Urbanization raises the heat in O.C.
August 7th, 2008, 2:00 pm · 11 Comments · posted by Gary Robbins, science writer-editor
The average annual temperature in Santa Ana has increased by 7.5 degrees in less than a century, a spike largely attributed to urbanization which has seen the city’s population climb from less than 15,000 to more than 350,000. The temperature has gone from a low of 59.7 degrees in 1920 to 67.2 in 1997, with yearly temperatures near the all-time high as recently as 2006.
“Santa Ana now has a lot more buildings, parking lots and streets, which absorb and hold heat, some of it through the night,” says Ivory Small, science officer at the San Diego office of the National Weather Service.
The NWS analyzed the city’s climate and weather based on daily temperature readings from the Santa Ana Fire Station, which has been recording temperatures since 1916. The upward trend is depicted here by Register illustrator Scott Brown.
Forecasters calculated the average yearly temperature by determining the average high and average low temperature for each month. Then they divided those figures by two and got the average monthly temperature. Then they added up the average temperature for January through December of each year and divided by 12, getting the average annual temperature.
Santa Ana’s population has been on a steady, and basically predictable, rise for decades. The average annual temperature also has risen steadily. But the temperature increase didn’t occur in a predictable, incremental year-by-year pattern. There were lots of hiccups. For example, the average high for 1961 was 64.0 degrees. Three years earlier, the average high was 65 degrees.
Scientists say the average temperature didn’t smoothly rise year-by-year partly due to natural variability. In other words, some years are hotter than others because of natural fluctuations in weather and climate.
But over the long-term, the average temperature has been going up in Santa Ana (click to enlarge image of the ‘city” in the 1920s.)
“The increase in temperatures in Santa Ana, as well as an increase in extreme heat days and in heat waves is primarily — about 60 percent — due to the ‘urban heat island effect,’ ” says Bill Patzert, a climatologist at the Jet Propulsion Laboratory in Pasadena.
“Santa Ana is embedded in the dramatic urbanization or ‘extreme makeover’ of Orange County. More homes, lawns, shopping centers, traffic, freeways and agriculture, all absorbing and retaining solar radiation, making Santa Ana and Orange County warmer.
“On a larger scale, Orange County is atmospherically connected to our ever-expanding and warming Southern California megalopolis. Global warming due to increasing greenhouse gases is responsible for about 40 percent of the overall heating observed in Southern California. ”
PATZERT AMENDS ESTIMATE: A couple of readers posted questions asking why Patzert felt that global warming accounted for 40 percent of the increase in Santa Ana’s yearly average temperature. Patzert sent me this email amending his original statement:
“Actually, I would correct my original estimate of the global warming share of Santa Ana warming at about 25%. How? In the past century, the local oceans, at the coast and offshore, have warmed about 2 degrees F. This ocean temperature rise is certainly due to the excess heat radiated by the atmosphere and absorbed by the Pacific and other oceans. (Fully,84 percent of the”global warming” is being absorbed by the oceans.)“Sea level rise is the unequivocal proof of this. (The global oceans haverisen 8 inches in the past century.) To the east the localmountains have warmed about the same. This can be seen in our shorter snow pack seasons. Thus my “estimate” that the Santa Ana rise is mostly local “heat island” (approximately 5.5 degrees F) with some larger-scale (ocean and unpopulated regions) “global” signal (estimated at 2.0 degrees F) added on.
“This partitioning of the local and global warmings agrees with many other scientist’s estimates. My point is that Southern Californians are warmingdue to our own ”
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August 7th, 2008 at 5:44 pm
It’s the same reason why people think that global warming is manmade. When all of the temps are being taken by weather stations
mostly in urban areas, it causes what’s called urban heat bloom. So, basically, most temps used by Algore are rising only because of it.
August 9th, 2008 at 2:22 am
Bill Patzert: You are quoted as having said, “Global warming due to increasing greenhouse gases is responsible for about 40 percent of the overall heating observed in Southern California.”
Please document the claimed percentage.
August 9th, 2008 at 3:17 am
Please explain how a 7.5 degree increase is 40% due to Greenhouse gases (GHG)? What is your evidence? What are your sources?
Is SoCal subject to a more intense effect of GHG than the rest of the planet?
Dude: After readers raised questions about Patzert’s figure, I raised the issue with Patzert. He emailed this amendment this morning:
“Actually, I would correct my original estimate of
the global warming share of Santa Ana warming at about 25%. How?
In the past century, the local oceans, at the coast and offshore,
have warmed about 2 degrees F. This ocean temperature rise is
certainly due to the excess heat radiated by the atmosphere and
absorbed by the Pacific and other oceans. (Fully, 84% of the
“global warming” is being absorbed by the oceans.) Sea level
rise is the unequivocal proof of this. (The global oceans have
risen 8 inches in the past century.) To the east the local
mountains have warmed about the same. This can be seen in our
shorter snow pack seasons. Thus my “estimate” that the Santa Ana
rise is mostly local “heat island” (approximately 5.5 degrees F)
with some larger-scale (ocean and unpopulated regions) “global”
signal (estimated at 2.0 degrees F) added on. This partitioning
of the local and global warmings agrees with many other scientist’s
estimates. My point is that Southern Californians are warming
due to our own “urban heat island” and GLOBAL (much larger than
local) WARMING.
August 9th, 2008 at 7:19 am
I wonder what evidence is used to assign the other 40% of the termature gain to CO2.
Since no reason is provided, I can only speculate that once again the scientists are using the rationale that since they can’t explain it through natural processes (like solar or ocean) then it must, by the process of elimination, be man caused.
The problem with that explanation is that it doesn’t actually prove that man is the cause. It simply assumes it to be so.
That doesn’t prove they are wrong - it just just doesn’t prove anyhting.
Dude: You raise an interesting question. I’ve emailed Dr. Patzert and asked for an answer.
Patzert’s Amendment: I just received this email from Bill Patzert: “Actually, I would correct my original estimate of the global warming share of Santa Ana warming at about 25%. How?
In the past century, the local oceans, at the coast and offshore,
have warmed about 2 degrees F. This ocean temperature rise is
certainly due to the excess heat radiated by the atmosphere and
absorbed by the Pacific and other oceans. (Fully, 84% of the
“global warming” is being absorbed by the oceans.) Sea level
rise is the unequivocal proof of this. (The global oceans have
risen 8 inches in the past century.) To the east the local
mountains have warmed about the same. This can be seen in our
shorter snow pack seasons. Thus my “estimate” that the Santa Ana
rise is mostly local “heat island” (approximately 5.5 degrees F)
with some larger-scale (ocean and unpopulated regions) “global”
signal (estimated at 2.0 degrees F) added on. This partitioning
of the local and global warmings agrees with many other scientist’s
estimates. My point is that Southern Californians are warming
due to our own “urban heat island” and GLOBAL (much larger than
local) WARMING.
August 9th, 2008 at 1:31 pm
Bill Patzert: The Pacific Ocean off the California Coast is a thermohaline circulation/meridional overturning circulation (THC/MOC) upwelling point. Sea surface temperatures (SSTs) oscillate there at a much greater amplitude. Please don’t confuse your audience by mixing topics, such as sea surface height.
Note: You changed your attribution percentage; you still haven’t documented your claim.
Regards.
August 9th, 2008 at 4:21 pm
Patzert states:
“This ocean temperature rise is certainly due to the excess heat radiated by the atmosphere and absorbed by the Pacific and other oceans.”
What is his reason for stating this? He has made a previous statement without supporting evidence, then produces this, another unsupported statement, in support of the previous one.
I scuba dive all year round and am very familiar with the variation of the thermocline with season. The long-wave “thermal” radiation from the atmosphere penetrates the ocean about, what, half an inch deep maybe?. The short wave “sunlight” radiation penetrates hundreds of feet deep.
Seasonal warming and cooling, which moves the thermocline up and down, cannot be due to the re-radiated heat from the atmosphere. The volume of ocean affected by long wave radiation is just miniscule in comparison to the volume heated by light.
I suggest that the ocean temperature is controlled by solar output reaching the surface, not “excess heat” from the atmosphere. BTW The oceans, as measured by 8 years of the NASA satellite program ARGO, are cooling slighlty, not warming.
Also, can Patzert explain exactly what he means by “excess heat” radiated by the atmosphere. And please, don’t be shy; we don’t bneed to be talked down to.
August 9th, 2008 at 7:01 pm
Dude, I think you will find that there is general agreement in the climate field that man’s contribution to atmospheric CO2 had little effect until the massive industrialization that followed WWII. I believe this is what the previous poster is referring to.
As for Patzert’s reply, it still doesn’t answer the main question. What evidence is there that the remaining 40% (or now 25%) of the excess heat is a result of CO2?
Just saying that comes from the ocean (or is global) doesn’t actually establish the cause. Or are we just supposed to assume it to be man caused?
August 10th, 2008 at 5:55 am
Gary:
I see that I am behind the curve on addressing your reply to my original questions.
Perhaps Patzert can explain the cooling trend in Sea Surface Temperature?
Or provide the unequivocal proof of the claim for an 8 inch rise in the sea level?
Or even sources for his claim of 25% contribution?
Personally, I think Patzert is just blowing smoke at you and has no documentation for any of his claims.
Anytime you want a more balanced approach for a future article, please feel free to contact me direct. I will happily provide proof for all my claims or refer you to individuals who can.
August 17th, 2008 at 8:01 am
no doubt “island” heating is man made; however, i believe there are other factors at play that influence ocean temperatures when one looks at the bigger picture. for example, here in manhattan i record at least 10 nights per year that hold in the low-mid 80s which is extraordinary for a northern city. it comes down to how much heat is retained with our brick/steel buildings, and lack of sea breeze overnight. at the same time, walk to central park and the temp is 10 degrees lower (which is where the official station is located at belvedere castle.) but pull us (and santa ana) up on google earth. compare these spots of land with the desert sw, or the saraha. it is like concluding one grain of sand on the beach matters to erosion control (or even a 10′ x 10′ plot of sand matters, whatever, it is still insignificant.) i believe it truly takes remarkable events (a major volcanic eruption) to alter these temperatures on grand scale. the length of time the scale changes always seems to snap back too.
Dude: I love Belvedere Castle.