Aid group Oxfam has called on other rich nations to follow the example of Germany, which has promised €750 million ($1 billion) for the U.N.’s fledgling Green Climate Fund.

“This announcement ends the deafening silence we’ve had so far around the empty Green Climate Fund that is supposed to support poor countries in the battle against climate change. Now others must follow suit,” Oxfam Germany’s Jan Kowalzig said.

“If rich countries such as the U.S., France, the UK, Japan and others manage to collect at least $15 billion in pledges ahead of the upcoming U.N. climate negotiations in Lima at the end of the year, this could give the talks a significant boost,” he added in a statement.

The announcement by Chancellor Angela Merkel on Monday at the Petersberg Climate Dialogue in Berlin, where some 35 ministers from around the world are meeting to discuss international climate action, is the only large pledge of money for the Green Climate Fund so far.

The fund was agreed at U.N. climate talks in 2010 but has been hampered by wrangling over its design. Now its operating rules have been settled, it will hold a first pledging conference for potential donors in the second half of November, before the U.N. climate conference in Peru.

Norwegian Foreign Minister Boerge Brende told Reuters earlier this month that Oslo will unveil its preliminary pledge for the fund - a “substantial contribution” - at a summit on climate change organised by U.N. Secretary-General Ban Ki-moon in New York on Sept. 23.

The fund aims to help poor nations pursue clean development and adapt to climate change impacts, including more floods, droughts, heatwaves and rising sea levels. It is regarded as a key part of the puzzle in securing a new global deal to tackle climate change due to be agreed in Paris in late 2015.

CLIMATE GAME CHANGER?

The fund so far has $55 million, mainly for its own administration and to help countries plan to receive the climate finance it will distribute, including $10 million from Seoul.

After a recent meeting in Oslo of senior officials from 24 developed and developing countries interested in contributing to the fund, Brende said the process of securing the fund’s first capitalisation had “got off to a good start”.

“Important progress was made in paving the way for pledges this year. I believe we are on the right track towards making the Fund a game changer in the response to climate change,” he said in a statement.

Developing nations say they want $15 billion in pledges from the rich this year to fund projects like solar power, geothermal energy or ensuring water supplies. The U.N.’s top climate official, Christiana Figueres, has called for “at least an initial $10 billion” for the Green Climate Fund.

The fund is expected to channel a large portion of the $100 billion a year wealthy countries have promised to mobilise by 2020 to help vulnerable states adapt to climate change and pursue low-carbon growth.

Oxfam’s Kowalzig said rich countries must ensure that money pledged to the Green Climate Fund contributes to rising overall levels of climate finance. At last November’s U.N. climate talks in Warsaw, governments adopted a decision urging developed countries continuously to boost climate finance through to 2020, he noted.

“So far rich countries have failed to confirm that such increases are actually happening or (are) planned for the future,” he said.

Wealthy governments have provided climate aid worth roughly $10 billion a year since 2010, but there are fears that amount may be on the decline at a time of budget austerity.