On The Question Of Anthropogenic Impact On Sea Ice Extent Variability

Since the 1960s, an increasing number of climatologists have become concerned that the impact of greenhouse gases accumulating in the atmosphere as a result of the burning of hydrocarbon fuels and of deforestation may produce disastrous climate change in the 21st century. The report of the Intergovernmental Panel on Climate

Change for 2007 (IPCC, 2007) estimates the concentration of carbon dioxide (CO2) in the atmosphere at 383 parts per million (ppm) in 2007, 37% over pre-industrial revolution concentrations (280 ppm in 1750), and higher than any concentration found in polar ice core records of atmospheric composition dating back 650,000 years—and possibly higher than any concentration in the last 20 million years. It is widely believed that the increased concentration of greenhouse gases reduces the Earth's long-wave emission, resulting in increased temperature in the troposphere and the surface. The basis for this belief rests mainly on two factors: (1) the global average temperature increased during the 20th century, as did the CO2 concentration, and (2) climate models predict even greater increases in temperature in the 21st century as CO2 emissions increase further.

Most of this climate modeling has been carried out on a global basis, but a few modeling studies were used to forecast changes in Arctic ice cover area to global warming induced by increased greenhouse gases. In this connection, coupled ocean-atmosphere general circulation models have usually been employed (e.g., Manabe and Wetherald, 1975; Vinnikov et al., 1999; Katzov, 2003; Johannessen et al., 2004). In addition to greenhouse gases, some of the models accounted for the influence of sulfate aerosol that forms in the troposphere as a response to warming and somewhat mitigates the role of greenhouse gases. The results of these model calculations show significant temperature increases due to predicted doubling of CO2 in the 21st century. However, the models greatly amplify this temperature increase due to an assumed global increase in atmospheric humidity. However, the models have difficulty accounting for the dynamic effects of clouds, aerosols, regional variations in humidity, oceanic changes, variability of wind fields, and other factors. As a result, depending on the assumptions they make, the results vary over a wide range. For example, the international Coupled Model Intercomparison Project (CMIP) compared several of these models and showed that their results differ by several times. Izrael et al. (2001) noted that the least effective components of modern global climate models are parameterizations of sea ice and cloudiness and their feedback mechanisms. Thus, we believe that these model projections of future ice area fluctuations are unreliable.

When Vinnikov et al. (1999) analyzed results of a set of climate models, they found that the models forecast a decrease in the mean annual ice extent in the Northern Hemisphere of 1.2-1.6 million km2 during the first half of the twenty-first century, followed by further acceleration of the decrease. Based on the same preconditions, a forecast of ice cover concentration during the summer period in 2081-2090 by Johannessen et al. (2004) indicates that a small area of ice with a concentration of 1-5 tenths will remain in the Arctic Basin by that time. These models are in line with the majority of climate models that predict a several-degree temperature rise in global average temperature, with even greater temperature increases in polar regions, due to a doubling of CO2 concentration in the atmosphere later in the 21st century. However, Makshtas et al. (2007) show that reconstructed SAT values significantly overestimate the real temperature values measured at the "North Pole'' drifting stations with an average systematic error in the summer months equal to + 1.2°C. There appear to be large errors in the model estimates of cloudiness and air humidity, which subsequently leads to distortion of the heat flux values, and hence of the simulated sea ice thickness and concentration.

Most climate models have concentrated on predicting a future global average temperature rise due to a doubling of C02 in the 21st century compared to the pre-industrial level of about 280 ppm. Only a few of these models have attempted to analyze global temperature variability in the past. Of particular note is the fact that global temperatures dipped from about 1940 to 1978, while C02 emissions increased. Several papers tried to explain this with computer models including the negative effect of aerosols (e.g. Nagashima et al., 2006 and Nozawa et al., 2005). However, as Rapp (2008) pointed out: "these papers appear to raise more questions than they answer." Inconsistencies in the changes over time of anthropogenic carbon dioxide emissions to the atmosphere and anomalies of global surface air temperature are convincingly presented in Klyashtorin and Lyubushin (2003).

In general, although climate models are based on physics, they inevitably include a number of adjustable parameters that are fitted to past temperature changes. We are not aware of a single climate model based on fundamental physics without adjustable parameters that has been subjected to a rigorous test against actual climate data. Climate modelers appear to assume that the Earth's climate would continue without change, were it not for greenhouse gas emissions. They do not take into account the possibility that natural climate cycles are also acting independently of effects induced by buildup of greenhouse gas concentrations. As we have shown in Chapter 4, there is evidence for cyclic variability of Arctic climates. Furthermore, there is considerable evidence for past variability of global climate as expressed in the so-called Medieval Warm Period (900-1100) and the Little Ice Age (1600-1850). These fluctuations appear to be as great as the temperature rise of the 20th century, yet, there was no contribution of greenhouse gases to these climate changes.

A major challenge in climate modeling is to understand the range of natural fluctuations, and separate these from climate changes induced by human activity (greenhouse gas emissions, land clearing, irrigation, ...). The models neglect natural fluctuations because they have no means of incorporating them, and put the entire blame for climate changes since the 19th century on human activity. As a result, they appear to project an extreme view of the future that seems unlikely to be reliable.

In Figure 5.1, the dynamics of global air temperature anomalies obtained from instrumental measurements over the last 140 years is compared with changes in world fuel consumption (WFC) (Makarov, 1998). The WFC curve shows an exponential increase, which doubles approximately every 30 years, increasing 25-fold since the middle of the nineteenth century. The global air temperature anomaly curve shows a positive trend of +0.06°C/10 years (Sonechkin et al., 1997). At the same time, there are cyclic changes with periods of about 60 years. The correlation between these curves changes its sign every 30 years, varying from —0.88 (1940 1970) to +0.94 (1970 2000). Hence, there is no direct linear connection between WFC (which indirectly represents C02 concentration in the atmosphere) and global air temperature. The authors of this study therefore conclude that the WFC increase is not an obvious cause of the increase in global air temperature.

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Figure 5.1. Comparative dynamics of the World Fuel Consumption (WFC) and Global Surface Air Temperature Anomaly (AT), 1861-2000. The thin dashed line represents annual AT, the bold line—its 13-year smoothing, and the line constructed from rectangles—WFC (in millions of tons of nominal fuel) (Klyashtorin and Lyubushin, 2003).

1360 1875 18?0 1905 1920 1935 1950 1965 1930 1995 2010

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Figure 5.1. Comparative dynamics of the World Fuel Consumption (WFC) and Global Surface Air Temperature Anomaly (AT), 1861-2000. The thin dashed line represents annual AT, the bold line—its 13-year smoothing, and the line constructed from rectangles—WFC (in millions of tons of nominal fuel) (Klyashtorin and Lyubushin, 2003).

Divine and Dick (2006) refuted the idea that changes in sea ice extent in the Nordic Seas from the second half of the nineteenth century to the end of the twentieth century resulted from the superposition of a natural 60-80 year fluctuation and a long-term trend caused by the "greenhouse effect," because the latter was clearly pronounced in the first part of the indicated period when "any anthropogenic impact was still negligibly small."

Sorokhtin's adiabatic greenhouse-effect theory (Kuznetsov and Sorokhtin, 2000; Sorokhtin, 2001) is of particular interest in this connection. He convincingly critiqued the idea that anthropogenic emissions of greenhouse gases have a decisive influence on Earth's climate. His theory, based on simulations and observational data, suggests that the temperature distribution in the troposphere is determined by convection rather than by radiation processes. Sorokhtin formulated several consequences of his theory that contradict the results of the model simulations mentioned above. In his opinion, the main factors responsible for the state of Earth's climate are solar radiation, solar activity, and the composition, pressure, and heat capacity of the atmosphere. An increase or decrease in carbon dioxide in the atmosphere is not a cause but rather an effect of the temperature change because the solubility of this gas in water decreases with increasing water temperature. The same conclusion was drawn earlier by Monin and Shishkov (1992). Aleksandrov et al. (2004) conclude that the "observed Arctic Basin variations in air temperature are in many respects inconsistent with the presumed climate changes simulated by climate models as responses to the greenhouse effect'' (p. 138-140).

In order for climate models to estimate climate change for any time interval, they must include the principal mechanisms leading to these changes. These models must describe and explain the observed state and variability of atmospheric circulation, air temperature, ocean circulation, sea ice movement, and many other parameters; unfortunately, these climate models are presently unable to do this sufficiently well. Therefore, we agree with Kondratyev (2004, p. 121) that the "observational data ... by no means contain a clear confirmation of the existence of anthropogenically determined global warming,'' while "the results of numerical climate modeling substantiating a hypothesis of greenhouse global warming and supposedly consistent with the observational data present no more than adjustment to the observational data.'' Many well-known scientists hold the same opinion (about 80 publications by such "unorthodox" authors are cited in Kondratyev (2004). Many scientists oppose the "greenhouse theory.'' Dobrovolsky (2000, 2002) summarizes the opinion of many alternative environmentalists worldwide that scientific data refute the existence of the greenhouse crisis. They are supported by dozens of prominent climatologists, whose studies are also reviewed by Dobrovolsky (2000, 2002) and Schulte (2008). However, the majority of climatologists favor the hypothesis of greenhouse global warming (Oreskes, 2004; Oreskes et al., 2008). The problem is that polarized viewpoints seem to have hardened into belief systems, almost like religions, whereas there are insufficient data to be certain about causes of climate change. As Tom Sawyer said in Mark Twain's classic: "Making predictions is difficult, especially about the future.''

While many climatologists are convinced of the decisive role of the accumulation of anthropogenic greenhouse gases in the atmosphere as the cause of a future catastrophic warming of the Earth with a significant decrease in the Arctic Ocean ice cover, this theory has the following generic weaknesses:

— There are large discrepancies in the results of simulations of climate change using coupled atmosphere-ocean models, which testifies to the uncertainties inherent in the models.

— These models are unable to simulate real historic climate changes.

— There have always been fluctuations in the Earth's climate that lie within the range of warming in the 20th century.

— The evidence of global warming (global warming, glacier retreat, sea surface warming, ...) began prior to large scale CO2 emissions (^1850-1880) and the rate has not been changed much with increased CO2 emissions over time.

— The temperature increase in the 20th century associated with a 100-ppm increase in CO2 is much smaller than the temperature change associated with 100-ppm variations in ice age cycles.

In addition to these generic issues, the following inconsistencies occur in regard to specifically Arctic phenomena:

— Thickness changes in landfast ice of the Arctic Seas, where only thermodynamic processes are active, are small and considered to be unreliable.

— Significant "thinning" of drifting ice during the last few decades of the 20th century has no direct relevance to the increased concentration of greenhouse gases, but rather is explained by relatively short-term anomalies in ice-cover dynamics.

— Data from numerous ice-drift observations do not confirm the increased drift speed in the Arctic Basin from the middle to the end of the 20th century that is assumed by climate modelers: the average ice drift speed in the Arctic Basin for monthly and six-month periods in the periods both before 1975 (ice drift data available from manned stations and DARMS) and after 1975, through 2000 (ice drift data available from manned stations and IABP buoys), nearly coincides, while ice export to the Greenland Sea increases during cold epochs and decreases during warm epochs (see Figure 4.14).

— Analysis of sea level change in the Arctic Seas (Proshutinsky et al., 2004) for 1954-1989 (0.189 cm/year) indicated that most of these changes can be explained by natural causes (steric, inverse barometer, and wind effects) while "the residual term of the sea level rise balance assessment, 0.048 cm yr-1, may be due to an increase in the Arctic Ocean and global ocean mass associated with melting of ice caps and small glaciers and also with adjustments of the Greenland and Antarctic ice sheets to the observed climate change.

— Claims of a constant decrease in the multiyear ice in the Eurasian sector of the Arctic Basin during the second half of the twentieth century are not correct: the boundary of prevailing old ice exhibited from 1-2 years to multidecadal variations by the turn of the century was similar or even closer to the coast in comparison to that for 1950s for the seas of the eastern region.

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