Carbon dioxide removal (CDR) approaches are efforts to reduce the atmospheric CO2 concentration. Here we use a marine carbon cycle model to investigate the effects of one CDR technique: the open ocean dissolution of the iron-containing mineral olivine. We analyse the maximum CDR potential of an annual dissolution of 3 Pg olivine during the 21st century and focus on the role of the micro-nutrient iron for the biological carbon pump.

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Albedo modification (AM) is sometimes characterized as a potential means of avoiding climate threshold responses, including large-scale ice sheet mass loss. Previous work has investigated the effects of AM on total sea-level rise over the present century, as well as AM's ability to reduce long-term (Gt103 yr) contributions to sea-level rise from the Greenland Ice Sheet (GIS). These studies have broken new ground, but neglect important feedbacks in the GIS system, or are silent on AM's effectiveness over the short time scales that may be most relevant for decision-making (<103 yr).

Geo-engineering schemes like reflecting solar radiation or sucking CO2 out of the sky will not be a feasible way to reduce emissions for the next several decades, a new EU-funded report has warned.

Carbon dioxide removal (CDR) is the only geoengineering technique that allows negative emissions and the reduction of anthropogenic carbon in the atmosphere. Since the time scales of the global carbon cycle are largely driven by

Oil-burning ships are fertilising the north Pacific with iron – inadvertently putting a proposed geoengineering idea into practice.

When a chartered fishing boat strewed 100 tonnes of iron sulphate into the ocean off western Canada last July, the goal was to supercharge the marine ecosystem. The iron was meant to fertilize plankton, boost salmon populations and sequester carbon. Whether the ocean responded as hoped is not clear, but the project has touched off an explosion on land, angering scientists, embarrassing a village of indigenous people and enraging opponents of geoengineering.

The deliberate injection of particles into the stratosphere has been suggested as a possible geoengineering scheme to mitigate the global warming aspect of climate change. Injected particles scatter solar radiation back to space and thus reduce the radiative balance of Earth. Previous studies investigating this scheme have focused primarily on sulphuric acid particles to mimic volcanic injections of stratospheric aerosol. However, the composition and size of volcanic sulphuric acid particles are far from optimal for scattering solar radiation.

The Conference of the Parties (COP) of the Convention on Biological Diversity (CBD) first turned its attention to geoengineering at its ninth meeting in 2008, in the context of ocean fertilization.

At the United Nations Framework Convention on Climate Change Conference in Cancun, in November 2010, the Heads of State reached an agreement on the aim of limiting the global temperature rise to 2 °C relative to preindustrial levels. They recognized that long-term future warming is primarily constrained by cumulative anthropogenic greenhouse gas emissions, that deep cuts in global emissions are required, and that action based on equity must be taken to meet this objective.

Geoengineering efforts to bring oxygen into the deep Baltic should be abandoned, says Daniel J. Conley.

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