Today we’re facing one of the biggest challenges mankind has ever faced: reducing CO2 emissions. One way of doing this –like most governments do– is designing laws and taxes to reduce emissions, or giving fiscal bonuses to companies or individuals who “live ecologically”. This way, many of these governments succeed in bringing down the emissions in their country. But these efforts are diminished if big players like India or China, who’re still economically growing and refuse to let new agreements impend their growth.

Many scientists are already thinking about a “plan B”, in case laws and rules can’t reduce the emissions, and have come up with various (some more realistic than others) methods of reducing CO2 in the atmosphere. The branch of science that comes up and investigates these methods is called geoengineering. Here are 3 methods people have come up with over time to reduce global warming or CO2 emissions:

Iron in the Oceans

Iron in the Oceans

A way to use our planet to combat global warming is to fertilize the oceans with iron.

Oceanographer John Martin said in 1988: “Give me half a ship load of iron... I could give you an ice age”[6883]. He meant to reduce temperature by stimulating the growth of phytoplankton in the oceans by “feeding” it iron. Phytoplankton are very, very small organisms who use photosynthesis to generate their energy.

The idea was simple: feed the phytoplankton more (with iron), and it’ll grow and take more CO2 from the ocean’s surface. The phytoplankton will process the CO2 and expell it as dead cells and excrements that end up on the ocean floor. Early results indicated that 1 metric ton of iron could reduce CO2 in the atmosphere by 30,000 to 110,000 ton[6884]. However, later was proven that the efficiency was actually much lower.

Another downside is that it the method would disturb sea life: it may result in more fish (which is good), but may also result in more algae and jellyfish (which is not good). More phytoplankton near the ocean’s surface may also absorb more sunlight, which causes the ocean to get warmer, and that’s what we’re trying to avoid. Besides, cold water is capable to hold more CO2 than warm water.

More issues: the organic material which is the result of the CO2 absorbed by the phytoplankton sinks to the ocean floor and gets dissolved. This process uses most of the little oxygen found near the bottom of the ocean, leaving none for the deep sea fish and organisms.

This method does not look very promising, since there are a lot of possibly downright disastrous disadvantages. Maybe the next methods have less downsides?

Sulfur in the Stratosphere

Sulfur in the Stratosphere

The Dutch award-winning Paul Crutzen is known for his research with the ozone layer. He even won a Nobel Prize in 1995 for his insights in the hole in the ozone layer. 

To reduce global warming, he said we had to try to reduce the amount of sunlight (thus the amount of warmth) that reaches earth, to compensate for the increasing temperature from CO2 emissions. A way of doing is to make the earth’s atmosphere more reflective[6885]. To make the atmosphere more reflective, Crutzen would bring massive amounts of sulfur into the stratosphere. After a chemical reaction, the sulfur becomes sulphates, which can reflect a lot of sunlight. It’s the same thing that happens when a volcano erupts. After the eruption of Mount Pinatubo in 1991, the earth’s temperature decreased by the amount of sulfur expelled[6886]. People would not experience any inconviences from this method.

However, in 2008, Simone Tilmes of the National Center for Atmospheric Research found the method would make the ozone layer above the north pole 15 to 76 percent thinner, and prolonging the restoration of the hole in the ozone layer by 30 to 70 years[6887]. Crutzen’s reaction was that he was willing to sacrifice a bit of ozone layer for the reduction of global warming. Remarkable for a man who had received a Nobel Prize for his work about the hole in the ozone layer.

Sun Shield in Space

Sun Shield in Space

Roger Angel, university of California, designed another method to reduce warmth from sunlight to compensate for the increased emission of CO2. Instead of staying on earth, he wants to take it to outer space. By blocking sunlight with a huge cloud of small space ships, he says it’d result in the reduction of global warming. An advantage over the previous method is that the amount of blocked sunlight is adjustable.

The only thing needed to execute this plan is a few billions of dollars. It’s very expensive to launch thousands of small spacecrafts to space and make sure they all remain on the same place for long periods of time. It’s money no organisation is willing to give – for now.

However, this idea is not as unrealistic as big structures being brought to space or being constructed on the moon and launched to space. However, a lot of money is still needed, and there may be a more cheap solution.

To Geoengineer or Not To Geoengineer?

Many of the methods described above are not very popular to the politicians. Since the decisions about climate change are made by politicians, they will probably get used only as a “really last option”. Many of them are not listed, and many of them are too unpredictable, too risky or simply too expensive.

However, some argue that the costs to implement one of these geoengineering solutions is only a fraction of the costs of agreements like the Kyoto Protocol. Geoengineering may even be used as an argument against global warming or CO2 reducing agreements. But it’d be unwise of politicans to cut back on scientific research on this matter, since maybe we will actually be needing geoengineering solutions in the future.