The total energy reaching us from the sun varies by only 0.1 percent across the solar cycle. Scientists have sought for decades to link these ups and downs to climate variations and distinguish their subtle effects from the larger pattern of human-caused global warming.

Building on previous work, National Centre for Atmospheric Research (NCAR) researchers used computer models of global climate and more than a century of ocean temperature data to answer longstanding questions about the connection between solar activity and global climate.

'We have fleshed out the effects of a new mechanism to understand what happens in the tropical Pacific when there is a maximum of solar activity,' says NCAR scientist Gerald Meehl, the study's co-author.

'When the sun's output peaks, it has far-ranging and often subtle impacts on tropical precipitation and on weather systems around much of the world,' he added, according to an NSF release.

The research was published in July in the Journal of Climate.