September 15, 2011
UCLA Climate Forecast Accuracy To 16 Months

A near doubling of the length of time large scale climate can be predicted.

Is it possible to make valid climate predictions that go beyond weeks, months, even a year? UCLA atmospheric scientists report they have now made long-term climate forecasts that are among the best ever predicting climate up to 16 months in advance, nearly twice the length of time previously achieved by climate scientists.

The granularity still falls far short of predicting temperatures of specific cities on specific days or when it will rain. But on a larger scale the predictions work. This has utility. Just known whether, say, summer will be more or less rainy could help guide crop choices.

Forecasts of climate are much more general than short-term weather forecasts; they do not predict precise temperatures in specific cities, but they still may have major implications for agriculture, industry and the economy, said Michael Ghil, a distinguished professor of climate dynamics in the UCLA Department of Atmospheric and Oceanic Sciences and senior author of the research.

The study is currently available online in the journal Proceedings of the National Academy of Sciences (PNAS) and will be published in an upcoming print edition of the journal.

"Certain climate features might be predictable, although not in such detail as the temperature and whether it will rain in Los Angeles on such a day two years from now," said Ghil, who is also a member of UCLA's Institute of Geophysics and Planetary Physics. "These are averages over larger areas and longer time spans."

Climate prediction over a few year time span can help guide water usage policy. Start stashing away more water in underground reservoirs before a drought even starts. Choose low water crops on low rain years - or do not even plant at all. Store more food before a drought.

What are the limits to prediction? How many things can't be known in advance due to, for example, chaotic events in the sun?

Share |      Randall Parker, 2011 September 15 07:52 AM  Climate Trends

Bruce said at September 15, 2011 8:47 AM:

NCDC suggests 1979 was the coldest winter in the US (Since 1895). And 2010 was the 15th coldest.

I wonder if they predicted those?

georgesdelatour said at September 15, 2011 11:58 AM:

When does "weather" become "climate"?

not anon or anonymous said at September 15, 2011 3:45 PM:

"When does "weather" become "climate"?"

When if fits the narrative.

not anon or anonymous said at September 15, 2011 3:45 PM:

"When does "weather" become "climate"?"

When it fits the narrative.

Engineer-Poet said at September 15, 2011 7:03 PM:
When does "weather" become "climate"?
When it's a multi-decade moving average.
Placebo said at September 15, 2011 8:46 PM:

What is their definition of "accurate"?

Bruce said at September 16, 2011 7:11 AM:

"When does "weather" become "climate"?"

When its convenient to those seeking grant money for their next chicken little type prediction.

LAG said at September 16, 2011 6:27 PM:

Where, exactly, did they perform this prodigy?

John Moore said at September 17, 2011 10:11 PM:

Many things cannot be predicted to to chaos in the atmosphere and the atmosphere/ocean systems. You don't need to go to the sun to find huge amounts of chaos.

In fact, chaos was discovered by a meteorologist building an early weather model.

Georg Felis said at September 22, 2011 2:42 PM:

Big whoop. The Farmers Almanac has been making predictions a year in advance for ages, with far higher accuracy rate than the current crop of dartboard PHDs.

Randall Parker said at September 23, 2011 9:36 PM:

John Moore,

I do not think we can know at this point just how much chaos will pose an obstacle for longer range climate predictions. We'll only know as the years go by as we watch how accurate the climate models get.

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