Photosynthesis removes carbon dioxide from the atmosphere

Keeping Up with Carbon

Table of Contents Show

Carbon storage and exchange
Changes to the carbon cycle
EDUCATION CONNECTION
How does photosynthesis pull carbon out of the atmosphere?
Does photosynthesis remove oxygen from the atmosphere?
How do we remove carbon dioxide from the atmosphere?

Narration: Troy Cline

Transcript:

Carbon is the basic building block of life, and these unique atoms are found everywhere on Earth. Carbon makes up Earth’s plants and animals, and Carbon is also stored in the ocean, the atmosphere, and the crust of the planet. A carbon atom could spend millions of years moving through Earth in a complex cycle. Understanding the carbon cycle- and how it is changing -is key to understanding Earth’s changing climate. On land, plants remove carbon from the atmosphere through photosynthesis. Animals eat plants and either breath out the carbon, or it moves up the food chain. When plants and animals die and decay, they transfer carbon back to the soil. Moving offshore, the ocean holds huge amounts of carbon—about 50 times the amount we find in the atmosphere. Stacey Boland: The ocean is sometimes called a carbon sink, meaning that it absorbs, or takes up carbon from the atmosphere. It takes up carbon through physical and biological processes- At the ocean’s surface, carbon dioxide from the atmosphere dissolves into the water. Tiny marine plants called phytoplankton use this carbon dioxide for photosynthesis. Phytoplankton are the base of the marine food web. After animals eat the plants, they breathe out the carbon or pass it up the food chain. Sometimes phytoplankton die, decompose, and are recycled in the surface waters. Phytoplankton can also sink to the bottom of the ocean, where they become buried in marine sediment. Over long time scales, this process has made the ocean floor the largest reservoir of carbon on the planet. Most of the ocean’s nutrients are in cold, deep water. In a process called upwelling, currents bring nutrients and carbon up to the surface. Carbon can then be released as a gas back into the atmosphere, continuing the carbon cycle. By cycling huge amounts of Carbon, the ocean helps regulate climate. Scott Doney: So when you think of climate, you don’t often think of the ocean. With climate- you think of, is it going to be hotter this year, or is it going to be colder this year? But the oceans are actually a great regulator, a controller of Earth’s climate. And they even are controlling how much carbon is in the atmosphere, which can slow down how quickly climate change is occurring. At the most basic level, the balance between incoming sunlight and outgoing heat determines Earth’s climate. Greenhouse gases act like a blanket, and trap heat in the atmosphere. Carbon dioxide is a greenhouse gas. In the past two centuries, humans have increased atmospheric carbon dioxide by more than 30%, by burning fossil-fuels and cutting down forests. The Earth has not experienced carbon dioxide levels this high for the past several million years. Researchers are learning that future climate change will depend on carbon levels in the land, in the atmosphere, and in the sea, and how these levels respond to human disturbance. About one-third of all human-generated carbon emissions has dissolved into the ocean. More than 80% of Earth’s added heat is now stored in the ocean. Stacey Boland: In the future, as the planet gets warmer, the water’s going to warm up, and warm water can hold less carbon than cold water…the other thing is, on a warmer planet, some of the currents are going to slow down, so we might not be forming as much of this cold deep water. So we won’t be able to transport carbon into the deep sea. So on the whole, the ocean’s going to become less effective at removing carbon from the atmosphere. Throughout most of Earth’s ocean, the warmer water, weaker circulation, and new temperature gradients that result from climate change will impact marine life and ecosystems. These changes affect the ocean’s ability to store carbon. Increased carbon dioxide in the atmosphere impacts marine life in other ways.. Stacey Boland: As the ocean absorbs more carbon dioxide, it becomes more acidic, and this can be a threat to some of the organisms that live inside the ocean. As Earth’s climate continues to change, how will researchers monitor something as big as the ocean, and something as complex as the carbon cycle? NASA Earth observing satellites give scientists the “big picture” view of our home planet. Varied satellites help researchers detect changes in ocean climate and ecology over time, providing vital insight into the health of our home planet.

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Carbon is the chemical backbone of life on Earth. Carbon compounds regulate the Earth’s temperature, make up the food that sustains us, and provide energy that fuels our global economy.

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Most of Earth’s carbon is stored in rocks and sediments. The rest is located in the ocean, atmosphere, and in living organisms. These are the reservoirs through which carbon cycles.

Carbon dioxide concentrations are rising mostly because of the fossil fuels that people are burning for energy.

Carbon storage and exchange

Carbon moves from one storage reservoir to another through a variety of mechanisms. For example, in the food chain, plants move carbon from the atmosphere into the biosphere through photosynthesis. They use energy from the sun to chemically combine carbon dioxide with hydrogen and oxygen from water to create sugar molecules. Animals that eat plants digest the sugar molecules to get energy for their bodies. Respiration, excretion, and decomposition release the carbon back into the atmosphere or soil, continuing the cycle.

The ocean plays a critical role in carbon storage, as it holds about 50 times more carbon than the atmosphere. Two-way carbon exchange can occur quickly between the ocean’s surface waters and the atmosphere, but carbon may be stored for centuries at the deepest ocean depths.

Rocks like limestone and fossil fuels like coal and oil are storage reservoirs that contain carbon from plants and animals that lived millions of years ago. When these organisms died, slow geologic processes trapped their carbon and transformed it into these natural resources. Processes such as erosion release this carbon back into the atmosphere very slowly, while volcanic activity can release it very quickly. Burning fossil fuels in cars or power plants is another way this carbon can be released into the atmospheric reservoir quickly.

New research utilizes airborne measurements of carbon dioxide to estimate ocean uptake.

Changes to the carbon cycle

Human activities have a tremendous impact on the carbon cycle. Burning fossil fuels, changing land use, and using limestone to make concrete all transfer significant quantities of carbon into the atmosphere. As a result, the amount of carbon dioxide in the atmosphere is rapidly rising; it is already greater than at any time in the last 3.6 million years. The ocean absorbs much of the carbon dioxide that is released from burning fossil fuels. This extra carbon dioxide is lowering the ocean’s pH, through a process called ocean acidification. Ocean acidification interferes with the ability of marine organisms (including corals, Dungeness crabs, and snails) to build their shells and skeletons.

Global carbon emissions are projected to bounce back to after an unprecedented drop caused by the response to the coronavirus pandemic, according to an annual report by the Global Carbon Project.

EDUCATION CONNECTION

Take a bite of dinner, breathe in air, or a drive in a car — you are part of the carbon cycle. The resources in this collection provide real world examples of the changes occurring in the cycle. There is much to learn about this essential topic and some of the resources highlight exciting career opportunities in this field of study.

How does photosynthesis pull carbon out of the atmosphere?

Forests sequester or store carbon mainly in trees and soil. During the process of photosynthesis trees pull carbon out of the atmosphere to make sugar, but they also release carbon dioxide back into the atmosphere through decomposition. Carbon and other gases within forests are captured and released on a cycle.

Does photosynthesis remove oxygen from the atmosphere?

Oxygen is a byproduct of photosynthesis. About 70% of the oxygen in the atmosphere that we breathe comes from algae in the ocean. Atmospheric oxygen from photosynthesis also forms the ozone layer, which protects organisms from harmful high-energy ultraviolet (UV) radiation from the Sun.