Craig Miller

Sunset on San Pablo Bay. Coastal areas saw a balmy end to September, accompanied by air quality alerts.

The Great American Heat Wave of 2012 arrived later in California than in many parts of the country — and it’s in no hurry to leave.

Having nudged the upper 90s on Sunday, Sacramento closed out the month of September with a record 26 days of 90-plus highs, surpassing the 1974 record of 24 days. The trend is forecast to continue into the first several days of October, with a chance of hitting 100 for the first time since mid-August. Farther north, Sacramento Valley towns like Redding and Red Bluff are suffering similar bake-offs.

Dry heat persisted up and down California, accompanied by red-flag warnings for fire danger along the South Coast. Of course, it’s that time of year, when the sea breeze backs around and “offshore flows” become the dreaded Santa Anas (in the south) and Diablos (in the north), notorious for fanning catastrophic wildfires. Air quality suffers during these periods, even without fires. Air quality regulators placed a Spare-the-Air Alert in effect for Monday in the San Francisco Bay Area.

For a vivid visual review of the world’s extreme weather in 2012, the World Resources Institute constructed a timeline of major events, which currently runs through August and WRI says it plans  to continue updating.

The National Oceanic & Atmospheric Administration (NOAA) has released a map that provides a telling snapshot of summer aberrations around the nation.

NOAA

While most of America cooked this summer, California bucked the trend.

David Kroodsma’s recent post for Climate Central provides excruciating detail of what the rest of the country was going through:

Using Climate Central’s record temperature tracker which draws on the National Climatic Data Center’s database, we found that June, July, and August saw more warm temperature records tied or broken than any other summer in the past decade: more than 26,500 record warm temperatures were set across the nation. By comparison, fewer than 3,500 record low temperatures were set — the fewest of any summer in the past decade.

It was a summer that brought new meaning to the term “Texas barbecue,” with NOAA confirming that the Lone Star State suffered the hottest summer on record for any state in the nation.

Using IPCC climate projections, the study models how climate change will impact California up and down the coast, including coastal cities like San Francisco and inland cities such as Riverside and Fresno.

Lead author Scott Sheridan, a geographer at Kent State University, says that the projected increase in heat-related deaths among those 65 and over are due in part to physiological reasons, but also to growing population size of this age group. By the end of the century, he says, the state’s population of people in this age bracket will increase from 4 million to 15.7 million. Sheridan says California communities that are already used to dealing with hotter temperatures, like the inland city of Fresno, may be better prepared to deal with the heat than relatively cooler coastal cities.

“On a hot 90-degree day in Riverside, everyone has the AC running. In San Francisco, not everyone has that luxury.” says Sheridan.

Sheridan says that heat-related deaths are projected to go up more in coastal cities like San Diego than in inland cities because people on the coast may be less acclimatized to extreme heat and the cities themselves may lack the preparation to deal with the public health consequences of lengthy, intense heat waves.

Projected heat-related deaths based on various climate change scenarios in San Diego. The red line indicates a high fossil fuel intensive scenario. Chart: CARB/EPA

“People that are acclimatized to warmer temperatures have a greater threshold for heat.” says Sheridan.

CARB spokesperson Dimitri Stanich says the study could lead to more local health policies in cities that are more vulnerable.

“Previously studies have focused on a macro approach to heat impacts but couldn’t specify impacts on California cities.” says Stanich.

Sheridan says one potential model for California cities is Philadelphia.  The health department there helped residents get fans, and it developed a buddy system to for neighbors to keep in touch during hot days. Philadelphia also has 60 cooling stations running during the summer, which can be found using this interactive map developed by the city’s Office of Emergency Management.

To see how temperatures are expected change in your region of California, check out the interactive Cal-Adapt tool from the California Energy Commission.

By Katrina Schwartz

Just as many Californians are puzzling over winter-like weather in June, climate scientists are saying hotter days are ahead for most of the West. According to a new Stanford study (available soon at this link), we may be in for permanently hotter summers sooner than expected. Of course, for climatologists, “sooner” is a relative term.

Photo: Craig Miller

Plenty of climate scientists have studied the relationship between climate change and extreme temperature shifts, but until now no one has tried to pinpoint a moment when summer temperatures will permanently shift into a new “heat regime”, in which the coolest summer temperatures will be hotter than the hottest summer temperatures of the previous regime. Findings by the Stanford team suggest that the shift will likely happen sooner and be more widespread than expected.

The research team led by Noah Diffenbaugh of the university’s Climate and Earth System Dynamics Group analyzed more than 50 climate model simulations and estimated a 50% likelihood that a permanent shift will happen in tropical parts of the globe in the next twenty years. In middle latitudes like Europe and North America that shift will likely happen in 40 to 50 years, the study suggests. The authors say that because temperatures don’t vary as widely near the Equator, it won’t take as much warming to bump those regions into a new “seasonal envelope”— a completely new summer temperature range.

The Stanford team applied the same climate models to historical data to see how well they could predict what actually happened between 1979 and 2008. They concluded that many areas of the globe are already experiencing these permanent heat shifts. In central Africa, the authors conclude, 40% of the land area has already experienced a permanent upward shift. The climate models were able to predict the same results, making the observable reality match the simulated prediction. This correlation gives Diffenbaugh confidence in his team’s predictions for the future.

The study has potentially dramatic effects on humans. Drastically warmer temperatures adversely affect human health and agriculture. Morbidity and mortality rates rise. The demand for energy increases while the ability to supply it decreases. Many crops important to the economy of the western United States like grapes, corn, soybeans, and cotton cannot handle extreme heat. While the study found that only the eastern and western parts of the U.S. would experience permanent summer temperature increases, Diffenbaugh was quick to point out to me that his team studied the most dramatic shift possible — a complete shift upward in temperature into a new seasonal range. He says that the effects on areas that don’t experience a permanent shift in the next 50 years — like the Midwest — could still be significant.

Diffenbaugh says he was intrigued by the wintertime comparisons in the study. He explained that the relative seasonal sameness of the tropics causes the bump up in temperature to happen quickly. In the mid-latitudes, however, the move into hotter regimes takes much longer because of overlays like arctic air movement that occur simultaneously to an overall warming trend.

Katrina Schwartz is former KQED News intern, now a freelance contributor to Climate Watch.

People along the West Coast from Seattle to San Diego, who have shivered through an unusually cool summer, can be forgiven for being just a little bit jealous of residents of the East Coast, where warm temperature records have repeatedly been smashed this summer. During June, July and part of August as well, it seemed that many coastal areas of the West were missing out on summer entirely.

Temperature departures from average during July, 2010. Note the cooler-than-average weather along the California coast. (Credit: NOAA/NCDC)

For example, whereas Washington, D.C. tied its record for the warmest month on record, with an average temperature of 83.1 degrees F in July, San Francisco recorded its coolest average July maximum temperature since 1971. Only one day reached the 70 degree mark in San Francisco during July. The Climate Central infographic below shows some of the contrasting statistics from early to mid-summer. The data goes through the end of July, but in general the pattern of warmer weather in the East and cooler conditions along the West Coast has continued through much of August, with a few exceptions. For example, a heat wave briefly brought record warmth to the West Coast in mid-to-late August, but such heat was the exception there this summer.

Comparison of early to mid-summer conditions along the eastern seaboard vs. the West Coast. The data in this graphic goes through the end of July. (Credit: NOAA/NCDC; California State Climatology Office. Design by Russell Freedman.)
Click on the image for a larger version.

The cool temperatures along parts of the West Coast may be related to the emergence of a La Nina event in the equatorial Pacific Ocean, which is characterized by cooler-than-average water temperatures. In addition, an area of cool waters persisted offshore of California, Oregon and Washington, and this may have contributed to the below average conditions as well. Persistent onshore winds blew cooler air into coastal California during July, according to the National Climatic Data Center. The cool water temperatures off the California coast, extending northward into the Gulf of Alaska, can be seen in the image below, along with the La Nina conditions along the equator.

Sea surface temperature anomalies from May 30, 2010 to August 28, 2010. Note the cool waters in the equatorial Pacific, related to La Nina. Cool water anomalies can also be found off California, Oregon, and Washington. (Credit: NOAA/ESRL)

By Andrew Freedman

California’s freakishly cool summer has been bucking a global trend this season. You’ve seen the headlines from Moscow and Pakistan–but that’s just part of the story. 2010 has featured several extreme heat events, as well as record flooding, in many countries worldwide. The number of countries that have set new national records for the warmest temperature recorded — 17 — would beat the old record of 14, provided that all of the new records are verified by meteorological agencies. According to meteorologist Jeff Masters of the private weather forecasting firm Weather Underground in Ann Arbor, Michigan, the countries that have set new records thus far this year comprise about 19 percent of the earth’s surface area.

This graphic shows the new record-high temperatures for the 17 nations that have broken their national records so far in 2010. If verified, the record set in Pakistan would also stand as the warmest temperature ever recorded in the continent of Asia. Click on the graphic for a larger version. (Graphic: Russell Freedman).

Masters wrote on his blog: “This is the largest area of Earth’s surface to experience all-time record high temperatures in any single year in the historical record. Looking back at the past decade, which was the hottest decade in the historical record, 75 countries set extreme hottest temperature records (33% of all countries.) For comparison, fifteen countries set extreme coldest temperature records over the past ten years (six percent of all countries).” According to Masters, Guinea, which is located in northwestern Africa, is the one nation so far this year to break its coldest temperature record, which occurred in early January.

The new record high temperature set in Belarus occurred during the Russian heat wave, which is still gripping portions of that country. Although Russia did not set any all-time record high temperatures, Moscow did, breaking 100 degrees Fahrenheit for the first time since records have been kept.

Temperature departures from average for July 2010, as measured by NASA. Note the warmth (in red) centered over western Russia. (Map: NASA Goddard Institute for Space Studies)

For the planet as a whole, 2010 has been extremely warm, with the June-to-July period ranking as the warmest on record for those two months combined.

Part of the warmth earlier this year may have been due to an El Nino event in the Pacific Ocean, which tends to warm the planet, but that event is no longer taking place. According to scientists, including Climate Central’s Claudia Tebaldi, man-made global warming is likely also playing a role in the record heat. Tebaldi and others have published studies showing that as the planet warms due to increasing concentrations of greenhouse gases, warm temperature extremes become more likely to occur.

A backyard thermometer in upstate New York (Photo: Craig Miller)

I wore a wool coat to work today.  And I’m ashamed to say that last night I turned the heat on in my apartment.  San Francisco is obviously a special place, particularly in July.  And by “special,” I mean foggy, windy, and cold.  Weather.com says that it was in the 50′s last night and this morning, but I have trouble believing that.

So I found it a little bit hard to relate this morning on a conference call with journalists and scientists talking about climate change, heat waves, and public health.   It seems that much of the world beyond San Francisco has been experiencing some unprecedented heat lately.  According to NOAA, global combined surface and ocean temperatures for January through May 2010 are the warmest on record.   But in California, according to Tom Evans of the National Weather Service (NWS), so far this summer we’ve experienced pretty normal average temperatures, and that’s what the NWS Climate Prediction Center is forecasting for the rest of the summer for most of the state, he said, although the southeastern portion of the state may be in for some hotter-than-normal weather in the coming months.

On the call this morning, which was put together by the Union of Concerned Scientists, the speakers were careful to point out that one or two heat waves cannot be considered evidence for global warming, just at the snowstorms on the East Coast this winter couldn’t be used to refute it.  (This recent article in the Christian Science Monitor has more about the heat waves and changing attitudes about climate change.)

However, said NOAA climatologist David Easterling, “Warming temperatures increase the probability of heatwaves.  By the end of the century, what we currently consider a heat wave, or an extremely hot day, might become the norm.”

Warming temperatures can impact public health in a number of ways, said Michael McGeehin, director of the National Center for Environmental Health at the Center for Disease Control.

“Climate scientists predict that the U.S. will see an increase in the duration, intensity, and frequency of heat waves, and we know that heat waves are a public health disaster,” he said.  “They kill.”

And they could kill in large numbers in the centuries to come, according to a recent paper by Matt Huber of the Climate Change Research Center at Purdue.  Huber was on the call this morning to discuss his analysis, which found that if CO2 levels continue to rise over the next 200 years, hotter temperatures could make areas that are home to 50% of the world’s population uninhabitable during heat waves in the the centuries after 2100.  Problems start happening when the heat index is about 130, he said.  (A temperature of 105 degrees F with a humidity level of 50% has a heat index of 134.)

“I personally think that we’ve already committed to at least 2 degrees (Celsius) of warming, but the kind of warming we’re talking about here, which is on the order of at least 10 degrees Fahrenheit, maybe more like 15 degrees Fahrenheit, that’s something that we can still decide to avoid,” he said.  “And from our calculations it looks like we should really try and avoid that.”

And it looks like that potential warming could be becoming reality faster than some expected.  A new study out of Stanford announced today finds that “exceptionally long heat waves” could become commonplace in the United States in the next 30 years, particularly in the western US.  The study, headed up by Noah Diffenbaugh of the Woods Institute, used climate models to analyze what might happen if global temperatures rise two degrees C above pre-industrial levels by 2039. (An increase of two degrees Celsius is the limit agreed upon in the non-binding  2009 Copenhagen Climate Accord (PDF).)

The Stanford researchers found that “an intense heat wave – equal to the longest on record from 1951 to 1999 – is likely to occur as many as five times between 2020 and 2029 over areas of the western and central U.S.”

The analysis predicts during the 2030s the worst heat waves maybe be even more frequent.

It’s 57 degrees in San Francisco this afternoon, and I am wearing a winter scarf at my desk.  Despite all these grim predictions, right now it’s hard not to think that a little extra heat might be nice.

Water cooler imprinted with heat safety tips. Photo: Sasha Khokha

It was like a pageant of farmers in plaid shirts; nearly a dozen speakers  in a Fresno County meeting hall, surrounded by vineyards. Farm leaders offered glowing praise of Cal OSHA’s new guidelines and training seminars that will help them comply with the state’s first-in-the nation heat safety rules–passed three years ago.

The love-fest with Cal-OSHA sets a new tone for agriculture. Growers have traditionally been at odds with the agency tasked with protecting the state’s workers. Farmers have challenged fines and complained about inspections. But despite the regulations,  six workers died last summer, including a pregnant teenage farmworker (some of the victims worked in construction or other outdoor jobs).

Part of the problem was that neither Cal-OSHA inspectors nor farmers had a very clear understanding of how to implement the rules. Is it enough to have an umbrella folded up in the back of a pickup in case it got hot? How hot? How much shade and water is enough?

Today, Cal-OSHA chief Len Welsh made it clear: when it’s 85 degrees or hotter, shade tents or umbrellas have to go up. And that shade should be no more than a two-and-a-half-minute walk away, according to the rules, which also require enough shade so that one-in-four employees are protected from the sun at any given time.

That’s still worrisome for leaders of  the United Farmworkers Union, who were conspicuously absent from the press conference. There are times, they say, when the temperature soars well above 100 or spikes suddenly and everybody should get a break. The UFW says the new guidelines are too vague, and Cal-OSHA’s publicity campaign to educate farmers isn’t enough. Union leaders say the state should impose more fines and criminal penalties when workers die in the heat.

The scientists analyzed 100 years of temperature data collected in downtown Los Angeles  and found that between 1906 and 2006 the average number of extreme heat days – those over 90 degrees – increased from 2 per year to more than 25 per year.  In that time, the average maximum daytime temperature for the city climbed 5 degrees.  Heat waves have also increased, from 2-day events to sweltering stretches that last for 1-2 weeks. The scientists predict that in the coming decades, 10-14 day heat waves will be the norm. 

The bottom line? Even though this summer was a cool one, Southern California is going to get warmer, for longer periods of time. ”Our snow pack will be less, our fire seasons will be longer, and unhealthy air alerts will be a summer staple” said study co-author Bill Patzert, a NASA climatologist and oceanographer.

The scientists assert that the main cause of this increase in temperature and heat days in Los Angeles is due the “urban heat island effect,” which makes urban areas 2-10 degrees Fahrenheit warmer than the surrounding rural areas.

Check out a historical temperature chart for downtown Los Angeles and a full report on the study here.