Dr.Suess is definitely correct to point to elements of opportunism in the LCR and Resistance responses to green issues. I went to the 2004 Marx Conference in Paris and attended a sessiion on eco-socialism addressed among others by leading LCR members Michael Loewy (the other signatory of the Eco-socialist Manifesto with Kovel) and Pierre Rousset. Rousset said something along the lines of "Today ecological issues are the big thing, just as in the 70's it was guerilla warfare in Latin America." None of this will be a surprise to those who have followed the history of the USFI current and its eternal search for the 'new mass vanguard'.
Perhaps instead we need to think more about why green politics seem to be more popular among young people than socialist politics.
Like Lawrie I have read 'The Enemy of Nature' and find much that is good in it - particularly the stuff on capitalism and ecology and the critique of the main mainstream green approaches. I agree with him that we need to face the challenge that eco-socialism poses to 'traditional' Marxism but I am not yet sure that eco-socialism provides the answers - certainly not Kovel's version which is ultimately mystical.