Ocean pipes could help the Earth to cure itself

Abstract

SIR-We propose a way to stimulate the Earth's capacity to cure itself, as an emergency treatment for the pathology of global warming. Measurements of the climate system show that the Earth is fast becoming a hotter planet than anything yet experienced by humans. Processes that would normally regulate climate are being driven to amplify warming. Such feedbacks, as well as the inertia of the Earth system-and that of our responsemake it doubtful that any of the wellintentioned technical or social schemes for carbon dieting will restore the status quo. What is needed is a fundamental cure. The oceans, which cover more than 70% of the Earth's surface, are a promising place to seek a regulating influence. One approach would be to use free-floating or tethered vertical pipes to increase the mixing of nutrient-rich waters below the thermocline with the relatively barren waters at the ocean surface. (We acknowledge advice from Armand Neukermans on engineering aspects of the pipes.) Water pumped up pipes-say, 100 to 200 metres long, 10 metres in diameter and with a one-way flap valve at the lower end for pumping by wave movementwould fertilize algae in the surface waters and encourage them to bloom. This would pump down carbon dioxide and produce dimethyl sulphide, the precursor of nuclei that form sunlight-reflecting clouds. Such an approach may fail, perhaps on engineering or economic grounds. And the impact on ocean acidification will need to be taken into account. But the stakes are so high that we put forward the general concept of using the Earth system's own energy for amelioration. The removal of 500 gigatonnes of carbon dioxide from the air by human endeavour is beyond our current technological capability. If we can't 'heal the planet' directly, we may be able to help the planet heal itself.

Assessing carbon dioxide removal through global and regional ocean alkalinization under high and low emission pathways

“…Their primary purpose is to reduce atmospheric CO 2 levels, and thus most CDR methods will also reduce the impacts of ocean acidification, although some proposed techniques such as ocean pipes (Lovelock and Rapley, 2007) and micro-nutrient addition (Keller et al, 2014) may actually lead to a regional acceleration of ocean acidification in surface waters.…”

Impact of episodic vertical fluxes on sea surface pCO 2

“…We will refer to processes that lead to a vertical flux of properties across the base of the ML, more generally, as 'mixing'. Potential mechanisms that can induce such events include negative buoyancy fluxes causing convection, frontal dynamics [12,13], localized upwelling/mixing owing to wind variability [14], storms and hurricanes [15], and proposed geoengineering schemes such as ocean pipes [16]. Indeed, the importance of such vertical mixing events on phytoplankton production and the biological pump is now widely recognized [17][18][19][20][21].…”

The role of CO2 in the Earth’s ecosystem and the possibility of controlling flows between subsystems

“…Jin and Gruber (2003) conducted simulations which show that fertilising only those oceans in the equatorial zone with iron for 100 years could reduce the atmospheric CO 2 concentration by 66 ppm. Other researchers (Lovelock and Rapley 2007) suggested a solution whereby layers of water at greater depths, but richer in nutritional substances, are drawn up close to the surface to promote the growth of algae. However, the above mentioned methods do not appear to be realistic.…”