If you make a mess, you should be responsible for cleaning it up. The increase in carbon dioxide (CO2) in the atmosphere is one of the main causes of global warming. And most of that CO2 has been produced by rich nations as they build factories, buy cars and live increasingly luxurious lives. Poor countries want the rich countries to pay the bill if they reduce their carbon emissions. But because the rich countries aren't happy with this solution, the world isn't currently working together to find an answer to climate change. China and India are the two largest developing countries. As their economies rapidly expand, their reliance on dirty and inefficient factories, and the growing number of cars on their roads, all add to our climate problems. But the US alone is responsible for one-quarter of all the CO2 that has ever been released by the burning of fossil fuels and the destruction of forests. Despite being the world's richest country, the US seems particularly unwilling to pay its share of the bill. Poor countries will be the first to suffer due to climate change. A warmer planet means increasing problems with the water supply in the world's driest regions, such as India and Africa. It will also create more floods, which are again common in poorer countries such as Bangladesh and China. Rich countries have in the past been generous in helping the poor deal with natural disasters such as floods, earthquakes and droughts. But now we're dealing with problems that science shows are caused by man. And science tells us who has caused most of these problems - the citizens of rich nations. Britain, Europe, the US and other rich countries have built up their wealth by exploiting poorer nations and their resources. A United Nations report calls for rich nations to follow the model they used after the second world war, when they financed the rebuilding of countries destroyed in the fighting. The UN says they should contribute about US$600 billion per year to help the poor cope with climate change. The US has refused this proposal. It seems simple enough to say those responsible for a problem should fix it. So ask yourself, since Hong Kong is rich by world standards, how much would you be willing to pay to solve the problem?