 A 2010 study published in "Nature" reported that marine phytoplankton had declined substantially in the world's oceans over the past century.Phytoplankton concentrations in surface waters were estimated to have decreased by about 40% since 1950, at a rate of around 1% per year, possibly in response to ocean warming.The study generated debate among scientists and led to several communications and criticisms, also published in "Nature".