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global warming

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A hot future awaits us

Climate and weather patterns are determined by phenomena like topography of the place, distance from the sea, wind patterns etc. It is hard to imagine that we ‘human beings’ could have anything to do with changing the climate. But are we really innocent?

The weather in any place refers to the condition outdoors over a short period of time. It can change within minutes, hours or a day. It can be sunny in the morning and raining heavily in the evening. Weather refers to daily changes in precipitation, barometric pressure, temperature, and wind conditions in a given location.

Climate, however, refers to atmospheric conditions in that place over relatively long periods of time. It is a synthesis of weather conditions over years and describes average or most common conditions, regular weather sequences like summer, monsoons, and winter and extremes, if any. So Bangalore is known for its mild climate, Chennai and Mumbai for their hot and humid climate, Delhi for its harsh summers and winters and Cherrapunji for its rainy climate.

Over the past few years we have been noticing unusual weather events across the world, especially severe heat waves, unusually high rainfall over short periods of time, snowfalls in places that do not usually have them and an increase in the number of hurricanes, typhoons and floods.

At the heart of the climate change issue is the phenomena of global warming and the greenhouse effect. Earth supports life, thanks to its gaseous atmosphere, which perform an important function of trapping the heat that leave the Earth’s surface. This regulates the planet’s average temperature and makes it suitable for life.

These gases are called Green House Gases (GHGs) and one of the chief GHGs is carbon dioxide.

The concentration of these greenhouse gases in the atmosphere is important to maintain the balance in Earth systems.

In addition to carbon dioxide, other naturally occurring GHGs are methane, nitrous oxide, and water vapour. Methane is released from inundated lands such as marshes and from cattle dung.

Humans are creating new GHGs like Hydro fluorocarbons and fluorocarbons. Global Warming Potential (GWP) is a measure of how much heat a greenhouse gas can trap as compared to carbon dioxide. Man made green house gases have significant GWPs when compared to CO2 and they remain in the atmosphere for a very long time.

But a matter of concern to us is the increase in the concentration of natural green house gases. Carbon dioxide is released by the burning of fossil fuels like coal, oil and biomass. Deforestation is resulting in lesser absorption of carbon dioxide.

Methane is released from inundated rice fields and when waste matter rots in an oxygen-free environment in garbage dumps. Cattle rearing for the meat industry are also contributing to increased methane emissions.

Since the mid 1800s, which is when the industrial revolution started, there has been a steady increase in CO2 levels in the atmosphere and this is most worrisome.

Climate scientists are studying ice samples to understand atmospheric conditions before measurement systems were in place. Over a period of many years’ ice and snow form many layers and during the buildup they trap air bubbles of previous times. Analysis of these air bubbles is helping us get an idea of green house gas concentrations during earlier years.

The sharp increase in the concentration of natural greenhouse gases is noticeable since the past 150 years and this data only reinforces the fact that human activities are responsible for this rise.

The increase in the concentration of gases that trap heat within the Earth’s atmosphere is resulting in global warming.

Global warming is an anagram of ‘ball is going warm’

Climate models calculate that the global mean surface temperature could rise by about 1 to 4.5 centigrade by 2100.

Global warming is creating an imbalance in climate regulating systems and this has widespread impacts increased temperature affects agricultural crops. A mere 0.5oC rise in winter temperature would reduce wheat yield by 0.45 tons per hectare in India. A 20C rise in temperature would lower rice yields by up to 0.75 tons / hectare in the high yielding regions.

In Haryana, wheat production has declined from 4106 kg/ha in 2000–01 to 3937 kg/ha in 2003–04, with maximum temperature rising by about 3°C during February–March in the last seven years. Thus, the direct impact of climate change on agriculture and food supply includes

  1. shortage in grain production resulting in less availability of food items, especially to the economically poor people,
  2. changes in agricultural inputs such as fertilizers and pesticides,
  3. shift in planting dates of agricultural crops,
  4. preference of crop genotypes due to adaptation to changing climate,
  5. soil erosion,
  6. lower fertility level and
  7. The incidence of pests, weeds and diseases in food crops will be more pronounced.

India contributes to about 5.6 million child deaths due to hunger every year, more than half the world's total  Half of children in India are underweight, one of the highest rates in the world and nearly double the rate of Sub-Saharan Africa

In the short term, increased melting of glaciers can cause floods and in the long term, glaciers will disappear, causing rivers to dry up and drought to occur.

The Chorabari glacier has retreated at the rate of 9 meters a year in recent years

The Dokriana has lost 20% of its volume over the past 3 decades.

The famous Gangotri glacier has also been in retreat- at an astonishing rate of 17 meters a year between 1971 and 2004.

Added to these glacial melts, increased snow cover melting could also be expected to change water flows in the rivers originating in the Himalayan region.

According to the IPCC, rainfall patterns are likely to be modified with some regions becoming more arid and others experiencing more rainfalls. Globally the frequency of heavy precipitation has increased, drought events have intensified, have been more frequent and taken place in wider areas, especially in tropics and subtropics.

Many parts of India are flood-prone, and extreme precipitation events, such as flash floods and torrential rains, have become increasingly common in central India as well as many urban centers over the past few decades.

In 2009 one of the worst flash floods in decades in Andhra Pradesh and Karnataka affected an estimated total of 2 million people. Thousands were marooned without food and drinking water.

On 26th and 27th July 2005, Mumbai city received 994 mm of rainfall over a period of 24 hours. The previous record high rainfall in a 24-hour period for the city was 575 mm, in 1974.

October 2005 was recorded as the wettest month in Bangalore over a 50 year period.

Assam saw its worst flooding in 50 years in July 2003.

The drought in 2002, one of the severest in the 130 year history of India affected 56% of the geographical area and the livelihoods of 300 million people in 18 states. About 150 million cattle were affected and the government allotted a financial relief of Rs 20,000 crores

Out of 5723 numbers of assessment administrative units (Blocks/Taluks/ Mandals) in the country, 839 units are “overexploited”, 226 units are “critical”, 550 units are “semi-critical”, 4078 units are “safe” and 30 units are “saline”.

Water stress is cited as one of the most pressing environmental problem facing the region. In India, gross per capita water availability will decline from around 1,820 cubic meters a year to as low as around 1,140 cubic meters a year in 2050.

Floods and droughts put India’s food security at risk. Human life is at stake.

When water resources are affected, people may not have clean water to drink. This can result in an increase in water-borne diseases like cholera and diarrhoea. It can also cause an increase in water related insect-borne diseases like malaria.

Not only is economic activity of the region affected, crores of rupees are spent on relief measures.

Reduction in per capita water availability in India is leading to an increase in water conflicts between states, between rural and urban areas and even between neighbors.

India has a large coastline and the potential impacts of one meter sea-level rise include inundation of 5,763 km2 in India. A sea-level rise of just 400 mm in the Bay of Bengal would put 11 percent of the Bangladesh's coastal land underwater, creating 7 to 10 million climate refugees.



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Please note that this is the opinion of the author and is Not Certified by ICAR or any of its authorised agents.