Bangladesh, Environmental, International, Life as it is, Political, Technical

We are hurtling towards a disastrous climate change (Part I)

The human race is staring at the disastrous climate change of their own making. The climate change clock is ticking remorselessly; it has gone past the 11th hour and, although not exactly on the 59th minute, but not too far from it. We pride ourselves to be civilised human beings, we claim unprecedented scientific and technical achievements; but we have failed to realise the damage we have inflicted and still are inflicting on our planet and our actions are anything but civilised. A large section of the human population under the guidance and influence of ‘civilised political leaders’ in many Western and Eastern countries is in complete denial of the climatic damage!

In order to appreciate how close are we to the tipping point of the irreversible climate change, we need to look at the factors that initiate climate change. The term ‘climate change’ embodies the totality of processes like global warming, sea levels rise, loss of polar ice caps, floods, fires, droughts and so forth. These processes do not take place for no reasons; there are deep rooted reasons for these effects.

The causes for these effects are multifarious. Causes range from emission of greenhouse gases from uncontrolled industrial activities, excessive exploitation of Earth’s resources, deforestation, rise in human population, demands for improved standards of living, increased air travel etc. All these factors contribute to climate change due to enhanced greenhouse gas emission. And the quantity that is primarily used to characterise climate change is the increase in global temperature.

The root cause of the increase in temperature is the increase in greenhouse gas concentration in Earth’s atmosphere. A sort of runaway situation has developed here. Increase in greenhouse gas leads to higher global temperature and higher global temperature leads to higher greenhouse gas. Unless decisive action is taken by human beings to arrest this situation, the human race is at peril. 

The legitimate question that arises here is that how can one assert this rise in global temperature leading to climate change is mainly due to human activities, when both natural processes and human activities do contribute to global temperature? That is a genuine question.  

The planet Earth had undergone over the millennia large climate swings. Scientists had looked into these variations in Earth’s climate over the past 650,000 years and found that there had been as many as seven ice ages during this period and in between ice ages there had been some warmer periods with increase in global temperatures. Modern human beings (Homo sapiens) had not yet evolved 650,000 years ago and so global temperatures could all be assigned to natural causes. There was no trend of temperature variation over this period.

When nearly 250,000 years ago, modern human beings emerged from the savannas in Africa, man started interacting with nature. But those primitive men had no way of exploiting the Earth; they were passive, subservient onlookers of nature.

Climatologists looked at the inter-glacial periods i.e. between two cold glacial spells and established a baseline temperature. After the baseline temperature was established, then any excess global temperature found over a period when human activity was known to have taken place can be assigned to human activities. This is an established scientific technique and it is applied to many scientific disciplines to separate out human activities from natural activities.

The planet Earth is blanketed by a layer of gases in the outer atmosphere. This atmosphere containing a variety of gases lets in solar radiation to come through, but blocks out or shields harmful ionising radiation from the outer skies. A small fraction of solar energy is reflected back from Earth’s surface to outer skies. Normally if the atmosphere is unpolluted, this reflected energy in the form of infrared radiation will escape to outer space. On the other hand, if there are pollutants such as carbon dioxide, methane etc, this radiation is held back and reflected towards Earth again. Thus, gradually excess energy is accumulated in the planet and its temperature goes up.

The types of gases that refuses to let infrared escape from Earth had been found to be carbon dioxide (CO2), methane gas (CH4), nitrous oxide (N2O), chlorofluorocarbon (CFC) and a few more. Atmospheric concentrations of carbon dioxide in ppm (parts per million) and methane gas in ppm over the period 1500 to the present time had been estimated by scientists and presented in the graphs below. The period 1720 to 1800 is the industrial revolution period when human activities kicked in large scale. Before this industrialisation period, humans were living in harmony with nature. It can be seen from both of these graphs that the industrial revolution was the spurt in increase in concentration which continued in accelerated fashion right up to the present day.

Greenhouse gas concentration from 1500 to 2000 AD

Along with these two graphs, one should consider the rise in global temperature which is shown below. The similarity in the overall shape and pattern of these graphs is striking and one can draw conclusion that are correlated. It shows beyond doubt that the rise in temperature above the 1850 to 1900 (industrialisation period) baseline is due to increased concentration of global warming pollutants – CO2 and CH4. There are other significant pollutants such as chlorofluorocarbon (CFC), but it is not shown here.

The CO2 concentration in pre-industrialised period was between 200 to 270 ppm and Earth had a thermally stable period. But now this concentration has risen to about 350 ppm leading to about 1ºC rise in temperature. But, if the present trend continues, by the end of the coming decade the temperature may well go up more than 1.5ºC and that would bring in very harsh conditions for all forms of life on Earth.

Global average temperature and industrial baseline.

From 1970s the scientists had been saying that human beings are damaging Earth’s atmosphere and its natural conditions and care should be taken to limit it or even reverse it. But political leaders of various persuasions, particularly Americans and vested interests dealing with fossil fuels, kept denying any global warming or any climate change etc. When confronted with increased severity and more frequent incidences of droughts, bush fires, floods, storms, tropical cyclones, cold spells etc, these climate deniers started saying that these are natural phenomena; nothing to do with human activities. Their denial is either based on ignorance or moral depravity.

Few countries holding such views are destroying the good work of large number of countries. Donald Trump, president of America, is the most famous deniers of all, mainly because America is the second largest polluter of the world and to limit polluting activities would cost America a lot. And hence denying the whole thing is the easy option. Pursuing such damaging policy, America, under Donald Trump, had withdrawn from the Paris Agreement in 2017.

The Paris Agreement of 2015 aims to limit global warming to 1.5ºC relative to a pre-industrial baseline. Its precise commitment is:

Holding the increase in the global average temperature to well below 2℃ above pre-industrial levels and to pursue efforts to limit the temperature increase to 1.5℃ above pre-industrial levels, recognising that this would significantly reduce the risks and impacts of climate change.

We all live in the same planet. If one country i.e. America, the second largest polluter, keeps damaging the planet for its own benefit, that would wipe out the sacrifices of large number of countries. America is pushing the Earth to a precipice for their selfish interests.

(The next Part (Part II) will deal with the likely consequences of the present predicament and the most likely prediction of the future scenario.)


  • Dr A Rahman is an author and a columnist

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