2020: The Year Climate Change Got Real for American Wine

As I write this, I'm staring out at a dim, yellow landscape, the indistinct sunlight filtered through a thick layer of atmospheric smoke. I have a sweatshirt on because the day has never really warmed up here in town. We had a couple of days this past week, prime ripening season in Paso Robles, where it barely made it out of the sixties. A photo, no filter applied:

We're not really complaining; as apocalyptic as it looks, the air has been cool and fresh at the surface, and we got a chance to catch up on harvesting after what was a scorching hot previous weekend. And plenty is ready. Pretty much all our Syrah. The Vermentino and Marsanne. Our first lots of Grenache Blanc. The smoke has reduced actual temperatures from model forecasts by some 20 degrees, and if we'd had the mid-90s weather that was forecast for this week, it's possible that new blocks would have ripened before we could get through the backlog that the last heat wave produced.

This smoke layer, driven by the fact that six of California ten largest fires ever are currently burning, is only the most recent of a series of unprecedented things we've seen in the 2020 growing season. A week ago, we had a heat wave that crested with back-to-back-to-back days that topped out at 109, 113, and 111. The Paso Robles Airport broke its all-time high with a 117 reading. And San Luis Obispo hit 120°F, which appears to be the highest temperature ever recorded in a coastal zone anywhere in North or South America.

Last month, we saw a trio of fires in the Central Coast produce so much smoke at the surface that we closed our tasting patio for four days because the air quality was so bad. On August 20th, San Luis Obispo had the worst air quality in the world. Those fires were sparked by a surge of tropical moisture, the remnants of Tropical Storm Fausto, that moved up the California coast and produced thousands of lighting strikes on August 14th and 15th. The fires lit by those lightning strikes were fueled by another heat wave that pushed temperatures over 105°F each day between August 15th and 18th.

Paso Robles is hot in the summer. Summer days over 100°F have never been rare here. But the increased number and distribution of these days, the fact that records are falling more often, the earlier and earlier beginnings to harvest (and the shorter durations between veraison and harvest), and finally the new, tropical-influenced rainfall patterns, are new. A few data points that I look at:

• Over our first 15 vintages, 1997-2011, we started our estate harvest in August 40% of the years. Since 2012, we have done so 78% of vintages. Similarly, in those first 15 years, there were six times we harvested into November, and another four that finished October 28th or later. Over the last 8 years, we haven't once harvested in November.
• It's not just harvest. This year's gap between veraison and harvest was just 35 days, breaking our record of 36, set in both 2016 and 2019. Before that, the record was 39, in 2015. 2013 was the first year that we saw 40 or fewer days between veraison and harvest. So, in less than a decade, we've seen this critical ripening period shrink by 15%. Crucial growing periods are getting hotter. 
• Our total growing season degree days, a rough measurement of the number of hours in which it's warm enough for grapevines to photosynthesize efficiently, shows that since 2000, our five warmest years have all come since 2012.

All those data points are indicative, but none of them are likely to on their own pose much of a threat to winemaking here in Paso Robles. But they feed into two phenomena that do: droughts and fires. I'll address droughts first. I wrote a 3-part blog series back in 2014 about our move toward dry farming as a part of being ready for what seems likely to be a drier future. In the research for that, I looked at EPA projections for rainfall showed that, depending on our success in reducing emissions, coastal California would see between 20% and 35% less precipitation annually by the end of the 21st Century:

That research has since been reinforced by studies of warming in the Pacific Ocean, which will have a complex series of consequences, including increased rainfall in places like northern Australia, the Amazon, and Southeast Asia, but less rainfall (and a later onset of the rainy season) in coastal California. This suggests that droughts, particularly the multi-year droughts like the one we saw between 2012 and 2016, will become more common.

Next, fires. It's not like California is a stranger to fires, but severe ones are definitely happening more often. I moved out here in 2002. The first time after that there was any smoke here was July 2008, when I wrote in a blog that two big fires to our north had burned some 73,000 acres in three weeks. (Note that that figure seems almost quaint now, with the horrific Creek Fire east of Fresno burning 160,000 acres in the first four days.) The second fire I noted in the blog was in 2016. Except for 2019, we've seen scary fires in California's wine country each year since then, and 2020 has already seen the most acres burned on record:

Just smashing records of all kind

Right on the heels of overtaking the record 1.9M acres burned in 2018, look at the cumulative #wildfire radiative power in 2020 with at least two months until we see any rain

source: @NOAA #CAfire #CreekFire pic.twitter.com/edBM8WZpTf

— Dave Marvin (@dmarvs) September 8, 2020

The fires are driven by a number of factors, including higher temperatures, lower humidities, poor utility maintenance, human encroachment into wildland areas, and accumulated fuel in the forests after a century of fire suppression. All of these encourage fires to be bigger, faster-growing, and more destructive than before. But what has set the worst ones off in recent years has been climate-related: either through dry winds spurring (and spreading) fires through downed power lines in periods before it has rained in California, or by tropical moisture that has sparked summer lightning.

The fires that impacted Northern California in 2017 and 2018 were produced by late-season (October and November) windstorms that spurred fires from an aging electrical grid. This is largely a governmental and regulatory failure. But while these windstorms aren't new, and don't particularly appear to be a function of climate change, thanks to climate change the time of year when these storms are common is more likely to still be summer-dry. That is why the climate change-driven later onset to the rainy season is a significant contributor to the number and severity of fires.

2020's fires in California have been different. The storms this summer that produced the first series of wildfires were driven by tropical moisture that was pulled into California. A warming climate produces more and larger tropical storms and hurricanes. 2020 has already seen so many tropical storms that I've begun to read articles about how NOAA might run out of names. The direct impacts of tropical storms and hurricanes on California are rare, and minor compared to their impacts in the Atlantic or the Gulf of Mexico. But the more of these storms that form, the greater the chance that tropical moisture can end up in unexpected places. These occasionally produce enough moisture to provide some short-term fire risk reduction (such as the July 2015 storm that dropped more than two inches of rain on us) but more often produce extensive lightning with only limited moisture. These sorts of storms introduce extreme fire risk. 

The combination of warmer days, dryer (and later-beginning) winters, and more frequent incursions of summer tropical moisture has combined to produce drastically more days with very high fire risk.

Our new work on #ClimateChange & autumn wildfire risk in California, led by Michael Goss, is out today in (open-access) ERL. We find that climate change has already doubled the frequency of extreme fire weather days since 1980s.(1/6) #CAwx #CAfire #CAwater https://t.co/kei6rJSZQO pic.twitter.com/W8Y7xn0tkn

— Daniel Swain (@Weather_West) March 30, 2020

So, what to do? That's the hard part. Most of the response has to come at the governmental level. Investments need to be made to modernize utilities. Forest management practices could be improved to reduce the amount of fuel that builds up. Cities, counties, and states should adopt growth plans that reduce the human/wildland interface as much as possible, both to reduce the opportunities for fires to start and to minimize the loss of life and property when they do. But ultimately, if climate change itself goes unaddressed, all these initiatives (none of which are easy or likely to come without resistance) are likely to be overwhelmed by the growth in the number of extreme fire days and fast spread of fires that do start.

Here's where regenerative agriculture comes in. One of its tenets is that agriculture has an important and necessary role in the reduction of greenhouse gases (and especially Carbon Dioxide) in the atmosphere. And plants, after all, are the best engines we have in doing so, since photosynthesis uses CO2 as one of its inputs, turning that carbon into carbohydrates. But modern farming produces more emissions than the plants it grows consume. Some of that is the fertilizer, derived mostly from petrochemicals. Some of that is the fuel for the tractors and other machinery. And some of it is the processing of the agricultural products.

Regenerative agriculture leads the way toward building carbon content in the soil, through a combination of permaculture, cover crops, reduction in tillage, and the replacement of chemical inputs with natural ones like compost or manure. Soils with more carbon content also hold more moisture, which will help California wineries weather the droughts too. We showed in the application process for our new Regenerative Organic Certification that it was possible to increase our soil's carbon content while growing grapes even in a dry climate like Paso Robles.

Regenerative farming is not just for wineries. It's what all farms, from row crops to orchards to fibers to livestock, should be moving toward. But vineyards offer some of the lowest-hanging opportunities for better farming, because wine is a value-added product with the resources to invest, and the investments tend also to make higher-quality grapes and longer-lived vines, providing return on the investments.

I can't imagine how California, Oregon, or Washington wineries can live through the 2020 vintage without worrying about how climate change might impact their future. A small silver lining could be encouraging more of that community to move toward regenerative farming. Consumers have a role to play here too. Before this year, there wasn't an available standard for moving to, measuring, and being audited for being regenerative. Now, with the launch of Regenerative Organic Certification, there is. If your favorite wineries are not farming regeneratively, you should be asking them why not. It's one of the tools we as farmers have to take some control over what is likely to be an increasingly volatile and dangerous future that might look like last week a lot more often than any of us would want.