What is climate change? A really simple guide

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Published 13 October 2021 Our Planet Now

World temperatures are rising because of human activity, and climate change now threatens every aspect of human life.

Left unchecked, humans and nature will experience catastrophic warming, with worsening droughts, greater sea level rise and mass extinction of species.

We face a huge challenge, but there are potential solutions.

What is climate change?

Climate is the average weather in a place over many years. Climate change is a shift in those average conditions.

The rapid climate change we are now seeing is caused by humans using oil, gas and coal for their homes, factories and transport.

When these fossil fuels burn, they release greenhouse gases – mostly carbon dioxide (CO2). These gases trap the Sun’s heat and cause the planet’s temperature to rise.

The world is now about 1.2C warmer than it was in the 19th Century – and the amount of CO2 in the atmosphere has risen by 50%.

Bar chart showing how the world has been getting warmer between 1850 to 2020

Temperature rises must slow down if we want to avoid the worst consequences of climate change, scientists say. They say global warming needs to be kept to 1.5C by 2100

However, unless further action is taken, the planet could still warm by more than 2C by the end of this century. A report in 2021 by the Climate Action Tracker group calculated that the world was heading for 2.4C of warming by the end of the century.

If nothing is done, scientists think global warming could exceed 4C in the future, leading to devastating heatwaves, millions losing their homes to rising sea levels and irreversible loss of plant and animal species.

What is the impact of climate change?

Extreme weather events are already more intense, threatening lives and livelihoods.

With further warming, some regions could become uninhabitable, as farmland turns into desert. In other regions, the opposite is happening, with extreme rainfall causing historic flooding – as seen recently in China, Germany, Belgium and the Netherlands.

People in poorer countries will suffer the most as they do not have the money to adapt to climate change. Many farms in developing countries already have to endure climates that are too hot and this will only get worse.

Infographic

Our oceans and its habitats are also under threat. The Great Barrier Reef in Australia, for example, has already lost half of its corals since 1995 due to warmer seas driven by climate change.

Wildfires are becoming more frequent as climate change increases the risk of hot, dry weather.

And as frozen ground melts in places like Siberia, greenhouse gases trapped for centuries will be released into the atmosphere, worsening climate change.

In a warmer world, animals will find it harder to find the food and water they need to live. For example, polar bears could die out as the ice they rely on melts away, and elephants will struggle to find the 150-300 litres of water a day they need.

Scientists believe at least 550 species could be lost this century if action is not taken.

Coral reefGETTY IMAGES

If temperatures continue to rise, almost all warm water coral reefs could be destroyed

How will different parts of the world be affected?

Climate change has different effects in different areas of the world. Some places will warm more than others, some will receive more rainfall and others will face more droughts.

If temperature rise cannot be kept within 1.5C:

  • The UK and Europe will be vulnerable to flooding caused by extreme rainfall
  • Countries in the Middle East will experience extreme heatwaves and farmland could turn to desert
  • Island nations in the Pacific region could disappear under rising seas
  • Many African nations are likely to suffer droughts and food shortages
  • Drought conditions are likely in the western US, while other areas will see more intense storms
  • Australia is likely to suffer extremes of heat and drought
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