Ocean fertilization : ecological cure or calamity

Abstract

The late John Martin demonstrated the paramount importance of iron for microscopic plant growth in large areas of the world's oceans. Iron, he hypothesized, was the nutrient that limited green life in seawater. Over twenty years later, Martin's iron hypothesis is widely considered to be the major contribution to oceanography in the second half of the 20th century. Originating as an ecosystem experiment to test Martin's iron hypothesis, iron fertilization experiments are now used as powerful tools to study the world's oceans. Some oceanographers are concerned that these experiments are catapulting ocean science into a new era. The vast stretches of ocean play a key role in the global carbon cycle, and thus in regulating Earth's climate. Some scientists, engineers and international policy makers claim that dissolving iron in the ocean will help stop global warming. Adding large amounts of iron to the oceans may drastically increase the amount of carbon dioxide that phytoplankton can capture from the atmosphere, thereby reducing the most common greenhouse gas. But intentional iron fertilization over great expanses of the ocean may have unintended consequences for the world's largest ecosystem. The open ocean is one of the planet's last frontiers and a part of the global commons. As such, using the open ocean as a means to solve the complex problem of global warming raises deep questions about how humans think of and use the Earth. The question remains: Should humans use the ocean as a means to regulate a changing climate?