The amount of energy entering the troposphere and stratosphere from space weather phenomena is trivial compared to the solar insolation in the visible and infra-red portions of the solar electromagnetic spectrum. However, some linkage between the 11-year sunspot cycle and the Earth's climate has been claimed.[35] For example, the Maunder minimum, a 70-year period almost devoid of sunspots, allegedly correlated to a cooler climate. One suggestion for the linkage between space and terrestrial weather is that changes in cosmic ray flux cause changes in the amount of cloud formation.[36] Another suggestion is that variations in the EUV flux subtly influence existing drivers of the climate and tip the balance between El Niño/La Niña events.[37] However, a linkage between space weather and the climate has not been demonstrated conclusively.