Chehalem's Harry Peterson-Nedry on
Global Climate Change and Oregon's Wine Crop

Summers get hotter, harvest gets earlier

As the Summers have gotten hotter,
harvest has come earlier

By Harry Peterson-Nedry,
Chehalem Winery
reprinted with permission
From Chehalem's Summer 2006
and Spring 2004 Newsletters

Over the last year we've planted two new blocks
of grapes in our Wind Ridge Vineyard on Ribbon Ridge that speak of the past and to the future.

Last spring, we planted a new block of Pinot Noir, using new rootstocks (3309), drip irrigation to start, and new spacings (2000 plants per acre), but employing old clones (Pommard), which began the industry. Considering the site's excellence, the pedigree of plant material that came from our first and best planting (5-Acre Block), and all we've learned since 1982, we're anticipating a great future for the block.

Last month, we planted an adjacent block with futuristic whites. As you know, I'm convinced Riesling is Pinot Noir in a white seersucker summer suit—complex, reflective of place, and elegantly ageable. We planted a block that includes enough of all the clones of Riesling available (6 or maybe 7) to make commercial-sized ferments, so we can learn about the breed as we grow the volume of world-class Riesling. And then, there's the block of Grüner Veltliner to really stretch comprehension, as we see with two acres what this great Austrian variety does here.

Because Things Are Changing

Harry Peterson-Nedry

We experiment partly because we're restless and curious—OK, because I'm restless. But partly, we look to change because we have to. I'm in the no-nonsense, scientific camp on the reality of Global Climate Change and bear a sense of urgency that things need now to be done—or eventually we're done.

Myriad sources and views of data, both long-term and short-term, confirm startling symptoms of our altered climate. Close to home, we have only to look at the consistently higher heat accumulations of recent vintages and the extremely remote probability that the last ten vintages in a row all being at or above the mean for the 1961–1990 period is by chance. Statistically significant, no doubt. (See graph at top of this page).

The evidence is so overpowering that vineyard owners, even in generations-heavy European regions that have grown and become identified by single varieties of grapes, are now asking: "What will we grow when it becomes too hot for what we know?"

Average Growing Season

Temperatures have continued to rise, pushing ripening in traditionally cooler regions like Burgundy earlier and almost outside appropriate ripening windows for Pinot Noir.

Dr. Gregory Jones of Southern Oregon University, a geographer/climatologist specializing in characterizing viticultural regions (his parents own Abacela in the Umpqua), has investigated climate changes over recent decades and their potential impact on normal ripening parameters of grape varieties worldwide.

Conclusions show improving ripening conditions with varieties that traditionally have had difficulty ripening in some years. And, with varieties that were well suited to regions historically, there are tendencies toward overripeness and early ripening that compromise finesse and elegance. With this change being ongoing rather than a single shift, it is ominous to hear the climate freight train gaining speed in the distance, without a plan to slow it.

We all must consider cause-and-effect, understanding what we've done to start this engine of change, so we can have a chance of slowing it. We must demand of ourselves, our companies, and our governments a will to change, even if it takes sacrifice. Or else, on our grandchildren's vineyard watch we'll be harvesting Tempranillo, Merlot, Cabernet, and Grenache in the Willamette Valley, rather than Pinot Noir.

The 2002 Vintage - Fluke ot Trend?

Is 2002 a great Oregon Pinot noir vintage, or just a great press release? All years are not created equal. We innately look for differences to intrigue the intellectually curious, to celebrate a product that is much like art in its ability to reflect diversity and stimulate creativity, to create a high-C against the choral sameness of passing years.

Wine regions worldwide are known to pronounce greatness at the drop of a hat, either because of impressionable winemakers caught up in the excitement of a new harvest, or because of over zealous marketers staring at warehouses of new wines—and sometimes because it is a great year. The Bordelais made vintage deification an art form years ago and much of the wine world has followed in their steps, aided by publications that need to make new judgments in order to sell copies. Sometimes they’re right and sometimes they’re just blowing smoke!

The assessment of the 2002 vintage of Oregon Pinot noirs doesn’t seem to be overly generalized or overly generous. No caveat emptor needed here, as this was likely the best overall vintage since 1998.

An almost perfect growing and ripening season gave size without losing elegance, gave richness without losing great acid structure. White wines from 2002 may be the best ever, and the weight seen there is continued in Pinot noir. The new releases show robust, friendly fruit, mouthfuls of it. But they’re just babies and will refine themselves as they mature. These wines will age as well as any vintage we’ve seen. Classic. Mother Nature in basic black and pearls.

Mother Nature has been good to us. Although 2002 was virtually perfect, we have seen six vintages with good ripening and without the infamous harvest rains, years when either warm summer weather has pushed ripening earlier or summer has extended into Indian Summer territory.

I wouldn’t suggest there is possibly (shh!) global climate change at work—we wouldn’t think of disagreeing with our government lest it be seen as a breach of homeland security or as threatening to industries and economies invested in generating greenhouse emissions, like the automotive and oil industries. We, the technologically most advanced country led by scientific wizards, wouldn’t ignore irrefutable data from multiple sources, refuse to sign Kyoto accords, be so arrogant as to think concerns and rules don’t apply to us just because we’re the biggest user and polluter, or just because of politics and the inconvenience it might cause our businesses—we wouldn’t, would we?

Corral Creek Vineyard, Harvest 2002

Global Climate Change

It isn’t a question of “if,” it’s a question of “how badly” our climate tomorrow will be affected by our profligacy today. Higher temperatures from increased greenhouse gases (like CO2) and aerosol particulates from 2-10º F, depending on model and assumptions you take—are a given, and we’re already seeing it. Besides fiery summers and more so warm winters, with daily temperature swings (day to night) decreasing, this upset to the earth’s equilibrium brings a threat of greater extremes like flooding and drought, as different regions respond non-uniformly to resultant increased precipitation.

I don’t want this to be a diatribe on climate change, although I wouldn’t rule it out in a later newsletter, but it needs to be mentioned as we view vintages of the last decade. If they are a taste of what can be expected, with half rainfall and 2003’s almost intolerable heat reflecting only a 1-2º F increase over the prior two years’ average temperatures, I will be looking for vineyard land on the flanks of Mt Hood or in a Canadian province.

How We Measure Seasonal Differences

Despite the stylistic influences winemakers have over vintage, Mother Nature crafts the most significant changes. Annually, the basic questions are “will we have enough heat and will the rains hold off until after harvest?” All other parameters we monitor just flesh out our view of heat and rain. Parameters such as timings of bud break, flowering, veraison (color change/seed hardening), and harvest record the rhythms of a vintage. Simple measurements of heat accumulation in degree-days and total inches of rainfall during the growing and ripening seasons generalize vintages.

Accumulated heat, in Degree Days over 50º F, show the warming trend. In the graph increased heat is apparent in years like 2003, which had the heat of a Region II growing site at 2500 degree-days or approximately 400 degree-days warmer than average, based on the old UC Davis grading system (the same Region II into which Napa, Santa Barbara and Auckland were placed).

Vintage 2002 is warmer than average by approximately 150 units also. However, the length of the ripening season is what made 2002 exquisite, with September 15-October 15 max temperatures averaging 71º F and having only a single day each above the 80s or below the 60s.

Average Highs and Lows over the last Thirty Years, with 2002
Highs superimposed showing a cooler Spring and warmer late ripening season

Rain in this month was a mere 0.76 inches. The next two weeks even permitted late season ripening, averaging 61º F, with no rain. This luxury is seen if you view harvest dates in 2002 being spread over an entire month, with a long 114 days from bloom to harvest. The 2004 vintage is beginning where 2003 left off, with higher accumulation than we've seen through early May (see black shaded curve beginning).

Heat Accumulation Curves for Recent Vintages--Ripening depends on adequate warmth during the growing season. However, how much heat and when it comes is vital to the character of the vintage. Measured in Degree-Days above 50F. Region I, Cool Climate, extends to 2500 degree-days in the UC-Davis system.

In general, my observation is that great vintages have in common enough warmth for full grape maturity, lack of an event that prematurely ends ripening (like rains or freezes), and a long, moderate ripening period. (See graph showing "tonnage by harvest date.") Appropriate crop sizes and absence of disease are necessary, but should be givens in well managed vineyards when weather cooperates. As in 2002, when all those requirements are met, wines have size, ripe flavors, deep colors, good tannin and acid structure and layers of complexity and spice. The spherical ideal is met, where no one wine attribute is dominant—where you see a great wine but can ’t attribute it to any one feature.

The Corral Creek and 3 Vineyard new releases show classic numbers for a great vintage, registering 14% alcohols, 6 g/L acids and 3.6 pHs. A classic, fully ripe but gradually ripened vintage, with no rain at the end, 2002 shows the attributes of a cool climate, giving ripeness, acidity and complexity in an elegant package. Oh, and did I say “classic”?

Projections leave little doubt, even with maximum uncertainty built into the model,
that temperatures will continue to climb over the next century-
-not a question of "if" but a question of "how much. "

Historical Phenological Data, Based on Ridgecrest Vineyards

Growing parameters for the last four vintages at Ridgecrest Vineyards, plus what is typical.
Gives a sense of variability, even between very good vintages--all vintages, even great ones, are not alike.


		2003	2002	2001	2000	TYPICAL
TIMING						rule of thumb

Budbreak:		17-Apr	14-Apr	25-Apr	13-Apr	15-Apr
bud opens to formal leaves			approx

Flowering:		17-Jun	22-Jun	23-Jun	21-Jun	20-Jun
barely visible flowers bloom and hermaphroditically pollinate

Veraison:		22-Aug	26-Aug	25-Aug	23-Aug	20-Aug
seed hardening and color change, begins ripening

Harvest:
	Corral Creek	28-Sep	5-Oct	4-Oct	29-Sep	1-Oct
	Ridgecrest (1st)	4-Oct	14-Oct	10-Oct	7-Oct	10-Oct
	Ridgecrest (last)	7-Oct	20-Oct	15-Oct	15-Oct	17-Oct

Growing Season:		2003	2002	2001	2000	1971-2000
	Degree Days (>50° F McMinnville, Year Total)	2555	2281	2320	2219	2100
	cumulative heat during year
	Degree Days (>50° F McMinnville, April-October)	2463	2196	2195	2203	2100
	cumulative heat during growing season only
	Other Years:	1999	1998	1997		1961-1990
	Degree Days (>50° F McMinnville, April-October)	1968	2352	2167		1970
	computed using hi-lo average

Harvest Parameters:		2003	2002	2001	2000	TYPICAL
	Days from Bloom to Harvest	109	114	109	108	110
	gradual, cool ripening giving finesse

	Yield (Tons/Acre, all varieties)	2.37	3.05	2.38	2.31	2.25
	cropload to ripen, as pruned

	Cluster Weight (g)	152	149	137	114	125
	measure of plant vigor

	Berry Weight (g)	1.10	1.24	1.13	1.22	1.15
	color, extract, juice ratio

	Brix	25.2	24.2	22.9	23.7	23.5
	sugar, alcohol, ripeness (+ correlation)

	pH	3.46	3.40	3.29	3.33	3.25
	K+, acid content, ripeness (inverse correlation)

	Titratable Acidity (g/L)	5.09	6.58	6.47	7.32	7.00
	acid, ripeness