lets dissect this.
Ok this is good stuff. But I think, in english, he is saying: "the fact that warming hasn't happened as expected is, regretfully, true. but I don't like it. we don't know for sure why we were wrong, but today we're pinning it on particulate matter (which we somehow forgot to put into our models), or just simply that our models were bogus. er..sorry, our "climate sensitivity estimate" was...hmm, what's the word, bad."
Ok this one is a doozy. Let's try a translation, shall we? : "darn, I was so busy worrying about carbon, I forgot to put aerosols into my models. we should all have an academic discussion about why I was wrong. but keep it academic. simply stating "I was wrong" doesn't sound too good for the funding. aerosols threw a wrench into our plans for global armageddon, and we're never forgiving China for that."