German Chancellor Angela Merkel used a historic address to the US Congress on Tuesday to issue a heartfelt plea on climate change, likening the problem to a second Berlin Wall.
"I'm convinced, just as we found the strength in the 20th century to bring about the fall of a wall made of concrete and barbed wire, we shall now show that necessary strength to overcome the walls of the 21st century," Merkel said.
She said those were "walls in our minds, walls of short-sighted self-interest, walls between the present and the future."
In a rare address to a joint session of Congress marking the fall of the Berlin Wall 20 years ago, Merkel said next month's high-stakes climate summit in Copenhagen hinged on strong US and European commitments.
Before her address, Merkel held talks at the White House with President Barack Obama, who hailed her as an "extraordinary leader."
But the German leader's message to the divided Congress on climate change was clear: the United States must join Europe in pledging meaningful action at a make-or-break summit in the Danish capital Copenhagen next month.
"No doubt about it, in December, the world will look to us, to the Europeans and to the Americans. And it is true, there can be no agreement without China and India.
"But I'm convinced, once we in Europe and America show ourselves ready to adopt binding agreements, we will also be able to persuade China and India to join in."
The December 7-18 summit is aimed at forging a treaty to tackle carbon emissions and their impacts, and encourage a switch to cleaner energy after 2012, when the current Kyoto Protocol pledges on curbing greenhouse gases expire.
In a sign of the difficulties facing Obama, Republicans on a key US Senate committee were absent Tuesday as debate opened on a Democratic proposal for sweeping climate change legislation.
Obama's Democratic allies have split on the issue, with some worried about the possible impact on industries in their home states, while his Republican foes have mostly united against the White House-backed approach.
The US House bill calls for cutting US greenhouse gas emissions by 17 percent from 2005 levels by 2020 and by 83 percent by 2050. The Senate's slightly more ambitious bill calls for a 20-percent cut by 2020.
As Germany prepared to mark 20 years since the fall of the Berlin Wall, Merkel poignantly thanked Americans for all the help and support they had given to defeat communism and bring down the Iron Curtain.
"I know, we Germans know, how much we owe to you our American friends. And we shall never, I personally shall never, ever forget this," said Merkel, who herself grew up in communist East Germany.
Merkel said Europe and America were united by common bonds of history and shared values.
"It was this basis of values that ended the Cold War and it is this basis of values that enables us now to stand the test of our times."
She paid tribute to the six million Jews and other victims who perished during the Holocaust, expressing regret for the "hatred, destruction and annihilation Germany brought over Europe and rest of the world," during World War II.
Merkel, who was reelected just in September, vowed her country's continuing support on a host of US initiatives, from the battle to defeat the Taliban and Al-Qaeda in Afghanistan, to efforts to rein in Iran's nuclear ambitions.
"Iran also knows where we draw a line," Merkel declared. "A nuclear bomb in the hands of an Iranian president who denies the Holocaust, threatens Israel and denies Israel the right to exist is not acceptable."
Merkel is only the second German chancellor to address the US legislature, after West German leader Konrad Adenauer spoke to separate sessions of each chamber in 1957.
After the White House talks, Obama said: "The alliance between the United States and Germany has been an extraordinary pillar of the transatlantic relationship," and he praised Merkel as "an extraordinary leader on the issue of climate change."