Global copper supply faces a long-term structural constraint as declining discoveries, falling ore grades and rising development costs make new mines increasingly difficult to build, according to a report by Goldman Sachs Research. The report said existing producers and projects capable of adding future supply could attract greater value as the market adjusts to tighter availability. The median copper mine now takes more than 16 years from discovery to first production. Output from existing mines is expected to begin declining from 2030, while higher prices alone may not deliver significant additional supply within a typical investment horizon. Goldman Sachs said the adjustment would therefore have to come mainly through prices and the valuation of established producers and difficult-to-replicate growth assets. Major copper discoveries have declined since the 1990s, while ore grades have fallen, particularly in South America. New projects are also increasingly located in remote areas, raising construction, operating and capital costs. These factors are making mine development more expensive and extending the period between investment decisions and production. The report estimated that average capital intensity rises by around 50 per cent between the pre-feasibility stage and the start of production, increasing from USD 10,600 per t to USD 15,900 per t. Its estimated capital costs for the projects covered were 25 to 90 per cent above company studies, indicating a significant risk of further increases during development. Goldman Sachs assessed a group of copper growth projects that could collectively add around USD 20 bn in net asset value and approximately 1 mn t of additional annual production by late 2035. Its risk-adjusted valuation framework accounted for development stage, cost increases, delays and the conversion of resources into reserves, with earlier-stage projects receiving larger discounts. The report said the timing and scale of new output would depend on execution, investment decisions and the ability to manage rising development costs.