What will be the impact of climate change on California workers if the US and other countries around the world fail to significantly reduce green house gas emissions? In other words, what happens in a "do nothing" scenario?

Climate scientists have established that climate change is caused by "greenhouse gasses," especially carbon dioxide, which trap the sun's heat and therefore raise the earth's temperature. Average California temperatures are already rising; they are expected to rise by 2-5 degrees Fahrenheit by 2050 and -- in a do-nothing scenario -- rise 4-9 degrees Fahrenheit by the end of the century.

The rising temperature of the earth has all kinds of serious effects that are plaguing us now and will do so even more over the course of this century if we just continue at our present course. In California:

• Sea level rise: San Francisco Bay's sea level rose by 7 inches in the 20th century. New scientific findings indicate that in a do-nothing scenario California sea level may rise by as much as 55 inches this century, and that the amount could be much higher. A twelve inch rise in sea levels would mean that ocean flooding that now occurs once a century will occur once a decade, risking breach of levees, flooding of agricultural land, and contamination of fresh water. The U.S. Geological Survey classifies much of the area around Los Angeles and San Diego and around the Humboldt, San Francisco, and Monterey Bays as at "very high" risk.

• Droughts: Precipitation is expected to grow more irregular, with greater risk of both flooding and droughts. Droughts have already increased and are expected to increase dramatically, with critically dry years three times as frequent. As more precipitation falls as rain rather than snow, an 80% decline in the Sierra snowpack is predicted, creating statewide water shortage in late spring and summer. Average annual water availability in Southern California may decrease by 40%.

• Forest fires: Intensified dry seasons are leading to larger and more frequent forest fires. The 2006 wildfires forced the evacuation of more than 900,000 people, the largest evacuation for fire in US history. In a do-nothing scenario the number of wildfires could increase by up to 169 percent by 2085.

• Floods: Higher sea levels and increased winter rains are likely to lead to levee failure, salt water contamination of fresh water, and destruction of habitats.

• Heat waves: In a do-nothing scenario, extreme temperatures that currently occur every 100 years are expected to occur nearly every year by the end of this century. The number of heat wave days in California cities will quadruple. High ozone days could increase by 80%.

Many of these effects will reinforce each other. For example, the combination of rising sea levels and floods from winter rains can combine to threaten levees.

These are conservative estimates; each year's evidence indicates that global warming and its climate effects are happening much faster than previously believed. Global warming may also lead to "tipping points" like melting of Arctic sea ice or release of frozen methane from the Arctic tundra that would lead to abrupt and even more extreme climate change.

Fortunately, there is a way to prevent the worst consequences of climate change. We can greatly reduce the amount of carbon dioxide and other greenhouse gasses we put into the atmosphere. The world's leading organization of climate scientists, the Nobel-prize winning Intergovernmental Panel on Climate Change (IPCC) says that climate can be stabilized by reducing developed country emissions to 25-40 percent of 1990 levels by 2020 and 85-95 percent by 2050. That will require big changes -- but if labor is involved in shaping those changes, we can ensure that they are worker friendly.

What climate change means for California workers -- some examples:
What will happen to California workers if we do nothing to reduce greenhouse gasses? We will look at the projected impacts climate change -- in a do nothing scenario -- will have on the following sectors over the course of this century: Agriculture, Construction, Government, Recreation, Tourism, Ports, Airlines.

Construction workers. The rise in sea level will threaten real estate along the coast and increasing wildfires will affect the entire state. California has over $900 billion in "near shore" homes at risk from water damage; in a do-nothing scenario housing prices along the coast are likely to plummet. The state has five million homes worth $1.6 billion, 40% of all homes, with high or greater fire risk. Adding fire and flood risks, $2.5 trillion of California's $4 trillion in real estate assets are exposed to climate risk.

The result of this risk is likely to be a sharp increase in insurance premiums and a long-term fall in real estate values, especially in high-risk locations. Areas threatened by flood and fire could become unbuildable. Water shortages could lead to additional restrictions on building. The consequences could range from new construction jobs to house the displaced to massive disinvestment followed by long-term depression in the construction industry. The impact on building trades jobs could be devastating. At the least, climate change is likely to lead to massive relocation of construction work, forcing building trades workers to migrate.

Health care workers: Climate warming is producing an increase in the number, length, and severity of deadly heat waves, increasing the incidence of strokes, heart attacks, and severe dehydration. One study predicts up to four times as many heat-related deaths in San Francisco, Los Angeles, San Bernardino, Sacramento, and Fresno in a do-nothing scenario. Another predicts 600 or more extra heat-related deaths per year in Los Angeles County alone. An 80% increase in high ozone days will multiply respiratory diseases like asthma. Increasing forest fires increase the deadly pollutant PM2.5, fine particulates that are responsible for most of California's pollution deaths.

In a do-nothing scenario, hospitalizations and other results of climate-induced ozone and heat waves will cost $24 billion a year. All this will put huge stress on an already stressed healthcare system at the same time that the broader negative economic impacts of climate change are likely to put pressure on health care funding.

Farm and agro-processing workers: Climate change will make water scarce and more costly, spread pests like the Mediterranean fruit fly and the bollworm, increase plant-and-animal killing heat spells, reduce winter chilly spells many plants need, and raise the price of fuel and fertilizer. The record July, 2006 heat wave led to a billion dollar loss for California's dairy industry. In one estimate, climate change will reduce California's agricultural profits by 15%. Climate change will also lead to big shifts in crops and locations. Both downsizing and crop change may lead to substantial reductions in farm worker employment. Heat waves and increased pollution will make farm labor jobs even unhealthier. Climate-caused disruption in other countries will increase immigration to California, increasing the number of farm workers competing for jobs and thereby driving down wages and making it even harder for farm workers to unionize.

Port and airline workers: Sea level rise, storms, and waves will threaten California's seaports and airports. Los Angeles, Long Beach, and Oakland seaports handle 40 percent of US container shipping and nearly a quarter of all foreign trade. Rising sea levels with high waves and tides are likely to damage port facilities. Port infrastructure has several hundred billion dollars of real asset exposure to changes in sea level, tides, and wave action.

San Francisco International Airport is 13 feet above mean sea level. Oakland International airport is nine feet about mean sea level. Both would be vulnerable to inundation from a rise in sea level. Crippled seaports and airports unable to support normal traffic would mean fewer jobs for port and airline workers.

Tourism and recreation workers. Nearly a million Californians work in tourism and recreation, five percent of the workforce. Many of the 350 million people who visit California destinations each year come because of outdoor attractions like beaches, ski resorts, parks, and golf courses. All are affected by climate change.

In a do-nothing scenario California's ski industry is projected to collapse, eliminating 15,000 jobs in the industry and at least as many in accommodation, dining, and other service industries. Beaches will suffer inundation from sea level rise and accelerated erosion. Even if sea level rises only three feet or so, the best-case scenario, it would cause a 26% reduction in beach width in Los Angeles and Orange County beaches and the elimination of Las Tunas beach. Sea level rise combined with flooding and coastal erosion could devastate Point Reyes National Seashore, including all known archeological sites of the Coast Miwok Indians; climate change is predicted to wipe out all the Joshua Trees in Joshua Tree National Park.

Nearly $100 billion in tourism and recreation assets at risk, with projected annual cost of200 million to7.5 billion in climate change damage costs. Hundreds of thousands of jobs would thereby also be put at risk.

Public sector workers. As the University of Maryland study The U.S. Economic Impacts of Climate Change points out, "The effects of climate change will likely place immense strains on public budgets, particularly as the cost of infrastructure maintenance and replacement increases. At the same time economic losses may translate into lost tax revenue."

Every cost of climate change in California we have discussed, from fighting forest fires to providing summer drinking water, will increase budget pressures. So will every reduced source of tax revenue, from closed ski lodges to reduced real estate values. The impact of these budget pressures on workers in the public sector is likely to be massive layoffs, permanent downsizings, further pressure on wages and benefits, speed-up, and deteriorating working conditions.

We will all pay the cost
Every flooded city, fire-ravaged forest, and heat-aggravated illness is a cost that is charged to every California worker and taxpayer. The damages if no action is taken will include tens of billions of dollars per year in direct costs, even higher indirect costs, and trillions of dollars of assets exposed to climate risk. These costs will be shared in one way or another by all the people of California. Almost everyone will get poorer than they otherwise would be.

The economic costs of climate change will be experienced partly in costs of direct damage. An individual whose house is flooded out or a town whose roads are destroyed will bear the initial brunt. So will those who get sick, stay home from work, or have to visit the hospital as a result of heat stroke, asthma, or epidemics. If the Pacific Coast Highway (Highway 1) is forced to close permanently, coastal communities up and down the state will be economically devastated.

But these direct effects are only a part of the picture. As the University of Maryland study The US Economic Impacts of Climate Change points out, "Secondary effects of climate change can include higher prices, reduced income and job loss."

Many products will cost more because "prices of raw materials and energy, transport, insurance and taxes" will increase. If there is not enough electricity or water to meet California's needs, their prices will go up. If more properties are destroyed, the price of insurance will go up. If farms are flooded or can't pay for electricity, the price of food will go up. For example, per capita residential electricity use could increase by 50% for air conditioning, putting a huge strain on the power system, costing households billions of dollars a year, and undoubtedly leading to far higher electricity costs.

Job loss may also result. "As the costs for doing business increase, competitiveness of individual firms, entire sectors or regions may decline. With this decline may come a loss of employment and overall economic security" and effects on "household income." The effects of climate change can be thought of as a "negative stimulus" to the economy, leading to reduced profitability, decreased investment, job loss, and falling wages. The painful economic conditions California workers have faced in the "Great Recession" since 2008 may be greatly intensified by the secondary effects of climate change.

Climate change will also create pressures for higher taxes, service cuts, or both. Fighting fires, fixing destroyed ports and airports, and providing more hospital care will all cost money. So will efforts to adapt to climate change by such means as elevating coastal highways, expanding water storage, and investing in power plants. One way or another the taxpayer will ultimately pay most of those costs.

Labor and the climate crisis
It is easy to respond to the threat of climate change can with denial, evasion, or despair. If climate change has already begun, is there any point in trying to halt it? If fixing it requires global cooperation, why not wait till other countries all agree on what to do? How can we ever address such a huge problem when even small changes are so difficult to make?

The threat of climate change and the steps needed to forestall it have been known for a quarter of a century. By failing to take meaningful action at the national and global level, we have already made some of these effects inevitable. But we can head off far worse effects if we make the reductions in greenhouse gas emissions that climate science says are necessary.

The labor movement in California and throughout the country has led the way in promoting "green jobs" that can help reduce carbon emissions while also helping fix our economy. But those green jobs will be few and far between without a commitment to converting to a low carbon, clean energy economy to avoid the worst impacts of climate change. While unions are only one among many forces needed to bring about that commitment, they can play a crucial leadership role as the voice of working people. After all, it is our members who will face the brunt of the impacts of climate change on and off the job.