Climate Change: The Science

There’s no more debating if climate change is a reality. Scientists agree: the world is getting warmer and human activity is largely responsible. Today, our planet is hotter than it has been in 2,000 years, and on track to grower hotter than it’s been in two million years.

Storm chasers and Doppler on Wheels truck near Fort Dodge, Iowa, USA.

Climate change is expected to increase the strength and frequency of extreme weather events around the world, like this major storm near Fort Dodge, Iowa.

© Greenpeace / Daniel Beltrá

Climate-denying corporations and politicians want you to believe climate change is a mystery, but science can actually tell us a lot about the causes and effects of our warming world.

What We Know

Years of scientific investigation have given us a clear understanding of what’s causing climate change and how humans are contributing. It works like this:

  • Certain gases in the atmosphere—like carbon dioxide—create what’s called the greenhouse effect, trapping in heat and regulating the Earth’s temperature.
  • Burning fossil fuels releases more greenhouse gases into the atmosphere, particularly carbon dioxide. While not the most potent greenhouse gas, carbon dioxide is by far the most emitted by human activities.
  • More greenhouse gases in the atmosphere means a more intense greenhouse effect, causing the Earth to keep getting warmer.
  • There’s more carbon dioxide in our atmosphere now than there’s been in the past 150,000 years.

We’re also learning more about the impacts of climate change, many of which have serious consequences for humans and wildlife.

  • Climate change is closely linked with the rise in extreme weather events we’ve experienced in recent years. Hurricanes, typhoons, floods and drought are all made worse by climate change.
  • Melting polar ice caused by warmer temperatures has huge ripple effects. Not only does it threaten the habitat of species like polar bears and penguins, it’s causing our sea levels to rise and threatening coastal cities and communities.

How We’re Changing the Climate

Global temperatures have risen and fallen over the Earth’s history for natural reasons. What’s unique about the warming we’re experiencing now is that it can’t be explained by those natural reasons, and that it’s happening faster than ever before.

Human activity plays a central role. The fossil fuels we burn to power our homes, businesses, cars and more all release carbon dioxide into the atmosphere, and deforestation for timber and agriculture is a major source of greenhouse gas emissions.

Humans are at the center of the problem, but this also means the power is in our hands. The choices we make today will determine the climate of the future.

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