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The Impact of Climate Change on Workers and Employers: The California Experience

May 25, 2023 (18 min read)

By Hon. Susan V. Hamilton, Former Assistant Secretary and Deputy Commissioner, California Workers’ Compensation Appeals Board

In 2022 there were 7,490 wildfires in California. They burned 362,455 acres, destroying homes and businesses and causing 9 fatalities. In large part, these wildfires can be attributed to 15 years of severely dry conditions in the State. [1] Then between December 31, 2022, and March 26, 2023, California was hit by a period of heavy rainfall caused by multiple atmospheric rivers, resulting in flooding that damaged homes, businesses and caused at least 22 fatalities. [2]

The U.S. Global Change Research Program [3] reports that Earth’s climate is changing faster than any period in the history of modern civilization and in the USA, alone, causing a wide range of impacts across every region of the country. According to The Fourth National Climate Assessment, Vol. I: Climate Science Special Report (2017), [4] in the last 115 years, global annually averaged surface air temperature has increased by nearly 2° F, making this period the warmest in modern history, and resulting in record-breaking extremes in weather events. Temperatures in California have risen almost 3° F since the beginning of the 20th century. In the 126-year period from 1894 to 2020, the 6 warmest years have all occurred since 2014. [5] Periodically California has experienced extreme precipitation events caused by atmospheric rivers, resulting in damaging flooding. The report describes California’s most serious climate hazards as severe drought and flooding.

The California Legislative Analyst’s study, Climate Change Impacts Across California (LAO, April 4, 2022) (LAO report) concurs. The LAO report describes California’s five key climate hazards as: (1) higher temperatures and extreme heat events; (2) more severe wildfires; (3) more frequent and intense droughts; (4) flooding due to extreme precipitation events; and (5) coastal flooding and erosion from sea‐level rise.

Climate Change and Workers’ Compensation

You might ask how is climate change relevant to work, in general, and to workers’ compensation, specifically? For one, research has demonstrated a relationship between temperature and occupational health. Both high and low temperatures increase injury rates. (Upjohn Study) [6] More days of extreme heat and wildfire smoke increase the risk of worker injuries, illnesses, and fatalities, especially for those who work out of doors without adequate air conditioning or ventilation (LAO report). Outdoor work isn’t the exclusive province of agricultural workers or firefighters, either. Indeed, many different occupational categories perform a substantial amount of outdoor work. Among a few are police officers and other first responders, landscapers, postal workers, utility workers, commercial fishery workers, recreational workers, and construction workers. More days of extreme heat are especially problematic for outdoor workers. While it may be possible for outdoor workers to avoid heat exposure in regions where hot temperatures are rare by adjusting work schedules, it is far less possible for outdoors workers in warmer climates to adjust their work schedules when days of extreme heat are common.

The Upjohn study found that in regions where temperatures regularly top 90° F, another day of extreme heat can impact worker health. The Upjohn study matched workers’ compensation injury rate data from across Texas, one of the warmest states, with workers’ compensation injury rate data from across the United States, and matched both with daily temperature data. A day exceeding 100° F increased workers’ compensation claim rates over the next three days by 3.5 to 3.7%. Heat exhaustion and heat stroke were common among the claimed injuries. Extreme heat exposure can also exacerbate chronic conditions and can cause reduced cognitive function, which leads to increased risk of injury and decreased productivity. [7] A worker’s cognitive impairment is especially problematic in industries engaged in hazardous work. Moreover, the Bureau of Labor Statistics reports that between 2011 and 2019 there were 344 work-related deaths due to heat exposure. This figure, the report cautions, likely reflects an undercount as many workplace safety experts believe that a significant number of heat-related deaths are either underreported or misreported as another cause, such as heart attack. [8]

Even though manufacturing and warehouse work is primarily performed indoors, workers employed in those occupations similarly face the risk of excessive heat exposure. Some facilities lack air-conditioning systems altogether, while in others air-conditioning and ventilation systems are inadequate given the size of the facility and/or the heat generated by equipment used by workers to perform their work. Commercial delivery drivers are also more likely to work in settings without adequate cooling. [9]

Some workers, such as firefighters, are exposed to both excessive heat conditions as well as wildfire smoke, which is especially problematic. Even on a short-term basis, exposure to wildfire smoke can have serious health consequences, like eye and respiratory tract irritation. It can also aggravate pre-existing respiratory and cardiovascular conditions. As warmer temperatures cause more sustained dry periods, the risk of wildfires increases. [9]

Sustained periods of drought are associated with dryer soil. Coccidiomycosis (“Valley Fever”) is a fungal infection that spreads by spores in dry soil. It can more easily proliferate in a drier climate with increased dust storms. All workers who primarily work outdoors are at increased risk for exposure to the infection. (LAO report).

There is little doubt that as our climate continues to warm, workers across many different industries are at risk of an increase in work-related injuries attributable to hotter temperatures. The National Safety Council reports that in 2021 the total cost of work injuries in the United States was $167 billion. This amount includes wage and productivity losses, medical costs, administrative costs, and employer costs. [10] Under California’s workers’ compensation system, an employer may be liable for workers’ compensation benefits arising from a workers’ heat-related injury. The Upjohn study finding that a day with a temperature exceeding 100° F increased workers’ compensation claim rates over the next 3 days by 3.5 to 3.7% is a strong indication that absent preventative measures, California employers can expect to see an increase in workers’ compensation claims as our climate continues to warm.

An increase in workers’ compensation claim rates isn’t the entire picture, either. An increase in workers’ compensation claims likely means a loss of productivity, as well, which translates to additional losses for both the employer and employee.

What It Could Mean to Work in a Warmer Climate

While climate change will impact all of us, workers, and employers in certain parts of California will be more directly impacted than others. Take, for example, the Central Valley, where agriculture and farming are primary industries. Often referred to as “USA’s breadbasket,” the Central Valley is one of our country’s most productive agricultural regions. We often take for granted the wide array of produce, fruits, nuts, dairy, meat, and poultry readily available to consumers year-round. But climate change could impact all of that. Prolonged drought and hotter temperatures could cause agricultural production to shift away from crops that are heavily reliant on irrigation towards others that are more drought tolerant. Currently our agricultural industry relies heavily on both abundant water and human labor to ready fields, plant crops, and harvest crops. But less water sources and different crops and/or agricultural methods could mean that there is a need for less human labor, or that workers will be required to relocate and learn new skills and practices. New crops and/or agricultural methods could mean the use of new technologies and practices that are costly for employers. It could also mean a loss of productivity.

In addition to agriculture, construction and manufacturing are other large industries throughout the Central Valley. Warmer temperatures pose new challenges for these industries, as well. Many California workers work primarily outdoors or in large manufacturing and warehouse environments. Hotter days could mean reductions in work hours so that outdoor work is performed only during the coolest times of day or the coolest seasons of the year. Such restrictions could mean a loss of productivity, adversely impacting both workers and employers. Hotter days will similarly impact both manufacturing and warehousing industries by requiring employers to either restrict work hours to the coolest times of day or by investing in larger air-conditioning and ventilation systems. Either way, there will be costs to both employers and workers.

The Central Coast is not immune from the effects of climate change, either. The intense period of rain from January through March 2023, brought widespread flooding to that region. In the Pajaro Valley, where much of California’s berries (strawberries, blueberries, blackberries, and raspberries) are grown, the Pajaro River flooded, putting hundreds of acres of farmland under water, and preventing farm workers from attending to their jobs. As many as several thousand people were evacuated from the town of Pajaro when it flooded. Most of the evacuees were agricultural workers, and the displacement interrupted their work. Over 1,500 acres of one large berry farm’s operations were flooded. That represents an investment of tens of millions of dollars that could be entirely lost if the berries cannot be harvested. [11]

Widespread flooding in the Central Valley between January 2023 and March 2023 brought a lost California lake back to life. In fact, the once dry lakebed has become so large with the wet weather that water experts predict it will take at least a year or longer to drain. Meanwhile, the town of Tulare, which is midway between Fresno and Bakersfield, has seen more than 100 square miles of roads, farms, and homes in the formerly dry lakebed completely submerged in floodwaters. Climate scientists predict that even more land will become submerged this summer as the record snowfall in the Sierra Nevada mountains melts into the rivers that feed the lake. Former agricultural land is underwater and both employers and workers have been displaced. Damages to date are reported to be in the range of hundreds of millions of dollars. Now landowners, local, state, and federal officials are faced with how to proceed forward. Homes and infrastructure must be protected, and the dominant agricultural industry does not want to see more of its high value fields of cotton, tomatoes and pistachios submerged in water. [12]

In the Sierra Mountains the primary industries are logging, grounds maintenance, recreation, and tourism. The impact of climate change (hotter days and/or more precipitation) will be felt by these industries as well. Outdoor work and activities could be restricted during periods of intense heat and/or wildfires. More precipitation could also result in flooding and landslides that prevent tourism, restrict work activities, and expose firefighters and emergency responders to increased occupational risks. Fewer tourists and recreational activities translate to losses by both workers and employers engaged in hospitality and recreational industries.

As sea levels continue to rise there is a risk that high-tide flooding will disrupt port-based commerce and the movement of goods. Such a disruption would adversely impact workers and their employers. It could also impact consumers as well. (LAO report)

Mitigating the Impacts of Climate Change upon Workers’ Compensation

How can we mitigate the effects of climate change? Government, of course, will play a critical role by implementing measures and adopting policies that aim to reduce emissions of greenhouse gases. California has already been a leader in its efforts to offset the impact of a warming climate. Employers will also play a crucial role. When hot days prevent or restrict work activities, worker productivity will be reduced because workers will need more breaks or will only be able to work a reduced shift. A decrease in worker productivity typically means higher costs, less profit and longer wait times for goods and services such as construction and manufacturing. The use of new technology and innovation may be able to mitigate some of the consequences of reduced productivity. If not, affected employers will face losss and the geographic regions impacted will see a decline in economic growth.

Even if employers implement adaptive measures to reduce the impact of climate change on their employees, they will likely incur additional expenses. For example, installing more robust air-conditioning and ventilation systems in manufacturing plants and warehouses could be very costly. Likely larger air-conditioning and ventilation systems would increase employer’s utility expenses, too. Air-conditioning is not a feasible option in agricultural, landscaping, construction, and even recreational industries. In those regions where outdoor workers are increasingly exposed to wildfire smoke, employers might choose to reduce the occupational risk of wildfire smoke inhalation by providing their workers with masks and air filters. These accommodations could be very costly. Further, in those regions prone to flooding, it might be necessary for an employer to relocate its facilities to another area. The costs of relocation and/or the modification of a structure would almost certainly be a costly endeavor. Safety of workers is paramount, and implementing measures to protect workers from the impact of a warming climate will be a costly undertaking for employers.

The state of California is also an employer, and like other governmental and private sector employers, the effects of climate change impose additional costs. As an example, during the period 2015-2016, California spent $1.9 billion to suppress wildfires. By 2020-2021, the cost to suppress wildfires increased to $2.9 billion. Costs for workers’ compensation and death benefits are likely to increase as California’s firefighters and emergency responders are faced with the effects of more catastrophic weather events. Hotter and more extreme weather makes it a near certainty that California will need to vastly expand its workforce, not only to respond to climate emergencies, but also to hire additional engineers, scientists, and other experts to develop strategies and technologies to mitigate the impact of climate change. (LAO report)

Legislative and Regulatory Efforts to Mitigate the Impact of Climate Change on Workers, Employers and Workers’ Compensation

Just as California has been a leader in implementing policies and measures to reduce the emission of greenhouse gases, it has also been a leader through the adoption of legislation and regulations to protect employees from sustaining injuries attributable to the impact of climate change. For example, in 2006 the California Occupational Health and Safety (CalOSHA) Standards Board adopted regulations requiring employers to provide workers with drinking water and shade at outdoor workplaces during hot periods. The regulations also require employers to train supervisors and staff to identify and prevent heat-related injuries.

In 2016, the Legislature adopted a law directing the CalOSHA Standards Board to adopt regulations regarding indoor heat illness prevention.

In 2020, the CalOSHA Standards Board adopted emergency regulations to require employers to provide their employees with N95 masks for voluntary use whenever the Air Quality Index for particulate matter 2.5 is greater than 150. The regulation requires use of N95 masks whenever the Air Quality Index for particulate matter 2.5 exceeds 250 unless other safety conditions are met.

In 2021 a law was passed that includes farmworkers as essential workers during health emergencies like wildfire smoke events. During health emergencies, farmworkers and other essential workers must be provided with personal protective equipment from the state stockpile. In addition, employers are required to provide wildfire smoke training to their employees.

The 2022 Legislative session was particularly robust regarding climate change related legislation. The Legislature adopted Government Code § 15562.5, which requires the Labor and Workforce Development Agency to establish an advisory committee to evaluate the effects of climate change on California’s workers, businesses, and the economy. The Advisory Committee can contract with academic institutions/organizations to conduct a study to address time away from work and lost wages due to heat, the frequency with which different types of occupational injuries occur at given temperatures and humidity levels, underreporting of occupational injuries and illnesses due to heat exposure, and evidence-based measures to minimize the effects of heat exposure on workers.

Next, Public Resources Code § 71410 was adopted. That new statute requires the California Department of Insurance to develop an extreme heat warning and ranking system in coordination with the California Department of Environmental Protection and the Department of Public Health.

Labor Code § 6721 was amended to require CalOSHA to create a heat safety standard for temperatures exceeding 105° F. In addition, the amendments established a stricter wildfire smoke standard and requires the use of respiratory equipment when the air quality index is 200 or more.

The Legislature also added Health and Safety Code § 123576, which requires the Department of Public Health to use findings from research on the impacts of extreme heat on perinatal health to develop guidance for pregnant women working outdoors.

The current 2023 Legislative Session is equally robust on the climate change front. A group of Senators introduced a trio of bills all geared toward transparency and accountability regarding climate change mitigation. Senate Bill 253 (Wiener) would require all large corporations ($1 billion annual revenue) that do business in California to publicly disclose their greenhouse gas emissions in line with the Greenhouse Gas Protocol, considered to be the gold standard of emissions reporting.

Senate Bill 261 (Stern) would require the State to contract with a climate reporting organization to review climate related financial risks facing companies doing business in California and preparing an annual public report.

Senate Bill 252 (Gonzalez) would bar the California Public Employees Retirement Board and the State Teachers Retirement System from investing in major fossil fuel companies.

Meanwhile, on May 18, 2023, the CalOSHA Standards Board conducted a public hearing on proposed regulation 3396, Title 8, California Code of Regulations. Section 3396 would create a standard to minimize heat-related injury and illness among workers working in indoor places of employment. The Initial Statement of Reasons for the proposed regulation observes that workers in such indoor facilities as warehouses, commercial kitchens, fast food restaurants, foundries, shipping containers, canning plants, manufacturing, and factories often work in hot environments without air-conditioning and are unable to take advantage of hot weather cease work policies that apply to their counterparts working in outdoor places of employment. In research regarding the necessity of a standard for indoor work environments, the CalOSHA Standards Board reviewed workers’ compensation injury data for heat-related injuries and illnesses of workers in indoor employment settings during the period 2010 to 2018. The research revealed a significant increase in the number of heat-related injury and illness claims between 2010 and 2018. [13] The proposed regulation would require employers to provide ample water to and encourage the frequent consumption of water by their employees. It would also require the indoor facility to include a cooling area where employees are able to cool down during their work shifts. Employers would be required to monitor employees within the cooling room to discern any signs of heat illness or injury and to facilitate necessary emergency treatment as required. Additionally, it would require employers to provide training to employees on heat-related injury and illness, the process of acclimatization, and the importance of water during periods of extreme heat. [14]

Where Do We Go from Here?

No doubt there will always be those who deny that our Earth’s climate is changing. Nonetheless, the overwhelming scientific evidence credibly demonstrates that the temperature of Earth is warming. Over the 126-year period from 1894 to 2020 recorded temperatures in California increased by nearly 3° F. Occupational injuries, illnesses, and fatalities attributable to heat-related conditions are equally well-documented. If California’s climate continues to warm as is predicted absence successful mitigation, there most likely will be more heat-related injuries, illnesses, and fatalities. Warmer days coupled with more extreme rain weather events and the predicted rise in sea levels could be devastating. Many different industries will be affected, and employers and workers will face new and daunting challenges. The economic impact of unimpeded climate change could be catastrophic. It will require an “all hands-on deck” approach. Some industries will need to adapt current practices to meet the new climate realities. Many employees will need to learn new skills and/or relocate to other regions of the state where they can work and live safely. Local and State government will need to be especially proactive to implement policies and enact laws and regulations in furtherance of health and safety. Now is the time for innovation and creative solutions to mitigate the impact of our changing climate.

Fortunately, California is ahead of many other States in recognizing the realities of climate change, its impact upon workers and employers, as well as its impact upon all Californians. California adopted a Climate Adaption Strategy Plan to promote the State’s climate resilience. [15] On April 4, 2023, Governor Newsom issued a progress report on actions taken in 2022 to achieve the goals of the plan. [16] There is a lot of work ahead to achieve the goals, but we have a clear roadmap. Workers and employers should be encouraged by the focus on promoting worker heath and safety and ensuring a vibrant California economy in the decades and centuries ahead.


  6. Climate Change and Occupational Health: Are There Limits to Our Ability to Adapt, Upjohn Institute Working Paper 19-299 ( up 19-299) (Upjohn study).
  7. Max, Kiefer et al., Worker Health and Safety and Climate Change in the Americas: Issues and Research Needs, 40(3) REV. PANAM SALUD PUBLICA, 192 (2016), https//
  9. George Town Environmental Law Review, Workers Among Most Vulnerable to Climate Change, Jan.12, 2021.

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