German Chancellor Angela Merkel met with US President George W Bush over lunch in Heiligendamm to try hashing out some of their differences before the Group of Eight (G-8) summit begins later on Wednesday.
The leaders of Germany and the United States appeared optimistic about bridging the divide on climate change at this year's summit while police struggled to keep protesters from reaching the seaside resort where the meeting starts later in the day.
As the leaders of the world's most industrialised nations were making their way to picturesque, coastal Heiligendamm, thousands of protesters swarmed near the fence surrounding the summit site, and several hundred reached the razor wire-topped fence, police said.
Protesters also managed to block two routes leading from the airport in Rostock.
Japanese Prime Minister, Shinzo Abe and, later, Italian Prime Minister, Romano Prodi, arrived at the airport there.
Both leaders were transported from the airport by helicopter.
German Chancellor Angela Merkel will lead the discussions with leaders of Britain, France, Japan, Italy, Russia, Canada and the United States.
The US has now acknowledged that global warming is a serious problem that must be addressed, and that doing so requires a global goal.
Europe and others have come around to Washington's view that no solution is viable without the participation of developing energy guzzlers such as China, India and Brazil, and that economic growth can't be sacrificed for progress on climate.
Japan wants the leaders of the world's richest countries and Russia to focus the upcoming summit on reducing global greenhouse gas emissions and set targets to achieve that aim, a senior official said on Wednesday.
Japan has already announced an "Abe Initiative" of short- and long-term goals to reduce greenhouse gas emissions.
Along the lines suggested by Abe, a Japan-EU summit on Tuesday agreed to cut emissions by half or more by 2050.
The EU and Canada have also announced numerical targets in the same direction.
Tokyo is calling for a new global warming pact to succeed the 1997 Kyoto Protocol, under which 35 industrialised nations agreed to cut greenhouse gas emissions by a combined five percent by 2012.
The United States, the world's top emitter of such gases, and Australia, the worst greenhouse-gas polluter per capita, have rejected the Kyoto agreement, saying it would hurt their economies.
The major source of diplomatic tension at the G-8 meeting is likely to be the US proposal to place elements of a missile defence system in the former Soviet satellite countries of Poland and the Czech Republic.
The G-8 includes Russian President Vladimir Putin and Bush.
Russia and the United States have been sparring over the proposal.
Washington says the plan is aimed at intercepting possible missile strikes from rogue states such as Iran and North Korea, but Russia says such attacks are virtually impossible and claims the proposed system is aimed at weakening Russia's missile capabilities.