PARIS (AFP) - Global firms responsible for tens of trillions of dollars in investments on Tuesday (April 19) urged the world's leading economies to sign the landmark Paris accord to limit global warming adopted at a UN summit in December.

Seven organisations that represent over 400 investment funds sent a letter to the leaders of G20 nations calling on them "to sign the Paris Agreement on April 22nd at the United Nations in New York."

"We believe that the Paris Agreement is an historic breakthrough that delivered an unequivocal signal for investors to shift assets towards the low-carbon economy," it says.

Most large banks and financial services companies are represented in the letter, including American giants like Blackrock, Goldman Sachs and Morgan Stanley as well as Britain's Aviva, HSBC and RBS. The firms manage over US$24 trillion (S$32.27 trillion) in assets.

While 195 nations sealed the world's first global climate deal in December, the agreement must still be signed and ratified before it can take effect.

The historic accord calls for global warming to be stopped in its tracks at "well under 2 degrees Celsius" above pre-industrial levels.

However, national commitments to slash greenhouse gases far fall short of that hugely ambitious goal, and how to close the remaining emissions gap has yet to be worked out.

Among the 193 member states of the United Nations, 147 have already committed to signing the Paris Agreement, according to French Environment Minister Segolene Royal.

"The early entry into force of the Agreement will send an important signal to investors that governments are translating into concrete action the momentous political will represented by the adoption of the Paris Agreement," the investors' letter says.