The Chief of the United Nations has warned Asia to quit its addiction to coal in a bid to tackle climate change. <br />'' <br />'' UN Secretary-General António Guterres said countries in the region were among the most vulnerable to global warming and should be on the front line of efforts to stop it. <br />'' <br />'' He cited a new study that found that Asian countries were at particular risk of climate-driven flooding. <br />'' <br />'' Coal is a major source of power in many Asian countries. Speaking to reporters in the Thai capital Bangkok today, Mr. Guterres described climate change as the defining issue of our time. <br />'' <br />'' The UN Chief referenced a study published on Tuesday, which found that climate change would put millions of more people at risk from coastal flooding by 2050 than previously thought. <br />'' <br />'' The majority of those implicated were in developing countries across Asia, the study said.<br />''