China“s commodity imports slumped in January after a surprising surge in December, as sea ice disrupted shipping and the country began to tighten monetary policy, spooking markets that had relied on its largesse in 2009.

For many copper traders, a fall of 20.9% in imports to 292,096 tons was a shock, as China had been expected to suck in more cargoes thanks to high local prices that allowed arbitrage trading. Uncertainty about China”s appetite for most raw materials may continue to worry traders as they try to figure out if January”s slowdown was simply a retreat to pre-December levels or a major turning point after record demand across the board in 2009.