Global warming and climate change are issues that are in the forefront today. However, many questions are frequently asked, such as:

u Are we really sure about climate change?

u What exactly is at stake?

u Is it more economics than science?

u How much of it is political?

u Are we fighting a war with nature?

u What is it that we are not talking about?

There are basically three broad aspects of climate change within which there are finer aspects:

u Scientific: Observation, understanding, modelling and prediction

u Socio-economic: Impacts, vulnerability, adaptation and mitigation

u Political: Exploitation and protection

It is now established that global temperature has increased from 1850 to 2007. There has been a continuous warming trend since 1976. It is also important to note that 1998 was the warmest year and there has been no further warming since 1998. However, there are many uncertainties in our knowledge of the earth’s climate because:

u Scientific meteorological records are very short compared to the climate scale

u What we know of the earth’s climate prior to the year 1800 is only interpretative

u What we know about the climate after 1800 is subject to error

u There is a lack of data over oceans and uninhabited areas

In 1901-2000, global warming was 0.6 °C but the likely error is of the order of ±0.2 °C.

The cause of global warming can be traced to the fact that the earth’s atmosphere is a mixture of gases: Nitrogen 78 %, Oxygen 21 %, Argon 0.9 %, and Carbon dioxide, Water vapour, Methane, Ozone, etc 0.1%. It is this 0.1 % part of the atmosphere that participates in the transfer of heat and controls temperature. Carbon dioxide, Water vapour, Methane, Nitrous oxide, etc, are called Green House Gases (GHGs) because they trap the heat that is emitted by the earth, in a manner similar to a greenhouse.

From 1750 to 2005, the concentration of Carbon dioxide, the most important GHG, has increased from 280 to 379 ppm on account of fossil fuel use and land-use change. Methane has increased from 715 to 1774 ppb because of agriculture, particularly rice cultivation. Nitrous oxide has gone up from 270 to 319 ppb due to use of fertilizers. Aerosols are another driver of climate change. They are particulate matter in the atmosphere which reflect, absorb or scatter radiation and cool or warm the atmosphere. They have an effect on clouds and precipitation and their influence on the earth’s climate is known to be significant but it is not understood completely.

If we are asked whether we fully understand all the causes of global warming, the honest answer would be “No!” The solar constant is 1366 w m-2 and the human-induced forcing is somewhere between 0.6 and 2.4 w m-2. So we are dealing with extremely small quantities whose error bars are as high as, or even higher than, their own values.

It is often asked that when we cannot forecast tomorrow’s weather with certainty, how can we predict the climate 50 or 100 years from now? Here the answer is “Yes, we can.” The reason is that while weather consists of rapidly changing processes in the atmosphere, climate is a combination of several slowly evolving processes: Atmospheric, oceanic, biological, geological, geophysical and bio-geo-chemical. The climate system has its own internal dynamics and external forcings as well human-induced forcings.

If we are to make an attempt at predicting the climate a century ahead, there is no other way but to construct a mathematical model. A climate model is a representation of the climate system as a set of equations which can be solved. It gives us a physical insight into the sensitivity of climate to various factors and it can be used to visualise future climate scenarios. Climate models can be very simple or very complex and they are of different types like: Atmospheric General Circulation Models, Ocean General Circulation Models, carbon cycle models and atmospheric chemistry models. There are global and regional models. However, there is no single climate model that can tell us everything. We need to run several models and each climate model serves only a certain purpose. It is not good for other purposes and the results of a climate model should not be applied to what is beyond its scope.

While interpreting the results of climate models the following aspects must be taken into consideration:

u Many of the climate processes are yet not fully understood (for example, aerosols)

u Some of the known processes cannot be accurately parameterised in models (for example, cloud formation and rain)

u All the data required by the models may not be available (either in quality and quantity)

u Models are compelled to make some or several assumptions

u Depending upon the assumptions made, different conclusions can be reached

u It is extremely difficult to model human behaviour and predict it over the next 50 or 100 years

It is also necessary to distinguish between climate predictions and climate projections. The projections are based upon what are called storylines and scenarios. Storylines consist of scenarios and scenario families, and a scenario is a plausible representation of the future concentrations of greenhouse gases and aerosols. The scenarios differ widely as per the various assumptions made by them about world carbon emissions, population growth, GDP and energy consumption. Climate projections are therefore subject to substantial uncertainty. Projections of global temperature rise up to 2100 are of the order of 1.1 to 2.9 °C for the low emission B1 scenario and 2.4 to 6.4°C for the high emission A1FI scenario.

It is vital for us to know how global warming could affect India and particularly our monsoon. An important observational fact is that the current rate of warming is relatively higher over the northern hemisphere (land) than the southern hemisphere (ocean). This implies a stronger land-sea thermal gradient which drives the Indian monsoon. According to one climate model, the temperature projections for 2071-2100 indicate warming all over the country and the warm areas are likely to become warmer. Wet areas could get wetter, and dry areas drier. However, global climate model simulations for 2100 monsoon differ widely.

It is a reassuring fact that All-India monsoon rainfall has not shown any increasing or decreasing trend so far. However, the anomalies in the monsoon rainfall do have an effect on India’s food grain production and GDP growth rate. The monsoon continues to be India’s only source of water and the extent of the irrigated area of the country is limited.

Sea level rise is going to be an outcome of global warming. It is also vital to know about this, as India has a 7500 km long coastline and many big and small islands. Coastal zone management becomes very important in the context of climate change. It is necessary to have a regulation of land use, proper planning of development activities, e.g, new ports, industries, etc, protection from increased flooding, measures against coastal erosion and conservation of natural ecosystems.

It is essential that we look upon climate projections with objectivity. If they come in the form of scary scenarios we should not get alarmed but examine their basis and credibility before contemplating radical action. We must remember that India has the wettest and driest places on earth, and droughts and floods are not new to us.

For tackling the problem of climate change on the political front, the United Nations Framework Convention on Climate Change (UNFCCC) was adopted in May 1992 in New York and signed at the 1992 Earth Summit in Rio de Janeiro by more than 150 countries. It contains commitments for all Parties. It was ratified by 188 countries as of February 2003. A Conference of Parties to the UNFCCC is held every year since 1995. The last COP was in December 2007 in Bali, Indonesia. The Kyoto Protocol to UNFCCC was adopted at COP-3 in 1997 in Kyoto, Japan.

The Kyoto Protocol contains legally binding commitments, but there is no way to enforce them. It covers 6 GHGs (greenhouse gases): CO2, CH4, N2O, HFC, PFC and SF6. The two main features of the Kyoto Protocol are

u Carbon trading and

u Clean Development Mechansim (CDM)

The Kyoto Protocol assigned targets to developed countries to reduce their GHG emissions and allowed the developing countries that do not have targets to sell emission reductions to developed countries. The idea was that reduction of emissions should not come in the way of sustainable development and assistance could be provided to developing countries for adopting clean energy and industrial processes.

The Kyoto Protocol comes to an end in 2012 and a successor agreement needs to be worked out. The G8 industrialized countries, together with the +5 developing countries – Brazil, China, India, Mexico, and South Africa – are actively involved in the negotiations.

Climate change is a subject of seemingly endless debates and negotiations among climate scientists, political leaders and industry giants. The latest negotiations on climate change were conducted at Accra in August 2008. The next COP-14 is to be held in Poznan, Poland in December 2008 and COP-15 in Copenhagen, Denmark in December 2009.

It would be prudent for us not to rush to conclusions. Climate observations have errors and uncertainties and the science of climate change is not complete but evolving. Climate models have many limitations and we should not stretch them beyond their scope. We should be careful in evaluating the impact of climate change. But most of all, we should not develop a guilt complex. We must realize that we are not the cause of the problem, but we are facing the consequences of a situation created by the industrialized nations. We are entangled in the problem because CO2 gets freely mixed in the atmosphere.

India’s CO2 emissions are very low while CO2 emissions by the U. S. have been continually increasing. We should not overlook the fact that the industrialised world is wasting power over luxury areas like gambling dens, while we do not have even the basic necessities of power and our children have to study in candlelight.

Fighting global warming does not mean that we go back to the dark ages. Nature permits exploitation, it is forgiving and tolerant. Agriculture could be quoted as the most benign example of exploitation of nature by humanity. However, we should not be reckless and we have a responsibility to future generations. Also, we should guard ourselves against political exploitation in the name of climate change.

For India, the future is in solar and wind energy. In the long run it is not going to matter how much electricity we save or how efficiently we use it, because the world will run out of fossil fuels some day in the future any way. India is situated in the tropical belt and it has a definite edge over the developed countries which are in the extra-tropics. We must launch massive research for exploiting solar and wind energy and to make it affordable for generation of electricity, industry and home needs.

In the context of climate change we must not forget that there are several critical problems that humanity is facing: Growing population, illiteracy, poverty, water resources management, drinking water, food security and others. There is much more to life than mere carbon. Let’s put climate change in the proper perspective.

R R Kelkar