There is the 2007 G8 National Academies statement signed by:
Academia Brasileira de Ciéncias (Brazil), Académie des Sciences (France), Accademia Nazionale dei Lincei (Italy), Russian Academy of Sciences (Russia), National Academy of Sciences (United States of America), Royal Society of Canada (Canada), Deutsche Akademie der Naturforscher Leopoldina (Germany), Science Council of Japan (Japan), Academy of Science of South Africa (South Africa), Chinese Academy of Sciences (China), Indian National Science Academy (India), Academia Mexicana de Ciencias, (Mexico), Royal Society (United Kingdom)
Please see:
It is important that the 2007 G8 Summit is addressing the linked issues of energy security and climate change. These are defining issues of our time, and bring together the themes of growth and responsibility in a way that highlights our duties to future generations....The problem is not yet insoluble, but becomes more difficult with each passing day. A goal of confining global warming to an average of 2 centigrade degrees above pre-industrial levels would be very challenging, and even this amount of warming would be likely to have some severe impacts.... We call on all countries of the world to cooperate in identifying common strategic objectives for sustainable, efficient and climate friendly energy systems, and in implementing actions toward them.

(2007) Joint science academies’ statement on growth and responsibility: sustainability, energy efficiency and climate protection
You have two joint statements by the national academies of sciences, one for eleven countries:
Academia Brasileira de Ciéncias (Brazil),Académie des Sciences (France), Accademia Nazionale dei Lincei (Italy), Russian Academy of Sciences (Russia), National Academy of Sciences (United States of America), Royal Society of Canada (Canada), Deutsche Akademie der Naturforscher Leopoldina (Germany), Science Council of Japan (Japan), Academy of Science of South Africa (South Africa), Chinese Academy of Sciences (China), Indian National Science Academy (India), Academia Mexicana de Ciencias (Mexico), Royal Society (UK)
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We urge all nations, in the line with the UNFCCC principles, to take prompt action to reduce the causes of climate change, adapt to its impacts and ensure that the issue is included in all relevant national and international strategies.

(2005) Joint science academies' statement: Global response to climate change
... and one for the national academies of sciences of sixteen countries:
Australian Academy of Sciences, Royal Flemish Academy of Belgium for Sciences and the Arts, Brazilian Academy of Sciences, Royal Society of Canada, Caribbean Academy of Sciences, Chinese Academy of Sciences, French Academy of Sciences, German Academy of Natural Scientists Leopoldina, Indian National Science Academy, Indonesian Academy of Sciences, Royal Irish Academy, Accademia Nazionale dei Lincei (Italy), Academy of Sciences Malaysia, Academy Council of the Royal Society of New Zealand, Royal Swedish Academy of Sciences, Royal Society (UK)
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We urge everyone - individuals, businesses and governments - to take prompt action to reduce emissions of greenhouse gases. One hundred and eighty-one governments are Parties to the 1992 UN Framework Convention on Climate Change, demonstrating a global commitment to "stabilising atmospheric concentrations of greenhouse gases at safe levels". Eighty-four countries have signed the subsequent 1997 Kyoto Protocol, committing developed countries to reducing their annual aggregate emissions by 5.2% from 1990 levels by 2008-2012.

(2001) The Science of Climate Change
There have also been separate statements issued by the following organizations:
Union of Concerned Scientists, Woods Hole Research Center, Intergovernmental Panel on Climate Change, United Nations Framework Convention on Climate Change, American Association for the Advancement of Science, American Meteorological Society, National Research Council, Canadian Meteorological and Oceanographic Society (CMOS), Federal Climate Change Science Program, National Oceanic and Atmospheric Administration (NOAA), UN Project on Climate Variability and Predictability, American Geophysical Union, Geological Society of America, American Chemical Society - (world's largest scientific organization with over 155,000 members), Federal Climate Change Science Program, 2006 - commissioned by the Bush administration in 2002, Stratigraphy Commission - Geological Society of London - The world's oldest and the United Kingdom's largest geoscience organization, Engineers Australia (The Institution of Engineers Australia), American Association of State Climatologists, US Geological Survey (USGS), National Center for Atmospheric Research (NCAR), NASA's Goddard Institute of Space Studies (GISS), Woods Hole Oceanographic Institute – Ocean and Climate Change Institute, World Meteorological Organization, United Nations Environment Program, Canadian Foundation for Climate and Atmospherice Sciences, International Council on Science, State of the Canadian Cryosphere (SOCC), Environmental Protection Agency (EPA), American Astronomical Society, The Australian Meteorological And Oceanographic Society, American Institute of Physics, Pew Center on Climate Change, World Wildlife Fund
There are also petitions signed by individual scientists, including one that has been signed by over 14,000.

Please see:
... in support of the president's decision to avoid regulating emissions that cause climate change, the administration has consistently misrepresented the findings of the National Academy of Sciences, government scientists, and the expert community at large. Thus in June 2003, the White House demanded extensive changes in the treatment of climate change in a major report by the Environmental Protection Agency (EPA). To avoid issuing a scientifically indefensible report, EPA officials eviscerated the discussion of climate change and its consequences.

2004 Scientist Statement on Restoring Scientific Integrity to Federal Policy Making
For collecting the above I am largely indebted to an M.J. Sparrow of the former Logical Science.

I would also argue that there is a foundation in science for this scientific consensus, one that consists of well-established elements. I have identified twenty-four of these elements.