Continental-Scale Temperature Variability during the Last Two Millennia

An international team of 78 researchers, including NCDC scientists, published the most comprehensive evaluation of temperature change at the surface of Earth’s continents over the past one to two thousand years. Published in Nature Geoscience, the paper entitled “Continental-Scale Temperature Variability during the Last Two Millennia” confirms a long-term cooling trend in nearly all of the regional temperature reconstructions, which ended late in the 19th century. Temperature variations across continents were noticeably more similar within the hemispheres than between the Northern and Southern Hemisphere, and distinctive periods such as the Medieval Warm Period or the Little Ice Age stand out, but do not show a globally uniform pattern on multi-decadal time scales. Reconstructing past regional climate variability as this study has can inform us about the regional expressions of climate change and the impacts of climate change on ecosystems and societies.

30 Year Mean Mean Temperatures Across Seven Continental Scale Regions Graph

Standardized 30-year-mean temperatures averaged across all seven continental-scale regions. Blue symbols provide the area-weighted averages, and bars show the twenty-fifth and seventy-fifth unweighted percentiles to illustrate the variability among regions; open black boxes are the unweighted medians. The salmon-color line from the later 19th century-on shows the 30-year average annual global temperature from instrumental data (relative to 1961–1990), scaled visually to match the standardized values over the instrumental period (R-hand scale). Salmon vertical bars indicate periods of the strongest cooling impact of combined volcanic and solar forcings.

Access the full article online http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1797.html.

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Check out the full Past Global Changes project press release, “First 2000-year temperature reconstructions for individual continents published.”