Some of the world's biggest investors have pleaded with governments of the world's largest economies, including Australia, to stick with their commitments to tackle climate change and to introduce carbon pricing to help achieve them.

There is strong speculation that American President Donald Trump could renege on his country's commitments under the Paris Accord signed in 2015, which aimed to hold temperature rises well below 2 degrees Celsius.

Now a group of investor organisations, committed to encouraging action on climate change has written to member nations of the G7 and G20 calling on all participants to move to implement the Paris agreement. The G7 is due to meet in Italy later this month and includes America, Canada, France, Germany, Italy, Japan and Britain.

Current signatories to the letter manage $20 trillion and in their letter also call for measures to encourage investments that will reduce climate change including carbon pricing, phasing out fossil fuel subsidies and introduce standardised international reporting rules for companies to disclose their climate risks.