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As the core + earthly influence the climate

The movements of the outer core fluid disturb the magnetic field and its ability to protect against cosmic rays, which in turn influence the formation of cloud cover on the planet

The final confirmation, albeit indirect, influence of human activities on climate is not from observations of the atmosphere, oceans and land surface, but the earth's core.

Geophysical Research conducted by NASA's Jet Propulsion Laboratory and the University of Paris Diderot, published in the Journal of Climate fact indicates a strong correlation between natural fluctuations in length of day and the existence of natural fluctuations in surface temperatures of the planet, once they are purged of the effects attributable to greenhouse gases linked to human activities.

The length of the day, defined as time required for a complete rotation of the Earth around its axis, which fluctuates slightly around the mean value of 24 hours. In the course of one year duration varies by about a millisecond, stretching out the winter and decreasing in summer.

But the length of the day also undergoes fluctuations over longer periods, deferred (twice a decade), and decennalei over periods of several decades, about 65 to 80 years, with variations for the latter type of fluctuations che arrivano ai 4 millisecondi.

Queste fluttuazioni sono troppo grandi per essere spiegate dai movimenti dell'atmosfera e delle masse oceaniche, e sono legate ai flussi di metallo liquido presenti nel nucleo terrestre, che possono essere dedotti dalle variazioni nel ampio magnetico del pianeta.

Già studi precedenti avevano rilevato una correlazione fra variazioni nella durata del giorno, e fluttuazioni fino a 0,2 °C nella media globale a lungo termine dell'aria alla superficie terrestre. Nella nuova ricerca i geofisici hanno condotto una revisione di questi studi determinando con maggiore accuratezza e affidabilità i valori relativi alle temperature del pianeta negli ultimi 160 anni, per poi metterli in relazione con climate models used in the study of the effects of greenhouse gases.

"Our research shows that over the last 160 years the ten year and longer-term in the temperature of the atmosphere correspond to changes in day length if we remove the significant effect of warming linked to the effects of anthropogenic greenhouse gas. The study implies that the human impact on climate over the past 80 years masks the natural correspondence that exists between the Earth's rotation, the angular momentum of the core and surface temperature, "said Jean Dickey, who with Steven Marcus and Olivier de Viron has coordinated the study.

As for the mechanisms involved, the researchers speculate that movements of the nucleus disrupt the protective action of the magnetic field with respect to cosmic rays which in turn influence the formation of cloud cover ALL of the planet, which changes the amount of sunlight reflected back into space and trapped in the atmosphere. (Gg)



(March 12, 2011)

Source: http://lescienze.espresso.repubblica.it/