In its Global Economic Outlook (GEO) for 2017, it said there is little doubt that increased trade protectionism and weaker migration flows will dampen growth in the advanced economies in the long term even though short-term budgetary measures are likely provide a boost for next year.
"The surge in populism and anti-establishment sentiment witnessed in the Brexit vote and Donald Trump's victory in the US presidential election seem likely to push structural policies in the direction of economic nationalism, entailing a reduction in trade openness and international labour migration," said the global credit ratings firm.
Britain's vote to leave the European Union and Trump's election are acts of populism, Fitch said, while revising upwards its global growth forecasts for next year by 0.1 percentage point both in 2016 and 2017 mostly on expectations of a fiscal boost in the US.
Global growth is now expected to pick up to 2.9 per cent in 2017 from 2.5 per cent this year as US investment recovers, fiscal policy is eased and recessions come to an end in Brazil and Russia.
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"Global growth is expected to pick up in 2017 as US investment recovers, fiscal policy is eased, and recessions come to an end in Brazil and Russia.
"China's stabilisation policies have been successful, and while policy is now turning a bit less accommodative, the slowdown in 2017 will be gradual," Fitch said.
Eurozone growth is expected to moderate somewhat as household real income growth slows, while Brexit-related uncertainty will drag down UK growth significantly. Japan's economy is unlikely to accelerate despite ongoing aggressive monetary easing.
Fitch's US growth forecasts have been revised upwards
modestly, by 0.2 percentage in 2017 and 0.1 percentage in 2018, to 2.2 per cent and 2.3 per cent, respectively.
"An important implication of the shift towards fiscal easing is that central banks are no longer alone in providing macro policy stimulus. While we have not changed our central view that the Fed will hike rates in December and follow up with two further hikes in 2017, this increases confidence that the normalisation of US monetary policy will progress at a faster pace than over the last year," Coulton said.
However, changes to the macro policy outlook are most pronounced in the US and with the ECB likely to announce an extension of asset purchases for six to nine months beyond March 2017, this has partly been reflected in renewed dollar strengthening.
"In emerging markets, the macro picture has brightened during 2016 as recessions in Russia and Brazil have started to bottom out and commodity prices have recovered.
It revised its China forecast for 2016 to 6.7 per cent from 6.5 per cent in September's GEO and 2017 up to 6.4 per cent from 6.3 per cent.
"Policy is now turning less accommodative in China, with a number of measures designed to cool the housing market, but the impact on GDP growth through 2017 is likely to be gradual," it said.
For emerging markets, the increase for China is more than offset by a weaker outlook for Mexico and India. Emerging market growth in 2017 has been revised down by 0.1 percentage points to 4.8 per cent.
"Second, in the event of the US imposing punitive trade restrictions on China, retaliatory actions could see a trade or currency war develop. This would be highly damaging for global market sentiment and would reduce world growth," Fitch added.