redOrbit: British Prime Minister Gordon Brown warned on Monday that world leaders must place priority on meeting at this year’s climate summit in Denmark in order to avoid a “catastrophe of unchecked climate change.” At the Major Economies Forum in London, Brown urged other world leaders to join him in appearing at this year’s climate summit in order to address a crucial need for cuts in carbon emissions. “We can’t afford to fail. If we fail, we pay a heavy price,” said …