From the Summit County Citizens Voice (Bob Berwyn):
scientists working at the International Pacific Research Center, University of Hawaii at Manoa say a new tree ring record extending back about 700 years has helped decipher long-term trends. The tree ring samples from both the tropics and mid-latitudes in both hemispheres support the idea that the unusually high ENSO activity in the late 20th century is a footprint of global warming said Jinbao Li, lead author of the study published online in the journal Nature Climate Change.
“Many climate models do not reflect the strong ENSO response to global warming that we found,” said co-author Shang-Ping Xie, meteorology professor at the International Pacific Research Center. “This suggests that many models underestimate the sensitivity to radiative perturbations in greenhouse gases. Our results now provide a guide to improve the accuracy of climate models and their projections of future ENSO activity. If this trend of increasing ENSO activity continues, we expect to see more weather extremes such as floods and droughts.”
The inclusion of tropical tree-ring records enabled the team to generate an accurate archive of ENSO activity, matched with records from equatorial Pacific corals and with an independent Northern Hemisphere temperature reconstruction that captures well-known teleconnection climate patterns.
These proxy records all indicate that ENSO was unusually active in the late 20th century compared to the past seven centuries, implying that this climate phenomenon is responding to ongoing global warming.