The Science Behind Climate Change

Standard Page - 2010-04-14
Climate scientists around the world agree with overwhelming certainty that climate change is the result of manmade activity. But if we are responsible for the cause, then we can also be responsible for the solutions to protect our climate and our future.

Climate scientists around the world agree with overwhelming certainty that climate change is the result of manmade activity. But if we are responsible for the cause, then we can also be responsible for the solutions to protect our climate and our future.

22 July 2009 Time Lapse Cameras Record Ice Breakups

A remote time lapse camera is situated high on the cliffs above Petermann Glacier, directed at a crack which has appeared in the ice far below. The camera will automatically make images once every minute, to produce time lapse films of the ice breakup. These provide a unique and revealing insight into how glacial ice breaks and drifts to sea. The installation of several time lapse cameras on Petermann and other glaciers in north Greenland is a joint initiative between Greenpeace and Extreme Ice Survey (EIS).

This massive and rapid change to our climate is like nothing humankind has seen before. As such, the science around it has been cautious and careful in reaching consensus over time.

But a strong consensus on climate change is here; the scientific community now agrees that climate change is real, it's caused by human activity and it's already happening.

Learn more about scientific consensus.

What we know

While there are still uncertainties, particularly related to the timing, extent and regional variations of climate change, there is mainstream scientific agreement on the key facts:

  • Certain gasses, such as carbon dioxide, in the atmosphere create a "greenhouse effect", trapping heat and warming up the earth.
  • Carbon dioxide concentrations in the atmosphere are now the highest in 650,000 years. With greater concentrations of greenhouse gases in the atmosphere, warming may speed up.

Learn more about the greenhouse effect.

Greenhouse gases

Since the Industrial Revolution, we have been burning fossil fuels (coal, oil, natural gas), which releases carbon dioxide into the atmosphere.

Carbon dioxide is the most significant greenhouse gas in terms of human effects because of the massive quantities emitted. Other greenhouse gases are released in smaller quantities, but have much more powerful greenhouse effects. Some gases also persist in the atmosphere for long periods of time – for example, perfluorocarbons have lifespans of 50,000 years.

Learn more about carbon dioxide emissions and other greenhouse gases.

Deforestation

Forests and peatlands are natural storehouses of carbon. As these trees grow, they absorb carbon dioxide from the atmosphere and give back oxygen. As the natural lungs of the earth, our ancient forests are instrumental in regulating the planet's weather and rainfall – but only if they are kept intact.

When forests are destroyed, the centuries-worth of carbon they have absorbed are released into the atmosphere. Human activity has been destroying vast swathes of forests at unprecedented rates in the last century.

Logging and burning of tropical forests creates about one fifth of global greenhouse gas emissions, more than that emitted from all the cars, planes, and trains in the world.

Learn more about deforestation.

What we can expect

A certain amount of additional warming – about 1.3º C (2.3º F) compared to pre-industrial levels – is probably inevitable because of emissions so far. Limiting warming to under 2°C (3.6°F) is considered vital to preventing the worst effects of climate change.

If our greenhouse gas emissions are not brought under control, the speed of climate change over the next hundred years will be faster than anything known since before the dawn of civilization.

There is a very real possibility that climate feedback mechanisms will result in a sudden and irreversible climate shift. No one knows how much global warming it would take to trigger such a devastating scenario.

Learn more about climate research and the scientific consensus on climate change.

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