IPCC (2007) and
Lomborg (2007)
In its Fourth Assessment Report, the IPCC states (Trenberth et al. 2007: page 311 therein): "... there is no significant trend in flood occurrences of the Elbe within the last 500 years (Mudelsee et al., 2003)."

Lomborg (2007: page 82 therein) reports "Likewise, in Europe, a study of the two major rivers, the Oder and the Elbe (which flooded Prague and Dresden in 2002), showed that over the past centuries summer floods show no trend and winter floods have actually decreased.", referring to Mudelsee et al. (2003).

As lead author of the cited paper, I remark that both citations are not entirely correct.

  • Over the past 500 years, winter as well as summer flood risk trends exhibit significant changes (Elbe, Oder).
  • Over the past approximately 100 years, winter flood risk trends exhibit significant downward trends (Elbe, Oder).
  • Over the past approximately 100 years, summer flood risk trends do not exhibit significant up- or downward trends (Elbe, Oder).
Estimating trends in flood risk is an inherently difficult statistical task. Few reliable and statistically robust results exist up to this date. Utmost care is required when reporting results or making general statements about the relation between climate changes and flood risk changes.

Hannover, 13 November 2007, Manfred Mudelsee


Lomborg B (2007) Cool It. The Skeptical Environmentalist's Guide to Global Warming. Knopf, New York, 253 pp.

Mudelsee M, Börngen M, Tetzlaff G, Grünewald U (2003) No upward trends in the occurrence of extreme floods in central Europe. Nature 425:166169.

Trenberth KE, Jones PD, Ambenje P, Bojariu R, Easterling D, Klein Tank A, Parker D, Rahimzadeh F, Renwick JA, Rusticucci M, Soden B, Zhai P (2007) Observations: surface and atmospheric climate change. In: Solomon S, Qin D, Manning M, Marquis M, Averyt K, Tignor MMB, Miller HL Jr, Chen Z (Eds.) Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, 235336.

Manfred Mudelsee

Climate Risk Analysis