President Barack Obama said Friday that the U.S. will commit $3 billion to an international fund to help poor countries fight the effects of climate change.

The announcement came just one day before the G20 Leaders Summit in Australia, and surprised many involved with climate policy, as it doubles what other countries had previously pledged in the days before the Nov. 20 deadline, reported Reuters.

"Along with other nations that have pledged support, this gives us the opportunity to help vulnerable communities with an early warning system, with stronger defenses against storm surge, climate resilient infrastructure, to help farmers plant more durable crops," Obama said at an event in Australia leading up to G20.

The fund will "allow us to help developing countries to break out of the false choice between development and pollution and will leap-frog some of the dirty industries that powered our development, go straight to a clean energy economy that allows them to grow, create jobs, and at the same time reduce their carbon pollution," said Obama.

Some believed the timing of the announcement put pressure on the G20 host, Australian Prime Minister Tony Abbot, who once called climate science "absolute crap" and had hoped the summit would focus instead on economic growth and jobs, according to Reuters.

Obama also called into light Australia's own climate change issues, and said longer droughts and more wildfires are likely.

"The incredible natural glory of the Great Barrier Reef is threatened," said Obama. "Worldwide this past summer was the hottest on record. No nation is immune and every nation has a responsibility to do its part."

The money will be contributed to the Green Climate Fund, which will see contributions from some 20 countries total. Japan pledged $1.5 billion in unison with the U.S., and other participating countries include France, Germany, Sweden and the Netherlands.

The fund's key distinguishing characteristic is that it has the opportunity to "mobilize significant flows of private capital," Abyd Karmali, managing director of climate finance at Bank of America Merrill Lynch, told Reuters.

Private sector investment will allow the fund to boost global markets in clean energy technologies and will create way for entrepreneurs and manufacturers, including those from the U.S., reported Reuters.