NEW YORK - Exxon Mobil Corp is pulling contributions to several groups that have downplayed the risks that greenhouse gas-emissions could lead to global warming, continuing a policy started in 2006 by Chief Executive Rex Tillerson. Exxon will not contribute to some nine groups in 2008 that it funded in 2007. It said in its corporate citizenship report that the groups' "position on climate change could divert attention from the important discussion on how the world will secure the energy required for economic growth in an environmentally responsible manner."