Earth's climate is continually varying on a wide range of time scales, from seasons to the lifetime of the planet. Most of this variability is natural, such as the periodic rapid warming trend in the Pacific Ocean known as El Niño. Climate change can also be induced by humans, however, through activities causing the emission of greenhouse gases, including carbon dioxide.
Greenhouse gases are accumulating in Earth's atmosphere as a result of human activities. Among climate scientists, there is general agreement that this build-up is likely the main cause of a rise in surface air temperatures and subsurface ocean temperatures in recent decades. The average ocean temperature, from sea surface down to 10,000 feet (3050 meters), has risen by 0.05 degrees C since the 1950s. Researchers have only just begun to determine the effects of such warming on marine ecosystems. This month, MPA News examines the scientific understanding of climate change in the marine environment, and what global ocean warming could entail for the planning and management of MPAs.