Mandy Chu Ka-man, 17 SKH Bishop Mok Sau Tseng Secondary School Global warming. A large amount of greenhouse gases are emitted when burning fossil fuels. Although the main carbon dioxide-emitting countries have agreed to take steps to solve the problem, I think it will continue. When the world's temperature climbs, many places will be submerged as a result of rising sea levels. Organisms may die as they cannot adapt to the hotter environment. They may even go extinct and the food chain will be affected. Janet Tang Man-wai, 17 SKH Bishop Mok Sau Tseng Secondary School Air pollution. As our world becomes more industrialised, factories and vehicles emit fumes such as carbon monoxide, which can be fatal if inhaled excessively. Unlike water pollution, which can be improved with better sewage treatment, it will not be easy to improve air quality if we continue to use our resources this way. We can filter the water, but it is hard to filter the air. There is no way back. Emily Law Hoi-tung, 17 SKH Bishop Mok Sau Tseng Secondary School Air pollution. The CO2 emitted from cars and factories has already caused the greenhouse effect. This will be much more serious in 50 years' time. The world's temperature will increase so much that the icebergs in the north and south poles will melt. Sea levels will rise and some countries, including parts of Hong Kong, will disappear under water. Also, could you imagine wearing a mask all day to protect against the toxic air? I really don't want this to happen. Bill Kwok Ka-yin, 16 Carmel Divine Grace Foundation Secondary School The Earth is surrounded by a layer of ozone which absorbs 90per cent of the sun's ultraviolet radiation. But there's a big hole in the ozone layer over Antarctica. In 50 years' time the situation will be worse. The hole enables more UV light to reach the ground, and people might get skin cancer if they are exposed to the sun for too long! The UV radiation also melts icebergs and causes a rise in global water levels. Willa Chan Choi-fong, 16 Tak Oi Secondary School Global warming. Factories are one of the major producers of greenhouse gases, which trap heat, causing the global temperature to rise. The increasing number of vehicles is another factor. Cars release carbon dioxide into the atmosphere, making the greenhouse effect worse. The Kyoto Protocol aims to limit greenhouse emissions, but some countries are reluctant to sign the protocol because it would harm their economic development.