"While I think the UK's role in dealing with a warming planet may have been made harder..., our commitment to dealing with it has not gone away," she told finance and business leaders at the 2016 Climate and Business Summit in London.
Yesterday, the UN's outgoing climate chief Christiana Figueres, told delegates "there is going to be quite a bit of uncertainty, transition and volatility for at least two years," following the Brexit vote.
The position of any candidate on this issue "will be absolutely central to who I support," she said, prompting a burst of applause from summit participants.
Johnson has, in the past, questioned whether human actions really are contributing to global warming.
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Rudd sought to allay worries that the Brexit vote would soften Britain's leadership role in the international campaign against dangerous climate change, or dampen clean energy investment by, or in, the UK.
Rudd's department of energy and climate change is due to unveil new goals Thursday for slashing greenhouse gas emissions.
A cross-party bloc of lawmakers have urged the government to accept an ambitious and binding target to cut emissions by 57 percent by 2032 from 1990 levels.
This would stand as one of the most ambitious carbon-cutting goals of any major economy in the world.
The current European Union goal, approved well before the Brexit vote, is to cut emissions by 40 percent by 2030 from 1990 levels.
"At least half of our innovation spending will go towards nuclear research and development," she told the meeting.