The campaign to undermine public trust in climate science has been described as a "denial machine" organized by industrial, political and ideological interests, and supported by conservative media and skeptical bloggers to manufacture uncertainty about global warming.[12][13][14] In the public debate, phrases such as climate skepticism have frequently been used with the same meaning as climate denialism.[3] The labels are contested: those actively challenging climate science commonly describe themselves as "skeptics", but many do not comply with common standards of scientific skepticism and, regardless of evidence, persistently deny the validity of human caused global warming.[4]