Scott's Antarctic Data Confirms Carbon Sequestration Increase

The nice thing about thisparticular proxy is that it isolated in time and space from the rest of theglobe.  Thus we get pretty solidconfirmation that the past two decades has seen a CO2 growing burst underway sufficientto establish magnitudes to some accuracy.

We thought as much, but thepicture was also fuzzy and this is a bench mark that can be used safely tocorrect other data shifts.

It is also a serious reminder ofthe importance of the day to day science of simple data
collection that needs to besupported better and not forgotten.

Captain Scott's century-old collections suggest marine life iscapturing more carbon

Mar 7, 2011

Tiny Antarctic marine creatures collected 100 years ago by Antarcticexplorer Captain Robert Falcon Scott give new clues about polar environmentalchange. By comparing present-day bryozoans – a sea-bed filter-feeding animalthat looks like branching twigs – with specimens from Scott's expeditionsscientists have found the first conclusive evidence of increased carbon uptakeand storage by Antarctic marine life.

Reporting this week in the journal Current Biology an internationalteam of scientists explain how they examined annual growth bands in skeletonsof specimens of bryozoans (Cellarinella nutti) collected from Antarctica's RossSea during the Census of Antarctic Marine Life. When compared with museumcollections in the UK, USand New Zealand– including specimens from Scott's expeditions – they found that since 1990bryozoans grew more rapidly than at any time before. The most likelyexplanation is greater availability of food (phytoplankton). The findingssuggest that this new growth is an important mechanism for transferring carboninto the sea bed.

Lead author, Dr Dave Barnes, of the British Antarctic Survey (BAS)says, "For the first time we've been able to use the longest record ofanimal growth as evidence of rapid recent change to life on the seabed. Scott'sbiological collections are considerable in quality and quantity and willcontinue to become even more valuable for determining how life responds tochange across time. Few biological studies in Antarcticago back more than 30 years, so these data are invaluable and highlight theimportance of long-term monitoring."

The spurt in growth means that animals reach the size earlier at whichocean currents snap them off. As the animals topple over they bury carbon,therefore increasing the seabed's potential as a carbon sink.
Source: BAS

Scott’s collections marking the end of growth each year. BritishAntarctic Survey, National Museum Natural History, Smithsonian InstitutionWashington D.C., Virginia Museum of Natural History (US), NIWA and Universityof Otago (NZ)).

The height and area or mass produced of, in annual sections of suchanimals varies with both age and the duration of food (phytoplankton)availability [4]. help reveal accelerating marine life growth in Antarctica

David K.A. Barnes1,*,
Piotr Kuklinski2,3,
Jennifer A. Jackson1, Geoff W. Keel4,
Simon A. Morley1, and
Judith E. Winston5

Scott remains famous for coming second to Amundsen in the race for theSouth Pole and the fatalities on the journey back to base, but scientificeffort on his expedition was never sacrificed and set many invaluable physicaland biological baselines. Amongst these were collections of benthos, such asthe bryozoan Cellarinella nutti, which records environmental information intree-ring-

For colonies in which a growing branch tip or tips are intact and thedate of collection known, each growth section can be back-measured and ascribedto a particular year. Growth data across years can be compared using anomalies(deviation from age-standardised averages). New initiatives, such as the Censusof Antarctic Marine Life, have led to recent collections. The current studyspecimens were collected in 2008 by McMurdo and Scott base personnel as well asby the RV Tangaroa cruises of the National Water and Atmospheric Institute(NIWA) of New Zealand.Older specimens were from Scott’s collections during the National Antarctic andBritish Antarctic expeditions (1901 and 1913), the Discovery expeditions (1936)and later research cruises of the 1950–1970s (held in the NaturalHistory MuseumLondon,

We examined 887 annual growth increments of C. nutti (Figure S1 inSupplemental Information, published with this article online) and found thatthe average annual growth of this species was 3.90 mm (± 0.05 SE) in height and46.19 mm2 (± 2.04 SE) in area between 1890 and 1970. This growth produces about30 mg of calcium carbonate per specimen per year and is similar in quantity tovalues measured in C. nutti from the Weddell Seain the 1980s and 1990s [5]. We then analysed the age-standardised anomalies andfound no significant increase or decrease over time between 1890 and 1970.There was however more variability in the data from the 1950s and 1960s than inearlier years (1946–1972 = 0.09 SE compared with 1890–1936 = 0.04 SE). From theearly 1990s to 2008 the mean growth of C. like growth check lines. We measured hegrowth of C. nutti in the Ross Sea from museum and newcollections and find no trend from 1890–1970 but a rapid increase from the1990s to present. This reflects coincident increases in regional phytoplanktonproduction. Thus it is the first evidence that greater surface productivity isbeing sequestered to the seabed and thus of increasing polar carbon sinks.

A key consequence of rapid recent regional warming is the changing ofparts of the planet from white (ice) to blue (sea) to green (phytoplanktonblooms) [1,2].

While many positive feedbacks (e.g., decreased albedo) have beendescribed, one significant negative feedback is a predicted [3] increase incarbon sequestered to the seabed. Evidence of increased sequestration can beindirectly provided by measuring growth of primary consumers but is hindered bythe lack -0.5 of early baselines and brevity of time series. The polar primaryconsumer C.  nutti has been collected formore than a century thanks to Scott’s refusal to give up science during thequest for the South Pole. Here we show that C. nutti, which forms annual growthbands (like tree-rings), provides the first evidence of recent rapid polargrowth increase.

The erect, branching bryozoan C. nutti, like some other bryozoans,brachiopods, and molluscs, produces check lines

Figure 1. Growth of Cellarinella nutti in the Ross Seaby year.

Data are mean and standard deviation (unfilled circles are singledatum). The regression line is significant (r2=74.3, F=50.1, p<0.001).Insert is a colony from 1903 (A) and 1936 (B). nutti increased (Figure 1) totwice (age means 1.1–3.8 mm) that during the rest of the century. This trendfrom the 1990s was highly significant (with p<0.001 even without the lasttwo years data) and eight of the ten highest mean growth values from 1890 to2008 occurred in the last decade. Pelagic data also suggest recent changes inthe Southern Ocean, with increases in salps but decreases in krill [6].

Benthic primary consumers are rich and abundant on continental shelves;thus, if increased growth measured in the Ross Seahas some generality it could prove significant in terms of carbon equestration.It is likely that the recent increase in growth of C. nutti is linked toregional increases in phytoplankton production [2]. The growth of a closely relatedspecies, C. watersi, has been shown to be directly linked to the duration ofits nanophytoplankton food supply [4]. On that basis, expectation would be thatC. nutti is growing for a longer season annually, rather than growing faster.Although there is little evidence of regional sea ice and temperature change, Arrigoet al. [2] suggest that the increase in phytoplankton production may be drivenby the cascade effect of increased upwelling due to west wind strengthening, causedby stratospheric ozone losses [1,2]. We think this to be the most likely explanationbut another possibility is shifts in dominance of phytoplankton prey species.

Long-lived species with annual growth increments, most famously thesubarctic ocean quahog Arctica islandica [7], can be used to gain powerfulinsights into past change. Our data provide the highest latitude record of acentury of growth.

Uniquely, the size and time span of C. nutti collections reducesconfounding age effects, which limit contemporary collections. Increased carbondraw-down would probably lead to long term sequestration by burial. AsCellarinella spp grow larger they present more resistance to water movement andfragment [4,8].

Observations [4] have shown that Cellarinella spp fragments can beburied within a season even in the turbulent shallows, so carbon accumulated islikely to be genuinely sequestered. The carbonate compensation depth (CCD) shouldbecome shallower as ocean acidification continues (which would reduce themagnitude of increased sequestration) but the CCD is somewhat deeper than thebryozoan data presented here, so we do not consider it further.

Calculation and quantification of the magnitude of such carbonsequestration increases by benthos will be further complicated by the varietyand patchiness of primary consumers, variability in overlying phytoplanktonperformance, and projected temperature changes.

Amundsen claimed that Scott’s “..British expedition was designedentirely for scientific research. The Pole was only a side-issue...”. Beingfirst to reach the pole was foremost in fundraising and probably in Scott’sthinking but coming second in the ensuing ‘race’ and dying there completelyovershadowed the many scientific achievements of the expedition.

The baselines that they established and crucial subsequent curation mayprove key to interpretation of trends with significance way beyond the polarregions.

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