The Carbon Cycle and Climate Change
Most of the carbon on Earth is sequestered in rocks, but it is also stored in the ocean, the atmosphere, soils, and plants. Carbon cycles between the Earth's spheres (geosphere, hydrosphere, biosphere, and atmosphere), sometimes quickly, like when fossil fuels are burned, and sometimes slowly, like when layers of sediment and shells form rock on the ocean floor. The movement of carbon between Earth's spheres is naturally balanced, but human activities since the Industrial Revolution are adding carbon to the atmosphere in a way that is out of balance. Rapid increases in the amount of carbon dioxide entering the atmosphere is causing the climate to warm. The extra carbon dioxide that is added to the atmosphere can remain there for centuries. To put the system back into balance, we must drastically reduce the amount of carbon entering the atmosphere and also remove carbon dioxide from the atmosphere to the other spheres.
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The Role of Carbon Dioxide in Climate Warming
Carbon enters the atmosphere both through natural processes, such as decomposition or volcanic eruptions and also as a result of human activity, such as burning fossil fuels. Carbon dioxide and methane (CH4) are two types of greenhouse gases that trap energy from the Sun in the atmosphere, which causes the planet to warm. Without any greenhouse gases, the Earth would be too cold to sustain life at current levels, but with the current rapid increase of greenhouse gases, the climate is warming too much. Human-caused carbon emissions have been rising since the 1850s when the Industrial Revolution brought about wide-scale use of combustion engines and the burning of coal for electricity. The concentration of CO2 in the atmosphere is increasing along with the increase in human-caused carbon dioxide emissions, as seen in the graph below.
The warming climate is causing many changes on Earth, such as melting ice sheets, sea level rise due to thermal expansion of ocean waters, and changing weather patterns which lead to drought in some areas and intensified storms in others. As more carbon dioxide enters the water, the oceans are becoming more acidic, which is harmful to marine ecosystems. The effects of increased carbon dioxide in the atmosphere are compounded by feedback loops, in which warming leads to more warming. For example, when warming surface temperatures cause ice sheets to melt, less energy from the Sun is reflected from the darker, ice-free surface, and instead is absorbed, which leads to more warming. Because of these and other types of feedback loops, the effects of adding carbon dioxide to the atmosphere are often compounded.
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Reducing and Removing Greenhouse Gases to Slow Climate Warming
To stop climate change, we need to reduce the amount of greenhouse gases, like carbon dioxide, in the atmosphere. There are two main ways that we can stop the amount of greenhouse gases from increasing: we can stop adding them to the air and we can increase the Earth's ability to pull them out of the air.
This is called climate mitigation. There is not one single way to mitigate climate change. Instead, we will have to piece together many different solutions to stop the climate from warming. Many of these solutions are already being implemented in places around the world. Some can be tackled by individuals, such as reducing energy use, riding a bike instead of driving, driving an electric car, and switching to solar power. Other actions to mitigate climate change involve communities, regions, or nations working together to make changes, such as: switching power plants from burning coal or gas to renewable energy sources, and growing public transit.
Learn more about removing carbon dioxide from the air:
Project Drawdown is a non profit research organization that exists as a resource to educate about climate solutions. They help to advance climate actions by reviewing and assessing climate solutions to ensure that communities, businesses, and even governments, are armed with the information they need to implement effective actions. "Drawdown" refers to the time in Earth's future when levels of greenhouse gases in the atmosphere are steadily declining. Many resources, including a download of The Drawdown Review publication, are available from their website at no cost.
Parts, Purposes, and Complexities Routine
The Parts, Purposes, and Complexities routine is one of Harvard’s Project Zero Thinking Routines which provide structure to help make student thinking visible. The Parts, Purposes, and Complexities routine can be used when introducing and exploring ideas to help students think about the complexity of a system or object and is used in this activity as a way to help students analyze the complexity of the different sectors where climate solutions are needed. As with any new classroom practice, the first time students engage with it they may need extra support. There are tips for launching the Parts, Purposes, and Complexities routine with your students provided along with the description of the routine at the link above.