Geoengineering: changing the earth's climate for better or worse?

Geoengineering - this is a concept that we will be hearing more and more about with regards to managing climate change. It doesn't necessarily involve us on a personal level, like buying fluorescent light bulbs or driving more fuel-efficient cars; this is large-scale proactive approaches where science and commerce are utilized to directly counter the effects of climate change and CO2 emissions rather than deal with root causes.

Basically, we are talking about taking the CO2 we have in the atmosphere and finding some other place to park it, often referred to as CO2 sequestration. There have been proposals to store it underground while others have focused on methods of increasing absorption by the oceans where it is stored at deep depths.

I was reading several reports on ocean sequestration and there are many techniques that have been studied and even experimented with on a small scale. The results and/or recommendations have been conflicting - in part due to the fact that none of this has been undertaken on a large, truly global scale so we are walking into unknown territory with only projections and theories to guide us. Here are some of the current concepts regarding ocean CO2 sequestration:

Ocean Fertilization: Using the addition of iron particles to induce greater phytoplankton blooms which will, as part of their normal biological process, consume more CO2 and then sink to the ocean bottom. Some scientists say this is a viable approach, others say that the results are not substantial enough compared to the costs and related effects that would impact the ocean ecosystem.

Ocean Nourishment: A variation on ocean fertilization wherein additional nutrients are added to the process that could enhance the growth of feeder fish populations, thereby providing additional benefits with an increased food source and potential commercial value to developing countries.

Alkalinity Change: A land-based process where a CO2 source is combined with limestone and sea water. Basically the reaction alters the pH level and binds the CO2 to the sea water, which is then discharged back into the ocean. The use of limestone, which introduces calcium carbonate, is expected to neutralize acidification and therefore have minimal impact on the marine ecology.

Direct Injection: When ocean sequestration is discussed, the storage of CO2 is to take place at great depths where CO2 actually forms a liquid more dense than seawater (below 3000 meters). There are proposals for direct injection that involve piping CO2 directly from sources like industrial plants or energy refineries into the ocean depths where it is trapped at depth, forming a kind of deep sea lake of near-solid CO2.

These are techniques that are currently being experimented with, but whether they ultimately prove to be physically or financially practical on a large scale remains to be seen. And what of the unforeseen ecological implications? Attitudes range and proposals are hotly debated within the scientific community. There are those that say that geoengineering represents "doing something rather than nothing" with the current and future volume of CO2 in the atmosphere, regardless of what preventive steps are taken. (Remember the Carbon Bathtub analogy I cited earlier this week? Even if we radically cut back on CO2 emissions, we will have excess amounts in the atmosphere to deal with for centuries.)

Geoengineering is not a silver bullet solution nor does it free us from addressing the ongoing sources of CO2 emissions. At best it could work in concert with CO2 reduction strategies, but it is technology that is new with unforeseen consequences and perhaps must operate on unimaginable scales worldwide. However, it may find its place because we don't have a choice.