«The solar and volcanic forcings we use are derived from reconstructions based on proxy data and are therefore also subject to considerable uncertainties, although recent explosive volcanic eruptions are likely to have cooled climate, and independent records of solar activity levels inferred from the cosmogenic isotope 10Be (43) and geomagnetic records (44) provide support to reconstructions (22, 45) that show generally increasing solar activity during the 20th century (12).» (sciencebits.com)
The temperature has gone up a lot since then, as solar activity levelled off. (dotearth.blogs.nytimes.com)
The past studies have found the highest solar activity levels in (since) the 1940's based on proxy data, but modern instrumental measurements do not show any trend since 1950's. (realclimate.org)