Scientists have been investigating some big ways of tackling climate change. Sometimes known as geoengineering, these could be huge projects costing many millions of pounds. Ideas put forward so far include:
Arrays of giant mirrors in space to reflect back incoming sunlight
Creating shiny clouds from seawater that cover huge areas
Fertilising the oceans to encourage the growth of microscopic green plants - phytoplankton - that photosynthesise
Creation of millions of artificial trees with CO2 absorbing leaves
Even filling the upper atmosphere with layer of suphur dioxide to act as a sunscreen has been suggested though this has led to serious concern about increases in acid rain.