Article on World Environment Day 

Global warming & climate change 

By Dr. Umesh Kulshrestha

The author Dr. Kulshrestha is a senior scientist working in Indian Institute of Chemical Technology (IICT), Hyderabad. He will present the paper in a seminar at Royal Guest House here on June 5, 2007 at 5.30 PM being organized by the Institute of Engineers’ (India), Agartala Local Centre and Tripura State Pollution Control Board.   

Global climate change is no more a controversy. The scientific community has reached a strong consensus that global climate is changing due to human perturbations. Man made activities such as fossil fuel combustion, land use changes, deforestation have been contributing increased concentrations of carbon dioxide and other greenhouse gases in the atmosphere. Pre-industrial concentrations of carbon dioxide were 280 ppmv but the present concentrations of carbon dioxide are around 379 ppmv. Since the middle of the last century, the concentrations of carbon dioxide, methane and nitrous oxide have risen by 25%, 110% and 8% respectively. According to Inter Governmental Panel on Climate Change (IPCC) Report on Emission Scenario, carbon dioxide levels may go up to 490-1260 ppmv by the end of 21^st century. Similarly, concentrations of other greenhouse gases such as methane, nitrous oxide etc. will also rise significantly.

Due to increased emissions of greenhouse gases, 0.6 ⁰C increase in global surface temperature has been noticed since 19^th century out of which around 0.3 ⁰C increase was only during past 25 years. The latest predictions are that global temperature will increase from 1.4 – 5.8 ⁰C from 1990-2100. However, it depends on regional responses and emission trends etc.

Increasing trend of temperature will warm the planet and consequently melting of glacier, sea level rise, frequent hot days, hot nights, heat waves, lesser winter, early spring, frequent hurricanes, effect on biodiversity, change in crop yield, human health effects, irregular weather phenomenon including extreme events will be observed frequently. The net effect of global warming will be region specific. For example, North America and Europe will be most affected regions while near equator regions will be least affected. Since, the global warming is expected to affect temperate regions severely; it is likely that global climate change may alter present demographic distribution in coming centuries.

At present, we have only two options for climate change- 1) to adapt and 2) to avoid. Adaptation is simple but risky option which allows any increase in concentrations of greenhouse gases and forces to adapt any changes. The avoidance, also called as mitigation is a better choice but more challenging. If we understand the severity of the climate change on our economy, society and environment, we must adopt mitigation to avoid any losses. Kyoto Protocol is one of the major treaties which will make significant progress (if implemented fully) in avoidance of climate change. Mitigation option can really save our planet Earth.

So far, Indian contributions of greenhouse gases are very small as compared to developed world. However, the need of the hour is to use renewable energy resources, to provide energy efficient domestic devices in rural areas, to check on deforestation, to have planned land use pattern changes. The important points where Indian scientists/engineers need to focus is to develop eco friendly cost effective technologies, to carry out systematic measurements of various parameters, to develop high quality modeling capabilities, to organize multi-dimensional field campaigns like Indian Ocean Experiment (INDOEX), Integrated Campaign on Aerosol Radiation Budget (ICARB), North India Land Campaign, Atmospheric Brown Cloud (ABC) and to spread awareness regarding environment and climate change among policy makers and public.

It is to be mentioned that most of the model predictions are based on measurements carried out at systematic observatories outside India. Models need to be validated based on regional observations. From Indian region, long term measurements with quality control are very few. It is required that India should focus upon network measurements coupled with modeling attempts to evaluate possible ecological losses due to climate change in the region. A lot more is expected from Indian Atmospheric Science community. For example Indian atmosphere is highly rich in soil derived aerosols which play important role in atmospheric processes including radiation budget. Comprehensive efforts should be made to quantify the role of mineral aerosols, sulphate aerosols and carbonaceous aerosols in radiative forcing and climate change in this sub-continent.