CAJ Geoengineering - Introduction

What is Geoengineering?

I have chosen this highly interesting topic because I  have recently watched a documentary called “Why are they spraying?”. I became quite interested in the topic and wanted to know more about it. I informed myself roughly what it is about. To really get absorbed in this topic, I chose Geoengineering to be my CAJ.

But what is Geoengineering? In short, Geoengineering is the intervention in the earth’s climate system to prevent the aggravation of climate change. To tackle the Earth’s climate problem, scientists have developed certain geoengineering techniques which can be categorised in two groups:

Solar Radiation Management (SRM) or Solar Geoengineering

The aim behind this engineering method is to reflect the Sun’s energy back into space and so reduce temperature rise caused by greenhouse gases in the atmosphere. There are certain ways to put these techniques in practice. The so called Albedo enhancement is a way to modify clouds or the land surface and increase the reflectivity of sunlight into space. Low level clouds, for example, tend to be very reflective to sunlight and even more when they are white. Altering these clouds through the process of “marine cloud brightening” could increase their reflectivity and consequently cool the climate. By enhancing the albedo of the earth more radiation could be reflected.

Another proposed measure to stop global warming is the usage of space mirrors, also called space reflectors, to block sunlight before it reaches the Earth. These mirrors would be positioned in the orbit of the earth to filter sunlight or reflect it. In order to reflect sunlight before it reaches the Earth, scientists have proposed a method which aims to inject stratospheric aerosols into the upper atmosphere, the stratosphere. Stratospheric aerosols are are small, reflective sulfate particles (or aerosols) such as sulfuric acid, hydrogen sulfide (H2S) or sulfur dioxide (SO2) and could reflect the sunlight back into space. This happens naturally when volcanoes erupt by sending ash into the stratosphere.

Carbon Dioxide Removal (CDR) or Carbon Geoengineering

 

Another way to stabilise the Earth’s temperature is to remove carbon dioxide from the atmosphere by countering the increased greenhouse effect and ocean acidification. However, the proposed techniques for Carbon Geoengineering need to be implemented on a global scale to significantly change the Earth’s climate. For example, planting forests or stands of trees in areas where there used to be no could increase carbon capture, meaning the capture and long-term storage of atmospheric CO2. This technique, known under the term afforestation, could only have a significant effect as a global-scale project. Another carbon removal method is called carbon capture and sequestration which aims to char biomass, burn it to create energy and then capture it in the soil. Carbon can also be captured directly from the air through large machines that can remove it or store it elsewhere. It is proved that ambient air capture can remove far more CO2 per acre of land footprint than trees and plants. Not only can carbon be captured in the soil but also in the ocean. Ocean fertilisation is also a Carbon Geoengineering technique and aims to increase the growth of phytoplankton in the ocean as it absorbs carbon from the atmosphere via photosynthesis.

 Rocks in the ocean can also be used as a means to remove carbon from the atmosphere. A technique which is called Ocean alkalinity enhancement aims to increase the ability of rocks such as limestone, silicates, or calcium hydroxide to store carbon by grinding them up, disperse and dissolve them. In addition to removing carbon, this technique could improve ocean acidification. Last but not least, the enhanced weathering technique is designed to  expose large quantities of minerals that will react with carbon dioxide in the atmosphere and store the resulting compound in the ocean or soil.