The greenhouse effect is a natural process where gases in our atmosphere trap heat close to the Earth's surface.
Main greenhouse gases:
Without these greenhouse gases, Earth would be too cold for humans to survive.
Greenhouse gases - Increase global temperatures by 33°C
They act like a blanket around the planet.
The Sun's rays enter the Earth's atmosphere, and heat is reflected back from the Earth's surface.
Some of that heat goes out to space, while some gets trapped by the greenhouse gases.
But human pollution is adding to these greenhouse gases, causing the blanket to thicken and trap more heat.
Carbon dioxide is one of the main greenhouse gases, released from the combustion of fossil fuels.
When humans use fossil fuels, this gas is released.
Today, the concentration of carbon dioxide in the atmosphere is higher than at any time in the last 650,000 years.
Trees and plants absorb carbon dioxide from the atmosphere, whilst oxygen is released through the process of photosynthesis.
Deforestation is reducing the planet's ability to absorb greenhouse gases.
In addition, when vegetation is burned, or left to rot, more carbon dioxide is released into the atmosphere.
Another of the five major greenhouse gases is methane, produced in significant amounts by cattle farming.
Methane is at its highest levels in over 400,000 years, and it's a particularly powerful greenhouse gas.
23 times more effective at trapping heat than CO2.
Agriculture, as a whole, contributes around 14% of all greenhouse gas emissions.
Scientists are largely agreed that human activities are accelerating the greenhouse effect.
And, despite the development of cleaner energy technologies, levels of carbon dioxide in our atmosphere are steadily rising.
As greenhouse gases increase, we can expect the temperature to rise too, as more heat is trapped within the atmosphere.