The Unintentional Iron Fertilization Experiment Impacting the North Pacific

The concept of using iron to fertilize the ocean as a way to mitigate climate change by promoting phytoplankton growth has been a topic of debate. While phytoplankton play a crucial role in absorbing carbon dioxide from the atmosphere when they die and sink to the deep ocean, concerns have been raised about the unintended consequences of large-scale iron fertilization.

One such unintended experiment is currently underway in the North Pacific Transition Zone, just north of Hawai‘i. Researchers, led by Nick Hawco, an assistant professor at the University of Hawai‘i, have been studying the impact of iron released from coal combustion and steel making in East Asia on the marine ecosystem in this region.

Through multiple expeditions and sampling efforts, the team has discovered that the unintentional iron fertilization is altering the ecosystem dynamics in the North Pacific. During the spring, phytoplankton in the region are iron-deficient, leading to a boost in phytoplankton growth when iron levels increase. However, this boom in phytoplankton results in the depletion of other nutrients, particularly nitrate, causing a crash in phytoplankton populations later in the season.

As a result of this unintentional iron fertilization, the base of the marine food web is being impacted, and the warming of the ocean is pushing phytoplankton-rich waters further away from Hawai‘i. The team’s research indicates that the impacts of anthropogenic iron on ecosystems are most intense in the North Pacific region, with potential implications reaching as far as Alaska.

While the study focused on the North Pacific, Hawco suggests that there are likely other key areas of iron release globally, such as in South America and Southern Africa, that could have similar impacts on marine ecosystems over time. The team’s findings underscore the need for further research and monitoring of iron levels in the ocean to better understand the long-term consequences of unintentional iron fertilization.

Despite the challenges of measuring iron levels in the open ocean, advancements in sensor technology offer hope for improved monitoring capabilities. Autonomous ocean robots equipped with sensors capable of measuring nutrients, including iron, could provide valuable insights into the impact of human activities on marine ecosystems.

In other news related to phytoplankton and climate change, a team of scientists from the UK’s National Oceanography Centre has deployed a fleet of ocean robots in the Labrador Sea to study ocean processes that help remove carbon dioxide from the atmosphere and store it in the deep sea.