Global firms responsible for tens of trillions of dollars in investments on Tuesday 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 $24 trillion (21 trillion euros) 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 two degrees Celsius" (3.6 degrees Fahrenheit) 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.

Last month was hottest March in modern times: US
Miami (AFP) April 19, 2016 - Last month marked the hottest March in modern history and the 11th consecutive month in which a monthly global temperature record was broken, US officials said Tuesday.

Officials at the National Oceanic and Atmospheric Administration (NOAA) said that the string of record-setting months is the longest in its 137 years of record-keeping.

The globally-averaged temperature over land and ocean surfaces for March 2016 "was the highest for the month of March in the NOAA global temperature dataset record, which dates back to 1880," the agency said.

Planet-wide, the average temperature was 2.20 degrees Fahrenheit (1.22 Celsius) above the 20th century average of 54.9 F (12.7 C), NOAA's report said.

"This surpassed the previous record set in 2015 by 0.58 F (0.32 C), and marks the highest monthly temperature departure among all 1,635 months on record."

These temperature spikes are a cause of concern in the scientific community because they indicate the pace of global warming is accelerating.

Last year was the hottest on record, edging out 2014, which held the title previously.

"Overall, the nine highest monthly temperature departures in the record have all occurred in the past nine months," NOAA said.

"March 2016 also marks the 11th consecutive month a monthly global temperature record has been broken, the longest such streak in NOAA's 137 years of record-keeping."

- Records in Australia -

The report showed that most of the Earth's land surfaces were hotter than average in March, "with record warmth notable across eastern Brazil, most of eastern and central Africa, much of southeastern Asia, and large portions of northern and eastern Australia."

Northwest Canada and northern and western Asia saw temperatures at least five degrees Fahrenheit (3 C) above the 1981-2010 average.

Australia endured its hottest March in the country's 107-year period of record, at 3 F (1.7 C) above the 1961-1990 average.

Sweden, Denmark and Norway were also unusually warm.

In contrast, France and Britain were slightly cooler than their 1981-2010 average for the month of March, at 1.4 F (0.8 C) and 0.4 F (0.2 C) respectively.

Far northeastern Canada, parts of northwestern Africa, and a region of south central South America were also chillier than average.

The Arctic region marked its second highest March temperature on record, with land readings overall at 6.01 F (3.34 C) higher than the 1981-2010 average.

In the world's waters, temperatures were also on the rise, registering the highest global ocean temperature for March since 1880, and beating out the previous record set last year.

"The seven highest monthly global ocean temperature departures have all occurred in the past seven months," said NOAA.