A comprehensive set of experiments performed at 0.1 MPa pressure between 204 and 289 K (Stern et al. {\it J. Phys. Chem. B} {\bf 2001}, {\it 105}, 1756; Circone et al., In {\it Gas Hydrates: Challenges for the Future}; Holder, G.D., Bishnoi, P.R., Eds., New York Academy of Sciences, New York; 2000; pp. 544-555) showed that methane hydrate dissociation rates were significantly depressed between 242 and 271 K. Above 271 K, the rate increased with increasing temperature. The dissociation rates at 1.0 and 2.0 MPa and at temperatures spanning the H${2}$O melting point have now been measured to determine if elevated pressures further depress these dissociation rates. Results will be used to optimize sI hydrate preservation during drill core retrieval in permafrost regions. Expected core retrieval conditions are at temperatures of 273 $\pm$ 5 K and at pressures that decrease from near 2.6 MPa (equilibrium pressure at 273 K) to 0.1 MPa. Pure, synthetic, porous methane hydrate samples were equilibrated at a temperature between 250 and 278 K and a methane pressure nominally 2 MPa above the hydrate equilibrium curve at that temperature. To begin an experiment, the pressure was rapidly decreased to 1.0 or 2.0 MPa (to P, T conditions outside of the methane hydrate stability field), then opened to a back pressure regulator, which can maintain a constant pressure to within 0.02 MPa of the set point. As the hydrate sample dissociated, the back pressure regulator released the methane to our custom-built flow meter, which measured the amount of released gas over time. Preliminary results at 2.0 MPa indicate that dissociation rates are wholly consistent with and slightly depressed below those at 0.1 MPa. At 0.1 MPa, the slowest dissociation rate occurs at 268 K, and at 2.0 MPa the average rate was slower (only 30% vs. 34% of the total methane released after 160 h at 2.0 vs. 0.1 MPa). Decreasing the pressure from 2.0 MPa to 1.0 MPa slightly increased the dissociation rate; returning to 2.0 MPa decreased the rate to near the prior value. At 0.1 MPa, similar reversible rate changes were obtained by varying the temperature from 268 to as low as 251 K. At 273 and 278 K, the dissociation rate at 2.0 MPa increases dramatically with increasing temperature. In the sample interior, the reaction temperature is buffered at 272.7-272.8 K, which is distinct from the H${2}$O ice point (273.0 K at 2.0 MPa). Experiments at 1.0 MPa are currently underway; initial results at 250 and 253 K indicate that dissociation rates are also depressed below those at 0.1 MPa.