Cullen_Climate.pdf

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Seeing Climate, Seeing Change

Heidi Cullen

Climate Central

February 11, 2014

Monday, February 10, 14



Outline

Climate Change

Observations of Changing Extremes

Extreme Weather Attribution




How do we process risk?

Source: Erin Sherman, Princeton




\




Climate is what you expect,weather is what you get.

- Mark Twain




Warm period

spanning last 12,000

yrs.

Emergence of

agriculture and

civilizations.

Does

complexity demand

climate stability?

Seeing Climate: The Holocene




Seeing Change: A Warming Trend




Seeing Climate Change




Seeing Climate

ChangeDavid Keeling Mauna Loa Observatory




Outline

Observations of Changing Extremes




Climate is what you affect,weather is what gets you.- Myles Allen, Oxford University




It’s a threat.



http://slidepdf.com/reader/full/cullenclimatepdf 13/31Monday, February 10, 14



Observations: Global Temperature






Observations: U.S. Precipitation




Observations: Heavy Precipitation




If temps were not

warming, # of record

daily highs & lows

would be even.

2000s: 312,746 dailyrecord highs vs.

156,494 daily record

lows.

2010s so far: 91,383

daily record highs vs.

38,881 record lows.

Business as Usual:

20-to-1 by 2050 and

50-to-1 by 2100.

Record High vs. Low Temperature



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\

New York City, with each passing year,

faces an escalating risk of Sandy-magnitude flooding events. Sea level rise has already nearly

doubled the annual probability of a Sandy-

level flood in the New York City region

since 1950.

Sandy-like flooding could occur once

every few decades in Manhattan, and on

the order of once a year in parts of New

Jersey and coastal Connecticut with

about 4 feet of sea level rise.

Global sea level rise caused Sandy to

flood roughly 25 square miles more than itwould have, putting the homes of an

additional ~38,000 people in New Jersey

and ~45,000 in New York City below the

storm tide - and in harm's way (~83,000homes).

Changing Risk: Hurricane Sandy-like Floods

Hurricane Sandy, October 2012




Outline








Source: Zhang et al., GRL, 2013.

PI for RX1day

increased ~4%

[1.4-6.8%] over

1951-2005 due to

human forcing.

Waiting time for

early 1950’s 20-yr

event reduced to

~15-yr.

Fraction of Attributable risk =

25%.






Connecting Climate to Weather

Europe 2003

70,000+ deaths

Summer of 2003:

likely warmest in Europesince AD 1500.

Paris Temp: 104F

Stott et al., Nature, 2004




E t W th Att ib ti




Source: Kerr, Nature, 2013.

2011 Texas heat/drought:

20x more likely to occur than

50 yrs ago given same

conditions in the tropical Pacific

Ocean.

2011 Thailand flooding:

climate change did not increasethe likelihood of heavy rainfall.


M H W



Moscow Heat Wave


E t W th Att ib ti




July temperatures in 2010 were

6oC above normal, of which <2oCcan be “blamed” on warming

since 1960.

So in terms of magnitude, the

event was indeed “mostly natural”.

But the (very likely mostly

anthropogenic) warming that

occurred since 1960 increased the

probability of an event of this

magnitude from one-percent-per-

year to three-percent-per-year.

So in terms of probability, it

could be argued the event was

“mostly anthropogenic”.




Conclusions

Climate change has made some

extreme weather events more likely,

some less likely.

We do not see evidence for a strong

human influence in all weather extremes.

Natural climate variability a factor in all

events.

There can be apparently conflicting

results for the same event.

Attribution results rely heavily on

models whose limitations may not be

fully understood.

Limitations include biases and poor

sampling in observational datasets.




Source: The New Yorker, December 10, 2012 .

Thank You.

[email protected]

@HeidiCullen on twitter

mailto:[email protected]



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