Effects of climate change in Europe

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Past 1,000 Years

For full article see Past 1,000 years in Europe

The story from Europe seems quite clear. There was a several-hundred-year period in the first part of the last millennium that was significantly warmer than it is currently. In addition, there is reason to believe the planet may be on a natural climate trajectory that is taking it back to a state reminiscent of the Medieval Warm Period. There is nothing we can do about this natural cycle except, as is implied by the study of Berglund (2003), reap the benefits. Berglund identified several periods of expansion and decline of human cultures in northwest Europe and compared them with a history of reconstructed climate “based on insolation, glacier activity, lake and sea levels, bog growth, tree line, and tree growth.” In doing so, he determined there was a positive correlation between human impact/land-use and climate change. Specifically, in the latter part of the record, where both cultural and climate changes were best defined, there was, in his words, a great “retreat of agriculture” centered on about AD 500, which led to “reforestation in large areas of central Europe and Scandinavia.” He additionally notes that “this period was one of rapid cooling indicated from tree-ring data (Eronen et al., 1999) as well as sea surface temperatures based on diatom stratigraphy in [the] Norwegian Sea (Jansen and Koc, 2000), which can be correlated with Bond’s event 1 in the North Atlantic sediments (Bond et al., 1997).”

Next came what Berglund calls a “boom period” that covered “several centuries from AD 700 to 1100.” This interval of time proved to be “a favourable period for agriculture in marginal areas of Northwest Europe, leading into the so-called Medieval Warm Epoch,” when “the climate was warm and dry, with high treelines, glacier retreat, and reduced lake catchment erosion.” This period “lasted until around AD 1200, when there was a gradual change to cool/moist climate, the beginning of the Little Ice Age … with severe consequences for the agrarian society.”

Temperature

For full article see Temperature in Europe

With respect to temperature, Hanna et al. (2004) indicate that of the handful of locations they examined for this variable, all stations experienced a net warming since the mid-1800s. The warming, however, was not linear over the entire time period. Rather, temperatures rose from their coldest levels in the mid-1800s to their warmest levels in the 1930s, whereupon they remained fairly constant for approximately three decades. Then came a period of rapid cooling, which ultimately gave way to the warming of the 1980s and 1990s. However, it is important to note that the warming of the past two decades has not resulted in temperatures rising above those observed in the 1930s. In this point the authors are particularly clear, stating emphatically that “the 1990s was definitely not the warmest decade of the 20th century in Iceland, in contrast to the Northern Hemisphere land average.” In fact, a linear trend fit to the post-1930 data would indicate an overall temperature decrease since that time.

Paleoclimatic studies from Europe provide more evidence is for the global reality of the solar-induced millennial-scale oscillation of temperatures pervading both glacial and interglacial periods. The Current Warm Period can consequently be viewed as the most recent manifestation of this recurring phenomenon and unrelated to the concurrent historical increase in the air’s CO2 content.

Precipitation

For full article see Precipitation trends in Europe

Alexandrov et al. (2004) analyzed a number of twentieth century datasets from throughout Bulgaria, finding “a decreasing trend in annual and especially summer precipitation from the end of the 1970s” and “variations of annual precipitation in Bulgaria showed an overall decrease.” In addition, they report the region stretching from the Mediterranean into European Russia and the Ukraine “has experienced decreases in precipitation by as much as 20% in some areas.”

In a study covering the longest time span of all, Linderholm and Chen (2005) derived a 500-year winter (September-April) precipitation chronology from tree-ring data obtained within the northern boreal forest zone of west-central Scandinavia. They found considerable variability, with the exception of a fairly stable period of above-average precipitation between AD 1730 and 1790. Additionally, above-average winter precipitation was found to have occurred in 1520-1561, 1626-1647, 1670-1695, 1732-1851, 1872-1892, and 1959 to the present, with the highest values reported in the early to mid-1500s; below-average winter precipitation was observed during 1504-1520, 1562-1625, 1648-1669, 1696-1731, 1852-1871, and 1893-1958, with the lowest values occurring at the beginning of the record and the beginning of the seventeenth century.

These findings demonstrate that non-CO2-forced wetter and drier conditions than those of the present have occurred repeatedly within this region throughout the past five centuries. Similar extreme conditions may therefore be expected to naturally recur in the future.

Floods

For full article see Floods in Europe

The IPCC authors report “a catastrophic flood occurred along several central European rivers in August 2002. The floods resulting from extraordinarily high precipitation were enhanced by the fact that the soils were completely saturated and the river water levels were already high because of previous rain. Hence, it was part of a pattern of weather over an extended period” (IPCC, 2007-I, p. 311). While admitting “there is no significant trend in flood occurrences of the Elbe within the last 500 years,” the IPCC nevertheless says the “observed increase in precipitation variability at a majority of German precipitation stations during the last century is indicative of an enhancement of the probability of both floods and droughts” (Ibid.)

Reynard et al. (2001) used a continuous flow simulation model to assess the impacts of potential climate and land use changes on flood regimes of the UK’s Thames and Severn Rivers; and, as might have been expected of a model study, it predicted modest increases in the magnitudes of 50-year floods on these rivers when the climate was forced to change as predicted for various global warming scenarios. However, when the modelers allowed forest cover to rise concomitantly, they found that this land use change “acts in the opposite direction to the climate changes and under some scenarios is large enough to fully compensate for the shifts due to climate.” As the air’s CO2 content continues to rise, there will be a natural impetus for forests to expand their ranges and grow in areas where grasses now dominate the landscape. If public policies cooperate, forests will indeed expand their presence on the river catchments in question and neutralize any predicted increases in flood activity in a future high-CO2 world.

It is clear that for most of Europe, there are no compelling real-world data to support the claim that the global warming of the past two centuries led to more frequent or severe flooding.

Glaciers

For full article see Glaciers in Europe

In the Swiss Alps, Huss et al. (2008) examined various ice and meteorological measurements made between 1865 and 2006 in an effort to compute the yearly mass balances of four glaciers. The most obvious conclusion to be drawn from these data is the fact that each of the four glaciers has decreased in size. But more important is the fact that the rate of shrinkage has not accelerated over time, as evidenced by the long-term trend lines we have fit to the data. There is no compelling evidence that this 14-decade-long glacial decline has had anything to do with the air’s CO2 content.

Not all European glaciers, however, have experienced continuous declines since the end of the Little Ice Age. Hormes et al. (2001) report that glaciers in the Central Swiss Alps experienced two periods of readvancement, one around 1920 and another as recent as 1980. In addition, Braithwaite (2002) reports that for the period 1980-1995, “Scandinavian glaciers [have been] growing, and glaciers in the Caucasus are close to equilibrium,” while “there is no obvious common or global trend of increasing glacier melt.”

In considering the results of the studies summarized above, among others, it appears there is no correlation between atmospheric CO2 levels and glacier melting or advancement in Europe. Several European glaciers are holding their own or actually advancing over the past quarter-century, a period of time in which the IPCC claims the earth has warmed to its highest temperature of the past thousand years.

Other Effects

Although many people have claimed that rising temperatures and CO2 concentrations lead to more pollen and more hay fever (Wayne et al., 2002), the analysis of Frei (2009) suggests that such is not the case in Switzerland. Frei analyzed time series of pollen counts and pollen season lengths in order to identify their trends, based on epidemiological data for hay fever in Switzerland for the period 1926 to the present and pollen data from 1969 to the present. Results indicated that pollen exposure has been decreasing since the beginning of the 1990s, whereas the rate of hay fever prevalence has remained “approximately unchanged in this period but with a slight tendency to decrease.”

References

Alexandrov, V., Schneider, M., Koleva, E. and Moisselin, J.-M. 2004. Climate variability and change in Bulgaria during the 20th century. Theoretical and Applied Climatology 79: 133-149.

Berglund, B.E. 2003. Human impact and climate changes—synchronous events and a causal link? Quaternary International 105: 7-12.

Bond, G., Showers, W., Cheseby, M., Lotti, R., Almasi, P., deMenocal, P., Priori, P., Cullen, H., Hajdes, I. and Bonani, G. 1997. A pervasive millennial-scale climate cycle in the North Atlantic: The Holocene and late glacial record. Science 278: 1257-1266.

Braithwaite, R.J. 2002. Glacier mass balance: the first 50 years of international monitoring. Progress in Physical Geography 26: 76-95.

Eronen, M., Hyvarinen, H. and Zetterberg, P. 1999. Holocene humidity changes in northern Finnish Lapland inferred from lake sediments and submerged Scots pines dated by tree-rings. The Holocene 9: 569-580.

Frei, T. 2009. Trendwende bei der Pollinose und dem Pollenflug? Allergologie 32(4): 123-127.

Hormes, A., Müller, B.U. and Schlüchter, C. 2001. The Alps with little ice: evidence for eight Holocene phases of reduced glacier extent in the Central Swiss Alps. The Holocene 11: 255-265.

Huss, M., Bauder, A., Funk, M. and Hock, R. 2008. Determination of the seasonal mass balance of four Alpine glaciers since 1865. Journal of Geophysical Research 113: 10.1029/2007JF000803.

Jansen, E. and Koc, N. 2000. Century to decadal scale records of Norwegian sea surface temperature variations of the past 2 millennia. PAGES Newsletter 8(1): 13-14.

Linderholm, H.W. and Chen, D. 2005. Central Scandinavian winter precipitation variability during the past five centuries reconstructed from Pinus sylvestris tree rings. Boreas 34: 44-52.

Reynard, N.S., Prudhomme, C. and Crooks, S.M. 2001. The flood characteristics of large UK rivers: Potential effects of changing climate and land use. Climatic Change 48: 343-359.

Related Links

Effects of climate change in Africa

Effects of climate change in Asia

Effects of climate change in North America

Effects of climate change in South America

Effects of climate change at the Poles

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