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By Dr. R K Pachauri

Climate Change

Climate Change. These are two words that you are probably hearing often these days. What is all the talk about? Is it something that the meteorologists should worry about? How does it concern you and me? That’s exactly what we will find out together.

Let’s start by taking one word at a time.

What is Climate?

There is a saying "climate is what you expect; weather is what you get". We often confuse weather and climate. Weather is what is reported on the TV every night—minimum and maximum of different places, cloud cover, wind conditions, rainfall, humidity, etc.  Weather describes what is happening outdoors in a given place at a given time.

The word climate describes the total of all weather occurring in a place over a period of years.

Climatologists generally consider 30 years as the time needed to find out the climate of a place.

It includes average weather conditions. Climate tells us what it’s usually like in the place where you live. For example Ahmedabad and Delhi have generally dry climate, but Mumbai and Visakhapatnam have humid climate; the climate in Bangalore and Pune is said to be pleasant, while Kochi has largely rainy climate.

How would you describe the climate of the place where you live? Think of five ways in which the climate affects you (e.g. what you wear, eat, how you live…).

What do all these have in common?

   They are, in some way or the other, connected to Climate Change.

What is Changing?

Weather can change in a short time… it may rain for an hour and then the sun may come out. Climate can change too! Climate change is natural and the Earth’s climate has been changing. The ice ages of the past are examples of change in climate. In the past such changes took a very long time. Today the rate of change is faster. And the change is that the earth is getting warmer!

Scientists who study the climate are still arguing about how fast the earth is warming and how much it will warm, but they do agree that the earth is warming. This time around it is humans that are responsible for warming.

Scientists have confirmed that the world is now warmer than it has been at anytime in the past 2000 years. Global temperature rose by about 0.6°C during the 20th century. About 0.4°C of this warming occurred in the last 35 years.

World temperature measurements began in 1860. The global average temperature is calculated based on millions of individual measurements taken from around the world. This temperature record is considered by climate scientists to be the most reliable information describing the state of global climate.

Humans have probably used more energy in the last century than in the preceding one hundred centuries put together.

How Can Humans Change the Climate?

By the things that we do and the way we live.

Once all climate change occurred naturally. Then about 220 years ago came the Industrial Revolution – people began using machines, factories came up and things began to be made by different processes. All these needed energy to run. Most of this energy comes from fuels like coal and oil which are known as fossil fuels. Burning fossil fuels releases gases like carbon dioxide, methane, etc. into the atmosphere. These are called Greenhouse Gases (GHGs). Before the Industrial Revolution human activity released very few gases into the atmosphere, over the last 200 years our activities are releasing huge quantities of GHGs into the atmosphere.

When do you send GHGs into the air?

When you

	Watch TV	You need electricity to run all these. Electricity comes from power plants. Most power plants use coal and oil to make electricity. Burning coal and oil produces CO2.
	Play a video game
	Use the air conditioner
	Turn on a light
	Listen to a music system
	Use the washing machine
	Use the microwave

GHGs and Climate Change: What’s the Link?

Earth is the only planet we know that supports life. Earth’s average surface temperature is 14.4°C. Our closer planetary neighbours are Venus and Mars. The average temperature on the surface of Venus is 449°C and that on Mars is -55°C.

It is the GHGs present in the atmosphere that absorb some of the sunlight and trap the heat near the earth’s surface, so that the earth is warm enough for life to exist. Without this the earth would be freezing cold. This natural mechanism is known as the greenhouse effect.

But too much of GHGs can create problems. As their quantity increases more heat is retained on the earth’s surface. This causes the phenomenon known as Global Warming. This warming of the earth is leading to a change in climate.

Scientists predict that if we continue releasing carbon dioxide at the rate we have been doing in the last 50 years, the CO₂ levels will double what it was before the Industrial Revolution. This could raise the earth’s average temperature by about 5° - 8° C by 2050. This raise may not sound like a lot but the consequences will be great.

How Warm is Warm?

We have all experienced a few “really hot” days every summer. That does happen. It is like having a fever for 2-3 days. But if temperatures continue to rise by even a small degree over a longer period of time, then the effects will be felt. This would be like when the fever does not come down and persists over many days or weeks.

The 1990s was the warmest decade of the 20th century. 1998 was the warmest year on record. 2002 was the second warmest year.

Global warming refers to the increase of the earth’s average temperature due to the build up of GHGs in the atmosphere. Climate change is a broader term that refers to long-term changes in climate, including average temperature and precipitation.

What will be the effects of a warmer world?

Weather Extremes

There will be more cyclones, storms and floods. Most places will become hotter; some will become drier and others wetter. We will experience more violent weather events; heat waves, drought, floods (because of heavier rainfall and melting glaciers) and intense storms.

Shrinking glaciers and melting sea ice

Glaciers and icecaps are sensitive indicators of climate change. Mountain glaciers are already shrinking. The glacier from which Edmund Hillary and Tenzing Norgay began their ascent of Mt. Everest in 1953 has retreated by about 4.8 km over the past 50 years. The Artic Sea ice is becoming very thin, especially in late summer. In August 2000 there was no ice at all at the North Pole, it was in a stretch of open water!

Rise in sea level

Melting of glaciers and polar ice caps will increase the water in the seas. This along with expansion of sea water due to warming would rise the sea level and this would submerge small islands and coastal areas. For example, Maldives is one such island nation that would be affected by sea level rise.

Delta regions are also high risk areas. Many of these regions are already prone to flooding. Thousands of people dependent on these fertile agricultural areas would suffer. A one-metre sea level rise would flood several coastal cities, and the thickly populated deltas in Egypt, Bangladesh, India and China, where much of the world’s rice is grown.
 

Agricultural production

Areas of the globe that are now producing rice, wheat and other food grains may not be able to produce the same quantity anymore because of global warming. This will eventually affect availability of food.

Increased evaporation and drier soils in some regions would result in prolonged droughts. In the drier areas need for irrigation would increase. Agriculture in warmer areas would also suffer from increased infestation of pests, crop diseases and weeds.

The flooding of coastal areas as a result of sea-level rise would lead to a loss of agricultural land. It would also lead to intrusion of salt water into coastal aquifers which would in turn affect agricultural production.

Loss of ecosystems and biodiversity

Plants and animals would be forced to migrate to keep up with climate shifts. Those that cannot migrate would disappear in the course of time. Those adapted to cool climates would become extinct as their habitats disappear. Shifts in regional climate would threaten many national parks, wildlife reserves and coral reefs and thereby affect the rich diversity of life that they have.

Scientists have projected that climate change is the single biggest threat to the 22,000 polar bears that remain in the world. Polar bears in the Arctic need sea ice to launch hunting expeditions for ringed seals, their primary prey. The sea ice is melting earlier in spring due to climate change. This means bears cannot hunt for longer periods to develop enough fat reserves. By the end of the summer they are skinny bears and are unable to bring up their young ones.

Effect on human health

Deaths due to heat waves and other extremes of climatic conditions are some direct consequences that we would face. Tropical diseases such as malaria, encephalitis, yellow fever and dengue fever could spread to the present temperate regions of the world. As many as 3 million people in the world die each year from malaria. Almost half the world’s population is at the risk of the disease which infects an estimated half-a billion people each year – that is one in twelve of the world’s population. This figure is four times higher than it was in 1990. Around 50 million cases of dengue are reported each year.

A WHO report estimated that over 150,000 people in developing countries are now dying each year from the effects of global warming ranging from malaria and malnutrition to extremes of heat and cold and flood.

The message is clear. Evidence is increasing all the time…

The world’s scientific community is almost united in agreeing that human induced climate change is a reality.

It is also clear that the effects of climate change cannot be simply reversed or ‘switched off’. The effects of global warming are projected to continue for the next hundreds of years. The GHGs already released into the atmosphere will not just disappear. They will linger – some like methane for decades, some like carbon dioxide for hundreds of years, and some gases like perfluorocarbons, even for thousands of years.

Even if all emissions of GHGs ceased tomorrow, the climate would continue to change, and with it the effects of life on our planet.

Is Anyone Worrying?

Well, some people still feel that all this talk is just a lot of “hot air”, they feel that climate change may be a temporary phenomenon that will magically disappear; others have faith that human ingenuity will lead to the development of some new technology that will take care of all these troubles.

But many people are taking this seriously. Scientists, Governments and people like you and me are worried.

What Should Be Done?

Scientists agree that the burning of fossil fuels is causing global warming and leading to climate change. Since these fuels are burned for energy, and everyone uses energy, everyone can help reduce global warming by just using less energy. That’s easier said than done. Modern life and lifestyles are so very dependent on energy.

Carbon dioxide is one of the GHGs responsible for global warming. Coal, petroleum, diesel, airplane fuel, natural gas, LPG contribute in a big way to the release of carbon dioxide. By using products or activities that use these fuels we are adding to the carbon emissions. There is a global call to cut carbon emissions.  By being aware of, and reducing excess use of such things, we can help reduce at least a small amount of carbon dioxide from being released.

Here’s a list of some such activities. Can you tell which of these are:

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