Oct. 20 (Bloomberg) -- Eric Hamacher came to Oregon from California's Napa Valley in 1995 to make wine from pinot noir, a temperamental, thin-skinned grape that thrives in cool climates and causes oenophiles to swoon.

Since he arrived, global warming has made Willamette Valley in northwest Oregon feel more like the land he left, he says. Hotter-than-normal summers have made for richer vintages with higher alcohol -- similar to wines from California.

Oregon wines from these hotter years have been popular with critics and consumers, many of whom prefer more generous fruit and less acidity. Yet some winemakers say the hot weather threatens to change the character of Oregon pinot noir, considered among the best in the world.

``If the trend continues with this kind of warmth, we're all going to move to British Columbia,'' says Hamacher, 41, whose forearms these days are stained purple with juice, seeds and skins from this year's vintage. His winery is in Carlton, 40 miles (64 kilometers) southwest of Portland.

Excessive heat is a problem because it can bake away the pinot noir's delicate berry flavors, says Matt Kramer, 54, a critic for Wine Spectator magazine who lives in Portland. ``It's like a redhead that burns in the sun.''

`Just the Beginning'

Harry Peterson-Nedry, founder of the Chehalem winery in Newberg, Oregon, keeps records of degree days -- a measure of the amount of heat received during the course of a year. His charts show that heat accumulation in McMinnville, in the heart of Oregon's wine country, has been above the 1971-2000 average of 2,100 degree days every year since 2001. In 2003, the total reached 2,555, 22 percent over the norm.

``The trend is definitely up,'' says Peterson-Nedry, 57. ``This is just the beginning.''

Statistics show that temperatures on Earth are rising. Last month marked the warmest September on record for land-surface temperatures worldwide, according to the Washington-based U.S. National Oceanic & Atmospheric Administration. Many scientists say that emissions from automobiles, power plants and similar sources are exacerbating the ``greenhouse effect,'' where certain gases trap heat in the lower atmosphere, raising the earth's temperature.

The warming, they say, has wide-ranging effects, possibly making hurricanes more powerful and depriving polar bears of sea ice they need to hunt marine mammals in the Arctic.

Until the 1980s, most of the world's pinot noir came from the Burgundy region of France, where the grape has been cultivated for at least 1,000 years. Winemakers in Oregon started planting it in the 1960s, betting that the grape would do well in the rolling hills of the Willamette Valley.

Blaming the Critics

The world took notice in 1979 when David Lett, the founder of Eyrie Vineyards, entered his 1975 South Block Reserve pinot noir in a Paris competition and took third place among some of the best pinot noirs of Burgundy. He placed a close second in a rematch with French vintners a year later.

Lett says he's not sure that global warming is affecting Oregon wine. A bigger threat is Robert Parker Jr., publisher of the Wine Advocate, and other critics who give high marks to big, fruitful wines, Lett says. Many vintners are conforming with the style to win sales, he says.

``Pinot noir should be a princess, not a monster,'' says Lett, 66. ``Who would you rather eat with?''

Pierre Rovani, who reviews Oregon wines for the Wine Advocate, says he has no bias against traditional pinot noirs, which tend to be more acidic. ``I will not allow him to say that I have a problem with wines that have high natural acidity,'' says Rovani, 41. ``Do Robert Parker and I believe that fruit should be ripe to make wine? Absolutely. Guilty as charged.''

`Sideways'

Long an obsession among wine aficionados, pinot noir reached more of the masses after last year's Oscar-winning film ``Sideways,'' about two buddies who go wine tasting on the central coast of California before one gets married.

The neurotic Miles, played by Paul Giamatti, adores pinot noir because, like him, it's thin-skinned, temperamental and can't grow without constant care.

Unlike the negative consequences of global warming such as fatal heat waves, warmer weather in pinot noir country has paid some dividends. Winemakers admit that the extra heat makes it easier to produce consistently good wines, if not great ones.

``It makes wine making more predictable here, but it makes it more predictably ponderous,'' Peterson-Nedry says. ``It dances less on the palate.''

Winemakers say this year could be different based on what they've seen during the ``crush,'' when they pick grapes in late September and October.

Changing Weather

Cold, wet weather prevailed in June, and the vines flowered in fits and starts. Late summer brought warm, dry weather, the norm in Oregon. Best of all for pinot purists, September and October were cooler, and growers could leave the grapes to develop flavor without becoming too high in sugar.

Then, right around harvest time, the temperature dropped and it started to rain. That's a nightmare for pinot noir because the grapes can become engorged with water, causing the skins to split. Its tight clusters also make the grape prone to rot.

``This is the kind of vintage where it's possible to make really good wine if you play your cards right,'' says Terry Casteel, 63, co-founder of Bethel Heights Vineyard.

Because of the cold and damp conditions that prevailed at the bloom in June, yields in many vineyards are down this year. Hamacher says his output is down 25 percent. ``The wines should be stunning but expensive,'' Hamacher says.

That would be good for winemakers. Drinkers, meantime, may be longing for a little more climate change.

To contact the reporter on this story: Anthony Effinger in Portland, Oregon on aeffinger@bloomberg.net.

Last Updated: October 20, 2005 01:18 EDT