Cooperative Extension San Joaquin County
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Posts Tagged: Daniel Sumner

UC ANR scientists contribute to California’s Fourth Climate Change Assessment

The California Natural Resources Agency released California's Fourth Climate Change Assessment today (Monday, Aug. 27), at http://www.ClimateAssessment.ca.govUC Agriculture and Natural Resources scientists contributed substantially to the report.

The Fourth Assessment is broken down into nine technical reports on the following topics:

  • Agriculture 
  • Biodiversity and habitat 
  • Energy 
  • Forests and wildlife 
  • Governance 
  • Ocean and coast 
  • Projects, datasets and tools 
  • Public health 
  • Water 

The technical reports were distilled into nine regional reports and three community reports that support climate action by providing an overview of climate-related risks and adaptation strategies tailored to specific regions and themes.

The regional reports cover:

  • North Coast Region 
  • Sacramento Valley Region 
  • San Francisco Bay Area Region 
  • Sierra Nevada Region 
  • San Joaquin Valley Region 
  • Central Coast Region 
  • Los Angeles Region 
  • Inland South Region 
  • San Diego Region 

The community reports focus on:

  • The ocean and coast 
  • Tribal communities 
  • Climate justice 

All research contributing to the Fourth Assessment was peer-reviewed.

UC Cooperative Extension ecosystem sciences specialist Ted Grantham – who works in the Department of Environmental Science, Policy and Management at UC Berkeley – is the lead author of the 80-page North Coast Region Report.  Among the public events surrounding the release of the Fourth Assessment is the California Adaptation Forum, Aug. 27-29 in Sacramento. For more information, see http://www.californiaadaptationforum.org/. Grantham is a speaker at the forum.

Other UC ANR authors of the North Coast Region Report are:

  • Lenya Quinn-Davidson, UC Cooperative Extension area fire advisor for Humboldt, Siskiyou, Trinity and Mendocino counties 
  • Glenn McGourty, UC Cooperative Extension viticulture and plant science advisor in Mendocino and Lake counties 
  • Jeff Stackhouse, UC Cooperative Extension livestock and natural resources advisor for Humboldt and Del Norte counties 
  • Yana Valachovic, UC Cooperative Extension forest advisor for Humboldt and Del Norte counties

UC Cooperative Extension fire specialist Max Moritz contributed to sections of the main report on Forest Health and Wildfire and to the San Francisco Bay Area Report

UC ANR lead authors of technical reports were:

  • Economic and Environmental Implications of California Crop and Livestock Adaptations to Climate ChangeDaniel Sumner, director of UC ANR's Agricultural Issues Center 

  • Climate-wise Landscape Connectivity: Why, How and What NextAdina Merenlander, UC Cooperative Extension specialist 

  • Visualizing Climate-Related Risks to the Natural Gas System Using Cal-AdaptMaggi Kelly, UC Cooperative Extension specialist 
Dan Stark, staff research associate  for Humboldt and Del Norte counties, contributed to the pest section of Fuel Treatment for Forest Resilience and Climate Mitigation: A Critical Review for Coniferous Forests of California.
Posted on Monday, August 27, 2018 at 3:23 PM
  • Author: Jeannette Warnert
Focus Area Tags: Environment

How is climate change affecting agriculture? It depends.

If the current trend of warmer winters continues in Yolo County, chill hours may be insufficient for many walnut varieties by the year 2100.

Of 12 crops examined in Yolo County, walnuts are most vulnerable, while processing tomatoes and alfalfa acreage may increase due to warmer winters.

In an effort to forecast how climate change may affect agriculture, University of California agricultural economists looked at how climate has affected crop acreage in the past. The effect of temperature changes on plants depends on local conditions and the crops grown. In a case study of Yolo County agriculture, warmer winter temperatures would reduce chill hours, potentially reducing yields for some crops while extending the growing season for others, according to a University of California study published in the peer-reviewed journal California Agriculture.

Insufficient chill hours can delay the opening of leaf and flower buds in crops such as walnuts, which may result in a smaller yield.
“Growers change crops depending on many factors, including climate change and market conditions,” said Hyunok Lee, lead author and research economist in the Department of Agricultural and Resource Economics at UC Davis. “The challenge was to separate the effects of climate on acreage. To isolate the climate effects from the market effect, we used an econometric model.”

This technique used in Yolo County could be used for projecting the effects of climate change on agriculture in other regions, said Lee.

Using about 100 years of climate data and 60 years of farm acreage, Lee and her co-author looked at the relationships between the evolution of local climate conditions and the acreage of 12 major crops grown in Yolo County. The crops included processing tomatoes, rice, alfalfa, wheat, corn, prunes, grapes, walnuts, almonds, safflower, pasture and other fruit.

“When we look at maximum and minimum temperatures, the minimum temperatures are higher while the maximum temperature stays about the same,” Lee said. “And the lower temperature is rising at a faster rate, especially in winter. That's good for winter crops, but not so good for crops that require chill hours.” Many tree crops require cold for a certain number of hours below a critical temperature, commonly 45 degrees Fahrenheit, to stimulate the growth of leaves and flowers.

Processing tomato acreage, which accounts for 90 percent of vegetable acreage in Yolo County at present, could expand by 14 percent by 2050 if current climate trends persist.
In Yolo County, warmer winters could result in increased rice, tomato and alfalfa acreage while winter wheat could decline.

Among trees and vines, the most sensitive to climate change are walnuts, which require more chill hours. Walnut acreage would decline, Lee said, while there would be a modest change in grape and almond acreage.

Lee emphasized that market conditions exert a great deal of influence on the crops growers choose to plant. Growers who consider trends in climate change may choose different cultivars rather than different crops, such as a walnut variety that requires fewer chilling hours.

Lee and co-author Daniel Sumner, director of the UC Agricultural Issues Center and Frank H. Buck, Jr. Professor in the Department of Agricultural and Resource Economics at UC Davis, based their acreage projections on following the trend of climate change for the past 105 years, but were not able to incorporate climate variability, extreme weather events, accelerated warming or availability of irrigation water in their modeling.

This research, which was part of a larger study of climate change and agriculture funded by a grant from the California Energy Commission, was also supported by the UC Agricultural Issues Center, a program of UC Agriculture and Natural Resources.

Posted on Tuesday, March 22, 2016 at 10:37 AM
 
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