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Menopausal Mother Nature

News about Climate Change and our Planet

Greenhouse gases: The global warming culprit

Greenhouse gases: The global warming culprit

On April 16, a staggering temperature of 40.6 degree Celsius was recorded in Dhaka, breaking the upper bounds of records over the last 50 years. Although the effects of global warming have manifested gradually over the past few centuries, the extremity of the weather has been on the rise during the recent decades — ranging from punishing droughts and wildfires to tumultuous floods, hurricanes and high tides. 

The damages, unfortunately, are permanent as the deterioration of habitats and ecosystems are resulting in global problems such as species extinctions, food crises, rising sea levels and increasing fatalities. Despite the stark evidence of such impending calamity, many still remain comfortable in their current pace of life. Perhaps outlining the basics to interested readers will aid in the half-hearted battle against climate change. 

Greenhouse effect, climate change, and global warming

Greenhouse effect, climate change, global warming is often used interchangeably, leading to considerable confusion. If the greenhouse effect was such a terrible phenomenon, then why do countries in cold regions have greenhouses to grow vegetation? Or is this an instance of a misnomer that is unrelated to the actual architectural structures? 

In reality, the greenhouse effect is a natural occurrence that retains heat to keep the planet warm for sustaining life. Like the reflective glass panes of greenhouses, greenhouse gases (GHGs) re-emit heat that is initially radiated into outer space. Hence, this effect is a natural process that makes our lives on earth possible. According to the National Oceanic and Atmospheric Administration, their absence would mean the global temperature would have been around -18° Celsius — nowhere near the ideal for many. 

Ancient ice core studies reveal that Earth’s climate responds to GHG levels. The earth’s surface temperature is a balance between the incoming and the outgoing heat energy. However, human activities like burning fossil fuels, deforestation and industrialization is driving this balance into extinction.

GHGs such as methane and carbon dioxide are primarily emitted from electricity and heat, manufacturing and transportation. Ever since the industrial revolution, excessive amounts of GHGs are released into the atmosphere more quickly than they can be removed. This has led to a higher concentration of gases circulating in the atmosphere for longer periods that is trapping more and more heat, resulting in higher global temperatures, and leading to the dreaded global warming.  

Greenhouse gases, their sources, and their duration in the atmosphere

Carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), ozone, and water vapour are the naturally occurring GHGs along with black carbon, aerosols and the man-made chlorofluorocarbons (CFCs). Their effect on climate change depends on their concentration, availability in the atmosphere, effectiveness in trapping heat, reactivity and finally how they are flushed out of the air. Derived from both natural and human sources, these gases vary in how they absorb and emit thermal energy.


The relative contributions of CO2, CH4, CFCs, and N2O to global warming are 60%, 20%, 14%, and 6% respectively. 

Carbon dioxide is the most abundant greenhouse gas and remains in the atmosphere anywhere from decades to thousands of years. Only half of all carbon dioxide that was emitted each year of the decade between 2011 and 2022 was absorbed by the land and sea. Nature balances carbon dioxide through exchange of the gas between the atmosphere, ocean, and land surface but it started to alter since the mid 1800 century with the burning of fossil fuels (coal, gas, and oil).

Transportation on road, emissions from ships and planes account for nearly one quarter of global energy-related carbon dioxide emissions. Overall fuels are responsible for 75% of the GHGs and 90% of all carbon dioxide emissions. Even though trees consume carbon dioxide as they photosynthesize, human needs have led to such drastic deforestation endeavors that it has further pushed mankind towards global warming.

On top of naturally produced methane, an excess occurs from agricultural activities, livestock farming (cattle and sheep), natural gas and transportation. Decomposed waste from landfill also emits large amounts of methane. Methane does not remain in the atmosphere for long as it gets broken down when it reacts with hydroxyl radicals (OH). Even though Methane’s lifetime in the atmosphere is shorter than carbon dioxide, it is 25 times more potent than carbon dioxide in trapping heat. Every year there has been a 1% increase of methane in the air since the 1960s — two times faster than carbon dioxide buildup. 

Nitrous Oxide (N2O) is naturally present in the atmosphere as part of the earth’s nitrogen cycle. Human influenced sources represent about 45% of the total output of N2O.  A greenhouse gas that is 300 times more potent than carbon dioxide in keeping unwanted heat in our ever-warming atmosphere, it can stick around for about 114 years. It is removed by chemical reactions, absorbed by bacteria and by UV rays and only a small percentage (about 1%) of airborne N2O gets converted by green plants into ammonia or other nitrogen compounds that plants can actually use. 

Despite the many greenhouse gases already being discussed, CFCs and their more recent replacements have been manufactured by people. Used as refrigerants, in air conditioners and aerosol sprays, they are only removed when high-energy light bombards them at a high level of the atmosphere. But hoping they would be removed even within a few years would be wishful thinking as these processes can take decades.

Time we presumably don’t have. 

One CFC molecule is 10,000 times more effective in trapping heat than a carbon dioxide molecule. CFCs can remain in the atmosphere for 110 years. They were banned by the Montreal Protocol agreement in 1987 and were phased out of use in the mid-90s due to their wreaking havoc on the ozone layer- a protective layer against detrimental UV-rays. 

On the other hand, water vapour is not a driver but a consequence of global warming that amplifies the warming effect. Increasing Earth temperature increases evaporation from both water bodies and land surface. Consequently, more water vapors cause greater heat retention, resulting in a vicious cycle of warming effects. Remaining in the atmosphere for only about nine days, they have the tendency to make wet regions wetter and dry regions drier. 

Lastly, black carbon (BC) or soot is formed from burning diesel, coal, wood and by the incomplete combustion of other fuels. Diesel engines and vehicles are the main emitters of BC and other particulate matters that regulate the air quality. It is short lived, having a lifetime of only days to weeks but unfortunately is highly effective in absorbing sunlight and heating the environment. 

s GHG emission a vicious cycle?

Growing population, globalization, and high consumption are the root cause of excessive GHG emission. The entire food production cycle is a major example. Starting from deforestation to land clearing, use of fertilizers, livestock raising, farm fuel consumption, food packaging, distributing and finally cooking and refrigeration —  numerous GHGs are emitted at different points. Humans have “unintentionally” created a global factory of GHGs that is slowly turning into the epitome of an unsustainable nightmare.

Until alternative renewable energies are in use- the growing cities, power hungry architecture, and consumerism of an ever growing population will continue to cause the rising GHG emissions that every nation should strive to contain. 

Maliha Mannan Ahmed is an entrepreneur and a public health communicator. She is the Founder and Managing Director of Organikare Limited. Shaniz Chowdhury is an associate of YPF Environment Policy Team and currently majoring in Economics. This is the first part of a series of articles on Politics and Policies of Climate Change, produced by YPF.


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