Sea and sky. The marine biosphere as an agent of change

Abstract

Ocean life, and particularly microscopic plankton, influences climate in the long, medium, and short term: in the long term by shaping the element cycles that are essential to the functioning of Earth as a system; in the medium term, through the exchange with the atmosphere of greenhouse gases; and in the short term, through the emission of trace gases and particles that affect the chemical and optical properties of the atmosphere. This article will focus on the short-term effects. The ocean represents a major source of sulfur, iodine and hydrocarbons to the troposphere and, being as immense as it is, it rivals the continents as an emitter of primary aerosols in the form of salt crystals, organic polymers and microorganisms. This breath of the sea, of a strong biogenic component, regulates the oxidative capacity of the atmosphere and influences the planet's balance of energy through its role in the formation and opacity of the clouds. The international efforts for the integration of global data, and particularly of the data registered by orbiting satellites, has made it clear that, as surprisingas it may seem, marine life not only influences the ocean's behavior but also leaves a daily trace in the sky; another piece of evidence about the fascinating architecture of the complex system that is our living planet.