Iron fertilization

Iron fertilization

Iron fertilization is a process that adds iron to the ocean to help tiny plants called phytoplankton grow. Phytoplankton use sunlight to make food through photosynthesis. This process also takes carbon dioxide from the air, which can help reduce the amount of carbon dioxide in the atmosphere. Reducing carbon dioxide is important for fighting climate change.

Iron is a key nutrient for these tiny plants, but it is often scarce in the upper parts of the ocean. Natural events like dust storms, volcanic eruptions, and even whale waste can add iron to the ocean. This can cause big blooms of phytoplankton. Scientists have also tried adding iron on purpose to see if it can help remove more carbon dioxide.

Many experiments have been done to study how well this works and what effects it might have on ocean life. While some people worry about possible risks, researchers say that so far, no big harmful effects have been seen. The idea continues to be studied as a way to help the environment, but there is still much to learn.

Process

Iron is an important element in the ocean that helps tiny plants called phytoplankton grow. These tiny plants use sunlight to make food through photosynthesis and take in carbon dioxide from the air. When there is more iron in areas that don't have enough, the tiny plants can grow more. This idea was first suggested in the late 1980s by a scientist named Martin.

Iron can get into the ocean in different ways, like when rivers or wind bring iron-rich dust or volcanic ash to the water. Even animals like whales help by eating plants deep in the ocean and then pooping near the surface, which adds iron and helps the tiny plants grow. Without enough whales, like in the Southern Ocean, there has been less carbon taken in from the air because the tiny plants don't grow as much.

Phytoplankton need sunlight and nutrients to grow, and they take in carbon dioxide as they do this. When they die, they sink to the deep ocean, where their remains can store carbon for a very long time.

There are some concerns about adding too much iron to the ocean. It might change the balance of nutrients and harm the ocean's food chain. It could also lead to harmful algae growing too much, which can be dangerous for sea life. While adding iron might help reduce carbon dioxide in the air for a little while, it's not clear if it will work well in the long term.

Methods

There are two ways to add iron to the ocean on purpose. One way is to use ships to put iron directly into the water. The other way is to let iron-rich dust from the air fall into the ocean.

When ships add iron to the ocean, they use a substance called iron sulphate. This helps tiny plants in the water, called phytoplankton, grow more.

Another way iron gets into the ocean is from dust in the air. For example, dust from the Sahara desert helps the Atlantic Ocean and the Amazon rainforest. This dust contains natural iron. Scientists have not tested ways to add more of this dust.

Experiments

Martin thought adding more plants in the ocean could help slow down global warming. He passed away after starting a test called Ironex I near the Galapagos Islands in 1993. After that, many teams did more tests.

These tests included Ironex II in 1995, SOIREE in 1999, EisenEx in 2000, and others up until 2012. One test in 2004 in the South Atlantic made lots of tiny plants called diatoms that sank to the ocean floor. Another test in 2009 showed the place of the test matters for how well it works.

In 2012, a test near Antarctica showed that adding iron made lots of tiny plants that took in air from the air and sank deep into the ocean. One test in 2012 near Haida Gwaii added iron to help fish grow, but many scientists said it was not done carefully.

Some companies wanted to do bigger projects, but some people worried about how it might change the ocean.

Science

Iron fertilization is a way to add iron to the ocean. This helps tiny plants called phytoplankton grow. Phytoplankton need iron to live, just like plants on land need nutrients.

When phytoplankton grow, they take in carbon dioxide from the air through photosynthesis. This can help lower the amount of carbon dioxide in the atmosphere.

Iron gets into the ocean in many ways. Ocean currents can push water with nutrients to the surface. Wind can carry dust from land over the ocean, bringing iron with it. Glaciers, rivers, and icebergs can also add iron to the sea. In some places, not enough iron stops phytoplankton from growing well. Adding more iron can help these tiny plants grow more. This happens naturally, but people have also tried adding iron on purpose to see if it could help reduce carbon dioxide in the air.

Financial opportunities

Since the Kyoto Protocol, many countries and the European Union created ways to trade credits for reducing carbon in the air. These credits are called carbon offset markets and they trade things called trade certified emission reduction credits. In 2007, these credits were worth about €15–20 for each ton of carbon dioxide (CO₂) removed.

Iron fertilization is one way to help remove carbon from the air, and it costs less than other methods like scrubbing or direct injection. It could cost less than €5 for each ton of CO₂ removed. In 2010, Russia set a minimum price for these credits. Scientists have noticed that the amount of tiny plants in the ocean, called plankton, has gone down since 1980. If we could bring back lots of plankton, it might be worth a lot of money in carbon credits. But a study from 2013 showed that iron fertilization might not be as good as other ways to reduce carbon, like carbon capture and storage.

Debate

Adding iron to the ocean might help slow down global warming, but many people are unsure if it really works. They worry about possible bad effects.

One idea called the precautionary principle says that if something might cause big problems, we should be careful until we know more. Because we don’t know enough about how adding iron will affect the environment, some leaders think we should not try it on a large scale yet.

Some people worry that adding iron could cause harmful growths of algae in the water. Even though most tiny plants in the ocean are harmless and important for sea life, adding iron in some places has been shown to create toxic algae that can hurt the food chain. Because of these concerns, many think we need more research before trying this on a big scale.

Main article: Precautionary principle

Main article: Harmful algal bloom

History

Scientists have studied how iron affects tiny ocean plants called phytoplankton for a long time. In the 1930s, a British scientist named Dr. Thomas John Hart thought some ocean areas had lots of nutrients but not enough life because they lacked iron. This idea was tested again in the 1980s by oceanographer John Martin, and his studies agreed with Hart's thoughts. These special ocean areas were named "high-nutrient, low-chlorophyll regions."

In 1988, scientist John Gribbin first suggested that adding iron to the oceans could help reduce climate change. Later that year, Martin made a famous comment about using iron to change global temperatures. A big volcanic eruption in 1991 added a lot of iron dust to the oceans. This led to a drop in carbon dioxide in the air and more oxygen in the water.

In 2008, international groups agreed that adding iron to the ocean for purposes other than scientific research was not allowed. Since the 1990s, many research teams have tested how adding iron can help these tiny plants grow. There is still debate about how well this method works and what effects it might have on the environment. Some of these tests happened in the South Atlantic and near the coast of British Columbia, Canada.