More than 150 countries have reached an agreement described as monumental to phase out gases that are making global warming worse. Hydroflurocarbons (HFCs) are widely used in fridges, air conditioning and aerosol sprays. Delegates meeting in Kigali, the capital city of Rwanda accepted a complex amendment to the Montreal Protocol that will see richer countries to decrease their HFC use from 2019.<br/><br/>But some critics say the compromise may have less impact than expected. US Secretary of State John Kerry, who helped forge the agreement in a series of meetings in the Rwandan capital, said it is a major victory for the Earth.<br/><br/>The new agreement will see three separate pathways for different countries. Richer economies like the European Union, the US and others will start to limit their use of HFCs within a few years and will decrease it by at least 10 per cent from 2019. <br/><br/>Some developing countries like China, nations in Latin America and island states will freeze their use of HFCs from 2024. Other developing countries, specifically India, Pakistan, Iran, Iraq and the Gulf states will not freeze their use until 2028. China, the world's largest producer of HFCs, will not actually start to decrease their production or use until 2029. India, will start even later, decreasing its first 10 percent reduction in use in 2032.<br/><br/>If the agreement is implemented in full it will make a big difference to global warming. Experts estimate it will reduce the equivalent of about 70 billion tonnes of carbon dioxide from the atmosphere by 2050.