over 50 organizations including the Royal Society, American Chemical Society, American Institute of Physics, American Physical Society, Australian Institute of Physics, European Physical Society, etc, etc, etc.
It's worth pointing out that there is significant dissent within the American Physical Society, with several prominent scientists leaving the organization over its unreserved endorsement of CAGW (catastrophic anthropogenic global warming, as opposed to the meaningless catch-all "climate change").
The real issue, which is obscured by all the noise around full-fledged denial (which isn't rational) is whether or not AGW represents a substantial threat to our future, among the wide array of issues facing humans. There is a good deal of evidence showing that the AGW models are overestimating warming. The world will wean itself off fossil fuels as solar, nuclear and other technologies fall in price, regardless of AGW concerns. The real question is whether we need to spend massive quantities of money and cripple first-world economies in the short term, or not.
The win-win scenario is vastly increased investment into nuclear electric generation. Nuclear is already the safest form of baseline power generation, and is 100% carbon free. Next-gen technologies offer the possibility of less than 5 per KWH electricity, and no possibility of meltdowns. The world needs plentiful, non-stop power going forward. The ONLY carbon-free way of achieving that is nuclear power, and this can be done with no sacrifice, and no penalty to the poor via increased energy prices.