- Natural experiments, such as volcanic eruptions, dust storms, wildfires, and icebergs, demonstrate that adding iron to nutrient-poor ocean waters stimulates phytoplankton growth, which removes carbon dioxide from the atmosphere.
- Phytoplankton blooms are reversible; when nutrient addition stops, growth ceases, indicating ecological safety with no observed long-term harm in numerous studies.
- Specific examples include iron from undersea vents near Tonga, dust from the Gobi Desert, ash from volcanoes like Kasatochi, and smoke from Australian wildfires, all leading to measurable increases in phytoplankton and carbon sequestration.
- The Southern Ocean is particularly responsive, with natural nutrient sources from dust, volcanic ash, and whale feces contributing significantly to phytoplankton productivity and carbon burial.
- Opposition to intentional ocean iron fertilization is argued to be politically motivated, rooted in climate policy ideologies focused on fossil fuel opposition rather than scientific evidence, which shows minimal ecological risk.