The supply of mined copper will steadily grow over the next five years even under a relatively conservative mine development scenario, according to a recently published research report by S&P Global Market Intelligence.

"There's going to be plenty of additional copper coming into the pipeline," said Kevin Murphy, the lead author of the study and a senior metals and mining research analyst with S&P Global Market Intelligence.

If only projects with a high probability of being finished come online in the next five years, they will add 1.3 million tonnes to supply. Taking into account forecast declines and closures, annual copper production would grow 600,000 tonnes to 20.7 million tonnes in 2021 from 20.1 million tonnes in 2016.

The high probability scenario depends largely on a couple projects under development. "The most significant are First Quantum Minerals Ltd.'s Cobre Panama project and BHP Billiton Group's expansion projects at the 57.5%-owned Escondida mine," Murphy said in the study.

Diverging the base case would require a major surprise in construction plans. "With the high probability [scenario] we took great pains to make sure these were financially stable companies developing the assets," Murphy told S&P Global.

The expected growth builds on sustained copper production increases over the past decade, as output grew 3% a year from 15.5 million tonnes in 2007 to 20.1 million tonnes in 2016, Murphy noted in the study.

Still, looking beyond the period analyzed in the study, Murphy said some analysts see production growth waning.

Mark Ferguson, associate director of metals and mining research with S&P Global, wonders if the dearth of recent discoveries in the past decade or so may come to bear on future supply beyond five years from now.

"That is going to be a huge question mark," Ferguson said.