From climate change to climate cleaning, what is the role of agricultural activities?

Hi readers

At the outset, I would like to apologize for delayed blog but, it was due to unavoidable circumstances. Many readers asked about the reasons that were very personal and I am grateful to all of them and wish them good health, especially in the ongoing gradually intensifying winter.

Dear readers, you must now be familiar with the words greenhouse gases (GHG), climate change and global warming and the nexus between them?

Greenhouse gases (GHGs) are atmospheric gases that trap heat and warm the planet through the greenhouse effect.

The greenhouse effect is a natural process where Earth’s atmosphere traps heat from the sun and warm the planet to a habitable temperature. Certain gases (GHG), absorb and re-radiate (emit) the Earth’s outgoing infrared radiation, preventing it from escaping into space. While this natural effect is essential for life, human activities like burning fossil fuels are increasing the concentration of these gases, leading to an intensified greenhouse effect and global warming.

The GHGs include water vapor, carbon dioxide CO₂, methane CH₄, and nitrous oxide N2O. Human activities like burning fossil fuels and industrial processes have significantly increased the concentration of these gases, especially CO₂, leading to global warming and climate change.

Global warming is a long-term heating of Earth’s climate system observed since the pre-industrial period (between 1850 and 1900) due primarily to fossil fuel burning, which increases heat-trapping greenhouse gases level in Earth’s atmosphere” and is just one aspect of climate change.

Earth’s average surface air temperature has increased almost 1.5 °C (about 2.5 °F: although there are controversies) since the Industrial Revolution. Natural forces cause some variability, but the 20-years average shows the progressive influence of fossil fuel burning and other industrial processes.

This is what  Intergovernmental Panel on Climate Change (IPCC0 says.

Now let’s see what climate change is?

It is a significant, long-term changes in the global climate comprising sun, earth, and oceans; winds, rain, and snow; forests, deserts and savannas, and everything that people do. But global climate system is more than all of this and also includes how the hurricane from the Pacific ocean originate, hit, brought more rain, and cause shifting  in global ocean currents that melt Antarctica ice which slowly makes sea level rise.

Dear readers, leaving aside the politics and reality of climate change, let’s assume that level of CO₂ is rising in the environment, then it will be an alarming situation because CO₂ is considered the most important gas for global warming primarily because of the

i. vast quantities emitted by human activities,

ii. its long atmospheric lifetime, and

iii. its substantial contribution to the total radiative forcing (the warming influence on the planet).

According to the

National Oceanic and Atmospheric Administration (NOAA), CO₂ alone is responsible for about 80% of the total heating influence of all human-produced greenhouse gases since 1990. While other gases like methane and nitrous oxide are more potent heat-trapping gases per molecule, CO₂ is far more abundant in the atmosphere due to human activities.

A significant fraction of emitted CO₂  remains in the atmosphere for decades to centuries, with a portion staying for thousands of years. This longevity means that past and present emissions cumulatively have a lasting impact on the climate system, essentially acting as a long-term “control knob” on Earth’s thermostat.

Cumulative Effect: Unlike water vapors, (which is the most abundant natural greenhouse gas but has a short atmospheric cycle), CO₂ accumulates in the atmosphere because natural carbon sinks (oceans and plants) cannot remove the excess CO₂ fast enough to keep up with human emissions. This continuous buildup creates an increasingly thick “insulating blanket” that traps more heat and increases warming hence, the Long Atmospheric Lifetime of CO₂ causes the planet to warm which in turn causes more water to evaporate, adding more water vapor (another greenhouse gas) to the atmosphere which creates a powerful positive feedback loop that further amplifies the warming effect, making CO₂ the primary driver of the current climate change. Hence, it is sheer volume of human-caused CO₂ emissions and the very slow natural removal process that makes CO₂ the single most significant driver of the current, rapid global warming trend. 

The question arises:

Why should we care about one or two degrees of global warming? After all, temperatures fluctuate by many degrees every day where we live?

The temperatures we experience locally and in short periods can fluctuate significantly due to night and day, summer and winter.  But the global temperature mainly depends on how much energy the planet receives from the Sun and how much it radiates back into space. The energy coming from the Sun fluctuates very little while the amount of energy emitted by Earth is closely knitted to the chemical composition of the atmosphere particularly the amount of heat-trapping greenhouse gases.

A one-degree global change is significant because it takes a vast amount of heat to warm all of the oceans, the atmosphere, and the land masses by that much. In the past, a one-to-two-degree drop was all it took to plunge the Earth into the little ice Age.  A five-degree drop was enough to bury a large part of North America under a towering mass of ice 20,000 years ago.

Another question is:

How to accelerate the removal of CO₂ from  the atmosphere?

One of the answers is through agricultural activities that involves reducing greenhouse gas emissions from farming and storing more carbon in the soil and biomass.

Placed table is an example where we made some calculations on the field grown cotton crop to exhibit how carbon removal from the environment can be accelerated.

The table shows that 0.7Mt of carbon from cotton fiber, 1.05Mt of carbon from cotton yarn and 0.81Mt of carbon from cotton pulp (which means roughly 2.56 Mt of carbon) can be sequestered from growing 1.7 Mt of cotton crops which stopped 9.395 Mt addition of CO₂e into the environment.

Please note: The carbon content of cotton is primarily a chemical fact about the material itself. The broader “carbon footprint” of cotton, which refers to the total greenhouse gas emissions from its production, is a different and much larger figure that includes energy use, fertilizer, and transportation.

This is only through one crop. If we could increase cotton production to 3.4 million metric tons, we can stop 18.79Mt addition of CO₂e into the environment. These calculations are made to convince you dear readers that we can accelerate the removal of CO₂ from the environment thorough agricultural activities.

There are several other crops growing around the globe. Imagine how much CO₂ is being removed while human activities are adding over 40 billion metric tons CO₂ to the environment annually, which probably has reached up to 41.6 billion tons in 2024. 

Another example is of Sesbania, which is a fast-growing legume green manure crop that enriches soil with nitrogen, improves structure, and enhances water retention by adding organic matter. It is a good choice for enhancing fertility, especially in rice-based cropping systems like those in South Asia, as it grows quickly, provides substantial biomass, and is tolerant to saline and waterlogged conditions.

For improving soil fertility and nitrogen levels, Sesbania rostrata: a stem-nodulating variety is exceptional for high biomass production that can provide significant amounts of soil nitrogen.  

Sesbania aculeata is a popular species for green manuring, especially in flooded rice, where it can accumulate high amounts of nitrogen and improve soil health.

Sesbania cannabina: Another common species for Asian agriculture which fixes nitrogen and provides organic matter to the soil.

Sesbania rostrata is known for its tolerance to salinity and waterlogged conditions and is good for reclaiming alkaline or saline soils thus making it suitable for use in problem soils.

All Sesbania Species are used for soil health and structure. By adding large amounts of organic matter through its fast decomposition, Sesbania improves soil structure, increases water-holding capacity, and protects against erosion, all of which enhance long-term soil productivity.

Organic matter added to the soil as Sesbania green manure is 3 tons/acre dry matter, i.e., 3000 kg biomass, 1200 kg C, 4400 kg CO₂ OR 4.4 tons of CO₂ sequestered and dumped into the soil/acre.

Rice is cultivated on 3.5-4 million hectares. Imagin if 10% of this area is subjected to green manuring, this will mean 0.4 million hectares or 1 million acres. Green manuring on 1 million acres means 4.4. million tons of CO₂ being sequestered and dumped in soil every year.

Together with Carbon sequestration, 50-kg N is added to the soil/acre, if 50% of this N replaces chemical N fertilizer, imagine how much reduction in GHG emissions (N2O, NO etc.) will occur?

Dear readers, climate change is a complicated issue. Most people do not understand even the difference between climate change and environment change. I will try to write a detailed article on this issue on my LinkedIn page very soon inshallah. Till then,

take care, Bye.