The ability of a solvent to dissolve a solute to form a solution is dictated by Le Chatelier's Principle. Le Chatelier's Principle applies to all chemical equilibria, not just the dissolving of gases in solvents. The principle states that changing the conditions of an equilibrium alter the position of this equilibrium to return it to its original state. The conditions that affect equilibrium are concentrations of reactants and products, temperature and pressure.
Dissolving gases in liquids is an exothermic reaction, meaning heat is lost. Therefore, putting heat back into the system re-balances the equilibrium toward its original state. This means that raising the temperature of the solution lowers the solubility of the liquid. Increasing the temperature of an aqueous solution of carbon dioxide causes more carbon dioxide to escape into its surroundings. This is why heating a glass of soda will cause it to lose its fizz and go flat.
A solution that contains the maximum possible concentration of a solute is called a saturated solution. At any given temperature, seas and freshwater bodies are saturated solutions of oxygen in water, and changes in the temperature of the water affect how much oxygen it can hold. The solubility of a gas is defined by its absorption coefficient, which is the number of cubic centimeters of gas that will saturate one cubic centimeter of liquid at a given temperature and one atmosphere pressure.
An increase in ocean temperature due to climate change, which has been predicted by many scientists, could have a catastrophic affect on marine life. Fish and other sea creatures need oxygen to live; this oxygen has come from the atmosphere and is dissolved in the water. Creatures extract this oxygen, and the carbon dioxide produced during their respiration is dissolved back into the water and transferred to the atmosphere. This carbon dioxide is then converted by plants back into oxygen via photosynthesis. Fish cannot survive in oxygen-poor water. It is feared that climate change could drastically affect sea populations by increasing sea temperature, thus lowering oxygen concentration.