Chico, 2030 - 2050

The term "projection" is used in two senses in the climate change literature. In general usage, a projection can be regarded as any description of the future and the pathway leading to it. However, a more specific interpretation has been attached to the term "climate projection" by the IPCC when referring to model-derived estimates of future climate.
Impacts are consequences of climate change on natural and human systems. Depending on the consideration of adaptation, one can distinguish between potential impacts and residual impacts.  Potential impacts are those that may occur given a projected change in climate, without considering adaptation.

Temperature

Climate Projection
It is expected that temperatures in the Southwest will rise by more than 3 degrees over the course of the 21st century. According to current climate change projections, daily average high temperatures are expected to increase in frequency, intensity, duration, and across a larger area. Warmer nighttime averages are also expected to increase. Into the future, experts predict that extreme heat events—several days or more of above average temperatures—will become more frequent and more severe. Historically, Chico has experienced an average of four extreme heat days. The Cal-Adapt software projects Chico will be averaging sixteen extreme heat days by 2030, with as many as 30 days possible in some years. The California heat wave of 2006 is an example of what the future holds.
The projected rise in temperature will have severe impacts on human health. Cases of heat-related illnesses such as nausea, dizziness, stroke, dehydration, and heat exhaustion are expected to rise. Chico is set to experience four times as many days above 103 degrees, which will increase cases of heat-related illnesses, as well as exacerbate pre-existing medical conditions. Higher temperatures will also mean greater instances of record high over-night-lows. When there is not a significant drop in temperature at night (at least 20 degrees Fahrenheit) the human body continues to behave in distress mode—high blood pressure, elevated heart rate—overtaxing the body. With longer heat waves, Enloe Hospital is likely to see an increase in patients admitted for care related to prolonged heat exposure. Disadvantaged and vulnerable individuals will suffer the greatest impacts as temperature and the number of extreme heat events increase. Children and the elderly, who collectively make up 37% of the Butte County population, are among the most vulnerable. Communities living in poverty—21% of the Butte County population—are also at a greater risk of suffering the negative health effects of climate change.

The rise in temperature also has the potential to affect California’s transportation infrastructure. Asphalt and other road maintenance materials are not currently designed to withstand long periods of heat. Longer and more intense heat waves mean the existing road surfaces in Chico and the surrounding area are expected to degrade much more rapidly in the future.

Potential Impacts

Wildfire

Climate Projection
It is expected that the Chico area will experience increases in fire risk between 2030 and 2050, especially in mountain areas. By 2050, communities in the North State are expected to experience a 2.6 percent increase in area burned in 2016. California wildfires have increased in recent years due to an extended fire season created by warmer temperatures in the spring and fall and the associated reduction in rainfall and snowpack. Increased wildfires can also have adverse health effects, as the smoke can lead to an increase in PM2.5 levels well beyond national standards for air quality. These issues are predicted to continue under plausible climate change models.
Increased wildfire activity will occur on the urban/wildlife interfaces around Chico, putting homes and other structures at a greater risk of destruction. Fires will be more frequent and more intense, putting Chico’s limited suppression resources under further strain. Higher temperatures will lead to a further rise in the Bark Beatle populations, which degrade the health of local trees, turning them into rotted, dry fodder for wildfires. Areas with drought-stressed tress, shrubs, grasses and other fire “fuels”—places such as Chico’s Bidwell Park—will be especially vulnerable to combustion. Overgrown vegetation along Little Chico Creek has a similar potential to act as a wildfire corridor, possibly drawing fires deep into town.

Property damage in California will increase under climate change scenarios. The majority of this damage will occur in the wildland-urban interface. Chico has many subdivisions located within this interface, and these neighborhoods are at an especially high risk of fire damage. More wildfires will also produce an increased amount of fine particulate matter (PM2.5) and air pollutants that affect people’s respiratory health. Wildfire-associated PM2.5 leads to an increase in respiratory hospital admissions. In Chico, increased wildfires and the smoke they produce will drive up admissions to Enloe Hospital for asthma, cardiovascular disease, bronchitis, bronchiolitis, and congestive heart failure. The elderly (65 and older) and small children (under 4) are most affected by an increase in PM2.5 levels.

Potential Impacts

Snowpack

Climate Projection
California has historically stored water in the form of dense and healthy snowpack. Warming average global temperatures will result in reduced snowpack. Because snowpack in the Sierras and Cascades serves as a reservoir for most of the freshwater used in California—second only to groundwater—any loss in storage will have major impacts on water accessibility and flow regimes. By the turn of the century, this could mean a 30% loss of spring stream flow, which in turn could mean a reduction in up to 25% of water available for agricultural use. Southwest climate projections suggest not only drier, warmer weather, but also increased storm systems and precipitation extremes during the winter. With an increase in winter rainfall and earlier melting of snowpack in spring, we can expect an increase in flood frequency and intensity.
The Sierra Nevada snowpack constitutes over a third of California’s water. As winters warm due to climate change, researchers estimate that snowpack in the Sierras will decline by 25 to 40 percent by 2050. As a result, the dry season in California is expected to extend further into spring and fall, creating conditions similar to those Chico experienced in 2015, when the government imposed mandatory water rationing. Low stream flows raise concerns about possible loss of hydropower in late summer and the potential for brown outs in Chico and the surrounding region. Dry, hot conditions also put the health of Chico’s legendary Bidwell Park at risk. A declining snowpack will impact local groundwater levels, which have been falling in the 21st century. A fall in the water table will lead to the death of shorter rooted trees, creating additional fire hazards, impacting wildlife habitats, and placing greater demands on city resources.

With the predicted warming, more precipitation will fall in the winter as rain instead of snow, increasing the frequency and severity of flooding. Extreme weather events are expected, such as back-to-back precipitation events that could overwhelm Chico’s ability to absorb and manage the runoff. Chico’s public works are prepared for a 200-year flood event, but projections anticipate those events happening with a frequency of 150-100 years. Under such conditions, Chico’s storm drains and wastewater treatment plant would be vulnerable to overload and possible failure if left unimproved.

Potential Impacts