Global Warming: Causes, Effects and Control Measures

A Warming World

What Global Warming and Climate Change Mean

Global warming is the ongoing rise in the Earth's average surface temperature. Driven by human activity since the Industrial Revolution, the planet has warmed by more than a degree, and the last decade was about 1.2 degrees Celsius warmer than the pre-industrial age.

Climate change is the wider term. It includes this warming and all its knock-on effects on the world's weather, oceans and ice, so global warming is best seen as the engine that drives the larger climate change.

Why Global Warming Matters

Why it matters is that a warmer world is a more dangerous one. The same rise in temperature that melts the ice also feeds fiercer storms, longer droughts and rising seas, touching food, water, health and the coasts.

It is now widely regarded as one of the defining challenges of the age. Understanding its causes, its effects and the ways to control it is central to the environment section of the syllabus.

How the Atmosphere Traps Heat

The Greenhouse Effect, Natural and Enhanced

The Earth stays warm because of the greenhouse effect. Sunlight passes through the atmosphere and warms the surface, which radiates the heat back as infrared; greenhouse gases absorb part of this heat and keep the planet far warmer than it would otherwise be.

This natural effect makes life possible. The problem is the enhanced greenhouse effect: by adding more gases, human activity traps extra heat, and the atmosphere now holds about half as much carbon dioxide again as it did before the industrial age.

The Main Greenhouse Gases and Their Sources

Not all greenhouse gases are equal. Carbon dioxide makes up about three-quarters of emissions, followed by methane at roughly a fifth, with nitrous oxide and the fluorinated gases making up the small remainder.

Each has its sources. Carbon dioxide comes mainly from burning fossil fuels and from deforestation; methane from agriculture, livestock and waste; nitrous oxide from fertilisers; and the fluorinated gases from industry.

The Causes of Global Warming

Burning Fossil Fuels and Industry

The chief cause of global warming is the burning of fossil fuels, the coal, oil and natural gas that power electricity, transport and industry. Each tonne burned releases carbon dioxide that the atmosphere has not seen for ages.

Industry adds further emissions, from cement and steel to chemicals and refrigerants. Because the modern economy runs largely on fossil energy, cutting these emissions is the central task of any response to warming.

Deforestation and Changing Land Use

Forests are the planet's great carbon sinks, drawing carbon dioxide out of the air. When they are cleared for farmland or timber, that stored carbon is released and the sink itself is lost.

Farming and changing land use add their own greenhouse gases, from the methane of paddy fields and livestock to the nitrous oxide of fertilisers. Together with fossil fuels, they make up the human causes of a warming world.

The Effects on the Global Climate

Rising Temperatures and Extreme Weather

The first effect of warming is felt in the weather. Heatwaves and wildfires are becoming more common, and a warmer atmosphere holds more energy and moisture, bringing more intense storms, droughts and heavy rainfall.

These extremes fall hardest on farming and on the poor. Shifting rains and fiercer heat threaten harvests and water supplies, so the consequences of climate change for food security are gravest in the warm, crowded countries of the tropics.

Melting Ice and the Rising Sea

As the world warms, its ice melts. Mountain glaciers and the great polar ice sheets are shrinking, and this water, together with the expansion of the warming ocean, pushes the sea steadily up the coast.

The IPCC has projected a global sea-level rise of the order of a metre by 2100. For a country like India, with a long, low and crowded coastline, such a rise threatens cities, deltas and the small island states of the Indian Ocean with flooding and the loss of land.

Warming Oceans and the Coral Reefs

The oceans take up much of the extra heat and carbon dioxide, and they pay a price. The seas grow warmer and more acidic, a change that is especially deadly for the world's coral reefs.

When the water is too warm, corals expel the algae that feed and colour them and turn white, a process called coral bleaching; repeated bleaching kills the reef. The Great Barrier Reef and India's own reefs in the Lakshadweep and the Gulf of Mannar have all suffered as the seas have warmed.

Control Measures: Mitigation and Global Agreements

Cutting Emissions at Source

The surest control measure is to cut the emissions at their source. This means switching from fossil fuels to clean energy, the wind, solar, hydro and nuclear power that produce little or no carbon, and using energy far more efficiently.

Alongside this, protecting and growing forests restores the carbon sinks, while cleaner transport and industry cut emissions further. Adapting to the warming already locked in, through sea walls and resilient crops, runs alongside this work of mitigation.

From the Kyoto Protocol to the Paris Agreement

Because the air is shared, warming can only be controlled by acting together. The world's climate treaty is the 1992 UN Framework Convention on Climate Change, and its first binding step was the Kyoto Protocol, adopted in 1997 and in force from 2005.

Kyoto set binding targets for the developed countries to cut their emissions, on the principle of common but differentiated responsibilities. It was succeeded by the 2015 Paris Agreement, under which all nations agreed to hold the rise in temperature well under two degrees Celsius.

Global Warming in the UPSC Exam

The Significance of the Climate Crisis

What is the significance of global warming is that it ties together almost every part of the environment syllabus, from energy and forests to oceans, disasters and international relations. It is a problem of science, economics and governance at once.

For the exam, a strong answer links the causes to the effects and then to the control measures, exactly as the recurring questions on global warming demand.

India's Response and the Wider Linkages

Contemporary linkages run from global warming to India's own policy. India has pledged to reach net zero by 2070, is expanding its renewable capacity rapidly, and acts through its national plan on climate change and its commitments under the Paris Agreement.

The warming of the seas is also remaking the weather, as the work on cyclones and climate change shows. Placed in the syllabus, global warming is a study in shared global action. The high-yield points are few and worth holding in mind.

• Global warming is the human-driven rise in Earth’s average temperature, about 1.2 degrees Celsius since the industrial era.
• It is caused mainly by greenhouse gases, above all carbon dioxide from burning fossil fuels.
• Its effects include heatwaves, melting ice, rising seas and coral bleaching.
• Control means cutting emissions through clean energy, efficiency and forests.
• The global response runs from the UNFCCC (1992) and the Kyoto Protocol (1997) to the Paris Agreement (2015).

Sources and Further Reading

• Wikipedia: Climate change
• Wikipedia: Kyoto Protocol
• Wikipedia: Greenhouse effect
• IPCC: Intergovernmental Panel on Climate Change
• NASA: Global Climate Change
• NOAA: Climate
• World Meteorological Organization (WMO)
• UNFCCC: The Paris Agreement
• Ministry of Environment, Forest and Climate Change