The article first highlights the poor results obtained by the 2009 Copenhagen Conference with reference to Environmentally Sound Technologies (ESTs), particularly climate technologies. It stresses that in the Copenhagen Accord there is no specific reference to intellectual property rights (IPRs) as a necessary tool to stimulate the transfer of climate technologies, especially to developing countries. The author argues that in certain cases IPRs are capable of obstructing the dissemination across countries of ESTs. This seems to be confirmed (i) by how IPRs legislations are devised in industrialized countries (e.g. the Bayh-Dole Act in the US) and (ii) by a sharp increasing of international patent litigation in this field. Some possible solutions to the above problem and recommendations are finally provided.