The government should do more to cut carbon dioxide pollution, says charity Friends of the Earth.
They launched the Big Ask campaign on Wednesday, to get the government to make a new law to cut the amount of the gas the UK puts out by 3% every year.
The government have already agreed to cut carbon dioxide levels by 60% by 2050, but the charity say without the law, that will be too difficult.
A spokesman said the government would think about any proposed law.
Lots of people think the carbon dioxide we put into the atmosphere is changing the climate.
Friends of the Earth backed up their calls for the new law with a survey, which they say shows 73% of people think the government isn't doing enough to fight climate change.
They have made a special advert to be shown in cinemas to highlight their cause.