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Climate Change Explained: What's Happening, Why It Matters, and What We Can Do About It

World · July 18, 2026 · Liam Chen · 8 min

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Global temperatures have risen 1.2°C since 1850 — here's what's causing it, what the consequences are, and whether we can still avoid catastrophe.

Climate change is the defining crisis of our time. Global temperatures have risen 1.2°C since pre-industrial times (1850), with 2023 the hottest year on record at 1.48°C above baseline. This is caused by burning fossil fuels (coal, oil, gas), which releases 37 billion tonnes of CO2 per year, trapping heat in the atmosphere. CO2 levels are now 420 ppm (parts per million), up from 280 ppm in 1850 — higher than any time in the past 3 million years. The consequences are already visible: extreme weather (heatwaves, floods, droughts), melting ice (Arctic sea ice down 13% per decade), rising sea levels (threatening 200 million people), and ecosystem collapse (coral reefs dying, species extinctions). The Paris Agreement aims to limit warming to 1.5°C (ideally) or 2°C maximum, but current policies put us on track for 2.7°C by 2100 — catastrophic. Here is everything you need to know about climate change — what is happening, why it matters, and what we can do about it.

What Is Climate Change?

Climate change is the long-term warming of the planet caused by human activity, primarily burning fossil fuels (coal, oil, gas), which releases greenhouse gases (CO2, methane, nitrous oxide) that trap heat in the atmosphere.

The greenhouse effect

The greenhouse effect is a natural process where gases in the atmosphere (CO2, methane, water vapour) trap heat from the sun, keeping the planet warm enough for life. Without the greenhouse effect, Earth would be -18°C (uninhabitable).

But human activity has increased greenhouse gas levels, intensifying the greenhouse effect and causing the planet to warm.

How much has the planet warmed?

Global temperatures have risen 1.2°C since pre-industrial times (1850). This may sound small, but:

• 1°C warming has already caused extreme weather, melting ice, and rising sea levels
• 1.5°C warming is the safe limit (Paris Agreement target)
• 2°C warming is the danger zone (catastrophic consequences)
• 3°C+ warming is existential (mass extinction, civilisation collapse)

2023 was the hottest year on record, at 1.48°C above pre-industrial baseline. We are on track to breach 1.5°C by 2030.

What Is Causing Climate Change?

1. Burning fossil fuels

Fossil fuels (coal, oil, gas) are formed from ancient plants and animals, buried and compressed over millions of years. When burned, they release CO2 (carbon dioxide), which traps heat in the atmosphere.

Global CO2 emissions: 37 billion tonnes per year (2023)

Sources:

• Energy (electricity, heating): 42% (coal, gas power stations)
• Transport (cars, planes, ships): 24% (petrol, diesel, jet fuel)
• Industry (steel, cement, chemicals): 19%
• Agriculture (livestock, fertilisers): 10%
• Buildings (heating, cooling): 5%

2. Deforestation

Forests absorb CO2 (photosynthesis), acting as carbon sinks. But deforestation (cutting down forests for agriculture, logging) releases stored CO2 and reduces the planet's ability to absorb CO2.

10 million hectares of forest are lost per year (an area the size of Iceland).

3. Methane emissions

Methane (CH4) is a greenhouse gas 80 times more potent than CO2 (over 20 years). Sources:

• Livestock (cows, sheep) — 32% (cows burp methane)
• Oil and gas — 30% (leaks from pipelines, fracking)
• Landfills — 20% (rotting waste)
• Rice paddies — 10%

4. Nitrous oxide

Nitrous oxide (N2O) is a greenhouse gas 300 times more potent than CO2. Sources:

• Fertilisers (agriculture) — 70%
• Industrial processes — 20%
• Fossil fuels — 10%

The Evidence

1. CO2 levels

CO2 levels are now 420 ppm (parts per million), up from 280 ppm in 1850. This is higher than any time in the past 3 million years.

CO2 levels are measured at Mauna Loa Observatory (Hawaii) and show a clear upward trend (the Keeling Curve).

2. Temperature records

2023 was the hottest year on record, at 1.48°C above pre-industrial baseline. The 10 hottest years on record have all occurred since 2010.

3. Melting ice

• Arctic sea ice is down 13% per decade (summer minimum)
• Greenland ice sheet is losing 280 billion tonnes of ice per year
• Antarctic ice sheet is losing 150 billion tonnes of ice per year
• Glaciers worldwide are retreating (90% of glaciers are shrinking)

4. Rising sea levels

Sea levels have risen 20 cm since 1880 and are rising 3.4 mm per year (accelerating). This is caused by:

• Melting ice (Greenland, Antarctica, glaciers)
• Thermal expansion (water expands as it warms)

5. Extreme weather

Climate change is making extreme weather more frequent and more severe:

• Heatwaves (Europe 2022: 60,000 deaths; India 2024: 50°C)
• Floods (Pakistan 2022: 1/3 of country underwater; UK 2024: record rainfall)
• Droughts (California, Horn of Africa, Mediterranean)
• Wildfires (Australia 2020, California 2020–2024, Greece 2023)
• Hurricanes (more intense, slower-moving, wetter)

6. Ecosystem collapse

• Coral reefs are dying (50% of Great Barrier Reef dead)
• Species extinctions are accelerating (1 million species at risk)
• Ocean acidification (CO2 absorbed by oceans, making them more acidic, killing marine life)

The Consequences

1. Sea level rise

Sea levels could rise 1–2 metres by 2100 (under current policies), threatening:

• 200 million people living in coastal areas (Bangladesh, Florida, Netherlands, Pacific islands)
• Major cities (London, New York, Shanghai, Mumbai, Lagos)
• Small island nations (Maldives, Tuvalu, Kiribati) could disappear entirely

2. Extreme weather

Climate change is making extreme weather more frequent and more severe, causing:

• Deaths (heatwaves, floods, droughts)
• Economic damage (billions in losses from floods, wildfires, hurricanes)
• Displacement (millions forced to flee homes)

3. Food and water shortages

Climate change is disrupting agriculture and water supplies:

• Droughts reduce crop yields (wheat, rice, maize)
• Floods destroy crops
• Heatwaves kill livestock
• Water shortages (rivers drying up, groundwater depleting)

This could lead to famines and mass migration.

4. Ecosystem collapse

Climate change is causing mass extinctions:

• Coral reefs are dying (50% of Great Barrier Reef dead)
• Rainforests are turning into savannahs (Amazon at tipping point)
• Arctic ecosystems are collapsing (polar bears, seals, walruses at risk)

5. Economic damage

Climate change could cost the global economy $23 trillion by 2050 (10% of global GDP), through:

• Damage from extreme weather (floods, wildfires, hurricanes)
• Lost productivity (heatwaves reduce worker output)
• Health costs (heat-related deaths, diseases)
• Migration (millions displaced)

6. Tipping points

Climate change could trigger irreversible tipping points:

• Greenland ice sheet collapse (raises sea levels 7 metres)
• Antarctic ice sheet collapse (raises sea levels 58 metres)
• Amazon rainforest dieback (turns into savannah, releases billions of tonnes of CO2)
• Permafrost thaw (releases methane, accelerating warming)
• Gulf Stream collapse (disrupts weather patterns, cools Europe)

Once these tipping points are crossed, they cannot be reversed.

The Paris Agreement

The Paris Agreement (2015) is a global treaty signed by 195 countries to limit climate change. The goals are:

• Limit warming to 1.5°C (ideally) or 2°C maximum (above pre-industrial levels)
• Reach net zero emissions by 2050 (balance emissions with removals)
• Provide climate finance (rich countries help poor countries adapt)

Are we on track?

No. Current policies put us on track for 2.7°C warming by 2100 (catastrophic).

To limit warming to 1.5°C, we need to:

• Cut emissions 50% by 2030 (from 2019 levels)
• Reach net zero by 2050

This is technically possible (we have the technology) but politically difficult (requires phasing out fossil fuels, which threatens powerful industries).

What Can We Do?

1. Phase out fossil fuels

The biggest priority is phasing out fossil fuels (coal, oil, gas) and replacing them with renewable energy (wind, solar, nuclear).

Progress:

• Renewables now provide 30% of global electricity (up from 20% in 2015)
• Coal is declining in rich countries (UK, USA, EU) but growing in developing countries (China, India)
• Oil and gas are still growing (despite climate pledges)

What is needed:

• No new fossil fuel projects (coal mines, oil wells, gas pipelines)
• Phase out existing fossil fuels by 2050
• Invest $4 trillion per year in renewables (wind, solar, nuclear)

2. Electrify transport

Transport accounts for 24% of emissions. Solutions: