Implications for Future Risk Management Strategies - Climate Change and Infrastructure, Urban Systems, and Vulnerabilities - page 65

Table 8. Climate hazards and coastal flooding events

Table 8. Climate hazards and coastal flooding events

Baseline 2020s 2050s 2080s

1- in 10-yr flood to reoccur, ~ once every ~ once every ~ once every 3 ~ once every 1

on average 10 years 9 (8-10) years (3-6) 8 years (1-33)years

Flood heights (in ft) associated 6.3 6.5 (6.5 -6.8) 6.8 6.8 (7.0 -7.3) 7.5 7.1 (7.4-8.2) 8.5

with 1- in-10 yr flood

1- in 100 yr flood to reoccur, ~ once every ~ once every 60 ~ once every 30 ~ once every 15

on average 100 years (65-80) 85 years) (35-55) 75 years (15-35) 45 years

Flood heights (in ft) associated 8.6 8.7 (8.8 -9.0) 9.1 9.0 (9.2-9.6) 9.7 9.4 (9.6-10.5) 10.7

with 1-in-100 yr flood

1- in 500-yr flood to reoccur, ~ once every ~ once every 370 ~ once every 240 ~ once every 100

on average 500 years (380-450) 470 years (250-330) 380 years (120-250 (300 years

Flood heights (in ft) associated 10.7 10.9 (10.9-11.2) 11.2 11.2 (11.4 to 11.7) 11.9 11.5 (11.8-12.6) 12.9

with 1-in 500 yr flood

*NOTE: Does not include the rapid ice-melt scenario. Numbers inside parentheses indicate central range (67% of model-
based distribution); numbers outside are full range.

Table 9. Qualitative changes in extreme events

Probable Direction

Extreme Throughout 21st

Event Century Likelihood

NOTE:
>50% is used when
the likelihood can
be estimated with
reasonably good
precision, and 33 to
66% is used when
there is not high
confidence in the
likelihood estimate.

Intense

More likely than not

hurricanes

Nor'easters Unknown

Extreme More likely than not

winds

These definitions of likelihood are used by the IPCC (2007) to describe potential outcomes:
> 99% Virtually certain
>95% Extremely likely
>90% Very likely
>66% Likely
>50% More likely than not
33 to 66% About as likely as not