US, China climate pledges fall short-German adviser

* German climate adviser says U.S., China pledges lacking

* Fears of 'green-washing' at Copenhagen climate summit

By Erik Kirschbaum

BERLIN, Nov 27 (Reuters) - A U.S. pledge to cut its greenhouse gas emissions by 17 percent below 2005 levels by 2020 is "ridiculously" inadequate considering the perils of climate change, a German government climate adviser said on Friday.

Hans Joachim Schellnhuber, head of the Potsdam Institute for Climate Impact Research, said as encouraging as it might seem that the United States and China made vows this week to curb carbon dioxide emissions, both offers are far from adequate.

"The worst possible result at Copenhagen would be a global 'green-washing', getting something that looks good on paper but in reality only represents stagnation," he told a group of foreign journalists in Berlin on Friday.

"There's too much at stake," added Schellnhuber, who is also an adviser to the European Union and will be part of Germany's delegation at the U.N. climate summit in Copenhagen next month.

Schellnhuber, who said he believes Germany could do more than its pledge to cut emissions by 40 percent by 2020, said he was most worried about falling support in the United States for robust steps to slow climate change.