When ice I
in an emulsion is compressed below 250 K, it melts to supercooled liquid water, avoiding the formation of other crystal phases. Here, we create emulsified high-pressure ices under high pressure and low temperature, and measure their temperature while these ices are decompressed at a constant rate at different temperatures. We detect metastable melting points of high-pressure ices, and identify their melting lines. We find what could be possibly two new ice phases, and discuss the relationship between decompression-induced melting and decompression-induced amorphization. Finally, we discuss briefly the analysis of experimental data and simulation results that are consistent with the hypothesized “second critical point” with temperature and pressure coordinates of approximately 200 K and 100 Mpa.