Reuters: The European Union must avoid backsliding on agreeing a package to fight global warming in 2008 even though economic turmoil may make targets hard to hit, the top United Nations climate change official said on Friday. Yvo de Boer said many countries were looking to the 27-nation EU to spearhead a fight against climate change with its plan to cut greenhouse gas emissions by 20 percent below 1990 levels by 2020. “My main concern is slippage and not having clarity on when the …