US President Barack Obama showed leadership on climate change at the G8 summit, but he will have to do more, at home and abroad, to help secure a UN deal later this year. Obama and his team helped secure a stronger agreement among developing and industrialized countries at the Italy meetings by reversing the policies of former President George W. Bush, world leaders and climate activists said. The Group of Eight rich nations and the Major Economies Forum, which includes 17 countries responsible for about 80 percent of the world's emissions, both backed a goal of limiting global warming to no more than two degrees Celsius (3.6 Fahrenheit) over pre-industrial levels. “On climate change, there's a much stronger (G8) statement, I think, this year than in past years,” Canadian Prime Minister Stephen Harper told reporters. “That's due principally in fairness to the new (Obama) administration, which has brought a commitment to dealing with this problem.” The United States had previously resisted the 2 Celsius goal, which scientists say is a critical threshold to avoid. “I think they get some credit both for shifting the US position on that issue - acknowledging the science and the urgency of it - and for working to bring along other countries,” said Alden Meyer of the Union of Concerned Scientists, referring to the Obama team. But environmentalists said Obama had to do more, domestically and internationally, for UN talks in December in Copenhagen on a new climate pact to succeed. The major economies forum, which Obama chaired, failed to convince China, India and other developing nations to sign up to a G8-supported goal of halving world emissions by 2050. “Real leadership would have meant that that meeting would have come out with targets to cut pollution,” said Phil Radford, executive director of Greenpeace USA. Radford said Obama should have pushed for stricter emissions cuts in a bill capping industrial carbon dioxide output that recently passed the U.S. House of Representatives. The bill is deemed crucial for US credibility in Copenhagen. “The president has not shown leadership at home,” Radford said. “He has hidden behind Congress while they weakened the bill.” The bill would require large companies in the United States to reduce greenhouse gas emissions 17 percent by 2020 and 83 percent by 2050, from 2005 levels. It could be watered down in the US Senate, where the bill faces steeper obstacles for passage. Antonio Hill, senior policy adviser on climate change for development organisation Oxfam, said Obama would have to become more personally involved in lobbying senators to back the climate bill. “I think we've seen really positive signs that's Obama's going to be willing to roll up his sleeves and get hands-on engaged with the passage of the Congressional bill through the Senate,” Hill said. Obama seemed to acknowledge that need during a statement to reporters after the climate forum in Italy concluded. “I think that as I wrestle with these issues politically in my own country, I've come to see that it is going to be absolutely critical that all of us go beyond what's expected if we're going to achieve our goals,” Obama said. European leaders said Obama's willingness to admit mistakes in past US climate policy helped set the tone for progress. “He accepts responsibility for some of the problems which originated in the US and engages to find both a political and intellectual solution,” European Commission President Jose Manuel Barroso told Reuters. “He doesn't give lessons to the others. This was the most relaxed G8 ever in my opinion, and he certainly contributed to that.”