Coralline Algae and the Case for Natural Climate Change

Guest post by Jim Steele

Director Sierra Nevada Field Campus, emeritus, San Francisco State University

There was a very revealing 2012 paper demonstrating the power and interconnections of natural ocean oscillations, “Marine proxy evidence linking decadal North Pacific and Atlantic Climate”. If you have ever played in the tide pools, you may have noticed the coralline algae: a pinkish‑red algae with holdfasts that encrust the rocks, as shown in the picture. Just as tropical coral allow scientists to reconstruct tropical ocean temperatures, a chemical analysis of the thick crusts of some coralline algae provides a record of temperatures in sub‑arctic oceans. Statistical correlations of the cyclic nature and connections between the Pacific Decadal Oscillation(PDO), the Aleutian Low and North Atlantic Oscillation(NAO) have been based on tree rings and other land proxies that fail to fully capture subsurface changes, so this is the first ocean proxy to provide a very coherent picture of recent climate change.

A quick review of the PDO illustrates the value of this new re‑construction. From a biological point of view the PDO is a “regime shift” that totally alters currents, winds and marine life approximately every 20 years. Salmon abundance alternates between Oregon and Alaska, abundant sardines alternate with abundant anchovies, and a host of other related changes that would require a book to properly address(see Chavez 2003, 2011).

The PDO is driven in part by El Nino cycles and internal climate feedbacks.

In the PDO’s warm phase, ocean temperatures in the Pacific resemble an El Nino year with warmer temperatures in the eastern Pacific and cooler temperatures to the north and west. In the cool phase, the PDO resembles a La Nina. Not only does the PDO’s regime shift totally reorganize marine ecosystems, the changing currents redistribute the ocean’s heat. Because the upper 10 feet of the ocean contains more heat than the entire atmosphere, the PDO, like an EL Nino, can dramatically alter the climate.

As the PDO entered its warm phase beginning in the early 1900’s to the late 1940’s, global temperatures rose. The unadjusted maximum temperatures for the overwhelming majority of USHCN weather stations show a corresponding 1940’s warm peak that has yet to be surpassed. During that time the Arctic Ocean warmed similar to today(see Bengstonn, 2004), and ice cores on the Antarctic peninsula show a similar 1940’s warm peak that remains the warmest for the 20^th century(see Schneider 2008). Between 1946 and 1976 the PDO reversed to its cool phase and global temperatures dropped. Then in 1976 the PDO reversed again to its warm phase and global temperatures rose igniting the global warming debate. In 1976, the temperature of the California Current suddenly jumped by 1 degree and there was a northward shift in warm water species that CO2 advocates argued was evidence of global warming. However there were alternative correlations.

The Aleutian Low strengthens during a PDO warm phase, which causes a circulation pattern that pumps more warm air and warm water northward. This caused Bering Sea Ice to retreat and Alaska and the Bering Sea were noted by the IPCC as one of the 3 fastest warming places on earth. Some climate scientist wrote that Alaska’s rapid warming could be explained completely by the warm phase of the PDO (see Hartman 2005) while others working in southern California predicted the warmer temperatures in the California Current would soon revert back to the 1970’s level(see Holbrook 1997). Thus there was a natural experiment to test the competing hypotheses. Natural variation predicted a reversal and CO2 predicted a continued and accelerating warming.

When the PDO began to enter its cool phase again in 1998, temperatures in the California Current from Washington to southern California dropped to the cooler 1970’s level as predicted by Holbrook (Peterson 2003). However, although the Aleutian Low began to weaken as expected during a cool phase of the PDO, temperatures in Alaska did not immediately change and the Bering Sea ice continued to retreat. Some advocates argued that this was proof that CO2 warming and not the PDO were driving those temperatures. They predicted the Bering Sea ice would continue to retreat with March ice extent dropping 25% by mid century.(Douglas 2010) However the PDO prediction has been vindicated again. After a 5 year lag, Alaska has become one of the most rapidly cooling regions on earth, as temperatures have been steadily cooling by 2.3°F over the past 10 years (see Wendler 2012) and beginning in 2003 Bering Sea ice began to recover reaching record extent in 2012. If we ignore that natural cycles and extend that trend into the future as advocates like to do, that means that Alaska will cool 23°F by the end of the century. But such futuristic trends, warm or cold, are just silly projections.

Ocean currents are much slower to respond to changing air currents due to their greater mass and greater inertia. Although the ocean temperatures had switched in the tropics and the Aleutian Low was weakening it was reasonable to expect ocean temperatures further north in the Bering Sea would lag by a few years, which is exactly what the coralline algae studied shows. Furthermore this studies shows that over the past centuries the algae in the North Atlantic will follow natural climate change in the Bering Sea with a ~5 year lag. This again corresponds to recent observations. In 2010 the Arctic Oscillation/NAO dropped into it negative phase and is continuing to parallel the PDO’s descent into a cool phase. As predicted a negative oscillation is hammering Great Britain and much of Europe with record cold and snow. However this new cooling trend contradicted CO2 predictions. Advocate scientist had not only predicted that snow would soon disappear from Great Britain, but that CO2 could control natural oscillations, and they predicted the Arctic Oscillation/NAO would continue to rise into its warm phase causing warmer European winters.

RealClimate’s moderator Gavin Schmidt co‑authored that prediction in 1999 writing “although the warming appears through a naturally occurring mode of atmospheric variability, it may be anthropogenically induced and may continue to rise.”(Shindell 199) In 2001 scientists from the National Center for Atmospheric Research wrote, “The proposed response to increased greenhouse gas concentrations through forcing from warmer tropical SSTs or a strengthened stratospheric vortex implies, however, that the positive index phase might continue”. (see Visbeck 2001)

Clearly their CO2‑driven models failed to capture the earth’s natural variations such as the PDO and NAO and their theories were forced to adapt. When a blocking High formed in the north Atlantic, it forced a weak category 2 hurricane to turn inland, which then morphed into Superstorm Sandy as the warmer ocean winds collided with colder continental air. This blocking High was generated by cold Arctic winds that had pushed further south than in previous decades because the Arctic Oscillation was now in its cool phase.

So to capitalize on Sandy’s tragedy, within 5 days of Sandy’s peak damage, Mark Fischetti wrote for Scientific American on October 30, 2012 “Did Climate Change Cause Hurricane Sandy?” He interviewed the standard perpetrators of climate doom Jim Hansen and Kevin Trenberth. And to implicate global warming, the advocates flipped‑flopped on the Arctic Oscillation/NAO. Now they argue that the cool phase of that oscillation is also due to global warming and referenced another model to “prove” it. Fischetti goes onto say the Trenberth had predicted this megastorm and referenced Trenberth’s “Warmer Oceans, Stronger Hurricanes”. However in that paper Trenberth had argued that the lack of hurricanes that followed Katrina was due to the cooling effects of La Nina years. Sandy, on the other hand occurred after a La Nina year had brought drought to America. Other than predicting the given that the future will bring a big storm, Trenberth got everything else wrong.

As for predictions of accelerated warming even Jim Hansen recently admitted, “The 5-year running mean of global temperature has been flat for the past decade”. With such failed predictions, the CO2 advocates are now relegated to arguing CO2 has caused the climate to “go crazy”. There is no longer a testable hypothesis to disprove CO2 climate change, because omnipotent and omnipresent CO2 moves in strange and mysterious ways. Warm or cold, floods or droughts, rain or snow, its always CO2. Such arguments of crazy weather, appear more like excuses for their failed predictions. And their blatant flip‑flops expose their crass eagerness to hijack every human tragedy to implicate CO2.

On the other hand, climate theories based on natural variations show that the climate is behaving as has been predicted. A cool PDO phase is reversing the trends of the warm phase and as predicted global temperatures stopped rising. A cool NAO is now following a warm phase. The growing cold and ice in the Bering Sea has been followed by growing cold in the North Atlantic. The graph from the study shows how ocean temperatures, algae and the Aleutian Low are all related. Although the author made no such predictions the graph also suggests a trend toward colder weather as the natural oscillations trend deeper into their cool phase. This certainly seems to be the case as China has also suffered its coldest winters since the last PDO cool phase. If history repeats itself, we should also expect CO2 advocates to continue to flip‑flop as they repeatedly try to convince their faithful believers that global warming causes global cooling.

From Hetzinger abstract, “Here we present an annually-resolved record (1818–1967) of Mg/Ca variations from a North Pacific/ Bering Sea coralline alga that extends our knowledge in this region beyond available data. It shows for the first time a statistically significant link between decadal fluctuations in sea-level pressure in the North Pacific and North Atlantic. The record is a lagged proxy for decadal-scale variations of the Aleutian Low. It is significantly related to regional sea surface temperature and the North Atlantic Oscillation (NAO) index in late boreal winter on these time scales. Our data show that on decadal time scales a weaker Aleutian Low precedes a negative NAO by several years. This atmospheric link can explain the coherence of decadal North Pacific and Atlantic Multidecadal Variability, as suggested by earlier studies using climate models and limited instrumental data.”

References:

1. Chavez,F.P., et al.(2003) From Anchovies to Sardines and Back: Multidecadal Change in the Pacific Ocean. Science 299, 217.
2. Chavez,. F., et al., (2011) Marine Primary Production in Relation to Climate Variability and Change. Annual Revie of Marine Science, vol. 3, p. 227–260.
3. Douglas,(2010) Arctic Sea Ice Decline: Projected Changes in Timing and Extent of Sea Ice in the Bering and Chukchi Seas. USGS Open-File Report 2010–1176
4. Fischetti, M. (2012) Did Climate Change Cause Hurricane Sandy? Scientific American, October 30,2012.
5. Hartman, B., & Wendler, G., (2005) The Significance of the 1976 Pacific Climate Shift in the Climatology of Alaska. Journal of Climate, vol. 18, p. 4821-4838.
6. Holbrook, S., et al., (1997) Changes in an Assemblage of Temperate Reef Fishes associated with a Climate Shift. Ecological Applications, vol. 7, pp. 1299-1310.
7. Hetzinger, S., et al. (2012) Marine proxy evidence linking decadal North Pacific and Atlantic Climate. Climate Dynamics, vol. 39, p.1447–1455, DOI 10.1007/s00382-011-1229-4.
8. Peterson, W., and Schwing, F., (2003) A new climate regime in northeast pacific ecosystems. Geophysical Research Letters, vol. 30, doi:10.1029/2003GL017528.
9. Schneider, D., and Steig, E., (2008) Ice cores record significant 1940s Antarctic warmth related to tropical climate variability. Proc. Natl Acad. Sci. USA 105, 12154–12158.
10. Shindell,D., and Schmidt,G., (1999) Simulation of recent northern winter climate trends by greenhouse-gas forcing. Nature, vol. 399, p.452-455.
11. Wendler,G., et al. (2012) The First Decade of the New Century: A Cooling Trend for Most of Alaska. The Open Atmospheric Science Journal, 2012, 6, 111-116
12. Visbeck, M., et al., (2001) The North Atlantic Oscillation: Past, present, and future. PNAS, vol. 98, p.12876–12877.