The paper by Bond et al shows tiny 0.25% variations in solar activity over the past 3000 years are responsible for temperature swings of up to ~3C in the North Atlantic [Sargasso Sea] and ~3.5C at the Greenland Summit.
Abstract: Surface winds and surface ocean hydrography in the subpolar North Atlantic appear to have been influenced by variations in solar output through the entire Holocene. The evidence comes from a close correlation between inferred changes in production rates of the cosmogenic nuclides carbon-14 and beryllium-10 and centennial to millennial time scale changes in proxies of drift ice measured in deep-sea sediment cores. A solar forcing mechanism therefore may underlie at least the Holocene segment of the North Atlantic's "1500-year" cycle. The surface hydrographic changes may have affected production of North Atlantic Deep Water, potentially providing an additional mechanism for amplifying the solar signals and transmitting them globally.
From the concluding paragraph of the paper:
"The results of this study demonstrate that Earth’s climate system is highly sensitive to extremely weak perturbations in the Sun’s energy output, not just on the decadal scales that have been investigated previously, but also on the centennial to millennial time scales documented here. The apparent solar response was robust in the North Atlantic even as early Holocene vestiges of the ice sheets continued to exert a climate influence and as the orbital configuration shifted from that of the Holocene optimum to the quite different regime of the last few thousand years. Our findings support the presumption that solar variability will continue to influence climate in the future, which up to now has been based on extrapolation of evidence from only the last 1000 years (25). If forcing of North Atlantic ice drift and surface hydrography is fundamentally linked to the Sun and begins in the stratosphere, then atmospheric dynamics and their link to the ocean’s circulation are much more important for interpreting centennial and millennial time scales of climate variability than has been assumed."