By SETH BORENSTEIN
AP Science Writer
UNITED NATIONS (AP) — The United Nations chief says Earth is facing a hellish problem in climate change and its leaders still aren’t doing nearly enough to curb carbon emissions that’s causing it. In his Wednesday special climate ambition summit he was pleading with major polluting nations to do more. Those nations remain silent. The only countries that are touting their efforts — “first movers and doers” the United Nations called them — are responsible for just one-ninth of the world’s annual carbon pollution. In the summit, only world leaders who have new concrete actions are getting to address their peers on the issue.