Pope Francis warned Thursday that it would be “catastrophic” for world leaders to let special interest groups get in the way of a global agreement to curb fossil fuel emissions as he brought his environmental message to the heart of Africa on the eve of crucial climate change talks in Paris. Francis issued the pointed warning in a speech to the U.N.’s regional office here after celebrating his first public Mass on the continent. The joyous, rain-soaked ceremony before 300,000 faithful saw the Argentine pope being serenaded by ululating Swahili singers, swaying nuns, Maasai tribesmen and dancing children dressed in the colors of Kenya’s flag. Francis has made ecological concerns a hallmark of his nearly 3-year-old papacy, issuing a landmark encyclical earlier this year that paired the need to care for the environment with the need to care for humanity’s most vulnerable. […]