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, which also takes carbon dioxide from the air. This can help reduce the amount of carbon dioxide in the atmosphere, which 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, causing 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, who thought that adding iron could help these plants grow and take in more carbon dioxide from the air.

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. However, sometimes other small animals eat the phytoplankton before they can sink, so not all the carbon reaches the deep ocean.

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 and even people. 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 because some of the carbon might come back into the air later.

Methods

There are two ways to add iron to the ocean on purpose: using ships to put it directly into the water, and letting 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 that can help cool the Earth by making clouds brighter and removing gases that warm the planet. Scientists have not tested ways to add more of this dust, but some ideas suggest using special sprays to add more iron to the air to help cool the planet.

Experiments

Martin thought that adding more plants in the ocean could help slow down global warming by taking in air from the air. He passed away not long after starting a test called Ironex I near the Galapagos Islands in 1993. After that, many teams around the world did more tests to learn more.

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

In 2012, a test near Antarctica showed that adding iron created 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 done in a way that was not very careful.

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

Science

Iron fertilization is a process that adds iron to the ocean to help tiny plants called phytoplankton grow. Phytoplankton need iron to live and grow, just like plants on land need soil nutrients. When they grow, they take in carbon dioxide from the air through photosynthesis, which can help reduce the amount of this gas in the atmosphere.

Iron gets into the ocean in several ways. Sometimes, ocean currents push nutrient-rich water to the surface. Wind can also carry dust from land over the ocean, bringing iron with it. Even glaciers, rivers, and icebergs can add iron to the sea. In some places, the amount of iron limits how much phytoplankton can grow, so adding more iron can lead to bigger blooms of these tiny plants. This process 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

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

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

Some people are also worried 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. Studies have also shown that adding iron might make climate change effects worse and do little to reduce the amount of carbon dioxide in the ocean. 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 long been interested in how iron affects tiny ocean plants called phytoplankton. In the 1930s, a British scientist named Dr. Thomas John Hart thought that some parts of the ocean, rich in nutrients but poor in life, might lack iron. This idea was tested again in the 1980s by oceanographer John Martin, whose studies supported 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 influence global temperatures. A major volcanic eruption in 1991 added a lot of iron dust to the oceans, which led to a noticeable drop in carbon dioxide in the air and an increase in 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, but 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.