\({T_1} = 127 + 273 = 400K,\,\,\,{E_2} = 16 \times {10^6}\)
\({E_1} = {10^6}J\,\,\,\,\,\frac{{16 \times {{10}^6}}}{{{{10}^6}}} = {\left( {\frac{{{T_2}}}{{400}}} \right)^4} \Rightarrow \,\,2 = \frac{{{T_2}}}{{400}}\)
\({T_2} = 800\,K\, \Rightarrow \,800 - 273 = {527^ \circ }C\)