In the climate policy debate, a rhetoric has evolved that attributes a high potential to "voluntary climate action". We turn to the population of Germany, the fourth largest cumulative GHG emitter, to obtain an Internet-)representative estimate of the individual willingness to abate one ton of CO2, the equivalent of 10 percent of annual per-capita CO2 emissions. The estimate derives from a large-scale (n=2,440) framed field experiment in which subjects choose between a guaranteed reduction of one ton of EU CO2 emissions and a randomly drawn cash award between €2 and €100. At €6.30, estimated mean WTP is considerably lower than prior hypothetical or non-representative estimates. Median WTP is non-positive. The almost bimodal nature of WTP in the population has important policy implications.