Tag Archives: geoengineering

Geoengineering (Climate Week #6)

Geoengineering represents several technological or large-scale approaches for offsetting the effects of climate change. Rather than conventional mitigation approaches that result in lower greenhouse gas emissions (such as switching to electric vehicles or investing in renewable energy), geoengineering approaches represent far more technical or radical interventions intended to stop climate change.

Broadly speaking there are two basic approaches:

  1. Greenhouse Gas Removal – removing greenhouse gases (but especially carbon dioxide) from the atmosphere. Methods for doing this include capturing gases as they are released, use giant air scrubbers to directly capture greenhouse gases from the air, or planting huge numbers of trees. The end result is less greenhouse gases in the sky, and lower average temperatures.
  2. Solar Radiation Management: making the Earth more reflective so that light from the sun bounces back into space. You can use artificial snow or reflective materials to protect ice sheets, paint roofs and buildings reflective colors, add reflective aerosols to the upper atmosphere, or even use reflective objects in space to reflect light away from the Earth. The end result is less solar radiation being absorbed by the Earth, and lower average temperatures.

You can probably guess that pretty much every geoengineering approach (with the exception of afforestation, planting huge numbers of trees) is controversial, with many detractors. Criticisms include geoengineering approaches being poorly studied, some approaches are currently expensive, some proposals have unknown negative side effects, some of these approaches have massive consequences for international relations, and pursuing geoengineering instead of climate mitigation could give polluting nations and companies an excuse to keep polluting.

Geoengineering isn’t a panacea – but, like I’m going to be saying for the rest of my life, climate change is dire enough that any and all solutions need to be on the table.

There are over a dozen geoengineering approaches already proposed, from relatively conventional like afforestation, to the truly sci-fi idea of adding orbital mirrors to reflect sunlight. But, whether conventional or radical, I’m going to be evaluating each approach for its effectiveness at stopping climate change and how easily it could be used at large scales.

Iron Fertilization (Climate Week #4)

“Give me a half a tanker of iron and I will give you another ice age.” Or at least, that’s what oceanographer John Martin said in 1988 about a radical and bizarre way of stopping climate change: dumping iron in the ocean. This is one of several geoengineering solutions to climate change, solutions that deliberately alter the environment to fight climate change.

To understand what iron has to do with climate change, you need to understand that most photosynthesis (the process plants use to take carbon dioxide out of the sky) doesn’t happen on land. The majority (50-85% depending on the estimate) actually happens in the ocean, done by microscopic algae called phytoplankton. These “wandering plants” take nutrients from the water, and carbon dioxide from the air, in order to make more phytoplankton. Then, the phytoplankton are either eaten by other marine creatures or sink to the ocean floor, preventing the carbon dioxide being released back into the atmosphere.

Iron is a necessary nutrient for photosynthesis – and it’s often the limiting nutrient. It turns out there are large parts of the ocean (HNLCs, or High Nutrient Low Chlorophyll zones) that have all the nutrients for phytoplankton growth, except for iron. While iron naturally enters the ocean through volcanic eruptions, upwellings of nutrient rich water, and iron dust from the land, the iron doesn’t have to be natural in origin to be effective.

The basic plan is this: take huge amounts of iron, in a form easily dissolved in water such as iron sulphate. Use ships to dump large amounts of this dissolvable iron in otherwise nutrient rich water. Large scale algal blooms are created, taking huge amounts of carbon dioxide out of the atmosphere into the deep ocean.

Give me a half a tanker of iron and I will give you another ice age.

How much iron would be required to actually make this work? How much would it cost? Would doing this cause ecological damage or other unintended consequences? Could it actually be effective at a large scale? Could there be a way to do this artificially on land, without risking damage to the oceans?

I’ll explore those questions in later posts.

It’s an unusual, even radical solution. And there are many people who not only dislike technological solutions to climate change on general principle, but who also don’t like that iron fertilization takes carbon dioxide out of the sky before we learn how to stop emitting it – potentially giving humans permission to pollute even more and make the problem worse.

Considering the dire situation we’re in with climate change, I think we need all options on the table – including the radical ones.