Methane is an important trace constituent of our lower atmosphere (the troposphere). It is a significant greenhouse gas absorbing infrared radiation from the Earth's surface potentially leading to global warming. The main mechanism for methane removal is reaction with the hydroxyl radical, CH4 + OH → CH3 + H2O The temperature of the troposphere declines with altitude. Calculate the relative change in the rate coefficient for the reaction at the Earth's surface (T = 295 K) and at the top of the troposphere (T = 220 K). The reaction has an activation energy of 19.5 kJ/mol.