AGU journal highlights -- August 6, 2008(PMC Paris France. Source: Geophysic...)

Source:

Geophysical Research Letters (GRL) paper 10.1029/2008GL033817, 2008; http://dx.doi.org/10.1029/2008GL033817

4. Deep evidence shows past and present warming

Reconstructing past climate provides a useful context for discussions of current and future climate changes. One way to assess past temperatures is by using temperature measurements in deep boreholes, which are narrow vertical shafts drilled several hundred meters into the ground. Because variations in the ground surface temperature over time affect the distribution of temperature in the subsurface, scientists can carefully measure the temperature at depth within these holes and then use mathematical formulas to infer past temperatures at the surface. By integrating a global database of terrestrial heat flux measurements with another database of temperature versus depth within boreholes and with the twentieth-century instrumental record of surface temperature, Huang et al. reconstruct the surface temperature history over the past 20,000 years. The authors clearly identify a long-term warming from the Last Glacial Maximum, a mid-Holocene warm episode, the Medieval Warm Period, the Little Ice Age, and the rapid warming of the twentieth century.

Title:

A late Quaternary climate reconstruction based on borehole heat flux data, borehole temperature data, and the instrumental record

Authors:

S. P. Huang and H. N. Pollack: Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan, U.S.A.;

P.-Y. Shen: Department of Earth Sciences, University of Western Ontario, London, Ontario, Canada.

Source:

Geophysical Research Letters (GRL) paper 10.1029/2008GL034187, 2008; http://dx.doi.org/10.1029/2008GL034187

5. Climate models may underestimate
'/>"/>