The world is working together to tackle climate change, the greatest threat to us today. Thousands of people are changing their everyday habits to slow down global warming by using public transportation whenever possible and by generating less waste. On the other hand, some people are thinking of a different approach to combating global warming: the artificial manipulation of the Earth's climate on a larger scale. Such idea is called geoengineering. While the former is about delaying global warming, geoengineering is a more aggressive way of eliminating the causes.

Global warming is caused by more solar energy trapped near the Earth's surface by greenhouse gases. Thus, global warming can be prevented by removing greenhouse gases from the atmosphere or by reducing solar energy coming to the Earth.

The carbon dioxide released into the atmosphere by today’s human activities is absorbed by plants, oceans and soil over time. However, it is not completely absorbed. Some remains in the atmosphere even after long periods of time, causing a greenhouse effect. There are several ways to get rid of extra carbon dioxide.

The easiest solution would be planting trees. Trees planted in wastelands can absorb more carbon dioxide. Restoring wetlands can be another solution, as they also consume carbon dioxide. However, these solutions are not very efficient. Some people suggest making artificial trees using carbon dioxide-absorbing materials, but it is still just an idea due to the lack of technology.

Another idea is to use biochar. Hundreds of years ago, indigenous people of the Amazon made and buried charcoal in the ground to fertilize the soil. In nature, dead animals and plants are decomposed by microorganisms and release carbon dioxide. However, the charcoal has not been decomposed by microorganisms, still retaining carbon as it was. If we make charcoal out of plants that have absorbed carbon dioxide by burning them in an oxygen-deficient environment, we will be able to bury carbon dioxide that would have been dispersed into the atmosphere.

The last idea to introduce here is using the ocean. The ocean is absorbing a lot of carbon dioxide even at this moment. More can be absorbed if the growth of phytoplankton, which consumes carbon dioxide, is facilitated by putting nutrients into the ocean.

How then can we reduce solar energy? Some of the sunlight entering the Earth is reflected back into space; bright objects such as glaciers and clouds reflect sunlight away from the planet. However, glaciers are shrinking due to global warming. This is a big problem because shrinking glaciers means less amount of sunlight reflected back to outer space and faster global warming.

We could artificially create more clouds to some extent. We can make clouds by dispersing tiny, suspended particles that can become cloud seeds. In areas where rain is needed, people create clouds in this way to make it rain. We can also make clouds even whiter by spraying fine sea water, or create thin clouds so that they reflect more sunlight rather than absorbing warm infrared radiation.

It may sound like a far-fetched idea, but some suggest ​installing a giant shade in an area of outer space to deflect sunlight. If we could block some of the sunlight entering the Earth's atmosphere, less energy would reach our planet. However, it would be difficult to install such a large shade; we could throw a lot of small pieces between the Sun and the Earth to reduce the amount of sunlight reaching the planet.

Such ​geoengineering ideas are still difficult to be realized due to technical difficulties and uncertainty about impacts on the ecosystem. Reckless attempts to prevent global warming can bring worse outcomes. Having said that, if we are to fight the major threat of climate change, we have to at least grasp at straws. Until the Earth is completely safe, these ideas will keep popping up.