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How Well Do We Know Climate Change?

A. K. Shyam, PhD's picture
Assessor Freelance Consultant

I am Dr. A. K. Shyam, intellectual acumen offering 44 years of established career in Environment, Health & Safety sector. I was associated with NABET, Quality Council of India as an Assessor...

  • Member since 2004
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  • Aug 15, 2022

I have been following the developments on this critical global issue ever since my first paper on Global Warming at the Hamburg International Conference in early 1990s.  Although a few thoughts have been penned here and there, its complexity seems to be getting more challenging as we progress year after year. It is also not easy for any single expert to throw up concrete steps to tackle the issue and therefore, it has to be a team work of many experts pooling their perceptions to seek ultimate solution. When we look at what is happening currently, it seems to me that we may have to draw inputs from chemical, physical, geological and biological processes that have successfully governed the climate of the past as we know and the disturbance we humans, have caused to this balanced environment. The cycles of chemical elements like carbon and nitrogen and gaseous emissions that are emitted into the atmosphere seem to be the central point of focus in order to gain an insight into this complex phenomenon.

While we seem to concentrate on carbon dioxide emissions, we tend to forget inter-related aspects like land use for example which has not received the attention that it deserves as it is believed to contribute about 20% of total carbon emissions.  Currently its contribution is 40% of the climate change impact addressed as ‘radiative forcing’ – the amount of energy balance between sun’s energy radiating down and the energy that Earth radiates back into space, a scientific concept that describes the process of global warming.


Land Use: As mentioned above, land use along with anthropogenic greenhouse gases contribute to global warming.  The initial step of land use change is converting forests into agriculture which emits methane and nitrous oxide.  We are simultaneously removing the sink for carbon dioxide by removing the forests. It is thus a paradoxical situation for increase of carbon dioxide in the atmosphere.

Fossil Fuels: Fossil fuels especially Coal deployed for power generation has been identified as the most visual sight of enhancing gaseous emissions into the atmosphere.  Aerosols emanated are not only bad for human health but depletes ozone as they are responsible for reflecting sun’s energy back to cool the planet. In addition, aerosols fertilize the land and ocean ecosystems helping them draw down carbon dioxide.

Although there are many sources of carbon emission which will be discussed later, the use of fossil fuels triggered change in energy policy in view of the increasing carbon dioxide concentration.


Climate change includes both global warming and its impact on Earth’s weather patterns.  While there have been previous periods of climate change, the current changes seem distinctly more rapid and not attributed to natural causes.  In fact, they are caused due to greenhouse gases mostly carbon dioxide and methane.  Fossil fuels deployed for power generation seem to contribute to this though agricultural practices, industrial processes and forest loss add to this.  Greenhouse gases being transparent to sunlight absorb heat and warms up the earth’s surface.  When the earth emits that heat (infrared radiation) the gases absorb it trapping the heat near the earth’s surface resulting in ‘Global Warming.  Biofuels’ as one of the options would not only reduce the gaseous emissions especially carbon dioxide (they don’t emit) but their cultivation consequently would reduce the carbon dioxide acting as sink for carbon dioxide and at the same time future land use need greater attention if we have to address this burning issue.

Although there has been a long history on Climate Change, it is better to restrict to the events that followed in the 20th Century when carbon emissions from fossil fuels reached on billion tons per year (1937).  Climate change got hardly registered on agenda of the First UN environment conference in 1972 and even Montreal protocol (1987) restricted chemicals that damage ozone layer. Intergovernmental Panel on Climate Change (IPCC) in 1988 started collating and assessing evidence on climate change and recognized that temperatures have risen by 0.3-0.6 degree C over the last century in its First Assessment Report in 1990.  Earth Summit of 1992 in Rio De Janeiro started talking about ‘stabilization of greenhouse gas concentrations in the atmosphere to 1990 level.  Kyoto Protocol (1997) directed developed nations to reduce emissions by 5% by 2008-12 but, US Senate did not ratify the directive.  Kyoto also introduced market-based mechanisms – International Emission Trading (ET); Clean Development Mechanism (CDM) and Joint Implementation (JI). The first part of IPCC’s fifth assessment report certainly declared that humans are the ‘dominant cause’ of global warming since 1950’s.

It was Conference of Parties (COP), the apex body of United Nations Climate Change Framework Convention UNFCC) formed in 1994 that addressed stabilization of greenhouse gas emissions and to protect earth from the threat.  Since its formation, COP has moved into the 26 meeting at Glasgow, Scotland in 2021.  The Glasgow Climate Pact (GCP) as it is addressed, aims at limiting global warming to 1.5 degree Celsius by 2030 as agreed under the 2015 Paris Agreement.  This in effect amounts to a cut of greenhouse gas emissions by 45% by 2030 and to zero overall by 2050 to achieve Paris goal.


As a result of climate change, weather predictions across the globe have become a serious challenge as it has hampered the ability of forecasting agencies.  India Meteorological Department (IMD) for example in India, has installed more radars and upgraded high performance computing system to meet this challenge. Monsoon rainfall though has not shown significant trend, heavy rainfall event has increased against light rainfall which has decreased due to climate change.  The additional changes due to instability are increase in thunderstorms, lightning and heavy rainfall and the severity of cyclones in the Arabian Sea is also increasing. Overall, the increase in the frequency of extreme weather events is posing a challenge to forecasters.


The effect of human-caused global warming (loss of Sea ice, melting glaciers, Sea level rise and intense heat waves) is indeed irreversible and is likely to worsen in the decades to come.  The Sixth Assessment Report of IPCC published in 2021 found that earth has already warmed by nearly 2 degrees Fahrenheit (1.1 degree Celsius) since pre-industrial times (1750) and is likely to reach or exceed 1.5 degree Celsius.

It is just not the fossil fuel burning that is alone responsible for the greenhouse gas emissions.  As brought out in the chart (Fig.1) there are other factors contributing to this rise.  This collective contribution unfortunately does not stay in the same form but gets modified depending upon the local, regional and national characteristics.  If we were to take coal in thermal power plant, coal burning not only releases carbon dioxide but also sulphur dioxide and oxides of nitrogen.  The consequent change that results is the formation of sulphuric acid and nitric acid in the presence of moisture is termed as ‘Acid Rain.  Imagine the kind of changes that occur when all the activities as cited in the diagram contribute directly or indirectly to the atmospheric composition.  In order to understand this we may have to take shelter in the atmospheric chemistry.


Atmospheric chemistry focuses on chemical processes within Earth’s atmosphere to understand implications of climate forcing, air quality and reciprocal interactions between atmosphere and biosphere.  This is achieved through application of models and one such model is constructed by automatic code generators (Autochem or Kinetic PreProcessor).  In order to test theoretical understanding of atmospheric chemistry, computer models (chemical transport models) are used.  In addition, numerical models solve different equations governing concentrations of chemicals in the atmosphere which may be simple or complicated.  In the 20th century atmospheric science has progressed from mere composition of air to how the concentrations of trace gases have changed over time and the chemical processes which create and destroy compounds in the air.

When we look at this phenomenon which is pretty dynamic, the changes seem to take place not only daily but even over periods of time rendering the atmospheric chemistry into the most challenging aspect of study.  In other words, by the time we understand atmospheric status today, much more would happen ahead of the next one or two years – of course depending on the newer activities that humans add to the already existing list.

Though the composition and chemistry of the atmosphere is important for several reasons primarily, it is because of interactions between the atmosphere and living organisms.  Humans who changed this composition affect human health, crops and ecosystem.  Acid rain as mentioned above, photochemical smog and global warming are a few of them.  Theoretical understanding of these changes have been attempted to find possible solutions by several governments specifically to address global warming.

Average composition of dry atmosphere, by volume



Nitrogen N2


Oxygen O2


Argon Ar


Water vapour

Highly variable – typically makes up about 1%

Minor constituents in ppmv

Carbon dioxide CO2


Neon Ne


Helium He


Methane CH4


Krypton Kr


Hydrogen H2




  • Carbon dioxide and methane concentrations vary by season and location.
  • Ppmv – represents parts per million by volume
  • Mean molecular mass of air is 28.97 g/mol.


Atmospheric science moved on from composition of air (please see above) to the concentrations of trace elements and their changes over time and chemical processes that create and destroy compounds in the air. The focus however shifted to treating atmosphere as single system – biosphere and geosphere, instead of mere atmospheric chemistry in isolation.  Instruments like GOME and MOPITT provide a global picture of air pollution and chemistry.  Another instrument LIDAR provides concentration profiles of chemical compounds and aerosol but, restricted to horizontal region.  Of the two models mentioned above – computer and numerical, the trade off in numerical is between the number of chemical compounds and chemical reactions modelled versus representation of transport and mixing in the atmosphere. What needs to be exercised is to treat earth system models to link climate, atmospheric composition and biosphere together and not in isolation.  


Biosphere comprising of several ecosystems was in harmony with the initial activities which were contained by various processes.  Meteoric rise in population thrust pressure on the potential of environmental balance as deforestation transforming the land for agriculture to meet growing demand of food triggered a paradoxical imbalance – ‘Carbon sink’ started diminishing and carbon dioxide rising.  Even the fossil fuel burning saw a gradual increase to meet the growing demand of power.  While the above activities resulted in soil erosion, air quality and undrinkable water, they perhaps went unnoticed as humans took it for granted.

Transportation of commuters, passenger baggage and freight movement was also a contributor to the changes in the atmosphere.  Despite all these activities contributing to the atmospheric potential, we started recognising it only in the 20th Century (1937) when the carbon emissions reached billion tons per year and were not even an agenda point of First UN Environment conference of 1972.  Many institutions were set up including Intergovernmental Panel on Climate Change (IPCC) in 1988 to collate and assess evidence on climate change. This was very closely followed by Earth Summit (1992) and Kyoto Protocol (1997).  The apex body of United Nations Climate Change Framework Convention’s (UNFCC) Conference of Parties (COP) have had several meetings so far since its inception in 1994 and the recent meeting at Glasgow in 2021 aimed at limiting global warming to 1.5 degree C by 2030 amounting to a cut of about 45%.

We have consumed almost 5 decades if one looks at the realization of global warming and the time taken to act but, unfortunately the situation is no better instead, turning worse from what it was.  This could perhaps be because of not only our inaction but also lack of perhaps proper understanding of the crisis called ‘Climate Change’.

Any disturbance in the principal domains of environment – Land, Air and Water gets reflected in many ways especially the air we breathe. But, the emissions into the atmosphere do not remain in the same state but gets transformed into complex compounds in the presence of other elements in the atmosphere.  What we seem to be addressing as ‘Climate Change’ is indeed just one of the several others.  Therefore, it would be pertinent if we understood the ‘Atmospheric’ implications in a much broader perspective rather than tackling just one of them – that too unsuccessfully.

Atmospheric models do provide a certain idea on the overall scenario of the atmosphere but, the reality could be far different.  However and considering the limitations at this juncture, we should start addressing the issue holistically at least from now on before it is too late. It is therefore pertinent to integrate data from various sources to find a proper solution to climate change.


An attempt has been made to look at global warming in a broader perspective as the world is experimenting many options including the ‘Carbon Neutral’ to address Climate change.  As brought out above, it is time to think differently considering the complexity of atmospheric chemistry and to find appropriate strategies and deal holistically. This is applicable considering the amount of electronic waste (mobiles, computers and TV) we are dumping right now and are preparing to add a few more to the list once AI and ML picks pace in the process of digitalization.

Greater attention on a better understanding of not only the atmospheric chemistry but even soil and water chemistry may facilitate in our attempt in this regard.

A K Shyam, 373 First Main, 1st Cross Vidyaranyapura Post, BENGALURU – 560 097. Mobile:9900204385;


A. K. Shyam, PhD's picture
Thank A. K. for the Post!
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Jim Stack's picture
Jim Stack on Aug 18, 2022

a very good report. You help so there are many parts to this pollution and we have to watch and make progress on many of them and they are inter related. It is too bad the US and many countries don't act until we have a crisis. Your ending comments are very important and I hope others act on it.  QUOTE=Greater attention on a better understanding of not only the atmospheric chemistry but even soil and water chemistry may facilitate in our attempt in this regard. 

A. K. Shyam, PhD's picture
A. K. Shyam, PhD on Aug 18, 2022

I am indeed excited that you endorse my views Dr.Stack.  It is so encouraging and I appreciate it, please.


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