Concern over human-driven climate change
constraining green-house gas emissions have increased scientific and policy interest in geoengineering − deliberate interventions in the Earth’s climate system that might moderate global warming. Proposed approaches involve either removing carbon di-oxide (CO2) from the atmosphere by biological or chemical means (to reduce the forcing of climate change), or reflecting part of the sun’s energy back into space (to counteract the forcing,
by altering Earth’s radiation budget). Experimental small-scale iron additions have shown increase in biomass of phytoplankton, however large-scale fertilization could have unintended impacts not only locally, but also in space and time. This document focuses only on scientific issues, whilst socio-economic, ethical and legal considerations are also highly important.