by Laura Lengnick, CFSA member and author of Resilient Agriculture: Cultivating Food Systems for a Changing Climate
For more than 40 years, Ken Dawson has grown organic vegetables and fruits in the Piedmont of North Carolina. He owns and manages Maple Spring Gardens, in Cedar Grove, is a founding member of the Carrboro Farmers’ Market, and is a long-time CFSA member (his farm is on this year’s 21st Annual Piedmont Farm Tour, happening April 23-24).
Ken first noticed the impact of climate change in the form of hot summer nights on his vegetables about 6 years ago. “Prior to 2010,” he says, “flowering, pollination and fruit set had never been an issue for us. In the 2010, ’11 and ’12 growing seasons, we had very poor fruit set on our late tomatoes due to excessive heat in July. That’s something I had never encountered before. Early September, when we normally have a lot of late tomatoes, there just weren’t any. They were great-looking plants with nothing on them.”
Tomatoes are pollinated during the day, but fertilization and fruit set take place at night, so it is nighttime temperatures that matter. While the optimum temperature range for tomato growth and flowering is between 72 and 82 degrees Fahrenheit (oF), optimum fruit set requires cooler nighttime temperatures between 60 and 70 degrees. Fruit set is greatly reduced outside of this range and fails completely if nighttime temperatures are above 92 oF. High humidity, which often accompanies high nighttime temperatures in summer, can also reduce tomato fruit set, if pollen grains become too sticky with moisture to make the transfer from male to female flowers.
Many other vegetable crops are sensitive to extreme temperatures when they are flowering and fruiting. Daytime temperatures above 90 oF can stop fruit set altogether on bell peppers, especially under dry conditions, and even temperatures in the 80s can decrease yield by half. Daytime temperatures over 86 degrees cause squash, pumpkin and other cucurbit flowers to close, so pollination must occur within the first few hours of early morning if temperatures are high. In many cucurbits – especially squash, cucumber and pumpkin –fruiting fails completely at temperatures above 90 degrees because the plants begin to produce only male flowers. And it’s not just warmer temperatures in spring and summer that are complicating food production in the Carolinas and beyond.
Warming winters are bad news for anyone who enjoys a good apple, tart cherries, or a juicy peach. Same story if you can’t wait for the first blueberries or raspberries of the year. Many of our favorite fruits require an extended period of cold temperatures to produce a healthy and abundant spring bloom. And warmer winters cause fruit trees and shrubs to bloom earlier in spring, which increases the risk of total crop loss from a late spring frost. Warmer winters also mean more pests in all sorts of crops, because more pests survive the winter to breed earlier and build higher populations that reduce crop quality and yields throughout the growing season.
Whether subtle or catastrophic, more variable and extreme weather are already having widespread effects on many of our favorite foods and these effects are projected to grow more intense in coming years. If you think that this problem is too big for you to make a difference – think again. If you eat, you can play an important role in mitigating climate change. It starts on the farm and continues in your kitchen by making the choice to eat local, sustainable and organic as often as you can. Although agriculture is usually viewed as a major contributor to climate change, it turns out that sustainable and organic agriculture has the proven potential to cool the planet.
Cooling the Planet Starts in Your Kitchen
As part of your observation of Earth day this year, consider making a commitment to take at least one of these four steps below and join many others around the world who have decided to become part of the delicious and nutritious solution to climate change!
Step One: Stop wasting food.
The global carbon footprint of food produced and not eaten is larger than the carbon footprint of most countries. If food waste emissions were a country, they would rank as the third largest source of heat-trapping gas emissions – behind only the USA and China. In the U.S., about 2% of total annual energy use is used to produce food that is later wasted by consumers. Here are some top tips for reducing your food waste: 1. Think before you shop – check to see what you already have in the fridge, use a meal plan to make a list, and stick to your list when you shop. 2. Don’t serve large portions and use small plates. 3. Love your leftovers – find delicious recipes to use up leftovers and make left-overs a feature on your weekly menu.
Step Two: When you have the choice, choose sustainable and organic food produced in your region.
Sustainable food, regionally-sourced, reduces food-related emissions and provides many community benefits. Sustainable farmers cultivate community resilience through practices that enhance soil and water quality, build human capacity for innovation, and contribute to the social and economic well-being of the communities that they serve. CFSA has a great list of where to find local food in the Carolinas.
Step Three: Eat pasture-based, local, sustainable and organic meat.
Buy local and direct whenever possible, and encourage your local grocers and restaurants to carry more local, sustainable, and organic meats, dairy products and seafood.
Step Four: Do your part to help our country achieve the commitment to reduce greenhouse gas emissions made last December at the U.N. Climate Change Conference in Paris.
Lend your support to one of the thousands of local, regional and national emission reduction projects already underway in the U.S. Learn more about your local, state or federal representatives’ positions on climate change, or get involved with a local group working to address climate change in your community.
We can do a lot as individuals to put our country on the path to a sustainable and resilient future, fueled by delicious, healthy and climate-resilient sustainable and organic food. Let’s get started!