Thirty nations meeting in Berlin have pledged $9.3bn (£6bn) for a fund to help developing countries cut emissions and prepare for climate change.
The Green Climate Fund was to have held at least $10bn by the end of 2014, so the pledge is just shy of the target.
The South Korea-based fund aims to help nations invest in clean energy and green technology.
It is also designed to help them build up defences against rising seas and worsening storms, floods and droughts.
Rich nations previously vowed that by 2020, developing countries would get $100bn (£64bn) a year from such a fund.
The US had already pledged $3bn and Japan $1.5bn. The UK, Germany and France have promised about $1bn each, and Sweden more than $500m million.
Smaller amounts were offered by countries including Switzerland, South Korea, the Netherlands, Denmark, Norway, Mexico, Luxembourg and the Czech Republic.
After co-hosting the donors' conference, German Environment Minister Gerd Mueller hailed the achievement, saying humanity must fight climate change so "it doesn't go the way of the dinosaurs".
Hela Cheikhrouhou, the fund's executive director, described the pledges as "game-changing", and said the money would be spent equally on climate change adaptation and mitigation, especially for the most vulnerable nations.
These include small island nations and Africa's poorest countries.
The UK's contribution will come from the £3.87bn budget set aside in the aid budget from 2011-2016 for helping poor countries get clean energy and adapt to climate change.
In Bangladesh for example, British cash is helping landless people living in precarious temporary sandbanks that appear for a few years in the middle of rivers.
The cash pays them to build their homes on earth platforms so their possessions are safe from flooding which is expected to get worse with climate change.
UK Prime Minister David Cameron has been under pressure from critics who say the UK should spend the money helping combat the effects of extreme weather at home.
The fund was agreed because developed nations have caused the majority of global warming so far - and their CO2 emissions stay in the atmosphere for 100 years. Poor countries asked for help to adapt to climate change they have not caused.
But as greenhouse gas emissions are a global problem, rich nations acknowledge a degree of self-interest in helping developing countries to invest in clean technology.
Ms Cheikhrouhou said raising the billions had created "renewed trust and enthusiasm" ahead of international talks in Peru next month, and in France a year later, on slashing worldwide carbon emissions.
The UN Intergovernmental Panel on Climate Change (IPCC) warned this month that time is running out to limit warming to 2C (3.6F) by 2100 from pre-industrial levels.