What was done
A history of global surface temperature over the past five centuries was reconstructed from 358 boreholes spread throughout eastern North America, central Europe, southern Africa, and Australia.

What was learned
Nearly 80% of the 358 borehole locations experienced a net warming over the past five centuries, while about 20% experienced a net cooling.  The mean temperature increase over the 500-year period for all stations was approximately 1°C.

What it means
This study documents the complexity of earth's climate system, illustrating the fact that not only can the magnitude of temperature change vary widely across the surface of the planet, but that even its sign may differ from place to place.  In the mean, however, the results concur with those of other recent global climate reconstructions, indicating that global temperatures have risen by about one degree Celsius over the past 500 years.