ASLR,
Many thanks for the links, I've clearly got homework to do, and I certainly don't mean to put more on your plate. Your patience, and everyone else's with my questions is greatly appreciated.
Thanks so much!!
JayW
As I only have time for re-posts at the moment, I provide the following two from the Antarctic folder; which indicate both the changes to the ENSO, and impacts of the ENSO, with continuing warming:
First re-post: "Many scientists are concerned that the Earth may be headed towards a Pliocene type of climate this century due to global warming. The linked reference indicates that changes in cloud cover/albedo for such conditions would rapidly induce the Equatorial Pacific Ocean into a permanent El Nino-like state. As cloud albedo is a rapid response feedback mechanism, such a change could happen in as little as a few decades from now (say 2040-2050). Permanent El Nino-like conditions would telecommunicate large amounts of heat from the Equatorial Pacific directly to West Antarctica.
N. J. Burls and A. V. Fedorov, (2014), "Simulating Pliocene warmth and a permanent El Niño-like state: the role of cloud albedo", Paleoceanography, DOI: 10.1002/2014PA00264
http://onlinelibrary.wiley.com/doi/10.1002/2014PA002644/abstractAbstract: "Available evidence suggests that during the early Pliocene (4-5 Ma) the mean east–west sea surface temperature (SST) gradient in the equatorial Pacific Ocean was significantly smaller than today, possibly reaching only 1-2°C. The meridional SST gradients were also substantially weaker, implying an expanded ocean warm pool in low latitudes. Subsequent global cooling led to the establishment of the stronger, modern temperature gradients. Given our understanding of the physical processes that maintain the present-day cold tongue in the east, warm pool in the west and hence sharp temperature contrasts, determining the key factors that maintained early Pliocene climate still presents a challenge for climate theories and models. This study demonstrates how different cloud properties could provide a solution. We show that a reduction in the meridional gradient in cloud albedo can sustain reduced meridional and zonal SST gradients, an expanded warm pool and warmer thermal stratification in the ocean, weaker Hadley and Walker circulations in the atmosphere. Having conducted a range of hypothetical modified cloud albedo experiments, we arrive at our Pliocene simulation, which shows good agreement with proxy SST data from major equatorial and coastal upwelling regions, the tropical warm pool, mid and high latitudes, and available subsurface temperature data. As suggested by the observations, the simulated Pliocene-like climate sustains a robust ENSO despite the reduced mean east–west SST gradient. Our results demonstrate that cloud albedo changes may be a critical element of Pliocene climate and that simulating the meridional SST gradient correctly is central to replicating the geographical patterns of Pliocene warmth.""
Second re-post: "The linked reference indicates (based on data from a snow pit at the South Pole from 1984-2001), that as we enter a positive IPO phase with increased frequency and intensity of El Nino events, we can expect a marked increase in wildfires, that on balance will act as positive feedback mechanism:
Robina Shaheen, Mariana M. Abaunza, Teresa L. Jackson, Justin McCabe, Joël Savarino, and Mark H. Thiemens, (2014), "Large sulfur-isotope anomaly in nonvolcanic sulfate aerosol and its implications for the Archean atmosphere", PNAS, doi: 10.1073/pnas.1406315111.
http://www.pnas.org/content/early/2014/08/01/1406315111Abstract: Sulfur-isotopic anomalies have been used to trace the evolution of oxygen in the Precambrian atmosphere and to document past volcanic eruptions. High-precision sulfur quadruple isotope measurements of sulfate aerosols extracted from a snow pit at the South Pole (1984–2001) showed the highest S-isotopic anomalies (Δ33S = +1.66‰ and Δ36S = +2‰) in a nonvolcanic (1998–1999) period, similar in magnitude to Pinatubo and Agung, the largest volcanic eruptions of the 20th century. The highest isotopic anomaly may be produced from a combination of different stratospheric sources (sulfur dioxide and carbonyl sulfide) via SOx photochemistry, including photoexcitation and photodissociation. The source of anomaly is linked to super El Niño Southern Oscillation (ENSO) (1997–1998)-induced changes in troposphere–stratosphere chemistry and dynamics. The data possess recurring negative S-isotope anomalies (Δ36S = −0.6 ± 0.2‰) in nonvolcanic and non-ENSO years, thus requiring a second source that may be tropospheric. The generation of nonvolcanic S-isotopic anomalies in an oxidizing atmosphere has implications for interpreting Archean sulfur deposits used to determine the redox state of the paleoatmosphere.""