Teleconnections in a warmer climate: the pliocene perspective
- 255 Downloads
Migrations toward altered sea surface temperature (SST) patterns in the Indo-Pacific region are present in the recent observational record and in future global warming projections. These SSTs are in the form of “permanent” El Niño-like (herein termed “El Padre”) and Indian Ocean Dipole (IOD)-like patterns. The Early Pliocene Warm Period, which bears similarity to future warming projections, may have also exhibited these Indo-Pacific SST patterns, as suggested by regional terrestrial paleo-climatic data and general circulation model studies. The ability to corroborate this assessment with paleo-data reconstructions is an advantage of the warm Pliocene period that is not afforded by future warming scenarios. Thus, the Pliocene period provides us with a warm-climate perspective and test bed for understanding potential changes to future atmospheric interactions given these altered SST states. This study specifically assesses how atmospheric teleconnections from El Padre/IOD SST patterns are generated and propagate to create the regional climate signals of the Pliocene period, as these signals may be representative of future regional climatic changes as well. To do this, we construct a holistic diagnostic rubric that allows us to examine atmospheric teleconnections, both energetically and dynamically, as produced by a general circulation model. We incorporate KE′, a diagnostic adapted from the eddy kinetic energy generation field, to assess the available energy transferred to these teleconnections. Using this methodology, we found that relative to our Modern Control experiments, weaker atmospheric teleconnections prevail under warm Pliocene conditions, although pathways of propagation still appear directed toward the southwestern United States from our tropical Pacific sector forcing. Propagation directly emanating from the Indian Ocean forcing sector appears to be largely blocked, although indirect teleconnective pathways appear traversing the Asian continent toward the North Pacific. The changes in the atmospheric circulation of Indian Ocean region in response to the underlying specified SST forcing (and indicated by Pliocene paleo-data) may have a host of implications for energy transfer out of and into the region, including interactions with the Asian jet stream and changes to the seasonal monsoon cycle. These interactions warrant further study in both past and future warm climate scenarios.
KeywordsTeleconnections Pliocene El Padre Indian Ocean dipole El Niño
Funding for this research was provided by the National Science Foundation, ATM-0323516 (to Chandler), and the NASA Climate Program.
- Dowsett HJ (2007) The PRISM palaeoclimate reconstruction and Pliocene sea-surface temperature. In: Williams M, Haywood AM, Gregory FJ, Schmidt DN (eds) Deep time perspectives on climate change: marrying the signal from computer models and biological proxies. The Micropalaeontological Society, Special Publications, The Geological Society, London, pp 459–480Google Scholar
- Meehl GA, Stocker TF, Collins WD, Friedlingstein P, Gaye AT, Gregory JM, Kitoh A, Knutti R, Murphy JM, Noda A, Raper SCB, Watterson IG, Weaver AJ, Zhao Z-C (2007) Global climate projections. In: Climate change 2007—the physical science basis, contribution of working group I to the fourth assessment report of the IPCC. IPCC, Geneva, pp 749–843Google Scholar
- Molnar P, Cane MA (2002) El Niño’s tropical climate and teleconnections as a blueprint for pre-ice age climates. Paleoceanogr 17(2):AN1021Google Scholar
- Ravelo AC (2008) Lessons from the Pliocene warm period and the onset of northern hemisphere glaciation. Eos Trans AGU 89(53):PP23E-01Google Scholar
- Schmidt GA, Ruedy R, Hansen JE, Aleinov I, Bell N, Bauer M, Bauer S, Cairns B, Canuto V, Cheng Y, Del Genio A, Faluvegi G, Friend AD, Hall TM, Hu Y, Kelley M, Kiang NY, Koch D, Lacis AA, Lerner J, Lo KK, Miller RL, Nazarenko L, Oinas V, Perlwitz Ja, Perlwitz Ju, Rind D, Romanou A, Russell GL, Mki Sato, Shindell DT, Stone PH, Sun S, Tausnev N, Thresher D, Yao M-S (2006) Present day atmospheric simulations using GISS ModelE: comparison to in situ, satellite and reanalysis data. J Clim 19:153–192. doi: 10.1175/JCLI3612.1 CrossRefGoogle Scholar
- Shukla SP, Chandler MA, Jonas J, Sohl LE, Mankoff K, Dowsett H (2009) Impact of a permanent El Niño (El Padre) and Indian Ocean dipole in warm Pliocene climates. Paleoceanogr 24:PA2221Google Scholar