How does rising atmospheric CO2 affect marine organisms?

Click to locate material archived on our website by topic


Arctic (Sea Ice - Extent) - Summary
Arctic climate is incredibly complex, varying simultaneously on a number of different timescales for a number of different reasons (Venegas and Mysak, 2000); and against this backdrop of multiple causation and timeframe variability, it is extremely difficult to identify the increase in temperature that has been predicted to result from the burning of fossil fuels.  The task is further complicated because many of the records that do exist contain only a few years to a few decades of data; and they yield different trends depending on the period of time studied.  Such is also the case with the records of Arctic sea ice extent.

Consider, for example, the study of Johannessen et al. (1999), who analyzed Arctic sea ice extent over the period 1978-1998 and found it to have decreased by about 14%.  This finding led them to suggest that "the balance of evidence," as small as it then was, indicates "an ice cover in transition," and that "if this apparent transformation continues, it may lead to a markedly different ice regime in the Arctic," as was also suggested by Vinnikov et al. (1999).

Reading Johannessen et al.'s assessment of the situation, one is left with the impression that a relatively consistent and ongoing transformation (a persistent reduction in the area of Arctic sea ice) is, in fact, in progress.  However, and according to their own data, this assessment is highly debatable and possibly false.  In viewing their plots of sea ice area, for example, it is readily evident that the decline in this parameter did not occur smoothly over the 20-year period of study.  In fact, essentially all of the drop it experienced occurred rather abruptly over a single period of not more than three years (87/88-90/91) and possibly only one year (89/90-90/91).  Furthermore, it could be argued from their data that from 1990/91 onward, sea ice area in the Arctic may have actually increased.

More questions are raised by the study of Parkinson (2000), who utilized satellite-derived data of sea ice extent to calculate changes in this parameter for the periods 1979-1990 and 1990-1999.  They report that in seven of the nine regions into which they divided the Arctic for their analysis, the "sign of the trend reversed from the 1979-1990 period to the 1990-1999 period," indicative of the ease with which significant decadal trends are often reversed in this part of the world.

Another example of changing sea ice trends is provided by the study of Cavalieri et al. (2003), who extended prior satellite-derived Arctic sea ice records several years back in time by bridging the gap between Nimbus 7 and earlier Nimbus 5 satellite data sets via comparisons with National Ice Center digital sea ice data.  For the newly-extended period of 1972-2002, they determined that Arctic sea ice extent had declined at a mean rate of 0.30 0.03 x 106 km2 per decade; while for the shortened period from 1979-2002, they found a mean rate of decline of 0.36 0.05 x 106 km2 per decade, or at a rate that was 20% greater than the full-period rate.  In addition Serreze et al. (2002) determined that the downward trend in Arctic sea ice extent during the passive microwave era culminated with a record minimum value in 2002.

These results could readily be construed to be compatible with the spin that is typically given them by climate alarmists; that is, they indicate an increasingly greater rate of Arctic sea ice melting during the latter part of the 20th century, when global warming is claimed to have occurred at an increasingly greater rate.  However, the results of these studies are not the end of the story, for still other studies have analyzed Arctic sea ice extent beyond the observational record using proxy data sources; and their results must be considered as well.  As Grumet et al. (2001) have described the situation, recent trends in Arctic sea ice cover "can be viewed out of context because their brevity does not account for interdecadal variability, nor are the records sufficiently long to clearly establish a climate trend."

In an effort to overcome this "short-sightedness," Grumet et al. developed a 1000-year record of spring sea ice conditions in the Arctic region of Baffin Bay based on sea-salt records from an ice core obtained from the Penny Ice Cap on Baffin Island.  In doing so, they determined that after a period of reduced sea ice during the 11th-14th centuries, enhanced sea ice conditions prevailed during the following 600 years.  For the final century of this period, however, they report that "despite warmer temperatures during the turn of the century, sea-ice conditions in the Baffin Bay/Labrador Sea region, at least during the last 50 years, are within 'Little Ice Age' variability," suggesting that sea ice extent there has not yet emerged from the range of conditions characteristic of the Little Ice Age.

In an adjacent sector of the Arctic, this latter period of time was also studied by Comiso et al. (2001), who used satellite imagery to analyze and quantify a number of attributes of the Odden ice tongue - a winter ice-cover phenomenon that occurs in the Greenland Sea with a length of about 1300 km and an aerial coverage of as much as 330,000 square kilometers - over the period 1979-1998.  By additionally utilizing surface air temperature data from Jan Mayen Island, which is located within the region of study, they were able to infer the behavior of this phenomenon over the past 75 years.  Trend analyses revealed that the ice tongue has exhibited no statistically significant change in any of the parameters studied over the past 20 years; but the proxy reconstruction of the Odden ice tongue for the past 75 years revealed the ice phenomenon to have been "a relatively smaller feature several decades ago," due to the warmer temperatures that prevailed at that time.

In another study of Arctic climate variability, Omstedt and Chen (2001) obtained a proxy record of the annual maximum extent of sea ice in the region of the Baltic Sea over the period 1720-1997.  In analyzing this record, they found that a significant decline in sea ice occurred around 1877.  In addition, they reported finding greater variability in sea ice extent in the colder 1720-1877 period than in the warmer 1878-1997 period.

Also at work in the Baltic Sea region, Jevrejeva (2001) reconstructed an even longer record of sea ice duration (and, therefore, extent) by examining historical data for the observed time of ice break-up between 1529 and 1990 in the northern port of Riga, Latvia.  The long date-of-ice-break-up time series was best described by a fifth-order polynomial, which identified four distinct periods of climatic transition: (1) 1530-1640, warming with a tendency toward earlier ice break-up of 9 days/century, (2) 1640-1770, cooling with a tendency toward later ice break-up of 5 days/century, (3) 1770-1920, warming with a tendency toward earlier ice break-up of 15 days/century, and (4) 1920-1990, cooling with a tendency toward later ice break-up of 12 days/century.

On the other hand, in a study of the Nordic Seas (the Greenland, Iceland, Norwegian, Barents and Western Kara Seas), Vinje (2001) determined that "the extent of ice in the Nordic Seas measured in April has decreased by 33% over the past 135 years."  He notes, however, that "nearly half of this reduction is observed over the period 1860-1900," and we note, in this regard, that the first half of this sea-ice decline occurred over a period of time when the atmosphere's CO2 concentration rose by only 7 ppm, whereas the second half of the sea-ice decline occurred over a period of time when the air's CO2 concentration rose by more than 70 ppm.  This observation clearly suggests that if the historical rise in the air's CO2 content has been responsible for the historical decrease in sea-ice extent, its impact over the last century has declined to less than a tenth of what its impact was over the preceding four decades, which in turn suggests that the increase in the air's CO2 content over the past 135 years has likely had nothing whatsoever to do with the concomitant decline in sea-ice cover.

In a similar study of the Kara, Laptev, East Siberian and Chuckchi Seas, based on newly available long-term Russian observations, Polyakov et al. (2002) found "smaller than expected" trends in sea ice cover that, in their words, "do not support the hypothesized polar amplification of global warming."  Likewise, in a second study published the following year, Polyakov et al. (2003) report that "over the entire Siberian marginal-ice zone the century-long trend is only -0.5% per decade," while "in the Kara, Laptev, East Siberian, and Chukchi Seas the ice extent trends are not large either: -1.1%, -0.4%, +0.3% and -1.0% per decade, respectively."  Moreover, they say that "these trends, except for the Chukchi Sea, are not statistically significant," which observations tend to discredit climate model qualitative predictions of amplified warming in earth's polar regions in response to increases in the air's CO2 content, which in turn tends to discredit their quantitative predictions of CO2-induced global warming.

In light of this litany of findings, it is difficult to accept the climate-alarmist position that Northern Hemispheric sea ice is rapidly disintegrating in response to CO2-induced global warming.  Rather, the oscillatory behavior observed in so many of the sea ice studies suggests, in the words of Parkinson (2000), "the possibility of close connections between the sea ice cover and major oscillatory patterns in the atmosphere and oceans," including connections with: "(1) the North Atlantic Oscillation (e.g., Hurrell and van Loon, 1997; Johannessen et al., 1999; Kwok and Rothrock, 1999; Deser et al., 2000; Kwok, 2000, Vinje, 2001) and the spatially broader Arctic Oscillation (e.g., Deser et al., 2000; Wang and Ikeda, 2000); (2) the Arctic Ocean Oscillation (Polyakov et al., 1999; Proshutinsky et al., 1999); (3) a 'see-saw' in winter temperatures between Greenland and northern Europe (Rogers and van Loon, 1979); and (4) an interdecadal Arctic climate cycle (Mysak et al., 1990; Mysak and Power, 1992)."  The likelihood that Arctic sea ice trends are the product of such natural oscillations, Parkinson continues, "provides a strong rationale for considerable caution when extrapolating into the future the widely reported decreases in the Arctic ice cover over the past few decades or when attributing the decreases primarily to global warming," a caution with which we heartily agree.

One final study of note that should be mentioned here is that of Bamber et al. (2004), who used high-accuracy ice-surface elevation measurements (Krabill et al., 2000) of the largest ice cap in the Eurasian Arctic -- Austfonna, on the island of Nordaustlandet in northeastern Svalbard -- to evaluate ice cap elevation changes between 1996 and 2002.  They determined that the central and highest-altitude area of the ice cap, which comprises 15% of its total area, "increased in elevation by an average of 50 cm per year between 1996 and 2002," while "to the northeast of this region, thickening of about 10 cm per year was also observed."  They further note that the highest of these growth rates represents "as much as a 40% increase in accumulation rate (Pinglot et al., 2001)."

Based on the ancillary sea-ice and meteorological data they analyzed, Bamber et al. concluded that the best explanation for the dramatic increase in ice cap growth over the six-year study period was a large increase in precipitation caused by a concomitant reduction in sea-ice cover in this sector of the Arctic.  Their way of characterizing this phenomenon is simply to say that it represents the transference of ice from the top of the sea (in this case, the Barents Sea) to the top of the adjacent land (in this case, the Austfonna ice cap).  And as what has been observed to date is but the beginning of the phenomenon, which will become even stronger in the absence of nearby sea-ice, "projected changes in Arctic sea-ice cover," as they say in the concluding sentence of their paper, "will have a significant impact on the mass-balance of land ice around the Arctic Basin over at least the next 50 years," which result, we might add, may well be far, far different from what the world's climate alarmists are currently anticipating.

Yes, the tales told by Arctic sea ice behavior are many and varied, as well as incomplete and even contradictory in some instances.  It will thus be a very long time indeed before we can accurately decipher the grand message they contain, if there even is a grand message, which is by no means certain.

References
Bamber, J., Krabill, W., Raper, V. and Dowdeswell, J.  2004.  Anomalous recent growth of part of a large Arctic ice cap: Austfonna, Svalbard.  Geophysical Research Letters 31: 10.1029/2004GL019667.

Cavalieri, D.J., Parkinson, C.L. and Vinnikov, K.Y.  2003.  30-Year satellite record reveals contrasting Arctic and Antarctic decadal sea ice variability.  Geophysical Research Letters 30: 10.1029/2003GL018031.

Comiso, J.C., Wadhams, P., Pedersen, L.T. and Gersten, R.A.  2001.  Seasonal and interannual variability of the Odden ice tongue and a study of environmental effects.  Journal of Geophysical Research 106: 9093-9116.

Deser, C., Walsh, J. and Timlin, M.S.  2000.  Arctic sea ice variability in the context of recent atmospheric circulation trends.  Journal of Climate 13: 617-633.

Grumet, N.S., Wake, C.P., Mayewski, P.A., Zielinski, G.A., Whitlow, S.L., Koerner, R.M., Fisher, D.A. and Woollett, J.M.  2001.  Variability of sea-ice extent in Baffin Bay over the last millennium.  Climatic Change 49: 129-145.

Hurrell, J.W. and van Loon, H.  1997.  Decadal variations in climate associated with the North Atlantic Oscillation.  Climatic Change 36: 301-326.

Jevrejeva, S.  2001.  Severity of winter seasons in the northern Baltic Sea between 1529 and 1990: reconstruction and analysis.  Climate Research 17: 55-62.

Johannessen, O.M., Shalina, E.V. and Miles M.W.  1999.  Satellite evidence for an Arctic sea ice cover in transformation.  Science 286: 1937-1939.

Krabill, W., Abdalati, W., Frederick, E., Manizade, S., Martin, C., Sonntag, J., Swift, R., Thomas, R., Wright, W. and Yungel, J.  2000.  Greenland ice sheet: High-elevation balance and peripheral thinning.  Science 289: 428-430.

Kwok, R.  2000.  Recent changes in Arctic Ocean sea ice motion associated with the North Atlantic Oscillation.  Geophysical Research Letters 27: 775-778.

Kwok, R. and Rothrock, D.A.  1999.  Variability of Fram Strait ice flux and North Atlantic Oscillation.  Journal of Geophysical Research 104: 5177-5189.

Mysak, L.A., Manak, D.K. and Marsden, R.F.  1990.  Sea-ice anomalies observed in the Greenland and Labrador Seas during 1901-1984 and their relation to an interdecadal Arctic climate cycle.  Climate Dynamics 5: 111-133.

Mysak, L.A. and Power, S.B.  1992.  Sea-ice anomalies in the western Arctic and Greenland-Iceland Sea and their relation to an interdecadal climate cycle.  Climatological Bulletin/Bulletin Climatologique 26: 147-176.

Omstedt, A. and Chen, D.  2001.  Influence of atmospheric circulation on the maximum ice extent in the Baltic Sea.  Journal of Geophysical Research 106: 4493-4500.

Parkinson, C.L.  2000.  Recent trend reversals in Arctic sea ice extents: possible connections to the North Atlantic Oscillation.  Polar Geography 24: 1-12.

Pinglot, J.F., Hagen, J.O., Melvold, K., Eiken, T. and Vincent, C.  2001.  A mean net accumulation pattern derived from radioactive layers and radar soundings on Austfonna, Nordaustlandet, Svalbard.  Journal of Glaciology 47: 555-566.

Polyakov, I.V., Proshutinsky, A.Y. and Johnson, M.A.  1999.  Seasonal cycles in two regimes of Arctic climate.  Journal of Geophysical Research 104: 25,761-25,788.

Polyakov, I.V., Alekseev, G.V., Bekryaev, R.V., Bhatt, U., Colony, R.L., Johnson, M.A., Karklin, V.P., Makshtas, A.P., Walsh, D. and Yulin A.V.  2002.  Observationally based assessment of polar amplification of global warming.  Geophysical Research Letters 29: 10.1029/2001GL011111.

Polyakov, I.V., Alekseev, G.V., Bekryaev, R.V., Bhatt, U.S., Colony, R., Johnson, M.A., Karklin, V.P., Walsh, D. and Yulin, A.V.  2003.  Long-term ice variability in Arctic marginal seas.  Journal of Climate 16: 2078-2085.

Proshutinsky, A.Y., Polyakov, I.V. and Johnson, M.A.  1999.  Climate states and variability of Arctic ice and water dynamics during 1946-1997.  Polar Research 18: 135-142.

Rogers, J.C. and van Loon, H.  1979.  The seesaw in winter temperatures between Greenland and Northern Europe.  Part II: Some oceanic and atmospheric effects in middle and high latitudes.  Monthly Weather Review 107: 509-519.

Serreze, M.C., Maslanik, J.A., Scambos, T.A., Fetterer, F., Stroeve, J., Knowles, K., Fowler, C., Drobot, S., Barry, R.G. and Haran, T.M.  2003.  A record minimum arctic sea ice extent and area in 2002.  Geophysical Research Letters 30: 10.1029/2002GL016406.

Venegas, S.A. and Mysak, L.A.  2000.  Is there a dominant timescale of natural climate variability in the Arctic?  Journal of Climate 13: 3412-3434.

Vinje, T.  1999.  Barents Sea ice edge variation over the past 400 years.  Extended Abstracts, Workshop on Sea-Ice Charts of the Arctic, Seattle, WA, USA.  World Meteorological Organization, WMO/TD No. 949, pp. 4-6.

Vinje, T.  2001.  Anomalies and trends of sea ice extent and atmospheric circulation in the Nordic Seas during the period 1864-1998.  Journal of Climate 14: 255-267.

Vinnikov, K.Y., Robock, A., Stouffer, R.J., Walsh, J.E., Parkinson, C.L., Cavalieri, D.J., Mitchell, J.F.B., Garrett, D. and Zakharov, V.R.  1999.  Global warming and Northern Hemisphere sea ice extent.  Science 286: 1934-1937.

Wang, J. and Ikeda, M.  2000.  Arctic Oscillation and Arctic Sea-Ice Oscillation.  Geophysical Research Letters 27: 1287-1290.