Keven Guillory

Climate Watch Sr. Editor Craig Miller with Producer Molly Samuel in the KQED studios.

After four years, numerous awards, and something just shy of 900 blog posts, the multimedia reporting effort that’s been known as Climate Watch is turning a significant page. KQED is combining our efforts with Quest, the station’s more broadly-based science and environmental news and programming effort.

We’ll continue to cover climate-related issues, as evidenced by the recent rollout of Heat and Harvest, a major multimedia project with the combined resources of Climate Watch, Quest and the Center for Investigative Reporting. Through a documentary now airing on public television stations throughout California, radio features on The California Report and an extensive lineup of online features, Heat and Harvest examines some of the ways in which climate change is already challenging farmers in the Golden State.

It’s by no means the first successful collaboration between Quest and Climate Watch. Past efforts have produced some high-profile “props,” including a 2011 AAAS Kavli Science Journalism Award for our TV segment on rising seas in the Bay Area.

The reorganization will, however, mean suspension of the Climate Watch blog, while we consider options for the most successful web strategy going forward. I’m proud of what we’ve done in this space, with groundbreaking work from our producers, Gretchen Weber and Molly Samuel, engaging, eye-opening posts from our freelance contributors, and unflagging support from our news director, Bruce Koon. I’ll miss doing it. I’ll miss writing and editing the posts and I’ll miss the lively discussions in our comments thread. Okay, most of the lively discussions.

I couldn’t resist going back and seeing what we were writing about when we first launched the blog, in the fall of 2008. Arnold Schwarzenegger was governor, organizing the first in a series of “climate summits.” The newly-elected Barack Obama would make a video appearance at that event and pledge swift, comprehensive federal action on climate change. We’re still waiting. Market analysts were speculating on what the price for a metric ton of carbon would be in California’s nascent cap-and-trade market (we still don’t know but will find out in about a month).

Though it may seem like the climate agenda has moved little in four years, climate change remains one of the critical challenges of our time. That’s becoming more evident with each passing year. Polls indicate that a strong majority of Californians agree, and expect policymakers to attend to both the consequences of a changing climate, as well as continued efforts to stem those consequences. So we’ll continue to monitor and report major developments on the science and policy fronts. Except now, we’ll be doing it with a much larger pool of talent. The KQED Science & Environment team includes a proven stable of writers, video producers and radio reporters, as well as specialists in education, digital production and social media. We’ll still be part of the climate conversation. We hope you will be, too.

Bodega Marine Lab / UC Davis

Scientists from UC Davis are studying oysters and mussels to figure out if organisms will be able to adapt to climate change.

This week, scientists from around the world are meeting in Monterey to discuss what they call the “other” climate change problem: the oceans are becoming more acidic. It happens as oceans absorb the carbon dioxide we add to the air through burning fossil fuels. It can be bad news for oysters, mussels and the marine food web. How bad? Scientists are hoping that ocean conditions off the California coast will help them find out.

At the Hog Island Oyster Company, near Point Reyes, Terry Sawyer orders oysters from hatcheries in Oregon and Washington when they’re small. They grow up in big mesh bags that sit out in Tomales Bay, where they get plump in the cold waters of the Pacific.

But a few years ago, Sawyer started getting calls from those suppliers. They couldn’t fill his orders.

“They would have tens of thousands of gallons of tanks that were absolutely full of larvae. They would have the entire system die or crash,” he says.

The hatcheries were filling their tanks with seawater that was becoming more acidic. Scientists say the oceans are 30% more acidic since the start of the Industrial Revolution. The more acidic the water, the harder it is for animals like oysters to develop their shells.

Sawyer is growing his own oyster larvae now so he’ll have a more predictable supply. But he says there’s no question that climate change is affecting his bottom line.

“We don’t know if we’re going to be able to survive the very real trending that is going on out there,” he says.

It’s trend that could affect the entire food web.

On a rocky point an hour drive north of Point Reyes, a team of scientists from the University of California’s Bodega Marine Lab is gathering. The rocks are covered in tightly packed, purplish mussels – what ecologist Eric Sanford calls the “foundation species” of the California coast.

“One that really defines the whole ecosystem, sort of the way corals define a coral reef,” he says.

Mussels are a key part of the food web. And so are a lot of animals with shells.

“Probably most people like the fact that we have things like whales and salmon off our coast and those organisms are likely to be impacted because their food source will be impacted,” says oceanographer Tessa Hill.

So the big question is: Will animals with shells be able to adapt to a more acidic future – where, in a hundred years, the oceans could be more than twice as acidic?

These California mussels could help answer that.

“They’re facing the most acidic water that you’d see in the ocean today,” says Hill.

Acidic water from the deep ocean rises to the surface on the West Coast in the spring and summer, when the wind is blowing. This upwelling makes the waters off California some of the most acidic in the world.

Inside their lab, Hill and Sanford show me jars full of young mussels, almost too small to see. Each jar is from a different part of the West Coast – from Oregon to Santa Barbara. They’re being grown in more acidic water to see if they’re better adapted to handle it, according to Sanford.

“So this is the issue we’re looking at is whether there might be genetic differences among different populations along the coast in their ability to cope with ocean acidification,” he says.

Steve Palumbi is a biology professor at Stanford University who is also working on the project. He looked at the genes of another shelled animal on the West Coast – sea urchins.

“We found they have lucky genes,” he says.

You can think of genes like a set of tools, Palumbi explains.

“If you happen to have bad plumbing, you will have more plumbing tools in your house.”

And there have been lots of plumbing problems on the West Coast – lots of acidic water.

“And so all these populations, urchins anyway, have had to get the tool set to deal with it,” he says.

Palumbi says in some urchins, they found around 100 genes that make them better adapted to more acidic water. That makes them more likely to survive and reproduce.

“This is good news because these organisms have the capacity to deal with more acidification,” he says. “But it’s not good news forever because all it does is give us a little breathing room. The trouble is right now, the rate at which the ocean is acidifying is way faster than it ever has before.”

Organisms will evolve, he says, but probably not fast enough to keep up. In the meantime, Palumbi and other scientists are mapping where the genetically resilient mussels and urchins are on the West Coast, so policymakers can look at protecting them.

New pests, a shrinking water supply and rising temperatures will alter agriculture in California.

Craig Miller

Tightening water supplies, encroaching pests and dwindling winter "chill hours," vital to many crops, are just some of the climate challenges facing California farmers.

Heat and Harvest, a new series from KQED Science and the Center for Investigative Reporting looks at the multiple climate challenges confronting California farmers. It’s no trivial matter. California’s Central Valley is widely known as “the nation’s salad bowl,” and there’s more than bragging rights at stake. Ag contributes more than $30 billion a year to the state’s economy.

Previously, Climate Watch has focused on efforts in the ag sector to conserve water or lower the carbon footprint. Some farmers are trying new technologies, others are experimenting with renewable energy. But meeting climate challenges on multiple fronts will, for some farmers and ranchers, be a matter of survival.

Here are links to some previous reporting from Climate Watch, from ag’s potential role in California’s emerging cap-and-trade program for carbon emissions, to innovation on the renewable energy front and new conflicts over land use.

Planting the Seeds for Greener Farms
Supporters of sustainable agriculture are looking forward to some “sustenance” of their own, after an eleventh-hour win in Sacramento. The new bills lays out an approach for ensuring that all proceeds from the sale of cap-and-trade permits be used to further reduce greenhouse gas emissions. Among the eligible activities listed in the bill are farming and ranching practices that reduce greenhouse gas emissions and sequester carbon.

Satellites Help Save Water on California Farms
Engineers at NASA and CSU Monterey Bay are developing an online tool that can estimate how much water a farm’s field might need. Satellites orbiting the earth take high-resolution pictures which are combined with on-the-ground data from farms.

Making Hay While the Sun Shines: A Flap over Solar Panels in Farm Country
Sun and open land make the San Joaquin Valley ideal for growing crops. But they’re also attracting an increasing number of large-scale solar power developers to the region. And that’s generating debate over whether farming the sun is really farming.

Making Renewable Energy from Farm Waste
California is just a few votes away from changing the rules to allow farmers to connect machines that create bioenergy to the electrical grid, a privilege that has thus far been reserved for farm-generated wind and solar energy.

New Map for Gardeners Won’t Help California’s Green Thumbs
It’s been more than two decades since the U.S. Department of Agriculture updated its Plant Hardiness Zones Map, used by gardeners across the country to determine what will grow in their yards. The new GIS-enabled map unveiled this week is a boost to people who live in places that get a lot of cold weather and may be seeing slightly warmer average winters now. Despite the new level of detail in the map, gardeners in California and the Bay Area in particular, won’t learn much from it.

NASA Earth Observatory

Aerosols—and clouds seeded by them—reflect about a quarter of the Sun’s energy back to space.

For all we know about climate change and the Earth’s atmosphere, it’s amazing how much more there is to learn. Earlier this month, a team of researchers led by University of Colorado’s Roy “Lee” Mauldin III announced the discovery of a brand new atmospheric compound tied to both climate change and human health.

Above certain parts of the earth, they found, the new compound is at least as prevalent as OH, also called the hydroxyl radical, long thought to be the primary oxidant responsible for turning sulfur dioxide, an industrial pollutant, into sulfuric acid. The new compound, it turns out, can play an equally important role. Sulfuric acid contributes to acid rain and results in the formation of aerosols, airborne particulates associated with a variety of respiratory illnesses in humans and known to seed the formation of clouds.

Mauldin made the discovery by investigating background levels of sulfuric acid in atmospheric samples that were not attributable to OH. He inferred that another compound must be responsible for the effect and was able to isolate it through a series of tests. No one else had ever made the connection before.

“As soon as I realized that we were observing a new oxidant, the light clicked on all over the place,” Mauldin said in an interview. “With anything that can produce sulfuric acid, if you can come up with something that occurs on a daily basis, or in this case 24/7, it can affect all sorts of things, including climate and human health.”

In few places is that effect more pronounced than in California. “Aerosols are a major public health problem in the Central Valley,” said Ron Cohen, Director of the Berkeley Atmospheric Sciences Center at the University of California. In fact, they’re worse in the Valley than just about anywhere else in the country — except maybe Los Angeles.

Mauldin believes that the new compound is emitted more heavily by trees than by man-made sources, meaning it may be less important to aerosol formation above the Central Valley than it is above the Finnish Boreal Forest where field research was conducted. But we don’t know that for sure. Nor do we know precisely how to calculate aerosols’ role in climate change.

In fact, aerosols are one of the least-understood variables in climate models, Cohen said. We do know that aerosols contribute to cloud formation, commonly understood to have a cooling effect on the earth. However, we don’t know whether aerosols are changing the height of clouds, which has complex implications for temperature: low clouds tend to have a cooling effect, while high clouds actually trap heat in the atmosphere. Furthermore, some aerosols reflect heat, while others absorb it.

The new compound offers science a new way of charting the formation of aerosols today as well as an important tool for determining what the atmosphere was like before we came along. Both uses are likely to fine-tune our ability to understand and forecast climate change moving forward. As far as what, precisely, it’ll tell us — well, that remains to be seen.

This post is based on a report produced by Climate Central, a non-profit climate education group.

Climate Central

Screenshot from Climate Central's Interactive Wildfire Tracker. Click on the image to see where wildfires are currently burning.

The 2012 wildfire season isn’t over yet, but already this year is shaping up to be the one of the worst on record in the American West. According to the National Interagency Fire Center, with nearly two months still to go in the fire season, the total area already burned this year is 30% more than in an average year, and fires have consumed more than 8.6 million acres, an area larger than the state of Maryland.

Yet, what defines a “typical” wildfire year in the West is changing. In the past 40 years, rising spring and summer temperatures, along with a shrinking mountain snowpack, have increased the risk of wildfires in most parts of the West.

Studies show that continued climate change is going to make wildfires much more common in the coming decades.

The National Research Council reports that for every degree Celsius (1.8 degrees Fahrenheit) of temperature increase, the size of the area burned in the Western U.S. could quadruple. According to the 4^thAssessment Report from the U.N.’s climate science panel, summer temperatures in western North America could increase between 3.6 degrees and 9 degrees by the middle of this century.

Key findings

Climate Central’s analysis [PDF] of 42 years of U.S. Forest Service records for 11 Western states shows that:

The number of large and very large fires on Forest Service land is increasing dramatically.  Compared to the average year in the 1970’s, the past decade saw:

• 7 times more fires greater than 10,000 acres each year
• Nearly 5 times more fires larger than 25,000 acres each year
• Twice as many fires over 1,000 acres each year, with an average of more than 100 per year from 2002 through 2011, compared with fewer than 50 during the 1970’s.

In some states the increase in wildfires is even more dramatic. Since the 1970’s the average number of fires of over 1,000 acres each year has nearly quadrupled in Arizona and Idaho, and has doubled in California, Colorado, Montana, New Mexico, Nevada, Oregon, Utah and Wyoming.

On average, U.S. wildfires burn twice as much land area each year as they did 40 years ago. In the past decade, the average annual burn area on Forest Service land in the West has exceeded two million acres — more than all of Yellowstone National Park.

Craig Miller/KQED

Continued climate change will likely make wildfires worse in the coming decades.

The burn season is two-and-a-half months longer than 40 years ago. Across the West, the first wildfires of the year are starting earlier and the last fires of the year are starting later, making typical fire years 75 days longer now than they were 40 years ago.

Rising spring and summer temperatures across the West appear to be correlated to the increasing size and numbers of wildfires. Spring and summer temperatures have increased more rapidly across this region than the rest of the country, in recent decades. Since 1970, years with above-average spring and summer temperatures were typically years with the biggest wildfires.

Other factors are believed to be contributing to more severe fires, such as the Forest Service’s 60-year policy of aggressive fire suppression (reversed in the 1990′s) that left more fuel for today’s outbreaks, but as average global temperatures rise, researchers project that the risk of wildfires in America’s West will accelerate.

A version of this post also appears at Climate Central, a content partner of Climate Watch.

Nat'l Snow & Ice Data Center

NOAA has created a startling animation of this year’s record shrinkage of ice in the Arctic Ocean. The 34-second clip zooms in from a western hemisphere view and presents as a time-lapse, tracking the ice from January 1 to September 14. This is the first time since NOAA started using satellites to monitor the Arctic in 1979, that sea ice area has shrunk to less than 4,000,000 square kilometers. What happens in the polar regions has a profound effect on the world’s climate.

NC State University

The U.S. has lagged behind other developed countries in capturing offshore wind for electricity..

The U.S. has lagged behind European countries in capturing offshore wind for electricity, but a spate of recent studies suggest that a bigger push might be in order.

The latest, from Stanford civil & environmental engineer Mark Jacobson concludes that off the East Coast alone is enough moving air to meet a third of the entire nation’s energy needs.

Running out the string quite a bit further, studies from Stanford and Lawrence Livermore National Lab point to a breezy bounty offshore and at higher altitudes that could theoretically power the planet, perhaps as soon as 2030.

Of course, that would take four million powerful turbines.

“If we put half over the ocean and half over land, we’d need about 0.6% of the world’s land for turbines,” Jacobson told listeners to KQED’s Forum program this week. “But all of that land, almost, is open space between the turbines, that can be used for multiple purposes, including rangeland, cropland, pasture land or just plain open space. The rest is over the water.”

Offshore turbines have several advantages over the wind farms that we’re used to seeing from the freeway. They can be mostly out of sight and earshot, for one thing, and are also likely to be a steadier source of power than most land-based “wind energy resource” areas. Looking at one area off Cape Mendocino, a Jacobson study from 2010 noted that offshore winds were “consistently fast throughout the day and night during all four seasons.”

“California has a tremendous offshore wind resource,” said Habib Dagher, who joined Jacobson and other experts on the program. Dagher, who runs the DeepCWind Consortium at the University of Maine, calculates that within 50 nautical miles of the California coast is about 587 gigawatts of untapped energy, the equivalent of more than 500 commercial nuclear power plants. The tricky part will be tapping it. The ocean depths off of California would likely require a whole new generation of turbines that ride the waves like big buoys.

In March, Dagher’s group will place an experimental floating turbine off the Maine coast. The scale-model test will offer insights into how giant six-megawatt turbines would perform offshore. He says research & development funding doesn’t support a bigger push right now, that the DOE wind research budget hovers between $70-80 million per year, “very small” compared to what much smaller countries are spending. Dagher says the U.K., for example, is aiming to get a quarter of its electricity from offshore wind farms by 2020.

North American Offshore Wind Project

Different approaches to offshore wind turbines could include "floating" turbines, which might be combined with tidal or wave energy.

“The offshore component opens up significant areas, added Dan Kammen, who heads the Renewable and Appropriate Energy Lab at UC Berkeley. “The marine environment is challenging and to make [those] systems work, we’re gonna need to really invest in it. The U.S. has been a bit slow in this regard.”

Dagher says that while conventional onshore wind farms are already cost-competitive with some fossil fuels, offshore development is about twice as pricey.

“These technologies, on a resource basis, are very much ready to compete,”said Kammen. “We just need to give them that shot.”

Molly Samuel/KQED

Mosquitoes under a microscope at the Sacramento-Yolo Mosquito and Vector Control District.

William Reisen began studying tropical diseases when he was drafted in the Vietnam War. He’d studied insects in school, so he worked as an entomologist for the Air Force. Eventually, his career led him to California, where he now heads UC Davis’s Center for Vectorborne Diseases. But even with his professional experience with mosquito-borne diseases, he says he never expected to see West Nile virus in the United States.

“Everybody was surprised,” he says. “If you were a betting person, and you wanted to guess the next virus that would cause trouble from abroad in North America, I think few of us would have expected West Nile.”

West Nile, a disease carried by birds and spread by mosquitoes, first made inroads in the U.S. in 1999, in New York. By 2003, it had reached California. In 2004 and 2005, there were hundreds of human cases; in those two years combined, 48 people in California died.

As I report in a story for The California Report on Wednesday, Reisen’s lab at Davis is a crucial cog in California’s West Nile Virus surveillance program. He and his team test thousands of mosquitoes and dead birds for the virus, and work with the California Department of Public Health and mosquito control districts around the state to track where the virus is flaring up.

Reisen’s not only interested in where the virus is now, though. He’s also looking to the future, and that means factoring in climate change. The mosquitoes that transmit West Nile thrive in hot and dry conditions. Temperature is especially important, since the warmer it is, the faster mosquitoes reproduce. They bite more frequently and the virus itself can replicate and spread more quickly (I unpack the details in the radio story; you can also read about them on this Scientific American blog post).

With temperatures likely to rise in California — and not only in the places that are already hot, but according to new research, on the coast, too — that’s good news for mosquitoes and the West Nile pathogen, bad news for people.

Molly Samuel/KQED

Mosquitoes ready to be tested for West Nile virus at the Sacramento-Yolo Mosquito and Vector Control District.

“It’s not a fun thing to get,” Reisen says. “It’s easy for epidemiologists to count numbers, but if it’s your grandmother in the hospital with a swollen brain and not recognizing you when you come to visit, it’s a totally different take-home message.”

Reisen still seems almost awed by West Nile’s success in North America.

“If you had to think of a Ugandan virus taking up shop someplace, certainly Saskatchewan wouldn’t be the first place you’d look,” he says, referring to recent outbreaks on the Canadian plains. “We never would have suspected that it would have successfully spread now from Canada to Argentina and from ocean to ocean.”

As the climate gets warmer, temperate regions will become friendlier to mosquitoes and tropical diseases. West Nile virus is not the only one to watch out for. Reisen rattles off a few others he’s worried could gain a toe hold in North America: Rift Valley fever, Japanese encephalitis, Chikungunya virus. Other scientists have expressed concern about Dengue fever. Malaria could begin to make inroads.

Vector-borne disease isn’t new to California. Malaria used to occur here. St. Louis encephalitis and western equine encephalomyelitis are both native insect-borne diseases. So the state has experience with mosquito control. California’s network of mosquito control districts dates back to 1917.

Molly Samuel/KQED

Luz Maria Rodriguez holds up a jug full mosquitoes that the Sacramento-Yolo Mosquito and Vector Control District tested for West Nile.

“We’ve had pretty good public health measures for many years,” says David Brown, the manager
of the Sacramento-Yolo Mosquito and Vector Control District. “I think a lot of folks have forgotten what it’s like to have mosquito-borne diseases from when your parents or grandparents had to deal with it.”

Brown’s district is one of the largest in the state, and he and his staff take a multi-pronged approach to mosquito control. They run education programs, encouraging people to get rid of standing water around their homes, whether it’s in a neglected birdbath, an old can or a roof gutter. They use pesticides to kill mosquito larvae and adult mosquitoes. They distribute mosquito-eating fish (for free; somewhere around 1.2 million fish a year) for people to put in ponds and unused swimming pools.

“To be a really good, comprehensive mosquito control program, it’s not a one and out,” Brown says. “A lot of folks think, well, we’ll just take care of the problem and then it’ll go away and we won’t have to worry about it again.” But Brown says with climate change looming, it’s as important as ever to keep up the combination of mosquito monitoring and mosquito control.

Molly Samuel/KQED

That's 149,427 mosquitoes, all tested in 2011.

Reisen has some concern that that’s not enough. His lab can turn around West Nile results in 24 hours. But West Nile is all they’re looking for.

“A good surveillance project should cast a broader net.” He says the state should be preparing to test for the other viruses that could appear here. Viruses and mosquitoes can hitch rides on airplanes and travel to new hemispheres overnight. As the world gets warmer, they’re able to survive and spread, too.

National Center for Atmospheric Research

A new study from the National Academy of Sciences advocates for more detailed and interconnected climate models.

In the effort to better understand the dynamics of the Earth’s changing climate, a recent report from the National Academy of Sciences calls for scientists to collaborate on a “new generation” of highly detailed and integrated climate change models.

According to the NAS release:

With changes in climate and weather . . . past weather data are no longer adequate predictors of future extremes. Advanced modeling capabilities could potentially provide useful predictions and projections of extreme environments.

Those “useful predictions and projections,” according to the report, could come in various forms — supplying farmers with better information about what to plant, year-to-year, say, or giving local officials greater insights into future flood risk, or providing climatologists with better information about specific parts of the country most susceptible to extreme heat.

Currently, a wide array of public and private entities – universities, cities and state governments – have embarked on their own climate models. In many cases, according to the NAS committee, this has resulted in a duplication of effort.

To encourage greater sharing and collaboration, the study proposes “a framework in which software, data standards and tools, and even model components are shared by all major modeling groups across the country.” The committee, made up of climate scientists from across the country, has also called for adopting “a common software infrastructure.”

In some ways, the NAS report mirrors some recent efforts here in California, where agencies and researchers have attempted to stitch large, disparate swaths of information into single, comprehensive reports – “news you can use,” as it were. A study released in July by the California Energy Commission, entitled “California’s Changing Climate,” offers up a portfolio of studies on a wide range of topics, from the effects of higher average temperatures on crop yields to the changing distribution and frequency of fires in a warmer climate.

According to Chris Bretherton, an atmospheric science professor at the University of Washington and chair of the NAS committee, this infrastructure can be thought of as a new open-source operating system, designed to tie together various regional models together into a larger — even global — framework.

“It’s a software engineering issue,” Bretherton told me. “The idea is to share the same key models and to have them talk to one another.” The more fine-grained and interconnected the climate models become, says Bretherton, the more powerful they will be in terms of guiding policy and decision-making.

But do such systems yet exist? Or are they, like the future climate events they aim to predict, merely hypothetical? Bretherton says there are some successful blueprints, pointing to an effort called the Community Earth System Model, an integrated climate model developed in the 1980s by the National Center for Atmospheric Research.

One California study released earlier in the year, dubbed C-Change.LA, seems to fit the mold of these “next-generation” regional models — the kind that one day could be folded into larger, more comprehensive ones. Touted by its developers as “the most sophisticated regional study ever developed,” C-Change-LA offers a neighborhood-scale assessment of future climate conditions between the 2041 and 2060 for the Los Angeles Metro Area.

State agencies are bracing for the public health threat from extreme heat. Heatwaves can have devastating effects on public health; in a 2006 heatwave in California, hundreds of people died [PDF]. And scientists predict in the future, heat waves will be longer, hotter and more frequent.

In the future, heat waves will be longer, hotter and more frequent.

To try to keep the health costs to a minimum, the California Climate Action Team, led by the California Environmental Protection Agency and the Department of Public Health, is developing a plan to prepare for extreme heat[PDF].

The state’s plan addresses building codes and urban planning, state and local emergency response plans, health care system preparedness and worker safety. The recommendations include making sure the most vulnerable people can be protected from high temperatures, protecting key parts of the power grid from air-conditioner overload and planting more trees in cities.

Temperatures this summer broke records across the country. California did get a bit of a heat wave, but, for the most part, it’s been shielded from the extreme heat that hit other states. California’s coastal cities have generally had a cooler-than-normal summer, but a new study says that trend may not hold.

The Scripps study finds that heat waves will come with more humidity, higher night time temperatures and will be stronger in coastal areas. Overnight lows are important, because cooler night time temperatures give people a chance to cool off. Hot nights aggravate the health effects of heat waves. And location makes a difference: as the state’s heat adaptation study points out, buildings in cooler areas often don’t have air conditioners. Plus, people who live in those cooler places just aren’t used to those high temperatures, and may be more susceptible to heat-related illnesses.

The state’s document is a draft: the California EPA is accepting public comments on it until November 1, via email, at climatechange@calepa.ca.gov.