By Anisha Sircar and Divya Chowdhury

(Reuters) - Commodity markets face greater fragmentation and supply disruptions if former U.S. president Donald Trump wins the Nov. 5 election to return for a second term, an HSBC economist said on Friday.

A weak start by U.S. President Joe Biden in the first the U.S. presidential debate on Thursday has led to heightened speculation over the potential return of a Trump presidency, including the implications of his trade policies and proposed tariffs on China.

Commodity markets, already contending with high prices driven by structural supply constraints, also face uncertainties from geopolitical tensions, said Paul Bloxham, HSBC's chief economist for Australia, New Zealand and global commodities.

"A rise in global trade protectionism or a shift in the pathway of that trend is a global macroeconomic risk we are watching out for," Bloxham told the Reuters Global Markets Forum (GMF).

"This would increase the risk of greater fragmentation of commodity markets and create a supply disruption supporting commodity prices."

Geopolitics, climate change, and the energy transition are combining to drive a global commodity market "super-squeeze", said Bloxham, who previously worked with the Reserve Bank of Australia's economic analysis department.

HSBC's statistical model in May indicated a shift to a 'super bull' from a 'weak bull' phase in commodities, despite already elevated prices. According to HSBC, commodity prices are unlikely to return to their previous trend, and are set to stay "permanently higher".

Bloxham expects large producers, particularly those involved in the energy transition materials such as copper, will benefit. He also said that Latin American economies, the U.S., Australia, and Indonesia were also potential winners.

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(Reporting by Anisha Sircar in Bengaluru and Divya Chowdhury in Mumbai; Editing by Edwina Gibbs)