Hello guys. Welcome to my blog. It has certainly been a while since I published the first part of this two-part article. Time has not been on my side if not, we would have concluded this article. Thanks once again for your patience. 

![climate-change-2254711_1280.jpg](https://cdn.steemitimages.com/DQmWzzFoLLwqbPJbiVRDwumUmxREKMKsmbK9GKkhDhYpmqP/climate-change-2254711_1280.jpg)
<sub>[Source: [Pixabay commons](https://pixabay.com/en/climate-change-global-warming-2254711/). CC0 licensed]</sub>

As a recap; [Part 1](https://steemit.com/science/@sciencetech/understanding-geoengineering-part-1-4f994ae3abe0a) of this article consists in the robust explanation of the concept of Geoengineering as a large-scale and intentional interventions carried out to ameliorate the unfavorable consequences of [global warming](https://en.m.wikipedia.org/wiki/Global_warming). We also noted that following the slow pace of development in alternative energy technologies, and the high rate at which greenhouse gas is being released into the atmosphere, time has come, according to some scientists, for a more radical approach to be adopted. Thus came the idea of Geoengineering technology which seeks to use two major approaches to counter the unfavorable effects of global warming. And then we extensively explored the techniques of one of the two approaches known as **solar engineering or solar radiation management (SRM)**. 

In this article, therefore, we will look at the other approach known as **Carbon dioxide removal or carbon engineering** and its techniques. And conclude by looking at the various arguments and controversies surrounding the feasibility of the emerging technology.    

### <center>**Carbon dioxide removal (CDR) or carbon engineering**</center>

Carbon dioxide removal schemes are designed to remove carbon dioxide from the atmosphere. This can be done in two ways: one, by direct capture and storage of carbon dioxide. The other way involves indirect promotion of various phenomena that naturally trap and sequester carbon dioxide from the atmosphere. One of such instances is **tree planting** <sup>[ref](https://en.m.wikipedia.org/wiki/Climate_engineering)</sup>. It must be noted that whatever techniques that have been chosen to be adopted have to be on global scale to have any significant impact in terms of reducing or removing carbon dioxide from the atmosphere <sup>[ref](http://www.geoengineering.ox.ac.uk/what-is-geoengineering/what-is-geoengineering/)</sup>. Having said that, below are the details of some techniques which have been proposed for carbon dioxide removal from the atmosphere:  

![glacier-583419_1280.jpg](https://cdn.steemitimages.com/DQmXquzoL5HaDd75v6yKa85B3hGreh3PLx3WvMw22FEtxbN/glacier-583419_1280.jpg)
<sub>[Source: [Pixabay commons](https://pixabay.com/en/glacier-argentina-south-america-583419/). CC0 licensed]</sub>   

### <center>**Ocean fertilization and iron seeding**</center> 

This technique seeks to promote the growth and development of phytoplankton which are actually tiny plants that float on the surface of water bodies, and which, like plants, absorb carbon dioxide from the atmosphere as they grow. It is thought that if the ocean and other water bodies are massively fertilized, its flora population, which is essentially phytoplankton, would increase in number and significantly reduce the amount of carbon dioxide in the atmosphere. This technique was originally the brainchild of ocean scientist [John Martin](https://earthobservatory.nasa.gov/Features/Martin/) who had proposed in 1989 that adding iron to ocean would stimulate the growth of phytoplankton with increased uptake of carbon dioxide. 

Again, when the phytoplankton population die, they would sink to seabed along with their trapped carbon dioxide and thus effectively removed it from the atmosphere. However, the preliminary results of [some studies](http://news.bbc.co.uk/1/hi/sci/tech/7856144.stm) have shown that Martin's hypothesis cannot significantly impact global warming on global scale. There is also the risk of blooms of phytoplankton increasing the acidity of the water body and harming marine fauna and flora. 

### <center>**Biochar**</center>

This technique was inspired by the ancient practice of Amazonian Indians, and involves assembling and burning waste agricultural products such as plant stems, stalks, and roots into charcoal. The burnt charcoal is then collected and buried to take its carbon content out of circulation. However, there is concern that this may disrupt natural ecosystem balance.

### <center>**Mounting ocean pipes**</center>

Climate scientist [James Lovelock](http://www.jameslovelock.org/) has always argued that the scales of current proposed carbon dioxide removal interventions are not large enough to achieve significant reduction of the atmospheric carbon dioxide. In 2007, he proposed [a system of giant vertical pipes](http://news.bbc.co.uk/1/hi/sci/tech/7014503.stm) measuring between 100 — 200m long with valves at the either of its ends and would have ability to bob up and down in the ocean. Since cold water is known to be biologically more supportive than warm water, the idea here is to have a system that will continuously move cold water from the bottom of ocean to the surface where it is thought to stimulate algal growth and increase the rate of carbon dioxide removal from the atmosphere.  

>...As it moved downward, cold water would rush in at the bottom. When it bobbed back up again, the cold water would spill out at the top...| <sub>[Source](https://www.explainthatstuff.com/Geoengineering.html)</sub>      

![Biochar.jpg](https://cdn.steemitimages.com/DQmTb4R9npMK3c7occSzuEYcaQwUnZ2x45TT9qcB28Mj6kR/Biochar.jpg)
<sub>[*Biochar sample*. Source: [Wikimedia commons](https://commons.m.wikimedia.org/wiki/File:Biochar.jpg). Author: K.salo.85. [CC BY-SA 3.0](https://creativecommons.org/licenses/by-sa/3.0/deed.en) licensed]</sub>

### <center>**Carbon capture and storage (CCS) techniques**</center>

This technology is also known as **sequestration**, and is highly promoted by those supporting our continuous dependence on the use of fossil energy. The idea seeks to prevent the release of more carbon dioxide into atmosphere via a system that will trap and convert it into a highly compressed liquid which can then be either used industrially or pumped deep underground for indefinite storage <sup>[ref](https://www.explainthatstuff.com/geoengineering.html)</sup>. However, this method does not remove already existing carbon dioxide from the atmosphere; it only prevents further addition. 

***

Other techniques include:

* enhancing ocean alkalinity by dispersion and dissolution of limestone, silicate or calcium hydroxide in ocean intended to increase carbon storage ability while preventing ocean acidification<sup>[ref](http://www.geoengineering.ox.ac.uk/wh/what-is-geoengineering/)</sup>.  

> * [Afforestation](https://en.m.wikipedia.org/wiki/Afforestation), [reforestation](https://en.m.wikipedia.org/wiki/Reforestation) and [forest restoration](https://en.m.wikipedia.org/wiki/Forest_restoration) to absorb carbon dioxide
    
***

Presently, there is growing debate as to whether Geoengineering projects are worth pursuing taking into account not only their cost and scientific feasibility but other factors as instigated by political, ethical and legal considerations. That being said; debate or no debate; concensus or no concensus, what's important, however, is the fact that Geoengineering technology that sounds like a scientific fiction only a few years ago is now being seriously deliberated upon. Thanks. 

### **References**
* <sub>[**what's Geoengineering?**](http://www.geoengineering.ox.ac.uk/what-is-geoengineering/what-is-geoengineering/)</sub> 
* <sub>[**Climate engineering**](https://en.m.wikipedia.org/wiki/Climate_engineering)</sub>
* <sub>[**Geoengineering**](https://www.explainthatstuff.com/geoengineering.html)</sub> 
* <sub>[**Everything you need to know about Geoengineering**](https://www.popsci.com/everything-you-need-to-know-about-geoengineering#page-6 )</sub> 
* <sub>[**Bioenergy with carbon capture and storage**](https://en.m.wikipedia.org/wiki/Bio-energy_with_carbon_capture_and_storage )</sub> 

Truly yours, 
@sciencetech 
STEM contributor