Indeed, Merkel goes into the talks with G8 leaders saddled with a law passed by Germany's former Social Democrat-led (SPD) government aimed out phasing out nuclear power by 2021, which she is opposed to.
This now forms part of the coalition agreement her conservative Christian Democrat-led political bloc forged with the SPD about three years ago to form the government she now heads.
But with Italy's elections in April paving the way for a more pro-nuclear coalition headed by Silvio Berlusconi, Germany is now the only member of the G8 club resisting expanding nuclear power as part of efforts to address the threat posed by global warming.
Ready for a nuclear rethink?
However, sensing a shift in the public mood in Germany about extending the life of the nation's remaining 17 nuclear reactors, Merkel and her supporters have attempted to fire up a fresh campaign for a German rethink on phasing out atomic power in the country.
Amid spiraling oil and gas prices, an opinion poll commissioned by German public broadcaster ARD and released this month found that 51 percent wanted the nation to continue along the path to phasing out nuclear energy.
But 44 percent of those polled by the pollsters Infratest dimap wanted a reconsideration. This represented an increase of 8 percent since December 2007.
Moreover, with Merkel and her supporters opposed to winding back nuclear power, the question has sparked fresh tensions in her coalition with the SPD and raised the prospect of atomic energy emerging as a key issue at next year national German election.
Speaking ahead of her trip to Japan for the G8 summit, Merkel lashed out at the decision to end nuclear power in Germany, saying it was "absolutely wrong." She repeated her call for a mix of energy sources for Europe's biggest economy including fossil fuels and renewable power as well nuclear plans.
G8 climate goals
The last G8 summit in Germany agreed that industrial powers would "consider seriously" at least halving carbon emissions blamed for global warming by 2050. But critics say that the agreement is meaningless without binding targets for what to do in the mid-term to 2020.
European Commission chief Jose Manuel Barroso voiced hope that the summit in the mountain resort of Toyako would at least agree on the principle of each G8 nation setting its own mid-term target.
"Serious consideration is not enough; we need a decision," Barroso told reporters. "It is not likely that during this summit we will achieve a concrete numerical target for a mid-term agreement," he said.
But "if we come with a long-term commitment of a 50 percent reduction by 2050 and a principle agreement on mid-term reduction, we can speak of success," he said.
A pro-nuclear G8
On Sunday, Barroso joined the debate in Germany on the future of nuclear power, telling the Bild am Sonntag newspaper that atomic energy could help to ease the current energy crisis.
A G8 communiqué stressing the importance of nuclear power in the battle to combat climate change could initially cause Germany a measure of political discomfort. But it could also have the effect of bolstering the chancellor's case for jettisoning Germany's current anti-nuclear law.
The US, backed by six other G8 members, has pointed to the building of more nuclear power plants as a way to cut greenhouse gas emissions.
Briefing the press on the sidelines of the G8, US President George W. Bush's environment advisor, Jim Connaughton, stressed the "green" properties of nuclear energy.
France developed nuclear energy to reduce foreign energy dependence after the oil shock of the 1970s. It now receives nearly 80 percent of its electricity from nuclear power and is a net exporter of electricity. The country has been constructing its first European Pressurized Reactor, or EPR, on the Normandy coast. It is expected to go into service in 2012.
Nuclear power provides 30 percent of Japan's electricity. The country is working to increase this to 37 percent by 2009 and 41 percent by 2017.
Britain, Canada, Italy, Russia are all broadly in favor of atomic power.
An EU survey published last Thursday found that some 44 percent of Europeans are either "totally in favor" or "fairly in favor" of nuclear energy, according to the survey, carried out in February and March.
The last time the survey was carried out in 2005 the figure was 37 percent.
Chancellor Merkel's supporters have launched a campaign to reverse Germany's push to shut down its nuclear reactors, also declaring "atomic energy is an ecological energy."
Nuclear supporters have also begun to argue that Germany could fail to meet future commitments to cut the CO2 emissions that cause global warming unless it reverses the phasing out law and extends the life of nuclear reactors.
But Merkel's Environment Minister Sigmar Gabriel, an SPD member, has hit back, insisting that "the risks of this technology could not be played down."
Instead, the SPD has sought to underscore the importance of pushing ahead with developing alternative energy sources such as wind and solar power.
With this mind, Infrastructure Minister Wolfgang Tiefensee, also a SPD member, has announced a dramatic expansion of wind energy, including the building of wind parks in the sea.
"We are emphasizing renewal energy and not atomic energy," Tiefensee told Germany's weekly Welt am Sonntag, adding that the aim was to make the nation independent of foreign sources of energy.