Daylight saving time (DST) starts on March 14 in North America. DST begins at 2:00 am first in New York, followed by Chicago, Denver, Los Angles and Anchorage in accordance with the time difference. In Europe, DST starts on March 28. European countries simultaneously switch to 1:00 UTC regardless of the time difference. DST was introduced in Germany and UK with the aim of saving the resources during the First World War. Since then, the number of countries that adopted DST has increased. However, there have been lively discussions on DST and changes in DST policy. For example, some countries have expanded DST against the background of recent global warming, while others have stopped DST because of no effect, or have introduced DST newly. When the Chilean earthquake occurred in 2010, the Chilean government extended DST until April 4 to avoid confusion. It can be said that they took the quick decision in time of emergency. In oreder to reduce greenhouse effect gas, how would each country control DST?