U.S. Department of Energy Office of Biological and Environmental Research

Searchable Research Highlights



First Evidence of Long-Term Human Influence in Pacific Decadal Oscillation
Published: November 01, 2010
Posted: November 05, 2010

Both natural systems, from salmon productivity to fires to river flow to the onset of spring, etc., and atmospheric variables are affected by decadal-scale natural fluctuations in northern Pacific Ocean sea surface temperatures, known as the Pacific Decadal Oscillation (PDO). However, it turns out that this natural climate variability may not be entirely “natural” after all. Two BER-funded scientists present the first evidence of a long-term human component in the PDO. They considered three definitions of a PDO index, two of which attempt to remove a global warming signal that could be present in the sea surface temperature data. These definitions were analyzed using sea surface temperature data from two observational datasets and from two coupled ocean-atmosphere model simulations of historical and future climate. In the 21st century scenarios, an anthropogenic component is systematically found in all three PDO indices. For the definition in which no attempt was made to remove a global warming signal, the human component is so large that it is already statistically detectable in the observed PDO index. This study illustrates the importance of separating internally-generated and externally-forced components of the PDO, suggests that caution should be exercised in using PDO indices for statistical removal of ‘‘natural variability’’ effects from observational datasets, and suggests that we should carefully examine other “natural” climate change fluctuations to understand the sources of the variations.

Reference: Bonfils, C. and B.D. Santer. 2010. "Investigating the Possibility of a Human Component in Various Pacific Decadal Oscillation Indices," Climate Dynamics. Online First.

Contact: Renu Joseph, SC-23.1, (301) 903-9237, Dorothy Koch, SC-23.1, (301) 903-0105
Topic Areas:

  • Research Area: Climate and Earth System Modeling
  • Mission Science: Climate

Division: SC-23.1 Climate and Environmental Sciences Division, BER

 

BER supports basic research and scientific user facilities to advance DOE missions in energy and environment. More about BER

Recent Highlights

Jun 22, 2017
International Space Station Observations Offer Insights into Plant Function
New instrumentation will be installed on the International Space Station to provide a unique opp [more...]

Jun 22, 2017
A Direct Measure of Basin-Wide Evaporation and Transpiration from the Amazon Rainforest
A water budget approach shows complex seasonal cycle and long-term changes in tropical forest fu [more...]

Jun 19, 2017
Isotope Delivery in Lignin: Not an Easy Path
Scientists attempt to overcome challenge of limited deuterium uptake by lignin for studies of bi [more...]

Jun 15, 2017
Review of Recent Advances in Understanding Secondary Organic Aerosols for Earth System Modeling
Researchers review recent findings on secondary organic aerosols and the impact on radiative for [more...]

Jun 15, 2017
Scientists Examine Extensive Surface Melting Event in Antarctica During 2015-2016 El Niño
Research observations provide clues on atmospheric contributions to an Antarctic melt event.
more...]