The CEO of the London Stock Exchange says Joe Biden could have a "huge" impact on global climate politics. 

David Schwimmer was speaking at the Green Horizon Summit – an online event that aims to encourage international finance to do more to tackle climate change.

When asked if, as U.S. president, Biden would change Washington's role in the climate change debate, Schwimmer said the "short answer is 'yes' – big change."

Under the Trump administration, the U.S. formally left the Paris climate agreement on November 4. Biden has said he would rejoin on the first day of his administration.

The Green Horizon Summit is a virtual event hosted by the former governor of the Bank of England, Mark Carney. Its guest list includes billionaire businessman Michael Bloomberg, the UK's Prince Charles and European Central Bank President Christine Lagarde.

Lagarde said she believes there needs to be more transparency from big companies on their environmental impact. Referring to the European Union, she said: "Believe it or not, climate change reporting remains optional – in part because the financial impact is still not understood."

Top of the agenda at the Green Horizon Summit was how to ensure a green economic recovery post-pandemic.

Mark Carney said: "What COVID has done, what this tragedy has exposed, is the problems with undervaluing reserves, ignoring systemic risk and not investing upfront. And so it is with climate change – the crisis that involves the entire world – and from which no one will be able to self-isolate."