global temperature stops rising for several decades. Explain why this graph might give a misleading impression if it only shows temperature.
A complete evaluation should include carbon dioxide concentration, ocean chemistry, precipitation, ecosystems, and social risk.
The graph might be misleading because temperature is only one climate indicator. If greenhouse gas emissions keep rising, carbon dioxide would still accumulate, ocean acidification could worsen, and the world could become dependent on continuing the solar radiation management program. - 9
List three criteria scientists and policymakers should use when evaluating a geoengineering proposal. For each criterion, explain why it matters.
Three useful criteria are effectiveness, risk, and reversibility. Effectiveness matters because the method should meaningfully reduce climate harm. Risk matters because unintended effects could damage ecosystems or communities. Reversibility matters because a method that can be stopped or corrected is generally safer than one with permanent consequences. - 10
Write a short evidence-based argument for or against conducting small-scale outdoor geoengineering research. Include at least one possible benefit and one concern.
A balanced argument can support research while still requiring limits, transparency, and public participation.
A strong answer should take a clear position and support it with reasoning. For example, a student might argue that small-scale outdoor research should be allowed under strict public oversight because it can improve scientific understanding before any large-scale use. The answer should also recognize a concern, such as environmental risk, public consent, or the possibility that research could reduce pressure to cut greenhouse gas emissions.