The COVID-19 pandemic reminded us of the disturbing problems that have developed in our relationships with nature within and beyond our state. We are also reminded how our responses and suggested solutions to these scientific problems must be data driven and evidence based, or we will cultivate big trouble and a lot of suffering. Even before COVID-19, countless lives and billions of dollars each year in California depended on our understanding of our natural world and how we fit in. While we focus on the COVID pandemic that is terrorizing our state, other natural systems and cycles are still working around us and impacting all of us, whether we pay attention to them or not. Living in constant crisis during this pandemic makes us far more vulnerable to the unexpected surprises-turned-catastrophes that nature could throw our way on any day. So, we’re paying attention.
The two previous stories on our web site used NOAA National Weather Service data to focus on the latest 2019-2020 rainy season and then to examine long-term temperature and precipitation trends for selected California locations. These stories quickly generated a series of questions that must be addressed if we are to understand the science behind climate change in California. We thank the students in Dr. Jing Liu’s Weather and Climate class for asking the questions that inspired this latest so-obviously-necessary follow-up story.
Here, we will use some of the results from a comprehensive research project, Indicators of Climate Change in California, published by the state’s Office of Environmental Health Hazard Assessment in May, 2018. This wide-ranging study gathered available data and research, from a wealth of diverse sources, about how our climate has been changing and the impacts these changes are having on the Golden State’s natural systems and cycles and its people.
Discussions about climate change have too often become emotionally and politically contaminated, so we will strictly adhere to the scientific method as we present the facts and evidence that combine to help us understand climate change science in California. Our goal here, as always, is to maintain our integrity and build trust by presenting an objective analysis of another common issue or problem. So, we will stick to the facts to answer your questions. We challenge you to at least briefly put aside your political and personal biases so that we can objectively share this scientific analysis of climate change that is affecting every Californian, whether plant, animal, or human.
What are the natural causes of climate change in California?
Earth’s natural systems and cycles were causing and adapting to many types of dramatic climate change long before humans arrived and such fluctuations will continue long after we are gone. These gradual natural cycles that occur over many thousands or millions of years include changes in Earth’s tilt on its axis and its elliptical orbit around the sun and gradual changes in atmospheric chemistry. You only have to examine the spectacular glacial landscapes of the Sierra Nevada and Trinity Alps or the ubiquitous Ice Age fossils at such locations as the La Brea Tar Pits or Diamond Valley Reservoir to see that California was cooler and wetter just more than 11,000 years ago and again through cycles dated hundreds of thousands and even millions of years earlier. We examine much of this science and many of these landscapes in our publication.
Through succession, our ecosystems are capable of gradually adjusting to these oscillations that may take many thousands of years. But they are punctuated by shorter-term events such as the rare larger objects from space that can impact and devastate Earth, or the greatest catastrophic volcanic eruptions that spew climate-changing volcanic debris and gases into our atmosphere and can cause immediate global cooling lasting for many months. Sun spot cycles are among the perhaps less significant natural short-term climate influencers. Our recent understanding of ENSO (El Nino-Southern Oscillation) and PDO (Pacific Decadal Oscillation) cycles remind us that large-scale changes in ocean currents off the California coast can also drive dramatic short-term shifts in our state’s weather and climate. But as scientists gathered more reliable evidence toward the end of the 1900s, it became apparent that the combined long-term natural oscillations alone would likely drive Earth into a cooler period. Just the opposite happened.
What are the main causes of climate change today?
At the same time, meteorologists and chemists were measuring troubling changes in Earth’s atmosphere that were driven by human activity. For many prior decades, scientists understood that our atmosphere was not primarily heated directly from the top down by shortwave radiation emitted from the hotter sun, but primarily from the bottom up by longwave radiation emitted by land and ocean surfaces warmed by that initial sunlight. We all know this as the greenhouse effect. Without those greenhouse gases that allow sunlight in but then selectively absorb longwave radiation from Earth’s surfaces, California would freeze over and life as we know it would be impossible. The Golden State would quickly become the Frozen State.
We know that these greenhouse gases that include water vapor, carbon dioxide, methane, and nitrogen oxides, are the thermal regulators for our atmosphere and their concentrations are increasing fast. We now have far more CO2 in our atmosphere than during at least the last million years, as technologies help us push those reliable measurements further back into the geologic record. And we have measured and confirmed that the main source of these growing CO2, methane, nitrogen oxides, and other greenhouse gases is human activity that includes our burning of fossil fuels. Put into crude and oversimplified language, it’s as if we are rolling up the windows of our car on a sunny day. The shortwave heat from the sun enters through our transparent windows to heat the inside of our car, but the longwave heat energy can’t get out. As humans dramatically change the chemistry of our atmosphere, more heat is trapped and climates are adjusting relatively quickly while nature distributes this additional energy.
How is climate change affecting California compared to world trends?
In California and most of the rest of the world, we have warmed by more than 1.5 degrees Fahrenheit (or about a degree Celsius) during the last century or so, although the rates of warming have dramatically increased since 1975. The many impacts include more frequent and dramatic weather anomalies that are challenging our natural and human systems to adjust and/or suffer severe and possible permanent damage. One of the many reasons we have labelled this new age the Anthropocene is that human-driven climate change is impacting every environment, every landscape, and every person, especially in California. Those noted natural cycles are still working in the background, but they seem to be overshadowed by human interference that is forcing this different kind of climate change. There are many other climate changes caused by humans beyond the chemistry of our atmosphere, such as the alteration of surfaces that is impacting Earth’s albedo and water cycles. As an example, robust urban heat islands are being measured in almost every California city.
(It is important not to confuse our discussion here with the separate problem of ozone depletion high in Earth’s stratosphere, where, thanks to heeding and applying our science and technologies, we have found helpful solutions and have made life-saving progress over the last few decades.)
Is the increase in greenhouse gases in California similar to global trends and how does this affect our climate?
Industries and other human activities emit more greenhouse gases around our urban areas, and so there are minor short-term spikes and dips that reflect human schedules and patterns around those areas. This is why we measure from remote stations, such as at the top of Hawaii’s volcanoes, far removed from those local sources and anomalies. But most greenhouse gases are quickly mixed and transported around the world and that is why the more recent measurements around California roughly match those made at more remote stations. This is also why we could shut off all emissions of greenhouse gases from California and see little immediate change when we measure their concentrations in the atmosphere. Even if we stopped emitting greenhouse gases everywhere in the world, their levels would only begin to slowly decline and it would take many decades before they returned to anything near their preindustrial revolution levels. After all, photosynthesis and our oceans can only gradually absorb the excess CO2. When you compare the GHG graphs to the earlier temperature graphs, you can see why the science points to the increasing global concentrations of greenhouse gases as driving forces responsible for most of California’s climate change today.
Are other pollutants causing climate change?
Yes, there are dozens of air pollutants that impact our health and some are contributing to climate change. For instance, some air pollutants that cause millions of respiratory illnesses and premature deaths are also reflecting solar radiation back into space before it can heat Earth’s surfaces, which may result in some cooling effects. These are examples of negative feedback mechanisms that can slow warming. It is ironic that necessary and successful efforts to clean up these particular air pollutants around our urban areas are making millions of people healthier and saving lives, but negating the pollutants’ sunlight-reflecting effects that could have slowed global warming a bit.
Black carbon is a different example. Some types of black soot and other dark particles that are expelled from diesel engines and other human sources are capable of absorbing direct solar radiation and then reradiating it to heat our atmosphere. These darker particles are especially efficient absorbers of sunlight when they settle on snow and ice surfaces, decreasing albedo, causing them to heat and melt faster. This is another reason why our snow packs and ice fields are, on average, melting faster each year and our few remaining glaciers are retreating. Likewise, smoke and ash drifting from larger and more frequent wildfires in our state has also settled on snow and ice surfaces, accelerating their melting. These are examples of the synergy of positive feedback mechanisms that can speed warming. And the data show they are dominating the climate change balance sheet.
The good news is that California has drastically cut black carbon emissions that once settled in the homes and lodged into the lungs of people who lived near or downwind of the state’s major transportation corridors and ports. And, unlike greenhouse gases such as CO2, these pollutants usually settle out of the atmosphere within days.
How are California’s Precipitation Patterns Changing?
Previous stories on our web site addressed the wild annual swings in precipitation that are common in California. Most southern California stations exhibit a slight decrease in average precipitation when these extremes are smoothed during the last century or so, but statewide trends beyond the extreme years are not as notable as the increasing temperature trends.
Scientists recognize that rising temperatures are lifting snow levels as storms produce less snow and more rain events. Higher temperatures are not only forcing earlier spring melts and runoffs, but they are increasing evapotranspiration rates. This decreases the total water available for runoff and further dehydrates ecosystems dependent on water supplies, especially into later summer months. This is another reason why water-starved plant communities have been burning hotter and more frequently as the fire seasons have expanded and become more severe.
How Do These Changes Affect Our State’s Hydrology and Water Supplies?
California’s hydrologic environments are evolving with the changing climate. As less water is stored in snow packs, peak discharge in mountain streams and rivers is higher and occurs earlier, with more water flowing during and directly following storms. Gradual releases from watersheds that once nurtured ecosystems are being replaced with alternating severe floods and droughts. This is challenging the Department of Water and Power and other water agencies in their efforts to balance flood control, water storage and distribution, ecosystem management, and power generation.
Is this why our droughts and floods seem to be getting more frequent and severe?
Viewing this data, it is no surprise that dramatic extremes from severe drought to flooding have cost California lives and many billions of dollars during single years of the last decade. Within the last ten years, the state’s worst drought in history ended with record flooding from relentless atmospheric rivers that nearly destroyed water project infrastructures, including Oroville Dam’s spillways.
How are Our Ecosystems Responding?
Biologists, biogeographers, and other scientists are recording and researching how nearly every California plant community is in a process of accelerated succession, responding to these changes. In general, plant communities and their flora and fauna are migrating north and to higher elevations where possible. Semi-arid regions are turning more arid, grasslands are replacing chaparral and oak woodlands, chaparral and woodlands are replacing marginal pine forests, and drier pine species are invading some higher elevation conifer forests where average tree height is decreasing.
Are These Changes Causing More Devastating Fire Seasons?
Fire ecology is complicated, but the climate change examined here is clearly encouraging the increasing severity and frequency of our fire seasons. Some non scientists outside California have blamed the state’s forest management, but most of the recent largest and most devastating fires have ignited and burned through grassland, coastal sage scrub, chaparral, and oak woodland plant communities. Some others burned through pine and other forest communities that were carefully managed since they were adjacent to vulnerable developments. Others started and burned through forests that are managed by the Federal Government. All of these ecosystems and landscapes have one thing in common: they are adjusting to climate change and other human impacts that include the introduction of invasive nonnative species.
, seasonIs climate change altering California landscapes in other ways?
Yes. One example is how our few remaining high country glaciers have been dramatically receding in the Sierra Nevada. Once again, this is a common trend around the world and the data previously examined here explains why. As high country slopes are increasingly exposed, these gradually disappearing glaciers and ice fields will no longer supply precious late summer meltwater to riparian ecosystems at lower elevations, further exacerbating the warming and drought problems.
Additionally, sea levels have already risen up to 7 inches along parts of our coast as global ice melts and as sea water expands when it warms. This results in increasing frequency of coastal flooding events and the inundation of landscapes farther inland during storms and high tides. The rate of sea level rise is also increasing, but these rates vary by location. For instance, the far north coast around Crescent City experiences little total change as mountain-building tectonic activity has simultaneously been lifting that local coastline above the ocean surface.
Accelerated groundwater pumping to alleviate water shortages during droughts has particularly impacted California valleys dominated by agriculture. As water table drawdowns have been measured in meters per year, surface subsidence up to several meters has been measured over many decades in places such as the San Joaquin Valley. In some coastal plains, such as the Salinas Valley, saltwater intrusion has contaminated aquifers several miles inland. Diversions of fresh water from the Sacramento-San Joaquin Delta, combined with other human activities, especially during drought years, continue to threaten water supplies, ecosystems, and landscapes as saltwater encroaches. Water insecurities resulting from less reliable rainy seasons and runoff years have exacerbated these problems.
Where in the state is climate change least and most noticeable?
As is the case globally, some California microclimates are changing faster than others, while a few may notice very little warming. Data suggests that warming in particular and climate change in general is less severe on the north coast and relatively greater as we move inland and toward the south. Decreasing average mountain snow packs are examples.
Is it possible that these climate change trends will end or even reverse?
This is an experiment that we have never run on such a grand scale, perhaps the greatest scientific experiment that humans have ever conducted on Earth, and so no person can predict the exact results in California. But the wealth of scientific studies confirm that the changes considered here will continue to accelerate as long as we continue adding GHGs to our atmosphere faster than nature can cycle them out. As an example, the COVID-19 pandemic at least temporarily slowed our production of all air pollution from transportation and industrial sources. The Golden State’s air quality improved and our production of GHGs slowed, but we continued to produce GHGs faster than nature could absorb them back into the oceans and terrestrial ecosystems and landscapes. No person knows if this will result in any noticeable slowing of climate change compared to what we would have otherwise experienced, but it certainly won’t stop it.
What is the most impactful change that will make the greatest positive difference?
The common sense solutions to these problems are much easier and less controversial than we have been led to believe. First, use the energy we have as efficiently as possible. In the old-fashioned spirit of waste not, want not, we must require our engines and machines to do the maximum work while using the least energy possible. This goes much further than saving our natural resources and improving our air quality: it will save everyone a lot of money in the long run. This includes the simplest smart decisions such as buying cars and other vehicles that fulfill our needs while demanding the best mileage, and building the healthiest living and working spaces that waste the least energy.
Encouraging proper insulation, passive solar designs, and air flow that celebrate the microclimates where we build are other examples of investing in the short term to save in the long term, while improving our health. The COVID-19 pandemic brought our savvy architects back into the forefront, those who have pushed us to create living and working environments that are positioned and opened up to allow natural light and the fresh air flow that we know creates healthier, more productive indoor spaces. It is unfortunate that some Californians were misled into emulating the costly, closed-up built spaces common to more hostile climates such as Chicago and New York, only to look out the window to healthier and more comfortable California air that could flow in for free. There is no excuse for repeating these mistakes, particularly within our mildest-climates-in-the-world coastal regions.
And, thanks to vastly improved designs with increasing efficiency, solar panels on roofs exposed to sunlight have become some of the least expensive sources of electricity and most rewarding long-term investments for homes and businesses. Today’s new solar panels often pay for themselves within ten years so they can deliver more than 20 more years of free power without generating all that air pollution. Building any new structure exposed to sunlight without solar panels in today’s sunny California helps define penny wise and pound foolish.
These practical, common sense decisions signal our intelligence, as opposed to the insanity of sticking with outdated methods and technologies that trash the planet and our state and drain our bank accounts. It is nonsensical that some in our popular culture and media are still debating whether to pick these easiest, no-brainer fruits from the tree while they choose to remain stuck in vicious cycles of waste and destruction that result from short-term thinking. Just as with any attempts to improve our health and financial stability and well-being, we know that these practical long-term investments are not only the keys to our security, but they will help us blaze our path toward a brighter future.
The good news is that California continues to lead the country and the world away from those archaic debates of 50 years ago and into a more promising twenty first century. Let’s hope that other states and nations will follow as the scientific evidence proves how Californians’ long-term future also depends on their short-term decisions. Since we have just scratched the surface here, we must now debate how we can use our ingenuity to further push that envelope of innovations that will allow us to reach toward a cleaner, healthier, and more efficient Golden State. We know that nature won’t be waiting around while we are debating.
Numerous California cities have built more secure futures by cutting waste and becoming more efficient. As an example, the organization known as Sustainable Works in Santa Monica has helped many thousands of individuals, businesses, students, and institutions save small and large fortunes as they also save natural resources and create healthier, more productive living and working environments. This success explains why Sustainable Works continues growing beyond any borders. Community organizations such as Climate Action Santa Monica have also successfully worked to educate and empower the public about these problems and their win-win solutions. These are examples, originating from within just one city, of the countless similar organizations and efforts in every region spreading positive ripples across the state. Meanwhile, government agencies are sharing best practices about how to become more efficient while we all save bundles of future taxpayer dollars.
There are also a host of independent cutting-edge communities in California that have made short-term investments to implement more sustainable and efficient energy practices, resulting in enormous long-term savings that drastically decrease residents’ carbon footprints. They include several Mutual Housing Communities around Sacramento at http://www.mutualhousing.com/
Additionally, though Muir Commons in Davis was the first new-construction cohousing development in the U.S., these communities have since appeared in nearly every California city: http://www.muircommons.org/
Though these communities that push the envelope and take us back to the basics may not be for everyone, they offer plenty of lessons about how we can more efficiently generate and use our energy resources.
We hope you have benefited from this California climate change question and answer session that wraps up our series of three weather and climate stories. We again thank all the people who gathered the wide range of research that was assembled in the publication of Indicators of Climate Change in California, published by the state’s Office of Environmental Health Hazard Assessment in May, 2018. We used many of their graphics here to answer questions since theirs represents one of the most comprehensive and credible publications that managed to assemble some of the most diverse research covering climate change in California to date. If you would like to see more details, go directly to the publication at: https://oehha.ca.gov/media/downloads/climate-change/report/2018caindicatorsreportmay2018.pdf
You might also consult the California Climate Change Center, a clearinghouse for climate change research in the state.
