-- Laurel Christensen has seen Michigan's warming trend first-hand. Christensen, who owns Northfield Farms and has worked in the plant business for 33 years, says plant species usually found in more southern climes -- like plumbago, crocosmia lucifer, lacecap hydrangea and even calla lilies -- are now grown and sold in Michigan. Her ground-level observations are reflected in a new National Arbor Day Foundation Hardiness Zone map showing rising temperatures and adding to the swirl of the nation's discussion about global warming.
The map shows the average low temperatures in most of Michigan and much of the United States have risen since 1990, the last time the U.S. government updated the data.
Christensen, whose company supplies landscapers and retail garden centers, didn't need the official data when it came to growing one of her favorites, creeping lily-turf with its spikes of violet flowers. It was once limited to warmer places such as Missouri and Kentucky, but she now sells it by the caseloads. At first, "we didn't grow it because it wasn't reputed to be hardy and people had trouble growing it," Christensen said Tuesday.
"The demand was always there, but the success (in growing it) wasn't there until recently." The multi-colored hardiness map -- upon which gardeners rely to identify what types of trees and flowers will flourish where -- suggests a nationwide warming trend and the increased chances of survival of flora in areas where two decades ago they wouldn't have stood a chance. The new map, based on 15 years of climate data, now places most of Michigan's Lower Peninsula in Zone 6, marking its average winter low between 0 and -10 degrees.
That's a warming up since 1990, when many of the same areas were in Zone 5, with an average low between -10 and -20 degrees. The maps were developed from data gathered by the National Oceanic and Atmospheric Administration's 5,000 stations. The shift places much of Michigan in the same hardiness zone with southern Indiana and Ohio, but also mountainous areas of North Carolina, New Mexico, California and Arizona.
Jeff Andresen, state climatologist, said the map confirms what scientists have observed in recent years. "The climate is warming in our region," he said. One possible explanation, he offered, is a lack of cold air moving into Michigan from Canada and the Arctic.
The result is a rise in winter's minimum temperatures since 1980, with northern parts of the state rising as much as 4 to 5 degrees. "That's a fairly large number," he said. The warming trend has been observed in middle and high latitudes around the world, he added.
"It is consistent with projections of a warmer world in the future," said Andresen, also an agricultural meteorologist at Michigan State University's geography department. Released just as scientists and politicians are wrangling over how much and how fast the planet is warming, the map -- with its dramatic temperature shifts -- has generated some controversy. Some commercial growers are not eager to adopt the new map, pointing out that it doesn't account for the unpredictably bad winter that can still strike and kill less hardy varieties.
"I don't care what the map says," said Marvin Wiegand of Ray Wiegand's Nursery and Garden Center, which grows trees, shrubs, plants and perennials in Lenox Township. "I can't afford to grow something for three or four years and have it die in the fifth year and have it thrown away." Meanwhile, officials at the U.
S. Department of Agriculture, which last published its own hardiness map in 1990, refuse to take a position on the new map. Instead, the department has contracted with Oregon Climate Service to publish an updated map, based on 30 years of climate history, doubling the time period accounted for in its 1990 version.
The 15-year time frame was also used in a 2003 draft -- which the department killed before it was published -- that showed a similar warming trend. The additional data from the extra 15 years will reach back to cooler years and as a result smooth out weather fluctuations, raising concerns from critics about whether the department is reacting to political pressure to downplay warming. "Issues of global warming had nothing to do with scrapping the map," said Kim Kaplan, spokeswoman for the Agricultural Department.
She said the draft was scrapped because it was incompatible with modern computer mapping software. She added, though, that those seeking evidence of warming should look elsewhere, because time periods of 15 and even 30 years are too brief to extrapolate climate trends. Still, the apparent uptick in temperatures encourages Suzanne Brousseau, a horticulturist from Northfield Township.
She is determined to have her -- also known as chaste trees -- live through the next several winters. Though her first tree lived a few years only to succumb to a winter chill, gentler winters -- and full sun exposure, mulching and burlap layers -- will hopefully spare two saplings she planted this summer. When they survive, "I say, 'yay!
I won! I beat the system!' And then I see if it makes it next year.
" You can reach Catherine Jun at (248) 647-7429 or cjun@detnews.com. Day trips to Canada plunge to new low Boaters fear changes in law Lions' Rogers won't be charged Midnight marchers protest high crime rate in Detroit -- Laurel Christensen has seen Michigan's warming trend first-hand.
News RSS