How does rising atmospheric CO2 affect marine organisms?

Click to locate material archived on our website by topic

Two Centuries of Runoff and Floods in Sweden
Lindstrom, G. and Bergstrom, S.  2004.  Runoff trends in Sweden 1807-2002.  Hydrological Sciences Journal 49: 69-83.

One of the core claims of died-in-the-wool climate alarmists is that floods will become more frequent and ferocious as the earth warms.  Hence, it is no surprise that during the last fifteen years, which Lindstrom and Bergstrom describe as having been "remarkably wet in Sweden," a number of floods occurred that garnered "considerable media attention."  They also note that outside of Sweden, "spectacular flood events in the rivers Rhine, Vistula and Elbe have received considerable attention," and that "the link between global warming and the occurrence of floods has been discussed," which is a polite way of saying that the global warming-flood connection has been hyped to high heaven.

What was done
To provide an historical perspective on the claim that global warming brings more numerous and more severe floods, the authors of this study analyzed runoff and flood data from more than 60 discharge stations scattered throughout Sweden, some of which provide information stretching as far back in time as the early to mid 1800s, when Sweden and the world were still experiencing the cold of the Little Ice Age.

What was learned
"In Sweden," say the authors, "the last 20 years of the past century were unusually wet, with a runoff anomaly of +8% compared with the century average."  However, they also report that "the runoff in the 1920s was comparable to that of the two latest decades," and that "the few observation series available from the 1800s show that the runoff was even higher than recently."  With respect to floods, they note that "flood peaks in old data are probably underestimated," which "makes it difficult to conclude that there has really been a significant increase in average flood levels," as is often claimed by climate alarmists and reported in the media.  In addition, they say that "no increased frequency of floods with a return period of 10 years or more, could be determined."

With respect to the generality of their findings, Lindstrom and Bergstrom say that conditions in Sweden "are consistent with results reported from nearby countries: e.g. Forland et al. (2000), Bering Ovesen et al. (2000), Klavins et al. (2002) and Hyvarinen (2003)," and that, "in general, it has been difficult to show any convincing evidence of an increasing magnitude of floods (e.g. Roald, 1999) in the near region, as is the case in other parts of the world (e.g. Robson et al., 1998; Lins and Slack, 1999; Douglas et al., 2000; McCabe and Wolock, 2002; Zhang et al., 2001)."

What it means
Clearly, for Sweden, several neighboring countries, and many other parts of the world, there is simply no compelling real-world evidence to support the climate-alarmist claim that global warming leads to more frequent and severe flooding.  In fact, the lack of such evidence over the last century -- which is typically described by climate alarmists as having experienced an increase in global temperature that is unprecedented over the past one to two millennia -- should surely qualify as proof of the falsity of their warming-induced flooding claim.

Bering Ovesen, N., Legard Iversen, H., Larsen, S., Muller-Wohlfeil, D.I. and Svendsen, L.  2000.  Afstromningsforhold i danske vandlob.   Faglig rapport fra DMU, no. 340. Miljo- og Energiministeriet.  Danmarks Miljoundersogelser, Silkeborg, Denmark.

Douglas, E.M., Vogel, R.M. and Kroll, C.N.  2000.  Trends in floods and low flows in the United States: impact of spatial correlation.  Journal of Hydrology 240: 90-105.

Forland, E., Roald, L.A., Tveito, O.E. and Hanssen-Bauer, I.  2000.  Past and future variations in climate and runoff in Norway.  DNMI Report no. 1900/00 KLIMA, Oslo, Norway.

Hyvarinen, V.  2003.  Trends and characteristics of hydrological time series in Finland.  Nordic Hydrology 34: 71-90.

Klavins, M., Briede, A., Rodinov, V., Kokorite, I. and Frisk, T.  2002.  Long-term changes of the river runoff in Latvia.  Boreal Environmental Research 7: 447-456.

Lins, H.F. and Slack, J.R.  1999.  Streamflow trends in the United States.  Geophysical Research Letters 26: 227-230.

McCabe, G.J. and Wolock, D.M.  2002.  A step increase in streamflow in the conterminous United States.  Geophysical Research Letters 29: 2185-2188.

Roald, L.A.  1999.  Analyse av lange flomserier. HYDRA-rapport no. F01, NVE, Oslo, Norway.

Robson, A.J., Jones, T.K., Reed, D.W. and Bayliss, A.C.  1998.  A study of national trends and variation in UK floods.  International Journal of Climatology 18: 165-182.

Zhang, X., Harvey, K.D., Hogg, W.D. and Yuzyk, T.R.  2001.  Trends in Canadian streamflow.  Water Resources Research 37: 987-998.

Reviewed 30 June 2004