HOW CLIMATE CONSCIOUS ARE WE?

These days are we not increasingly hearing about how our climate is changing and how often we are affected by climatic catastrophes? I am sure many of you have at least heard about the UN Climate change conference or the Conference Of Parties (COP) that just finished.

For those of you who do not understand the crisis, please read on. Climate change today is caused by human activities along with some astronomical phenomena like sunspot activities and Milankovitch oscillations also play a role. However, since the crisis is accelerated by human actions, I am concentrating on that.

Green House Effect and the Green House Gases

Climate change activities today are focused on reducing the global average temperature. With the Green House Effect being the major reason behind increasing global temperature or Global Warming, we are striving to decrease the amount of Green House Gases (GHG) in the atmosphere.

Sun is our main source of energy and the sun’s radiations are what help us to sustain life on Earth. Earth receives a part of the sun’s radiation (in short wave form) and gives it back to the atmosphere (as long wave terrestrial radiation). A constant temperature is maintained in the earth through this process. This is a very complex process to explain.

To put it in simple terms, whatever heat that we receive is given back. Remember, energy can neither be created nor be destroyed and it can be only transformed from one form to another. So even if energy is lost in some process, that will be gained in another process. In the diagram, the yellow radiations are the incoming radiations from the sun, which are absorbed by the Earth. A small part of it is reflected back by the atmosphere before reaching the earth. Whatever earth absorbs, should be given back, as energy is not destroyed. The red lines depict this energy that is given back (terrestrial radiation).

However, the GHG in the atmosphere absorbs a part of this terrestrial radiation and maintains the overall temperature. Today, the amount of this GHG in the atmosphere has increased and they tend to absorb more of the radiation, not allowing it to go back. Since the radiation is held back it obviously increases the global temperature or causes Global Warming. We cannot get rid of the GHG completely for it is what helps to sustain life. Without them, the global average temperature would have been less than -15 ^OC than the current 15^OC.

So, the problem at hand is its increasing level due to human activities like industrial and vehicular emissions on large scale. The main GHG are water vapor, Carbon dioxide, methane, nitrous oxide, and ozone. Though the amount of water vapor is the highest, it does not cause trouble as water cycles quickly. The next important gas – Carbon dioxide is the main reason for today’s climate crisis. Most of our climate change activities are also concentrated on decreasing the level of Carbon dioxide.

The other GHGs are also dangerous. The global warming potential of a gas is measured by taking Carbon dioxide’s Potential as the base, which is 1.

GAS	GLOBAL WARMING POTENTIAL	LIFETIME (YEARS)
Carbon Dioxide	1	50-200
Methane	21	12
Nitrous Oxide	310	200
Hydrofluorocarbons (HFC)	140-11700	1-270
Perfluorocarbons (PFC)	6500-9200	800-50000
Sulphur hexafluoride (SF6)	23900	3200

How is the amount of Carbon dioxide increasing

The CO₂ concentration in our atmosphere was about 280 ppm in 1850, which is more than 400 ppm now. This increase did not happen overnight but is the result of human activities since industrialization. We have been burning fossil fuels, producing cement, carrying out land clearing, forest combustion, and deforestation for our own gains.

Plants take in carbon dioxide for photosynthesis and this gets stored in them as food. When they decay, this carbon still remains in them. By extracting and burning fossil fuels, we are releasing this stored CO₂ into the atmosphere. The sad reality is that we are returning the CO₂ the plants pulled out for millions of years in just a few years, disturbing the balance.

The same goes for land use change and deforestation. In both these processes, the soil is disturbed and it leads to the emission of stored carbon into the atmosphere. In converted soils, decomposition also takes place at an accelerated rate and releases more carbon into the atmosphere. It can even lead to a decrease in the ability of soils to act as an effective carbon sink (ability to absorb carbon).

Industries and electricity production are the two sources that emit more carbon dioxide along with transportation.

With that said, some of our ancient agricultural practice like slash and burn (or Jhum cultivation) is of great concern as they not only burn the existing forests down but also change the soil orientation leading to more carbon emissions.

The many effects of increasing Carbon dioxide

As discussed earlier, global warming is a vital threat that results in extreme weather patterns, increased disease conditions, and a risk to the life of organisms and ultimately our own existence.

When the temperature in the atmosphere increases, the ice caps and glaciers begin to melt. This can further lead to a rise in sea level and will in turn submerge the coastal land along with saline water intrusions. This week, we even had the news of finding a 46,000-year-old zombie virus in Siberia, under the melting ice/permafrost.

In the oceans, CO₂ and water combine to form Carbonic acid, a weak acid that dissociates easily into Hydrogen and Bicarbonate ions. The carbonic acid also decreases the pH of the ocean water (into the acidic range). This phenomenon is known as Ocean Acidification.

H₂O + CO₂ ➡     H₂CO₃

H₂CO₃ ➡ H⁺ + HCO₃^-

Organisms like corals and oysters make their shells by combining calcium with seawater. When the ocean acidifies, the carbonate ions bond with the free hydrogen ions, in turn making it less available for shell building and for maintaining the calcium structures. With an even lower pH, the calcium shells might even dissolve, threatening their existence.

The likelihood of extreme climatic events like heatwaves, flooding, cyclones, hurricanes, and changes in rainfall patterns will severely affect life. Biodiversity loss in land and ocean will have many direct and indirect effects on living beings. Recently, studies have also shown that the increase in CO₂ levels will affect the photosynthetic metabolism of plants as well, which again is life-threatening.

Carbon dioxide emission removal

There are many simple ways that we can practice like improving energy efficiency, conserving energy, switching from fossil fuels, changes in land use patterns, and land management.

Afforestation and preventing deforestation is something everyone can do and has a large effect. Plants require CO₂ for photosynthesis and absorb them in huge quantities. They also give out oxygen that we require to maintain life. The Amazon rainforests are called ‘Lungs of the World’ for a reason. So, next time, if you can’t plant a new tree, at least try saving what we already have.

The same goes for the oceans. Phytoplankton is small water algae that need CO₂ for Photosynthesis. These algae act as a food source for marine organisms and the amount of phytoplankton in our oceans is more than we can imagine, acting as another important sink of CO₂. Ocean water also absorbs CO₂ when its concentration increases in the atmosphere. But, the increasing amount of CO₂ in oceanic water is not safe for some of our marine organisms.

More modern methods are designed and employed these days to capture carbon. These are collectively known as Carbon Capture and Storage (CCS).  It involves capturing CO₂, transporting it for storage for further processing, or depositing it somewhere permanently so that it does not enter back into the atmosphere. The storing of CO₂ is also known as Carbon Sequestration.

Carbon capture can be either pre-combustion or post-combustion. In pre-combustion, the fossil fuel is heated with oxygen before burning which results in the production of Carbon Monoxide and Hydrogen. While H₂ is used as fuel, the CO is treated with water to produce CO₂. In post-combustion, the effluents released after burning the fossil fuels are directed to an absorber column to separate CO₂. There is also the Oxy-fuel combustion method, in which the fuel is burnt with oxygen and results in the production of a gas mixture containing CO₂. This CO₂ is later separated.

The most common places captured CO₂ is stored include depleted reservoirs & mines, underground geological storage, and deep oceans, where it remains trapped. For example, the CO₂ is injected into rock formations in a supercritical form and remains there at a temperature of above 31.1^OC and pressure above 72.9 atmospheres. These methods are cost-intensive and scientists are trying to design technologies that can cut down the costs. 

End note: To know more about climate change activities read the follow-up article titled 'Climate discussions to the forefront'.