Transcript A century of climate change in Alaska: Models vs. Reality (based on a true story) Dr.

A century of climate
change in Alaska:
Models vs. Reality
(based on a true story)
Dr. Richard A. Keen
University of Colorado, Boulder (Emeritus) [email protected]
NWS climate observer, Coal Creek Canyon, CO
IPCC WG-I AR-5 expert reviewer
Why Alaska? Alaska (and Colorado) are
predicted to have more warming than any
of the other states: 4oC (7oF) by 2100
Alaska
 Colorado
Alaska is a
Global Warming
poster child.
Part I: Reality
Data analysis contracted by NPS (Thanks!) and presented
in NPS documents …
Monitoring Seasonal and Long Monitoring Seasonal and
Long-term Climate Changes/Extremes in the
Central Alaska Network (CAKN)
Pamela J. Sousanes, Richard A. Keen, Kelly T. Redmond, and David B. Simeral
• Temperature stations:
• 95 NWS co-op stations catalogued with
periods of record from 1 to 111 years
•
38 in and near Denali
•
50 in and near Wrangell-St. Elias
•
7 in and near Yukon-charley
• 50 stations have records > 10 years
• Very long term stations, or merged
combination of stations, yield 9 time
series >88 years.
• Climatic Oath:
• First do no harm (to the data)
One station’s record
Nine stations combined. 5-year means reveal decadal
changes but retain ~20 independent samples.
Alphabet Soup: correlate temperature with
some indices used to describe the climate,
from NOAA/ESRL, to find “cause”.
| NP | PDO | TREND | PNA | WP | NAO |
EP/NP | NAOJ | NOI | QBO | GAM | SOI |
AAO | AO | MJO | ESPI | ENSO | MEI | Nino
1+2 | Nino 3 | Nino 3.4 | Nino 4 | BEST | TP
EOF SST | ONI | Nino 1+2 | Nino 3 | Nino 3.4 |
Nino 4 | TNI | WHWP | PWP | Tropical Pacific
EOF SST | MDR | MDRMTROP | TNA | TSA |
CO2 | WHWP | AMO | AMM | NTA | CAR | TSI
| ASAP | PDQ | OMG | MOJO | GOJO | BO |
NP = North Pacific index,
a measure of the atmospheric pressure over the North
Pacific Ocean.
When the pressure goes down, the Low is stronger, and
Alaska gets warmer southerly winds.
Alaska
Aleutian Low
Temperature and NP:
When pressure goes down, temperature goes up.
NP explains 61% of the temperature variance (R=0.79)
The NP is the atmospheric
component of the oceanic PDO
(pronounced Pee-Dee-Oh)
• The name means..
• Pacific Decadal Oscillation
• Because it’s in the Pacific, and the
feedback loop alternates (Oscillates)
every few Decades.
• The last switch – to warm Alaska – was in
1977.
• It may have switched back to cold Alaska
in 2006 – but it takes a decade to be sure.
PDO/NP cycles
are natural,
lasting 20 - 66
years, typically
around 30
years.
▲ Alaska Cold
▼ Alaska Warm
Fig. 2. Tree-ring based NPI reconstruction. (a) Actual and estimated Dec–May NPI for the 1900–83 calibration period:
(b) Reconstruction of Dec–May NPI from 1600–1983 based on North Pacific tree-ring data. Highlighted phase shifts
identified using intervention analysis (significant at the 90% confidence limit).
Journal of Climate Volume 18, Issue 24 (December 2005): pp. 5253–5265 Tropical–North Pacific Climate Linkages over the Past Four Centuries
Rosanne D’Arrigo, Rob Wilson, Clara Deser, Gregory Wilesd, Edward Cook, Ricardo Villalba, Alexander Tudhope, Julia Cole, and Braddock Linsley
Tree-Ring Laboratory, Lamont-Doherty Earth Observatory, Palisades, New York
Subtract the NP/PDO effect to see what else is going on.
Not much – everything else is a fraction of a degree.
The Arctic Oscillation AO explains another
5 percent of the variance (66 percent total)
CO2 explains 4 percent of the residual, or 1 percent
of the total variance – about 0.2 degree C.
Part I – Data - Summary so far…
Decadal temperature variability is due mostly to
NP/PDO (61 %), with a smaller AO influence.
Internal/Natural climate variability rules Alaskan
climate change.
Solar, CO2, and other influences are minimal.
Temperature (and Snowfall , too) shows no sign of a
secular trend.
Part II: Models
Alaska predicted to warm 4oC by 2100 (IPCC)
Alaska
Alaska: 4oC warming by 2100
1oC has already happened, according to IPCC
WRONG →
WRONG →
IPCC version of Alaska’s climate history,
decadal averages courtesy Hadley CRU…
…Compared to actual observed station data.
CRU adds in 1oC of “warming”
Meanwhile, the models show a 1oC warming.
What do the models not show?
Hint: begins with “P”
Right, PDO! Alaska’s climate variations show
the effect of the NP/PDO. The models don’t.
‒
+
‒
NP/PDO + or –
+
IPCC report says this about the PDO…
They admit that the models
“underestimate the PDO”, but then say:
(Paraphrasing)
“Changes … over the last 50 years …
exceed model estimates … due to internal
variability (PDO) alone, indicating that
anthropogenic changes … may already be
underway”
IPCC: changes exceeding the modeled version
of natural changes are due to non-natural
AGW
Even though the models “underestimate”
natural changes.
“People underestimate the power of models.
Observational evidence is not very useful.”
-- John Mitchell, Chief Scientist UK Met Office
& IPCC
The power of models, indeed.
Rolling dice simulates the PDO better than
the IPCC’s billion $$ models.
An easy out: “the Climate has done so-and-so since
1950, or 1970”, while ignoring what it did before then.
Part III:
The other Hot Spot:
Colorado.
Coal Creek Canyon
co-op station.
IPCC: 2oF warming
over 30 years.
Bumper sticker science
Colorado, and the rest of the world, hasn’t warmed in
12-15 years (since 1998 or so).
IPCC Santer et al. (2011): “To separate human-caused
global warming from the “noise” of purely natural
climate fluctuations, temperature records must be at
least 17 years long.” (but not more than 32 years)
OK, how about 28 years?
0.5oF warming, ¼ of IPCC’s guess
Is 160 years enough?
Colorado: ¼-degree warming since 1849!
The overall warming gets even smaller when you
remove those adjustments NCDC added in.
What’s it all mean …
IPCC models (and modelers) predict drastic
warming for Alaska and Colorado.
Alaska and Colorado aren’t warming.
Observed climate variations are mostly due to
“natural/internal variability”, e.g., PDO etc.
IPCC models cannot replicate natural/internal
variability, so they cannot predict the climate.
The Warmers “Jimmy” the data to make it agree
with the models and look like it is warming.
The Fine Print
Anything I might have said that could sound like an opinion
is not necessarily that of any organization that receives
federal money.
I write books, too. About weather.
And a PhD thesis about climate change in the Arctic.
Conclusion: jet stream winds and storm tracks are the major factors.