Steel is the dominant metallic material. The production per year is 1.8 billion tons, of which 30% can be produced out of recycled melted scrap. The huge rest amount has to be newly produced from oxide minerals reduced by CO in blast furnaces, followed by partial removal of C by O2 in converters. The CO2 emission of these two processes is enormous, approx. 2.1 tons of CO2 per 1 ton of steel. Steel making thus becomes the largest single greenhouse gas emitter worldwide (~ 8% of all emissions). ROC is intensively involved in basic research needed to drastically cut down these CO2 emissions, by up tp 80% and beyond. This is the biggest single leverage we have to fight global warming.