Climate variability and change: Trends and impacts on California agriculture

Summary

Stefan Partek, Cooperative Extension Specialist at UNICEF California, presents an insightful overview of climate variability and change, and their significant impact on California agriculture. The state, a leading global producer, faces challenges from warming temperatures, reduced chill hours, changing precipitation patterns, and decreased snowpack. These climate shifts threaten crop yields, especially for temperature-sensitive crops, and exacerbate drought and wildfire risks. Partek stresses the need for proactive climate adaptation strategies to ensure resilience in agriculture, highlighting the importance of both mitigation efforts and adaptive measures to safeguard California’s agricultural future.

Takeaways

• 😀 California is a major agricultural hub with over 76,000 farms producing more than 400 commodities valued at $34 billion.
• 🌍 The state is a leading global producer of almonds, pistachios, and fresh market vegetables, as well as milk in the U.S.
• 🌦️ Climate variability, including phenomena like El Niño and La Niña, significantly influences agricultural weather patterns and water availability in California.
• 🌡️ Climate change has caused a steady increase in both minimum and maximum temperatures in California, especially affecting crop yields and water supply.
• ❄️ The reduction in snowpack, a key water source for the state, is expected to continue, with projections showing a 40% decrease by 2100 under higher emissions scenarios.
• ☀️ There has been a marked increase in 'hot nights' in California, which contributes to crop stress and reduced yields, particularly in temperature-sensitive crops like almonds and strawberries.
• 💧 Increasing consecutive dry days are reducing water availability for irrigation and raising evaporation rates, exacerbating drought conditions in California.
• 🌱 The length of the frost-free season in California has increased, which can be beneficial for annual crops but detrimental to perennial crops that rely on chill hours.
• 📉 Climate models predict a 10-30% reduction in crop yields for some California crops, such as tomatoes, rice, and cotton, due to rising temperatures.
• 🔥 Rising temperatures increase the risk of wildfires in California, with potential economic impacts and disruptions to agriculture, particularly in high-risk areas.
• 🌾 Proactive climate change mitigation and adaptation strategies are essential to help California agriculture remain resilient to the growing risks of climate change, including adjusting farming practices and improving water management.

Q & A

What is the focus of Stefan Partek's work at UNICEF California?

Stefan Partek's program focus at UNICEF California is primarily on climate adaptation in agriculture. He works with the Sierra Nevada Research Institute at UC Merced.

What are the key facts about California agriculture that Stefan Partek shared?

California has over 76,000 farms producing more than 400 commodities with a farm gate value of $34 billion. It is the leading producer of almonds, pistachios, fresh market vegetables, and milk in the U.S. Some of the state's top ten valued commodities include milk, almonds, grapes, cattle, strawberries, and walnuts.

How does climate variability differ from climate change?

Climate variability refers to short-term fluctuations in climate patterns, such as those caused by El Niño and La Niña, typically lasting from 6 to 18 months. In contrast, climate change refers to long-term, statistically significant shifts in climate, such as rising temperatures and changing precipitation patterns, which occur over decades or longer.

What are El Niño and La Niña, and how do they affect climate?

El Niño and La Niña are climate phenomena related to temperature changes in the equatorial Pacific Ocean. El Niño occurs when sea surface temperatures in this region are warmer than normal, while La Niña occurs when they are cooler. El Niño generally brings wetter and cooler conditions to the southern U.S., while La Niña brings drier and warmer conditions. These patterns affect global weather and climate, including in California.

What is the Pacific Decadal Oscillation (PDO), and how does it impact climate?

The Pacific Decadal Oscillation (PDO) is a climate pattern that oscillates over a much longer period—typically 10 to 20 years—compared to El Niño and La Niña. The PDO affects sea surface temperatures in the Pacific and has significant impacts on weather patterns in the U.S. and globally, including warmer conditions along the U.S. West Coast during its warm phase.

What are some of the observed climate change indicators in the U.S. over the last 100 years?

Over the past century, the U.S. has seen an average temperature increase of about 0.13°F per decade, with some regions, like the southwestern U.S., warming by 2 to 3.5°F. Seven of the ten warmest years on record globally have occurred since 1998. Other indicators include increased frequency of extreme precipitation events and a reduction in snowpack in places like California.

Why is the increase in minimum temperatures (Tmin) particularly significant for California agriculture?

The increase in minimum temperatures (Tmin) is particularly significant because it can lead to higher respiration rates in crops, reducing yields. Additionally, warmer minimum temperatures may result in fewer chill hours during the winter, which are crucial for crops like certain fruit trees that require cold temperatures for proper bud development.

How is climate change affecting California's snowpack, and why is this important?

California's snowpack has been declining, with projections suggesting that by the end of the century, the snowpack could decrease by up to 40%. The snowpack is an important natural water storage system for the state, especially for irrigation in agriculture. A reduction in snowpack will significantly affect water availability for farming.

What are the projected impacts of climate change on California agriculture by 2070-2099?

By 2070-2099, climate change could result in significant impacts on California agriculture, including a 30-60% loss of Sierra snowpack, more heatwaves, and an increase in critically dry years. Crop yields for certain crops like tomatoes, rice, and cotton could decrease by 10-30%. Additionally, the increase in wildfires and droughts could further stress the agricultural sector.

What are some climate adaptation strategies California farmers can use to cope with climate change?

Farmers can adapt to climate change by adjusting planting dates, selecting crops that are more suited to changing temperatures, and implementing water-efficient irrigation systems. Modifying crop choices and planting schedules to match changing frost-free seasons and chill hour requirements can also help mitigate the impact of warming temperatures on crops.