CLAW hypothesis

In the CLAW hypothesis, it is assumed that a particular phytoplankton plays an important role in the climate system of the earth, and forms part of the Gaia -called self- control system of the earth. Due to global warming the growth of this phytoplankton is stimulated, causing more dimethyl sulfide (DMS ) is produced. This leads to a higher aerosol concentration in the atmosphere, which in turn causes a cooling of the atmosphere. Conversely, brings cooling a reduction of phytoplankton growth with them, which reduces the concentration of the cooling DMS.

The hypothesis was put forward by scientists Robert Charlson, Lovelock, Andreae and Stephen Meinrat O. Warren and published in 1987. The name of CLAW hypothesis is composed of the first letter of the last name of the author.

The hypothesis

The CLAW hypothesis is that a change of solar radiation leads to an increase in metabolic rate of phytoplankton. This can either be the result of an increased metabolic activity by the stronger insolation, or a result of the higher temperatures involved. Growth of phytoplankton in this case acts as a negative feedback ( negative feedback ). For negative feedback, a mechanism that counteracts the original change to obtain the initial state exists.

Certain phytoplankton, such as Coccolithophores produced dimethylsulfoniopropionate ( DMSP ) in dependence on its rate of growth. DMSP in turn decomposes into dimethyl sulfide (DMS). DMS is oxidized in the atmosphere to sulfur dioxide. The resulting sulfate aerosols have a cooling effect on the climate, forming condensation nuclei. So it is the change in this way cloud formation that alters the radiation balance of the Earth.

The described feedback effects between phytoplankton, DMS and climate are discussed controversially. Although a connection between global warming and DMS production could be found, but this effect is very small.