A century of climate change in Alaska:Models vs. Reality

(based on a true story)

Dr. Richard A. KeenUniversity of Colorado, Boulder (Emeritus)

richard.keen@colorado.eduNWS climate observer, Coal Creek Canyon, CO

IPCC WG-I AR-5 expert reviewer

Alaska

Colorado

Why Alaska? Alaska (and Colorado) are predicted to have more warming

than any of the other states: 4oC (7oF) by 2100

Alaska is a Global

Warming poster child.

Part I: RealityData 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 |

Aleutian Low

Alaska

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.

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.

▲ 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

PDO/NP cycles are natural,

lasting 20 - 66 years, typically

around 30 years.

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 another5 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: ModelsAlaska predicted to warm 4oC by 2100 (IPCC)

Alaska

Alaska: 4oC warming by 21001oC 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”

‒ + ‒ +

NP/PDO + or –

Right, PDO! Alaska’s climate variations show the effect of the NP/PDO. The

models don’t.

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.