Ewire: Biden joins 2020 field but climate platform unclear

Former Vice President Joe Biden is making his 2020 presidential bid official, with many politicos suggesting he starts at or near the front of a huge Democratic field, but the precise contours of his climate change policy stance remain something of a Rorschach test even though the issue is one of several high-profile issues dominating the primary. Several months ago, when Biden was still publicly weighing the idea of a campaign, he told a U.S. Conference of Mayors event that...