Rai hit the Philippines late in the typhoon season: most cyclones develop between July and October. Scientists have long warned that typhoons are strengthening more rapidly as the world becomes warmer because of human-driven climate change. The Philippines -- ranked among the most vulnerable nations to the impacts of climate change -- is hit by an average of 20 storms every year. More than 500,000 people were still in evacuation centres or sheltering with relatives, the national disaster agency said Thursday. Thousands of acres of crops have been wiped out, fishing communities devastated and tourism operators left with no livelihood. Long queues of people waiting to refill empty water drums or fill up motorbike fuel tanks have been seen across the affected regions.