The graph above is based on data from these organisations :-
HadCRUT - Hadley Research Center of the UK Met Office
NOAA - National Oceanic and Atmospheric Administration
Berkeley Earth - California based non profit organisation providing land and oceanice temperature data
NASA GISTEMP - Surface temperature analysis run by NASA
Japan Met JRA - Japan Meteorological Agency
ECMWF - European Centre for Medium-Range Weather Forecasts supported by most of the European Nations
I think you can safely say that its been peer reviewed



