Achim Steiner, head of the UN Environmental Programme (UNEP) said the world couldn’t afford to wait until the year 2050 to tackle the pressing problem of climate change.

“The Arctic is melting away as we speak,” Steiner told German radio channel, MDR Info, adding there were increasing signs that climate change was progressing much more rapidly than previously thought.

German environmental group, NABU, also urged setting more ambitious goals to slash greenhouse gas emissions. “The biggest polluters of the world wallowed in nuclear energy fever rather than agreeing on measures needed to fight climate change,” NABU President Olaf Tschimpke said.

Politicians from Germany’s environmentalist Green Party and the pro-business Free Democrats (FDP) spoke of “pathetic results” at the summit and said the 2050 target is worthless without a tighter timetable to tackle the problem.

Leaders of the world’s eight richest countries who ended a three-day annual summit in Japan on Wednesday agreed on a “shared vision” to halve global CO2 emissions by 2050, an advance on the wording of last year’s G8 summit document, which promised only to “seriously consider” the move. However, G8 leaders are widely believed to have sidestepped several crucial but contentious issues, including the base year for pledges to slash greenhouse gases and specific midterm targets for cuts.

G8 leaders‘ stance on other issues, including spiraling oil and global food prices and aid to Africa, came in for much criticism too. The G8 summit in Japan set a five-year deadline for the major industrial powers to provide $60 billion in aid promised a year ago in Germany to fight disease in Africa. The nations renewed a commitment made three years ago to double aid for Africa to 25 billion dollars by 2010.

G8 leaders also called on nations with sufficient food stocks to release some of their reserves to help others cope with soaring prices and said it was “imperative” to remove export restrictions.

But the promises to fight the food crisis and promote Africa’s development were “much too vague, cowardly and too short-term,” said Ulrich Post from aid group Welthungerhilfe. He added that industrialized countries needed to cut subsidies to their own farmers and end biofuel imports from developing countries. Green politicians Jürgen Trittin and Bärbel Höhn also urged the EU and the US to overhaul their agricultural policies in order to battle global hunger.

Michael Sommer, head of the German Trade Union Association (DGB) described the results of the G8’s Japan summit as a “declaration of bankruptcy” towards the social problems of globalization.