Klimaforschung bei GKSS Hans von Storch Institut für Küstenforschung GKSS Forschungszentrum Malente, 7. März 2005

Haupthema: Küstenforschung How is global change affecting the coastal system? What is the present state and present change of the coastal zone? In beiden Fällen ist „Klima“ als globaler Faktor und als regionale Realisierung von überragender Bedeutung.

Coastal areas are made up of coastal sea coastal land catchment What is the coast – Somewat vagueley defined The source of anthropogenic materials such as POPs, heavy metals, nutrients Affected by climate variabiloity and change climate variability and change

Klimaforschung bei GKSS … Regionales Klima der Küste(n) Historisches Klima und Perspektiven für die Zukunft Soziales Konstrukt von Klima, Klimawandel, -forschung und -politik

Regionales Klima der Küste(n) Rezente Veränderungen des Sturmklimas und Szenarien (50-100 Jahre) Historische Veränderungen des Sturmklimas (200 und mehr Jahre) Rezente Veränderungen von Statistiken von Sturmfluten und Seegang, und Szenarien Einfluss von veränderlichen geophysikalischen Eigenschaften auf marine Ökosysteme

Institute for Coastal Research GKSS, Germany Assessing ongoing change of coastal climate. Deriving scenarios of plausible, possible futures of coastal climates. Special emphasis on wind-related aspects, i.e., wind force, storm surges and ocean waves. Special emphasis on North Sea and Baltic Sea. Participant in HIPOCAS, PRUDENCE and ENSEMBLES.

Empirical evidence about extratropical storm variability Estimates based upon pressure readings Lund and Stockholm Bärring and von Storch, 2004 Estimates based upon repair costs for dikes in Holland de Kraker, 1999 Very little evidence available

Climate risk assessments done with these models Reconstruction of past and ongoing state and change PCPnP futures (PCPnP = plausible, consistent, possible but not necessarily probable = scenarios)

NCEP Globale Reanalysen ( 210 km x 210 km ) 1958 - 2002 BAW - TELEMAC 2D Wasserstand und barotrope Strömung 21.02.1993 12 UTC REMO Windgeschwindigkeit und Richtung 21.02.1993 12 UTC HIPOCAS: Für Rekonstruktionen verwendete Modellkette Gebiet hier: Nordsee und östlicher Nordatlantik WAM sig. Wellenhöhe und Richtung 21.02.1993 12 UTC Rekonstruktionen am Beispiel einer neueren Arbeit, dem HIPOCAS Hindcast Auflösung etwa 50 x 50 km Auflösung zwischen etwa 100 m und 5km Auflösung etwa 5 x 5 km

HIPOCAS Validation Extreme values 2, 5, and 25-year return values with 90% Confidence limits based on 1000 Monte Carlo simulations.

Vergleich von Proxies und Rekonstruktionen (WASA Update / Alexandersson) Vorteile beider Methoden, wenn in Kombination angewandt.

C/year Stormcount 1958-2001 t <  t >  Weisse , pers. comm. Linearer Trend Stuerme in Anzahl/Jahr ermittelt fuer den Zeitraum 1958-2001.  alle Stuerme >= Bft 8 (17.2m/s)   Relativer Trend, d.h. Aenderungen relativ zum langjaehrigen Mittelwert. beachte, dass der bei schweren Stuermen oft nur 1-3 betraegt. Signifikanz wurde mit Hilfe Mann-Kendall Test getestet. Da wo die Nullhypothese "kein Trend" mit 5% Irrtumswahrsch. verworfen werden muss wurde das 95% Konfidenzintervall "D" fuer den Trend "x" geplottet (x-D <= x <= x+ D) Weisse , pers. comm.

Ocean wave height reconstruction Oben Trends jaehrliche 99% Percentil sig. Wellenhoehe, Punkte: geplante Windparks, Kreuz: Nordseeboje (Beobachtungen), Solid: HIPOCAS RCM/NCEP reconstruction Dashed: WASA/DNMI SLP reconstruction Red: Local observations 50%, 90%, 95% and 99%iles.

A2 - CTL: changes in 99 %-iles of wind speed (6 hourly, DJF): west wind sector selected (247.5 to 292.5 deg) HIRHAM RCAO REMO5 CLM Woth, pers.comm.

Projections for the future / surge meteorological forcing: HIRHAM / RCA Differences in inter-annual percentiles of surge / A2 - CTL: HIRHAM Differences in inter-annual percentiles of surge / A2 - CTL: RCA Woth, pers.comm.

SREs emission scenarios: Impact on global sea level According to scenario A2 and the specific set of GCM / RCMs, water level may rise in extreme situations by as much as 40 cm + 30 cm = 70 cm along the German North Sea coast. IPCC, 2001 SREs emission scenarios: Impact on global sea level

Historisches Klima und Perspektiven für die Zukunft Globale Sichtweise. Klimasimulation mit globalem Klimamodell (ECHO-G) von Holozän und Eem. Szenarien IPCC A2 und B2. Nutzung dieser Langzeitsimulationen zur Methodenkritik, z.B. Hockeystick.

Conceptual models Minimum complexity models which sum-up the 1st order processes with the purpose to explain the basic features. Not meant to predict spatial and temporal details, but to “explain” the dynamics and sensitivities of climate. Example: 0-dimensional energy balance model (EBM) of Earth surface temperature

Quasi-realistic Models Models of maximum complexity, which feature as many processes as is possible given the computational resource. Meant as a tool to simulate in space-time detail the trajectory of climate. Quasi-realistic models do not “explain” but allow for “numerical experiments”.

Quasi-realistic models

Quasi-realistic climate models … … are dynamical models, featuring discretized equations of the type Are 20 proxies enough to reconstruct the global mean temperature? with state variables Ψk and processes Pi,k. The state variables are typically temperature of the air or the ocean, salinity and humidity, wind and current. … because of the limited resolution, the equations are not closed but must be closed by “parameterizations”, which represent educated estimates of the expected effect of non-described processes on the resolved dynamics, conditioned by the resolved state. Do temperature and precipitation proxies yield the same NAO reconstruction?

atmosphere

ocean

ECHO-G simulations „Erik den Røde” (1000-1990) and “Christoph Columbus” (1550-1990) with estimated volcanic, GHG and solar forcing

Extratropical storminess Pre-industrial: 1550-1850 change from pre-industrial to industrial period 1850-2000

Same index as function of time. .. .. .. .. Mean number of storm days in winter per grid point averaged over the pre-industrial and industrially influenced periods of Erik and over the climate scenario A2 for each hemisphere. Same index as function of time. c) and d) same, but for North Atlantic region (90W-30E) and North Pacific region (150E-90W).

Mimicking MBH?

Soziales Konstrukt von Klima, Klimawandel, -forschung und -politik Survey unter Klimaforschern in 1996 und 2003 (Bray) Diskussion von Adaptation und Mitigation (Spiegel-Interview in 2003) Darstellung des Klimaproblems in Medien, durch Wissenschaftler (mit Stehr)

Bray‘s survey We can say for certain that, without change in human behavior, global warming will definitely occur some time in the future. Climate change is mostly the result of anthropogenic causes. (Top: histogram, bottom: boxplot; 1 = strongly agree; 7 = strongly disagree; N = total number of responses)