Category Archives: weather forecasting

Forecasting Controversy Swirling Around Computer Models and Forecasts

I am intrigued by Fabius Maximus’ We must rely on forecasts by computer models. Are they reliable?

This is a broad, but deeply relevant, question.

With the increasing prominence of science in public policy debates, the public’s beliefs about theories also have effects. Playing to this larger audience, scientists have developed an effective tool: computer models making bold forecasts about the distant future. Many fields have been affected, such as health care, ecology, astronomy, and climate science. With their conclusions amplified by activists, long-term forecasts have become a powerful lever to change pubic opinion.

It’s true. Large scale computer models are vulnerable to confirmation bias in their construction and selection – example being the testing of drugs. There are issues of measuring their reliability and — more fundamentally — validation (e.g., falsification).

Peer-review has proven quite inadequate to cope with these issues (which lie beyond the concerns about peer-review’s ability to cope with even standard research). A review or audit of a large model often requires over a man-years or more of work by a multidisciplinary team of experts, the kind of audit seldom done even on projects of great public concern.

Of course, FM is sort of famous, in my mind, for their critical attitude toward global warming and climate change.

And they don’t lose an opportunity to score points about climate science, citing the Georgia Institute of Technology scientist Judith Curry.

Dr. Curry is author of a recent WSJ piece The Global Warming Statistical Meltdown

At the recent United Nations Climate Summit, Secretary-General Ban Ki-moon warned that “Without significant cuts in emissions by all countries, and in key sectors, the window of opportunity to stay within less than 2 degrees [of warming] will soon close forever.” Actually, this window of opportunity may remain open for quite some time. A growing body of evidence suggests that the climate is less sensitive to increases in carbon-dioxide emissions than policy makers generally assume—and that the need for reductions in such emissions is less urgent.

A key issue in this furious and emotionally-charged debate is discussed in my September blogpost CO2 Concentrations Spiral Up, Global Temperature Stabilizes – Was Gibst?

..carbon dioxide (CO2) concentrations continue to skyrocket, while global temperature has stabilized since around 2000.

The scientific consensus (excluding Professor Curry and the climate change denial community) is that the oceans currently are absorbing the excess heat, but this cannot continue forever.

If my memory serves me (and I don’t have time this morning to run down the link), backtesting the Global Climate Models (GCM) in a recent IPCC methodology publication basically crashed and burned – but the authors blithely moved on to re-iterate the “consensus.”

At the same time, the real science behind climate change – the ice cores for example retrieved from glacial and snow and ice deposits of long tenure – do show abrupt change may be possible. Within a decade or two, for example, there might be regime shifts in global climate.

I am not going to draw conclusions at this point, wishing to carry on this thread with some discussion of macroeconomic models and forecasting.

But I leave you today with my favorite viewing of Blalog’s “Chasing Ice.”

Forecasting Controversy – the Polar Vortex

Three short, amusing videos to watch while keeping warm as the snow falls in Las Vegas and most other places are plunged into subzero weather.

The Polar Vortex Explained in 2 Minutes from the White House.

This video clip, originally distributed through the Office of Science and Technology Policy, kicked off the controversy.

Rush Limbaugh Response

Rush Limbaugh, always a reliable source on science and general systems theory, says the polar vortex was invented by liberal conspirators to scare folks.

Limbaugh is Full of Hot Air

Weatherman Al Roker fired back at Limbaugh’s ‘Polar Vortex’ Conspiracy, showing a page from his meteorology textbook from way back when, defining the term,”polar vortex.”

But can the Polar Vortex – recognized as a real weather phenomenon for decades – be forecast and is it related to climate change?

Well, this year there was an interesting split between weather forecasting services. As an article reacting to the October 16 release of the NWS Long Range Forecast notes .. the commercial forecasters are telling us to brace for the return of the Arctic air in the U.S. while the federal forecasters have countered by saying another wavy vortex dipping far south is “unlikely.”

Thus, we had NOAA: Another warm winter likely for western U.S., South may see colder weather           .

Well, the National Weather Service and its Canadian counterpart missed the big cold snap in November and the current incursion of artic air to lower lattitudes, due to shifting of the polar vortex.

Accuweather and the Weather Channel, on the other hand, scored big on their forecasts.

At the same time, Internet studies do not show that Accuweather has any leg up in long range forecasting –  snow in New York, for example – beyond a few days from the release of the forecast.

Also, the scientific basis for linking climate change and these polar vortex events is tenuous, or at least multi-factor.

Thus, a recent article in Nature – Weakening of the stratospheric polar vortex by Arctic sea-ice loss – concludes [footnote numbers removed] –

Through a combination of observation-based data analysis and climate model experiments, we provide corroborative evidence for the notion that Arctic sea-ice loss over the B–K seas plays an important role in weakening the stratospheric polar vortex. Regional sea-ice reductions over the B–K seas cause not only in situ surface warming but also significant upper-level responses that exhibit positive geopotential height anomalies over Eastern Europe and negative anomalies from East Asia to the Eastern Pacific along the wave-guide of the tropospheric westerly jet. This anomaly pattern projects heavily into the climatological wave, intensifying the vertical propagation of planetary-scale wave into the stratosphere and, in turn, weakening the stratospheric polar vortex. Therefore, planetary-scale wave generation by sea-ice losses and its upward propagation during early winter months underline the link between surface climate variability and polar stratospheric variability.

The weakened stratospheric polar vortex is often followed by a negative phase of the AO at the surface, favoring cold surface temperatures across Northern Hemisphere continents during the late winter months (Supplementary Fig. 1). Several physical mechanisms for this downward coupling have been proposed. They include the balanced response of the troposphere to stratospheric potential vorticity anomalies and wave-driven changes in the meridional circulation. It is also suggested that the tropospheric response involves changes in the synoptic eddies. However, it has been difficult to isolate the key process, and the detailed nonlinear processes involved are still under investigation21

As a final remark, we note that Arctic sea-ice loss represents only one of the possible factors that can affect the stratospheric polar vortex. Other factors reported in previous works include Eurasian snow cover, the Quasi Biannual Oscillation, the El-Nino and Southern Oscillation and solar activity.

I think it’s probably possible to show – through psychological and historical studies – that human decision-making over risky alternatives is most likely to fail with respect to (a) collective choices over (b) complex outcomes where target events have relatively low probability, although possibly huge costs. This makes the climate change issue and responding appropriately to it hugely difficult.

Top image from Medical Daily