“Climate change in the Netherlands”

Albert.Klein.Tank @ KNMI.nl

UGV symposium Global Change, 22 March 2006

Source: CRU/MetOffice, UK

Since 1975, warming dominates in all seasons, except Autumn

Source: Klein Tank, 2004

Source: IPCC, TAR, Chapter 2, 2001

upper 10-ptile 1961-1990

the year 1996

lower 10-ptile1961-1990

upper 10-ptile 1961-1990

the year 1996

lower 10-ptile1961-1990

“cold nights”

upper 10-ptile 1961-1990

the year 1996

lower 10-ptile1961-1990

“cold nights”

“warm nights”

Station De Bilt (The Netherlands)

warm nights

cold nights

Observed trends (days per decade)for 1951 to 2003

Alexander et al., J.Geophys.Res., 2006

Relation between relative trend bq/X required for 80% detection probability (5% level) and series length Nfor extreme events with average return period Tret

Source: Klein Tank and Können, J. Climate, 2003

21365~ retTXbq

6x

23~ NXbq

3x

Day-count indices of extremes

Geostrophic winds based on pressure triangles; blue circles are 95th and red crosses 99th percentiles (standardized units)

updated from: Alexandersson et al., Climate Res., 2000

Wind study the Netherlands 1962-2002

Smits, Klein Tank, Können, Int.J.Climatol., 2005

Observed trends for 1962-2002

Annual precipitation Netherlands

Precipitation fraction due to very wet days

1) Identify very wet days using a site specific threshold = 95th percentile at wet days in the 1961-90 period

2) Determine fraction of total precipitation in each year that is due to these days

3) Trend analysis in series of fractions

eca.knmi.nl

Groisman et al., 2005

“Amplified” response of very wet days(trends over last 50 yr)

Temperature

Source: IPCC TAR, 2001

Source: IPCC AR4 simulations (partly available at: climexp.knmi.nl)

+5.8°C

+1.4°C

Source: Katsman,

2006

Sea level change globally

Departures in the Eastern North Atlantic

Summer precipitation change inHadley Centre climate model simulations

blue = daily extremes

red = seasonal total precipitation

Source: Selten, Dijkstra, Kliphuis, et al., CLIVAR, 2003

simulation 19simulation 7

CHALLENGE project(62 model-simulations of August rainfall totals

in NL)

KNMI will soon present new climate change scenarios for the Netherlands, which replace the WB21 scenarios from 2000:

29 May 2006

THANKS !

htpp://eca.knmi.nl

http://www.knmi.nl/scenarios

mailto: Albert.Klein.Tank @ KNMI.nl