Bloomberg: Costa Rica’s Christiana Figueres took charge of United Nations climate talks, calling on nations to do the quot;politically possiblequot; and take smaller steps rather than striving for an all-encompassing deal to halt global warming. After the UN climate summit in Copenhagen in December failed to produce a new treaty, about 190 countries are still grappling to agree on more ambitious greenhouse-gas cuts to contain the global average temperature rise to 2 degrees Celsius (3.6 degrees …