Image: Art Zeigler.

The leaves on tomato plants wither and droop. Higher winds knock avocados and other fruit from their branches. At sea, warmer waters trouble the existence of kelp, crustaceans, and fish. These are just some of the local climate change phenomena that are challenging our agriculture and seafood industries. Our farmers and fishermen are nonetheless proving to be resilient to these challenges. They are, as well, leading the world in efforts to fight climate change.

At Sea

Image: Dave Rudie.

The world’s oceans have absorbed most of the heat that has resulted from anthropogenic CO2 emissions. In the last 30 years, heat waves in the oceans have increased by 50%. Ocean temperatures are expected to rise by one to seven degrees Fahrenheit within the next 80 years. That can have significant ramifications for seafood, including the catches off our coast.

Theresa Sinicrope Talley with California Sea Grant, based at Scripps Institution of Oceanography, says there are natural shifts in the sea life off our coast as waters warm and cool with the seasons and decadal regime shifts. Sardines, mackerel, and spiny lobster are more common during warmer periods, while sablefish, halibut, and albacore favor colder waters. “The extreme events associated with climate change may exacerbate these fluctuations,” she says. “For example, during the 2013–2018 marine heat waves we saw not only the usual warm phase species but also more tropical species, like dorado, mahi-mahi, marlin, and bluefin tuna, and also more toxic algal blooms.” Dr. Talley also warns that warming waters may be exacerbating diseases and pathogens in our waters, such as sea star wasting and sea urchin black spot disease.

According to Dr. Talley, the giant kelp growing in the waters off our coast dies back in warmer conditions, jeopardizing the survival of the creatures that rely on the kelp for food and shelter, such as sea urchins and some rockfishes. At the same time, this enhances other organisms, such as the shorter, understory kelps. The species most affected by environmental change are the ones that fit into narrow habitat niches, especially ones that aren’t very mobile.

More frequent and intense storms brought about by climate change can also make seafood fishing more difficult and even dangerous. Rising ocean levels may soon affect docks and other fisheries infrastructure.

According to the National Oceanic and Atmospheric Administration (NOAA), close to one-third of anthropogenic CO2 has been absorbed by the world’s oceans, which makes the water about 30% more acidic than it was before the beginning of the Industrial Revolution 200 years ago. The more acidic seawater makes the building of seashells more difficult for oysters, clams, sea urchins, and corals.

This ocean acidification has already affected local seafood production. With operations in Carlsbad’s Agua Hedionda Lagoon, Carlsbad Aquafarm grows clams from “seed,” almost microscopic clam offspring, which they ship in from the Pacific Northwest. In 2007, the production of clam seed was almost completely decimated because of ocean acidification, with a failure rate of 90 to 95%, forcing the seafood farm to change operations and produce its own seed.

It may seem that all these developments are making our local seafood more precarious, yet Dr. Talley says that fishermen are kept abreast of developments by the latest science, making the commercial fishing off San Diego’s coast some of the most responsibly managed in the world.

A trip to the Tuna Harbor Dockside Market, just north of Seaport Village, confirms the present health of the fishing off San Diego’s coast. Standing behind the trays of ice that display appetizing albacore and rockfish, Kris Honing, who captains a boat that fishes the North and South Pacific, says that the fishing in San Diego has never been better. “In the 1990s, I would have to go out 800 to 1,000 miles to get the catch I now get close to shore,” he says. Other fishermen at the market echo his sentiment, waxing over their increased catches that they credit to the better science and regulation currently performed by NOAA.

Talley cautions, “Despite some fish being more plentiful lately, being adaptable to changes in fish availability is a work in progress.

Fishermen need the ability to fish more opportunistically, including the ability to switch between gear types, fishing grounds, and permit types as fish availability changes. Our fleet as a whole has a diversity of gear types needed to adapt, but the shoreline infrastructure to support changing catch is not in place. Further, this portfolio fishing approach tends to be most challenging for small businesses that may not have the means to afford more gear, permits, and skilled labor.”

“Our fishermen want to fish what’s abundant and leave alone what is not,” continues Talley, “but they need more support, such as fishing-friendly ports, access to financial capital, and their own ownership and management of fishing quotas to make this happen.”

On Land

Hannah Gbeh, executive director of the San Diego Farm Bureau, says that climate change has started to affect San Diego farms, primarily through extreme weather events, which have become more common. “Wind is a big issue now, and we now have heat waves in times of the year that before weren’t times that we would have heat waves,” she says. “The winds can blow fruits off the trees, such as avocados, citrus, or apples, and make them unmarketable. High winds also snap tree trunks and branches, which can result in significant crop or orchard losses.”

Solidarity Farm: Image: Daniel Padilla.

Warmer temperatures make plants use more water, forcing farmers to change watering schedules and be even more water smart than they were before. Farmers are using banding around trees that measure the expansion and contraction of the trees’ roots, which is a way of measuring how much water the plants need. This information is then sent to the farmer’s smartphone, where the farmer can set an appropriate watering schedule for the plants. Gbeh says that farmers are similarly using smart technology for soil monitoring. “And we’ve seen a lot of farmers switch to a drip irrigation system, which can significantly reduce water use.”

Water use also contributes to climate change. In California, up to 20% of the energy used in the state is used to move and treat water; much of that energy use results in greenhouse gas emissions, so every drop of water saved equals less carbon in the air in what Gbeh describes as a “win on all sides.” More recycled water, which has a significantly lower carbon footprint than our other freshwater sources, is being sent to our local farms.

As the source of 11% of greenhouse gas emissions, industrial agriculture relies on heavy tilling, which pulls carbon from the soil and releases it into the atmosphere. Ellee Igoe, co-owner of Solidarity Farms in Pauma Valley, has made the carbon sequestering no-till methods a part of her farming practice. “We were inspired by actually experiencing the effects of climate change,” she says. “We had a heat event. The temperature went up to 122°. Everything died.”

As Igoe explains, farming soil can act like a “carbon sponge.” As farm soil is left in a more natural state without being tilled, a community of beneficial organisms returns to the soil. The water-holding capacity of the soil also increases. For every percentage increase in the water-holding capacity of her farm’s soil, the farm’s water use is reduced by one acre-foot, the equivalent to 325,851 gallons. She says, “We’ve had some soils on the farm go from one and a half percent of water holding to seven percent. That is a lot of acre-feet of water saved.”

The greater amount of water in the soil gives the plants a fighting chance against the more extreme heat waves. The temperature at Solidarity Farms recently went to 104°, yet the plants on the farm proved to be more resilient to the heat. And more carbon in the soil reduces global warming. Igoe says, “Building topsoil is the most efficient way of drawing down greenhouse gasses.”

Lake Henshaw in the Palomar Mountains is one of the main sources of raw water for the City of Escondido and San Diego’s North County. The reservoir is part of the San Luis Rey River watershed, with much of the water filling it pumped from a large inland aquifer beneath it. Image: Ron and Patty Thomas.

Ironically, climate change may help some San Diego farmers. In a scientific paper published last year, researchers looked at almonds, avocados, and oranges grown in California. Climate change is expected to reduce frost exposure for these crops by an average of 63% by 2050. Although San Diego does not experience the number of frost nights that other parts of the state experience, frost exposures here are expected to decline by even more—by 75%. This can translate into savings for the farmers because they won’t have as many nights of using smudge pots or spraying gallons and gallons of water to keep frost off their crops.

Farmers use a lot of energy running their smudge pots to heat their fields during frosts. They also fight frost by spraying water, lots of it, on their orchards. Fewer frost nights will result in millions of dollars in energy savings and tens of thousands of gallons of water saved for the counties of California that produce these crops, including San Diego County.

Image: RyanJLane.


Seafood and kelp for sale at the Tuna Harbor Dockside Market. Image: Maria Hesse.

If you’re interested in reducing your carbon footprint, supporting local agriculture and locally sourced seafood is a step in the right direction. “The most environmentally friendly action that anyone can take is to purchase their food locally,” says Gbeh. “Buying locally produced food reduces vehicle miles traveled. It also means less time for that item to be refrigerated—and much of local food is bought without packaging, which takes additional greenhouse gasses to produce. And you can feel good about buying in San Diego because we are the leaders and the best when it comes to environmental sustainability. You can buy local food at farmers’ markets, and many of the local food markets label the locally sourced food.”

Dr. Talley is also upbeat in encouraging locally sourced seafood and encourages consumers to be flexible when they enjoy something from our local catch. She says, “Embrace the variability in our local seafood selection! Be willing to eat with the season and whatever other conditions the ocean presents to us. Seasons, longer-term warm and cold ocean water phases, and regulations implemented to protect fishery stocks all result in catch and, therefore, local seafood selection varying with time—and sometimes in unexpected ways. Adaptable buying practices will support adaptable fisheries.”

Check out the Tuna Harbor Dockside Market for fresh seafood on Saturday mornings, and refer to California Sea Grant’s Discover California Seafood resources and NOAA’s Fish Watch for additional information about sustainable seafood.

Edible San Diego Issue 66 Summer 2022
Cover Image by Dave Rudie.

Published in the print edition of Edible San Diego's summer 2022 issue.

Read issue 66 online now.

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About the Contributor
Paul Hormick
Paul Hormick is a horticulturist and environmentalist with a master’s degree in Environmental Science and Policy. As a freelance writer, his interests are in the environment, current events, music, and the arts. He is the author of As We Believe: Conversations of Religion and Faith. Paul lives in San Diego with his wife, Bryna.