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Global warming? Climate change? What’s it all about?

We know some people find the whole issue of climate change confusing. A few still debate whether it’s really happening, and its causes. Others argue over the best ways of controlling it. Our easy-to-follow guide will bring you up to speed on the science and clear up misconceptions.

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Carbon dioxide (CO2) – a natural gas, essential for all life on earth. It's absorbed by plants as they grow, and emitted by all life forms when they die (or are burnt as fuel). Other than water vapour, it’s the most common ‘greenhouse gas’.

Greenhouse gases (GHG) – including carbon gases like CO2 and methane, they are vital in the Earth’s atmosphere in certain quantities because they help trap and retain some of the sun’s heat (the ‘greenhouse effect’). This makes life as we know it possible on Earth – without it the world would be mostly frozen. But too much is dangerous too...

Carbon cycle – the natural processes that emit and absorb carbon gases across the globe, keeping overall levels stable, and our climate suitable for an abundance of life.

Smoking chimney

Human activity – over the past 150 years, the world’s industrialised nations have unwittingly upset the delicate balance of the carbon cycle by burning huge amounts of fossil fuels (concentrated carbon, like coal, oil, gas), as well as breeding vast numbers of methane-producing livestock, and cutting down the forests that naturally absorb CO2 from the air.

The extra carbon in the atmosphere has been raising global temperatures.

Global warming – doesn’t mean we’ll all have warmer weather in future. As the planet heats, climate patterns change, with more extreme and unpredicted weather across the world – some places will be hotter, some colder. Some wetter, others drier.

We know the planet has warmed by an average of nearly 1ºC in the past century. Might not sound much, but small rises can create big problems for people and wildlife.

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2º is too much – a rise of just 2ºC means:

  • severe storms and floods in some countries, droughts in many more 
  • seas become more acidic, coral and krill die, food chains are destroyed
  • no Arctic ice in summer – not just bad news for polar bears, it also means global climate warms faster.


Satellite image of Arctic ice © NASA

Tipping points and feedback effects – as the earth warms, the impacts can fuel each other and accelerate, causing runaway, irreversible changes.

For instance, polar ice reflects sunlight away from the Earth. When it melts (and Arctic sea ice is already predicted to be mostly gone in summer by 2020), more heat will be absorbed. And thawing permafrost releases trapped methane, just as drying forests and warming oceans emit their stores of CO2, all further increasing the greenhouse effect.

Beyond 2º – scientists predict possible rises of up to 6º this century if we don’t drastically cut greenhouse gas emissions.

We barely want to think about what this would mean. Rainforests dying. The melting of the ancient ice sheets of Greenland and Antarctica. Dramatic sea level rises. And people and animals suffering along the way. That’s why we must act now.

Wind turbine

A global climate deal – this is urgently needed to set strict and binding  emissions targets on the developed, industrial nations – as the ones who largely caused the problem while benefitting from the commercial gains.

We need to cut GHG emissions at least 40% (below 1990 levels) by 2020, and at least 80% by 2050. A useful immediate aim is for everyone to reduce their emissions 10% by the end of 2010.

A fair global deal must also put money aside to assist devloping countries to adapt to the unavoidable impacts of climate change, and grow as low-carbon economies.

Cap and trade, and other forms of carbon emissions trading – where a limit is put on total emissions and industries and countries buy and sell their entitlements – may be useful. But it's certainly not a silver bullet, and could be open to abuse, so must be carefully controlled.


Climate change denial – some people might try to tell you: "Global warming is natural" or "The Earth is actually cooling" or "There's nothing we can do anyway"...

Here's the truth:

  • it's true the Earth’s climate has always changed, and temperatures risen and fallen over thousands of years. But it's happening now at a far faster rate than ever before, which doesn’t give the world’s species (including ourselves) much time to react or adapt.
  • it's true the Earth was in a cooling cycle, slowly heading for another ice age in a few thousand years – but the wholesale burning of fossil fuels has upset that cycle, vastly increasing the greenhouse gases in the atmosphere. 
  • The good news is, if we accept that we’re a major cause of climate change, we can choose to do something about it. But we have to do it soon. 

You can...


Remember:
reducing energy use > keeps down emissions > keeps down global temperatures.