World leaders have today agreed to pursue "substantial" but unspecified cuts in greenhouse gases and pledged to reach a United Nations deal by 2009 on long-term measures to fight global warming.
German chancellor Angela Merkel, hosting the summit of the Group of Eight (G8) in the seaside Baltic resort town of Heiligendamm in Germany, had hoped to gain commitments from member countries to slash emissions by 50 per cent by 2050.
Instead, the club of industrialised nations - Britain, Canada, France, Germany, Italy, Japan, Russia and the United States - agreed that "resolute and concerted international action" on climate change was urgently needed.
US president George W. Bush and Russian leader Vladimir Putin met for the first time following a series of diplomatic clashes that some analysts said heralded a new Cold War.
At the meeting, Mr Putin proposed using a radar system in Azerbaijan to develop a missile shield as an alternative to a disputed US plan to base it in the Czech Republic and Poland.
"We can do this automatically, and hence the whole system which is being built as a result will cover not only part of Europe but entire Europe without an exception," Mr Putin said.
He said the plan would mean Russia did not need to follow through on a threat to train missiles on Europe.
Protests against the summit continued around the venue, with demonstrators blocking road access and stopping a steam train shuttle from running.
Police patrol craft rammed two inflatable speed boats that breached a security zone around the venue, tipping environmental activists into the Baltic and injuring three of them.
The final summit text confirmed that the G8 would act to stem the rise in global warming gases, followed by "substantial" reductions, the most serious commitment to action on the issue by the United States, the world's largest polluter.
Leaders also vowed to pursue a new global climate deal by 2009 that would extend and broaden the Kyoto Protocol, noting that the EU, Canada and Japan all want emissions halved by the middle of the century.
New climate proposals unveiled by the US president last week would be integrated into the established United Nations process - a key demand of European countries.
The language represented a partial victory for Ms Merkel, who has won credit for keeping up pressure on Bush to commit to broader global efforts to curb the gases scientists say risk swelling sea levels and causing more heatwaves and flooding.
"In my opinion this is a very, very substantial and significant step forward," Ms Merkel said.
British prime minister Tony Blair, who put the climate issue on the global agenda at a G8 summit in Gleneagles, Scotland two years ago, hailed the agreement as a "major step forward".
However, French President Nicolas Sarkozy was less enthusiastic: "If you want me to say that we could have done better then, yes. I want to speak frankly."
The United States, the only G8 country that did not sign up to Kyoto, has been reluctant to commit to firm emissions targets before non-G8 powers like China and India make pledges to cut.
Mr Bush, who unveiled his own plan for cutting emissions beyond 2012 last week, says it is too early to set numerical targets at the June 6th-8th summit of the G8 in Heiligendamm, Germany.
Standing alongside Mr Blair, Mr Bush said: "We are deadly earnest about getting something done," adding: "The US will be actively involved if not taking the lead in a post-Kyoto framework."
The United States is the only G8 nation outside the UN's Kyoto Protocol, which sets cuts in greenhouse gases running to 2012.
Mr Bush plans to call together the leading 15 greenhouse emitters - led by the United States, China, Russia and India - to agree on cuts beyond 2012 by the end of 2008.
Other topics that the summit will consider include aid to Africa and foreign policy issues ranging from Iran to Kosovo.
Security remains tight around the summit venue, a luxury hotel in the small seaside town of Heiligendamm.
This morning police in power boats chased down several smaller Greenpeace craft trying to break through the security cordon, ramming one and dumping its occupants into the Baltic.