According to the conclusions of a new research sponsored by the US National Science Foundation (NSF), and conducted by experts at the Pennsylvania State University (Penn State), it would appear that multiple proxy datasets can be used to gain more data on ancient climates.
Researchers figured out that data collected from the US Pacific Northwest, including tree ring counts and oxygen isotope readings, could be used to test theories covering past climates. At first, scientists believed that the datasets – which do not lead to the same values – represented a problem.
Counting tree rings and measuring oxygen isotopes lead to two different conclusions, when it comes to figuring out the amount of precipitations that fell over a certain area at one point. Since the results are contradictory, climate researchers were convinced they had a serious problem on their hands.
What the new study suggests is that the different conclusions are nothing to worry about. In fact, they are good for conducting studies of Earth's past climates, and especially of areas in the American West.
“We generally understand that the Medieval Climate Anomaly, a warm period in much of the northern hemisphere that occurred about 950 to 1250 was a dry period in the American West,” expert Byron A. Steinman explains.
“But there is complexity to the patterns of drought and it may not have been dry in winter in the Pacific Northwest,” adds the scientist, who holds an appointment as a postdoctoral researcher in meteorology at Penn State.
In the case of the Pacific Northwest, where the team conducted its new investigation, tree ring data suggested that Medieval Climate Anomaly summers had dry conditions, whereas the isotopic oxygen analysis suggested winters a lot wetter than expected.
The research team found “a strong centennial timescale relationship over the past 1,500 years between winter precipitation amounts in eastern Washington and Pacific Decadal Oscillation temperature anomalies.”
Details of the investigation appear in the latest issue of the esteemed journal Proceedings of the National Academy of Sciences (PNAS). “The tree ring data and isotope data match up on a short term, decadal scale. On a longer term, century scale, the records diverge,” Steinman concludes.
The work also features experts from the University of Pittsburgh, the Ohio State University (OSU) and Idaho State University.