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Climate change needs to be tackled at the policy level and at the level of implementation. BE’s Kishore Biswas spoke to Professor Jayanta Bandyopadhay, an expert on various climate change issues, who is currently a Distinguished Fellow at the Observer Research Foundation, Kolkata.

Q. People talk about the dangers of global warming. Can you please explain the real issue?

A. Thank you for raising this topic. Let me first clarify that there is a need to straighten the causal links related to global warming. A fundamental change has been noticed in the measured annual average temperature at the surface of the Earth. This growth in annual average temperature has been noticed since the systematic measurement of atmospheric temperature had been initiated.

This systematic upward movement of atmospheric temperature is now called global warming. However, changes in the temperature of the surface of the Earth are not new. Temperature of the Earth’s surface has varied based on factors like changes in the amount of energy reaching the Earth from the Sun and also based on the variation in the distance of our planet from the Sun. As a result, the Earth has seen periods of glaciation and as well as heating.

However, the warming of about 1° C that occurred in the past two centuries could not be tallied with the changing inputs of energy received from the Sun during that period. Hence, scientific enquiry was taken up to find the reason behind this unexplained heating. In the 1850s, scientists in Europe related the warming with increasing concentration of a number of heat trapping gases like CO2 and CH4 in the atmosphere. These gases got the name Green House Gases (GHG). Most GHG emissions have been linked with burning of fossil fuels during and after the industrial revolution.    

 Q. There are two opinions on this: one that global warming is mainly a natural phenomenon and the other, it is a human creation and can be controlled by proper policies and their implementation. What is your take on this?

A. The baseline is the measured temperature data of the world. There are no two opinions on the increase in the average global surface temperature during the last 200 years. The Intergovernmental Panel on Climate Change (IPCC) has gone into this question in details. Comparisons between solar energy inputs and the rise in average global temperature has made it clear that this phase of warming cannot be explained on the basis of changing solar inputs. On the other hand, the extra heating fits well with the increasing GHG concentrations in the atmosphere. If there is a denial of the GHG-based explanation, an alternate explanation has to be placed for scientific scrutiny and comparison. Science advances though such comparisons.

Q. How is global warming affecting us now and how can it affect us in the future? What is the main challenge?

A. For the last century, we have a recorded 1° C rise of atmospheric temperature. The level of warming in diverse parts of the world is not uniform. However, warming of the atmosphere has several crucial effects that affect diverse parts of the world differently. Most directly, a warmer atmosphere will evaporate more water from the land and oceans, making more water circulating along the global water cycle, causing higher global precipitations.

There are many other important effects. The oceans will heat up and expand in volume, leading to the rise of their levels and encroach on coastal areas. With more CO2 around, the chemistry of the oceans will change causing damage to marine biodiversity. The availability of fish for humans will drop. Higher temperatures in the mountains will reduce the stock of ice in the Cryosphere. Lower parts of the glaciers will flow down to the oceans, adding to the rise in the sea level.

Now let us take up the impact in the form of climate change. In addition to the total amount of water in circulation, there will be a great uncertainty in the rainfall pattern, increasing floods and droughts - affecting agricultural productivity and production and threatening human food security. The warmer oceans will generate favourable conditions for the formation of more intense cyclones. The Bay of Bengal will be affected seriously as a result.  

The main challenges are to ensure drastic reduction of GHG levels, so that warming in future can controlled within the 2° C limit and then ensure cooling. In 1900, the total emission of carbon was about 2.5 G tonnes per year. In 2015 that figure reached about 12 G tonnes. Our present economic path has been driven by fossil fuels and we have to find an alternate path. This is proving to be very difficult, politically and culturally.

Q. Many observers believe that the Himalayas and the main rivers of the continent are facing different threats due to global warming and climate change. Would you elaborate?  

A. Yes, indications are clear that the Himalayas, which can be regarded as the climate maker of Asia, is impacted seriously by global warming and climate change. It has been observed and predicted that the higher regions of the Himalayas are warming at a rate that is more than two times the global average. Our three large rivers, Brahmaputra, Ganga, and Indus are critically dependent on the rainfall run-off and the snow/glacier melt from the Himalayas. The Indus gets about half of its total flow from snow/glacier melts, while the rainfall in the Himalayas feeds the other two rivers. The older hydrological status of these rivers will change quite rapidly and we have to adapt to the new regime. This is a difficult scientific and governance challenge.

Q. Although carbon emission in India is insignificant as compared to like the US and China, why do many observers state that India is the most affected country due to climate change among the most populated countries?

A. You have touched upon two different issues. The first is the issue of responsibility of countries for the creation of the problem. The second is the role we can play in addressing the problem. The total accumulated GHG can be traced back to the initial uses of fossil fuel, mainly in Europe. However, in the last few decades, China and India have also made quite a good contribution to the GHG accumulation. We need to follow an energy path that should be free from fossil fuels in a few decades. Our people in the last two centuries have made no significant contribution to the GHG accumulation but should not follow the fossil fuel intensive energy path of the present industrially advanced countries. This is our scientific and policy challenge.