Definition: In this task, you need to generate an appropriate title for the given summary of some paragraph. The generated title must be short and should include the main topic of the given text. Your summary should be less than 20 words long.
Input: Half of the world's population now lives in cities - a proportion that's set to rise to two-thirds by 2050. Yet cities are vulnerable to the worst impacts of climate change precisely because their locations are fixed. As the UN's climate panel meets in Berlin, how are urban centres coping with the test?

Cities on frontline of climate change struggle