Colloquium “Searching the climate record for a human signal” 31 aug 2011

Climate scientists must communicate uncertainties and their consequences

Bart van den Hurk

(Involved in KNMI Climate Change Scenarios)

Colloquium “Searching the climate record for a human signal” 31 aug 2011

Climate scientists must communicate uncertainties and their consequences

Emphasised by antagonists of anthropogenic greenhouse

warming (AGW) theory

Emphasised by “alarmists”

Originate from• natural variability• imperfect models & knowledge• unknown future developments

Originate from• physical hazards• vulnerability of society• perception/political view

If there is uncertainty, there is risk

Colloquium “Searching the climate record for a human signal” 31 aug 2011

If there is uncertainty, there is risk

Average temperature change 2090-2100 relative to 1990

Pro

babili

tyuncertainty

0Cannot

be claimed

Defined as (politically)“relevant”

by e.g. Dutch Delta Committee

risk

Colloquium “Searching the climate record for a human signal” 31 aug 2011

Positioning KNMI’06 scenarios

Average temperature change 2090-2100 relative to 1990

Pro

babili

ty

0

G G+ WW+

Designed to explore possible future conditions

not presented as forecasts Supporting adaptation of society

to extreme conditions

relevance of different scenarios varies across applications

Colloquium “Searching the climate record for a human signal” 31 aug 2011

ConcludingUncertainties and risks are connected

Ignoring possibility of AGW or alarmist exaggerating implies strong scientific bias and not in the spirit of KNAW code of conduct

Making future explorations is relevant. Scenarios are useful tools for this