Mountains with 85 percent of current snow. Twenty-year droughts in the Southwest. Collapsing aquifers and economic losses.
The Fourth National Climate Change Assessment, released by the White House Friday, Nov. 23, describes the future Cal Poly is already adapting to.
Cal Poly professors are not surprised. The on-campus farms are already leading with some effects, and are planning ahead to prevent the impact of future harms.
“The bottom line to all of this is agriculturally we have to be able to adjust to a changing environment, and that adjustment doesn’t happen quickly,” horticulture and crop science professor Jeffrey Wong said.
Wong specializes in genetic research and said that although he believes humans can adapt to climate change, they will not be able to adapt quickly enough to prevent food shortages.
Warmer temperatures will allow more pests to survive. Bugs are typically killed during cold winter seasons, horticulture and crop science professor David Headrick said. Raising temperatures also expand pest and disease range.
“Increased drought, heat waves, and reduction of winter chill hours can harm crops and livestock,” the assessment authors wrote.
Good news first. The decrease in rain will cause water-carried diseases to decrease, horticulture and crop science professor Lauren Garner said.
Cal Poly’s irrigation system will prevent changes in soil acidity which rain-dependent areas of the state will experience, Garner said.
Warmer temperatures can cause more agriculture in Australia, bioresource and agricultural engineering professor and Irrigation Training and Research Center Director Stuart Styles said.
Cal Poly’s climate is buffered by coastal winds and a mild climate, Headrick said, meaning the university will not experience the effects of change as much as farmers in the valley communities.
Atmospheric Carbon Dioxide—Parts per million
Source: National Oceanic and Atmospheric Administration Earth System Research Laboratory
The wine industry will have to change. Production will continue at the same pace, wine and viticulture professor Federico Casassa predicted, but the time-held traditions of the industry will have to adapt. Casassa specializes in enology, making grapes into wine, and worked as a full-time Argentinian winemaker then researcher before coming to Cal Poly.
Rain will fall in fewer but more extreme storms, Casassa said. Grape growers used to leave vineyards until harvest, but now they have to watch the weather and inundate the vineyards with water before heat waves.
For hundreds of years, grape growers have planted vines in rows facing North-South to maximize sunlight, but growers will have to plant rows East-West to save grapevines from the too-harsh sunlight.
Some Australian growers are using mists to prevent vines from drying out, and Casassa helped test a common-sense shade cloth driven by Cal Poly student Michael Overholt at Tolosa Vineyards & Winery.
Southern England has grown so warm they can make sparkling wine, an industry dominated by France for hundreds of years, Casassa said.
These changes to the industry are not massive disruptions, but they change an industry that is extremely rooted in tradition at the demand of consumers, Casassa said.
“It’s not the same as producing soybeans,” Casassa said.
A 25-year drought will definitely affect Californian wines, though.
When told about the 50 percent probability of a multi-decades drought, Casassa said it would be bad.
“A drought will affect the wine industry terribly. There’s nothing else to say about that,” Casassa said.
Grapevines also require a cold period in winter, so buds know that they should not come out yet. Warmer winters mean buds wake up early, and freeze in January. Temperatures are predicted to increase between five and 11 degrees Fahrenheit by the end of the century, according to the Fourth National Climate Change Assessment.
Growing apples may be a challenge. Apple trees require cold temperatures in winter as part of their annual cycle, horticulture and crop science professor Lauren Garner said. Warmer winters mean less apples are produced. It is a part of the tree’s metabolic seasonal cycle. If the Horticulture and Crop Science Department keeps the same breed of trees in their orchards, students would see fewer apples produced.
Frost days per year—Cold needed for apple and fruit production
Source: National Aeronautics and Space Administration, National Snow and Ice Data Center
Cal Poly can adapt by planting a different apple breed.
“With expecting increase in temperatures, we are going to need to be careful about our plant selection,” Garner said.
Students and faculty will have to consider root structure and chill hours closely to keep up apple production. The roots will have to take in more water, and the tree must start its cold cycle at a higher temperature.
Every tree planted lasts for around 20 years. A mistake in tree selection will last a while.
“It’s not like an annual crop where you can change it every year,” Garner said.
Genetic researchers are developing crops which are more tolerant to salt and drought, but they will not be developed quickly enough, Wong said. Salt is a necessary consideration when planting because consistent rain clears away salt build-up, which affects plant growth. Cal Poly students farm primarily with irrigation, so salt build-up is not a worry for the campus, Garner said.
Genetic breeders take 10-12 years to develop a new breed of an annual crop, according to Wong. Rainfall, temperatures and soil are changing yearly, and an adapted crop 10 years away will simply not come fast enough to feed the nation.
“The bottom line to all this is agriculturally, we have to be able to adjust to a changing environment, and that adjustment doesn’t happen quickly,” Wong said.
Direct gene-editing does not bring any more hope.
Wong said CRISPR, a recently developed method to directly edit genetic code based on bacteria from strep throat, is not applicable in creating crops that can withstand farming conditions in 20 years.
Geneticists can only use CRISPR to turn off problematic genes. It can turn off genetic diseases or toxins which a plant normally secrets. Wong could not think of any genes which when turned off would make a crop more drought-tolerant.
California will have to invest in more reservoirs. Water is naturally stored in snowpacks along California mountains until it thaws in spring, allowing water to slowly fill up reservoirs and aquifers. Rainfall is also absorbed into the ground, where it follows underground currents between soil called aquifers, which make 40 percent of agricultural water in the United States, according to the report.
Warmer winters mean less snow. Less snow means water can overflow existing water storage and flow into the ocean, Cal Poly Irrigation Training and Research Center Director Stuart Styles said.
More extreme weather patterns also mean water runs off into streams instead of being collected in aquifers, Casassa said. Less water in aquifers causes aquifers to collapse, since soil falls into itself without water holding the ground up. The collapse of aquifers is irreversible.
The amount of snow in California mountains has already decreased by 25 percent and is expected to increase by at least 60 percent according to University of California, Los Angeles scientists Neil Berg and Alex Hall, referenced by the assessment.
Snowfall in Sierra Mountains: Expected decrease of 60-85 percent by 2100
Source: Donner Pass Station, Natural Resources Conservation Service
Warmer temperatures do not mean less water, Styles said. It does mean water will not be stored in snow.
“I think California is going to get really hammered on that,” Styles said.
There are two options for Californians to take, Styles said. They can either deal with more winter runoff in winter, or build more dam storage.
Existing dams can be upgraded, like the Shasta Reservoir in Northern California, where proposals to increase the walls of the reservoir range from 15 to 100 higher vertical feet, Styles said.
Offline reservoirs are the best choice, Styles said. Offline reservoirs are reservoirs built away from rivers, but connected to the water source with man-made channels.
If California built offline reservoirs, they can avoid interfering with historically significant tribal areas next to rivers.
One proposed offline reservoir is the Sites Reservoir near Chico, California. The San Luis Reservoir in Merced County is an existing offline reservoir.
Cal Poly will not have enough water if a multi-decade drought occurs.
Cal Poly mostly gets water from Whale Rock Reservoir in Cayucos, a reservoir built jointly by Cal Poly, the City of San Luis Obispo and the California Men’s Colony. Whale Rock can hold 39,000 acre feet of water. That is 12.7 billion gallons, or the volume of enough football fields stacked on top of each other to reach seven miles high. It currently has nine billion gallons of water. Cal Poly has rights to a third of the reservoir’s water.
Whale Rock will not have enough water to last a 10-year drought, Styles said. The Fourth National Climate Change Assessment says a multi-decade drought is possible.
One study cited by the assessment, by Toby Ault of Cornell University, says that a multi-decade drought in the Southwest in this century is close to 45 percent. A 35-year drought is between 10 percent and 50 percent likely.
It would not be the first time that the campus has had a water shortage. In 1991, Cal Poly was nine years into what a campus farm superintendent said was a drought, according to a Mustang News article. It had not rained adequately since 1982. Cal Poly was “slowly running out of water.” The College of Agriculture began using drip irrigation to adjust, and had to cut back on the number of cattle, sheep and pigs which students could raise.
Cal Poly’s Master Plan calls for new infrastructure to deliver more domestic water to campus, but it does not specify the source.
A changing climate has allowed invasive species to expand, Headrick said. Sudden Oak Death Syndrome and Golden Spotted Oak Borer have been attacking California oak trees for the past fifteen years, Headrick said. The recent drought weakened oak trees around the state, making them more susceptible to the disease and pests.
The entirety of San Luis Obispo County is under quarantine for the Asian Citrus Psyllid. The bug used to be limited to certain climates, but have been making their way north as temperatures warm. They can carry a disease that kills citrus trees, forcing Cal Poly’s citrus workers to apply insecticides to every case before they ship them out because of state and federal quarantines and slowing production, Headrick said. “It devastates farmers.”
“We’re accepting this burden because this pest can be so damaging, because it’s the lesser of two evils,” Headrick said.
The drought weakened the immune systems of trees across the state, allowing invasive bark beetles to eat trees from the inside out, Headrick said. Bark beetles killed a record 129 million trees in California in 2017, according to CAL Fire. The dead trees pose a major wildfire risk.
White House researchers proposed mitigation measures in the Fourth National Climate Change assessment. They recommend reducing greenhouse gases and expanding wind and solar energy to generate electricity. Fossil-fuel combustion accounts for 85 percent of United States greenhouse gases, they said, and the rest comes from agriculture, city-scaping, industrial processes and fossil fuel extraction.
They also recommend individuals make daily choices to reduce carbon footprints.
The largest emissions in the U.S. come from transportation, the assessment authors wrote.