Rising temperatures, rising sea levels and a disappearing snowpack were part of a scary story told to SCV Water Agency officials recently as they learned the effects of climate change over the next 100 years.
Last week, members of the SCV Water board were presented data collected and interpreted by state researchers preparing California’s Fourth Climate Change Assessment.
The latest climate assessment was intended to advance “actionable science” that would serve the growing needs of state and local-level decision-makers from a variety of sectors.
“As (greenhouse gas) emissions increase, these figures show us the effects as far as temperature goes,” said Sarah Fleury, associate water resources planner for SCV Water, who gave the presentation.
“Business as usual,” she said, “takes us past 2 to 3 degrees by mid-century and continues to go up from there.”
“They broke the state down into nine regional reports which they had never done before,” Fleury told the board.
“And they did that because the vast majority of the adaption planning is going to happen at the local and regional levels,” she said.
And, SCV Water is one of those local planners.
L.A. County changes
Key projected climate changes for Los Angeles County including the Santa Clarita Valley include:
- Continued future warming over the L.A. region is expected. Across the region, average maximum temperatures are projected to increase around 4-5 degrees F by the mid-century, and 5-8 degrees F by the late-century.
- Extreme temperatures are also expected to increase. The hottest day of the year may be up to 10 degrees F warmer for many locations across the L.A. region by the late-century. The number of extremely hot days is also expected to increase across the region.
- Despite small changes in average precipitation, dry and wet extremes are both expected to increase. By the late-21st century, the wettest day of the year is expected to increase across most of the L.A. region, with some locations experiencing 25- to 30-percent increases. Increased frequency and severity of atmospheric river events are also projected to occur for this region.
- Sea levels are projected to continue to rise in the future, but there is a large range based on emissions scenario and uncertainty in feedbacks in the climate system. Roughly 1-2 feet of sea level rise is projected by the mid-century, and the most extreme projections lead to 8-10 feet of sea level rise by the end of the century.
- Projections indicate that wildfire may increase over Southern California, but there remains uncertainty in quantifying future changes of burned area over the L.A. region.
Since 2006, the state has undertaken four comprehensive climate change assessments, designed to assess the impacts and risks from climate change and to identify potential solutions that would help local agencies like SCV Water form policy actions.
The recommendation made by state officials to decision-makers such as the SCV Water board was: “Continue to integrate climate change into existing planning and decision-making processes that traditionally excluded climate change considerations.”
Water officials are among the decision-makers most affected by climate change, according to those who prepared the assessment.
“Climate change will further complicate the challenging task of satisfying freshwater demands across the Los Angeles region,” they concluded.
According to the assessment researchers, Including the factors of climate change into existing into water management models, they said, would help agencies such as SCV Water maintain water resources for residential, commercial, agricultural and recreational purposes.
By 2100, the average annual maximum daily temperature is projected to increase by 5.6 degrees to 8.8 degrees.
By 2050, the state’s agricultural production could face climate-related water shortages of up to 16 percent in some regions.
By 2100, the water supply from snowpack — from which SCV residents receive half their water — is projected to decline by two-thirds.
Researchers preparing the assessment, reflecting on the significance of this finding alone, noted, “Water management practices in California face growing challenges from continued climate change and extreme weather.”
Water officials would do best, they said, to use probabilistic hydrological forecasts, groundwater storage and better measurements of the snowpack.
Researchers also had some dire predictions relating to the frequency of wildfires increasing.
If greenhouse gas emission continues to rise, one study found that the frequency of extreme wildfires would increase and the average area burned statewide would increase by 77 percent.
Coastal areas received some harsher news from the assessment.
In looking at the rise in sea levels, between 31 and 67 percent of Southern California beaches may completely erode by 2100 without large-scale human intervention, the study said.
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