Click For Photo: https://ichef.bbci.co.uk/news/1024/branded_news/15D4F/production/_110532498_gettyimages-93449365.jpg
"The moment of crisis has come" in efforts to tackle climate change, Sir David Attenborough has warned.
He spoke as BBC News launched a year of special coverage on global warming.
Answers - Range - Readers - Questions
Here are our answers to a range of readers' questions.
Climate change will need to be tackled by governments worldwide, through measures like the 2005 Kyoto Protocol. This brought nations together for the first time in a single agreement on tackling climate change.
Everyone - Carbon - Footprint - Amount - Greenhouse
But everyone has a carbon footprint. This is the amount of greenhouse gases like carbon dioxide - which contributes to global warming - released into the atmosphere by people's actions.
This can be reduced in a number of ways. According to a recent report by a group of international scientists, transport is responsible for 34% of a household's carbon footprint in high-income countries like the UK. The report calls for a major programme of investment in the rail and bus network, with lower ticket prices and investment in safer cycling.
Climate - Change - Drive - Train
Climate change: Should you fly, drive or take the train?
Home heating presents another challenge and opportunity. It is responsible for 21% of a household's carbon footprint.
Thermostat - Houses - Heating - Systems
This could be cut by turning down the thermostat, having better-insulated houses and changing to low-carbon heating systems.
According to the United Nations, the current world population is about 7.7 billion and could reach 9.7 billion in 2050.
Population - Growth - Demand - Food - Energy
This population growth drives higher demand for food, greater energy consumption and more competition for resources. And it increases the production of the gases that cause global warming.
And a recent major study, by a global group of 11,000 scientists, concluded that the world needs to stabilise its population.
Study - Deal - Controversy - Authors - Action
The study has attracted quite a deal of controversy, but its authors say such action is needed if the world is to avoid what they call "a catastrophic threat" from climate change.
It is estimated...
Wake Up To Breaking News!