The warning comes as the Intergovernmental Panel on Climate Change (IPCC) prepares to publish its special report on 8 October where it is expected to say that the Paris aim to limit the increase to 1.5°C is only possible with more urgent and deeper emissions cuts.
In its analysis of the rate of carbon transition in the G20 economies, PwC found that emissions are rising again as the the move to a low-carbon economy "lags behind global economic growth".
The report said that none of the countries in the study are achieving the decarbonisation rate needed to limit warming to 2°C.
"There seems to be almost zero chance of limiting warming to well below two degrees — the main goal of the Paris Agreement," said PwC director of climate change Jonathan Grant.
Risks to business, he said, include "fragmented, knee-jerk regulation" as well as the physical effects of climate change.
Governments, he added, should get on with implementing solutions.
"Recent reforms to the EU Emissions Trading System that raised the price of carbon this year are a good example of what’s needed."
The analysis found that as global gross domestic product (GDP) grew at 2.8% last year, and energy demand increase 2.1%, emissions rose 1.1% a 3 year plateau.
While carbon intensity continued to fall at a rate of 2.6%, it was short of the 3% average necessary to meet the national targets pledges in Paris.
PwC said the gap between current decarbonisation rate and that needed to limit warming to 2°C was widening.
Although the chance of meeting the Paris goal was minimal, the report said widespread use of carbon capture and storage could still make it possible.
The report found that coal consumption returned to growth at 1%, the biggest factor in emissions changes in recent years.
Meanwhile, renewables sources grew at 17%, with solar seeing the biggest growth at 35%.
Among the G20 countries, China leads with a decarbonisation rate of 5.2%, with Mexico, Argentina, the UK and Brazil behind it.
But "not one of the G20 countries achieved the 6.4% rate required to limit warming to 2°C this year".