Beijing (AFP) – China said Friday it was ending cooperation with the United States on key issues including climate change — a move Washington decried as “fundamentally irresponsible” as relations between the two superpowers nosedive over Taiwan. The damaging rift, which carries significant geostrategic risk, was triggered by Chinese fury over a visit by US House Speaker Nancy Pelosi to Taiwan, which Beijing claims as its territory and has vowed to retake — by force if necessary. It has since Thursday encircled the self-ruled, democratic island with a series of huge military drills that have …