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Climate Shifts Changing New Weather "Normals"

As the new decade opens up, researchers are gathering data that will redefine weather pattern averages for the nation



Map courtesy ncdc.noaa.gov

As the new decade opens up, researchers are gathering data that will redefine weather pattern averages for the nation.

The "new normals" will update the averages for temperatures, rainfall and snow. A climate normal bases itself on the weather patterns of a particular region over a 30-year period. Every decade, in accordance with international agreements, the National Climate Data Center releases new temperature and rain and snowfall normals for 10,000 regions across the country.

This may sound like an academic or a laboratory exercise, but for some businessmen, utility regulators, wildlife agencies and others, tinkering with the meaning of "normal" can mean big changes. They range from future sales and budgetary issues to difficulties with songbirds and trout.

The current normals rely on weather patterns that occurred between 1971 and 2000. The new normals, which will be released later in the year, will drop the 1970s -- a decade marked by cool temperatures -- and add the hottest recorded decade in history, the 2000s.

"There's pretty big differences between those decades," said Anthony Arguez, NCDC's climate normals project manager. "Average temperatures are going to be a little higher in most regions."

Perhaps most significantly, winter averages in the upper Midwest will be warmer. Arguez anticipates a 1- to 2.5-degree-Fahrenheit change for upper Midwest temperatures in January. Preliminary data comparing minimum January temperatures and maximum July temperatures between the 1970s and the past decade also show warmer summers for the western third of the country. The southern central section of the country, including Missouri and Oklahoma, showed an overall summer cooling of about half a degree, but Arguez played down its significance.

Rain and snowfall averages are also expected to change along with the temperatures, but it's too early to tell by how much. Arguez noted a general drying in the West, but he said he wasn't sure of the scale. He doesn't expect precipitation to change as much as the temperature.

With these changes comes a pronounced effect on the industries and organizations that rely on the normals.

Industries anticipate the changes
Aside from the daily weatherman, farmers and travel agents are among many who rely on climate normals. Knowing the climate average can help determine the productivity of a crop or where the best weather for a beach vacation will be.

Power companies rely heavily on the normals. Some states use the normals to regulate gas and electric companies, but many utilities base rates on the 1971-2000 normals regardless. In recent years, the normals' inability to keep up with a warmer climate hurt some of the power companies. In that sense, many will be relieved when the new ones kick in.

"Utilities have been waiting for the 1970s to leave," Arguez said.

But some couldn't wait long and started calculating their own normals instead.

One example is Consumers Energy, which provides gas and electric power to the majority of Michigan. For a long time, the utility used the 30-year normals to forecast its sales in the year ahead. The problem was that the earlier years had much cooler averages than the more recent years. Warmer temperatures brought in less revenue than expected.

Simply put, the sales forecasts didn't match the weather.

"If you use the older normals that have a lot of cold weather, it forces your sales impacts to be higher," said Linda Clark, a gas sales forecaster for Consumers Energy.

Consumers Energy now relies on a 15-year normal, which just averages NCDC data from the most recent years. Clark says switching to the 15-year normal made her forecasts better, although they haven't been exempted from the harsh economy. At the end of each year, she compares the previous year's actual sales to her initial forecasts using both the 15- and 30-year normals. Three-fourths of the time, the 15-year normal is more reliable, she said.

But with shortened normals comes a risk of underplaying recorded changes to the climate. Even the updated 30-year normals will mask some of the temperature changes of recent history.

"When people switch over to the 1981-2010 standards, the effects on climate change aren't going to be as pronounced," Arguez said.

Other utilities adapted alternative normals years ago. Xcel Energy, which provides power in eight different states, including Minnesota, Colorado and the Dakotas, started using 20-year normals nearly 20 years ago. They're updated at the beginning of each year to add the previous year's temperatures to the averages.

Alternative normals
Utilities aren't the only organizations turning to other studies to make sense of what's to come. The Tennessee Wildlife Resources Agency recently released a climate change report that projects a mean temperature increase of 5 degrees in the state over the next 50 years.

The agency's report aimed to spell out the impact a warmer climate will have on Tennessee's species and their habitats. It found that a warmer climate could affect the paths of its migratory songbirds and threaten extinction on its only native trout.

For its part, NCDC is looking into alternate ways to determine new types of normals to compare the 30-year averages with. Since a lot of organizations use the normals to plan for the future, one way could involve updating the normals every year instead of every decade.

Another would focus on significant climate trends to help figure out a shorter period of time to base the normals on. A third is to develop a "hinge" that would place the normals on a linear trend past 1975, which Arguez said was the year the temperatures started rising. In that case, normals would be up when temperatures warm and down when temperatures cool.

These, and seven or eight other potential alternatives, all hinge on whether NCDC gets a grant it recently applied for. If that happens, the earliest they will be available is 2013.

The new normals are set to be released in phases, with the first set for June and the second by the year's end.

Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC. www.eenews.net, 202-628-6500

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