Monday, July 29, 2019

California Dreaming and Erosion “Crises”

published in the Pacific Tribune July 24th 

What’s Natural? 

California Dreaming and Erosion “Crises”

California's Undulating Coastline

California’s spectacular coastline attracts tourists from around the world. Headlands of granite or basalt resist erosion, defiantly jutting out into the sea. Pocket beaches form where focused wave energy bites into softer sandstones and uncemented stream sediments. Relentless waves undermine and steepen cliffs bordering 70% of California’s shoreline. Over hundreds and thousands of years, natural erosion sculpted our awe-inspiring undulating coast. 

But beauty is in the eye of the beholder - likewise the magnitude of a “coastal crisis”. The Los Angeles Times recently published ‘California coast is disappearing under the rising sea. Our choices are grim’. They inaccurately painted natural erosion as a recent crisis due to COinduced climate change. However, California’s erosion “crisis” must be understood within a greater timeframe.

Since the end of the last ice age, sea level has risen 400 feet. Over 18,000 years, San Francisco’s regional coastline marched 25 miles inland, advancing 7 feet a year - more than twice California’s average. My beautiful home town of Pacifica was featured in that Times’ article because it lost several homes unfortunately built on loosely cemented sand and gravel deposited 100,000 years ago when sea level was 20 feet higher. Although the ocean’s landward march has slowed over the past 5000 years, northern Pacifica’s fragile coastline still retreated by over 7 feet per year between 1929 and 1943. Despite a warming world, the average rate of cliff retreat then markedly declined since 1943.

The ill-fated Ocean Shore Railway, initiated in 1905, foreshadowed California’s erosion problems. To give tourists awesome views, tracks were laid on a ledge dug into steep coastal cliffs. But landslides were common, and costly repairs forced the railway to close. Today, only 25% of the railway ledge built by 1928 still exists. Undeterred, designers of California’sscenic Pacific Coast Highway hoped to give automobile travelers similar breath-taking views. Again, landslides were common. Only 38% of the highway constructed by 1956 still remains. Geologists tell us such landslides constantly altered California’s modern coastline for hundreds of years.

There are few straight lines in nature. Our coastlines undulate. Likewise, our climate oscillates, and coasts erode episodically. Between 1976 and 1999 (the warm phase of the Pacific Decadal Oscillation), California experienced more frequent El Niños. Over 70% of California’s 20th century disappearing coastline eroded during El Niño events. El Niños bring more storms and more destructive waves. El Niños bring more rains that saturate soils and promote landslides.  The Pacific Decadal Oscillation then switched to its cool phase. It brought more La Niñas and more drought, but fewer winter storms and less erosion. In 1949, also a time of less erosion, Pacifica’s government believed homes setback 65 feet from the edge of a bluff would be safe. They never suspected a single El Niño event would move the cliff edge 30 feet landward 50 years later.  

Pacifica California's  eroding coastline

There are some who see human structures as a blight on California’s natural coastline. In response to natural erosion, they suggest we abandon the coast. They argue California’s only choice is “managed retreat” versus “unmanaged retreat”.  Although well engineered seawalls can protect homes and businesses, some environmentalists called seawalls a coastal “crisis”. California’s Coastal Commission recently pledged seawalls will “only be permitted if absolutely necessary”. But the Commission’s policy only fosters a mishmash of emergency fixes. Randomly armored properties deflect destructive waves downstream, accelerating erosion in a neighbor’s unprotected property. Coastal cities must construct well-engineered sea walls, without any gaps.

Because sea walls prevent erosion, the Commission ill-advisedly fears local beaches will be lost if denied locally eroded sand. The Times parroted that belief writing, ‘for every constructed seawall, a beach is sacrificed’. But is that true? San Francisco’s O’Shaughnessy sea wall built in 1929 prevents erosion of the fragile sand dunes supporting Golden Gate Park. Yet SF’s north ocean beach continues to grow. Without a seawall, San Francisco’s south ocean beach rapidly eroded, and threatened infrastructure now requires a sea wall.

Sources of beach sand fluctuate, and simplistic sea wall analyses are very misleading. Sand is stored and transported to beaches in many ways. Streams and rivers supply the most sand needed to nourish a beach, but mining SF bay’s sand has deprived nearby coastal beaches. Furthermore, ocean oscillations shift winds and the direction of currents that transport sand. Beaches grow for decades then suddenly shrink. Although some argue our beaches face a rising sea level “crisis”, archaeologist determined that despite more rapidly rising sea levels 5000 years ago, many California beaches grew when supplied with adequate sand.

Lastly, it’s interesting to note scientists suggested Pacific islands also face an erosion crisis due to rising sea levels. But the latest scientific surveys determined 43% of those islands remained stable while land extent of another 43% has grown. Only 14% of the islands lost land. So, I fear exaggerated crises only erode our trust in science.

Jim Steele is director emeritus of the Sierra Nevada Field Campus, SFSU

Wednesday, July 10, 2019

Celebrating America’s Environmental Stewardship

published in the Pacifica Tribune July 10,2019

What’s Natural? 

Celebrating America’s Environmental Stewardship

I resent the one-sided mis-characterization of humanity as “destroyers of our environment”. Humans certainly had negative impacts on most ecosystems. However, in contrast to a recent United Nations report insinuating we are threatening one million species with extinction, humans have been working hard to restore nature and prevent further extinctions. Most endangered species are still staggering from disruptions initiated centuries ago. But now humans are correcting past mistakes.

Islands have been extinction hotspots. Sixty-one percent of all known extinctions have occurred on islands and 37% of today’s critically endangered species are found only on islands. The main driver of island extinctions has been purposeful or unintentional introductions of alien species. Introduced species are implicated in 81% of all island extinctions. With no natural predators, Island species did not evolve needed behaviors to avoid introduced rats, cats and stoats.  Researchers now suggest eradication of rats and other introduced mammals could prevent the extinction of up to 75% of threatened island birds, reptiles and mammals. 

Similarly, past introductions of disease decimated island species whose immune systems were ill-prepared to combat alien pathogens. For example, after sailors inadvertently introduced mosquitos into Hawaii in the early 1800s, mosquitos began transmitting avian malaria. By the late 1800s Hawaii’s lowland birds were noticeably disappearing, even in undisturbed habitat. Mosquitos were restricted to warmer lowlands, so cooler high elevations served as a refuge. But high elevation birds regularly migrate to the relative safety of lowland valleys during winter storms, so are still threatened by malaria. Due to landscape changes, introduced predators and introduced diseases, Hawaii became known as the extinction capital of the world. Unfortunately eradicating introduced diseases will be extremely difficult.

Extinct Hawaiian Akialoa lanaiensis

In 1750 Russian fur farmers began introducing red and arctic foxes to the Aleutian Islands. Breeding birds that once thrived in predator-free environments were deemed fox food. By 1811 native Aleuts complained foxes were reducing once abundant seabirds but populations continued to plummet. The Aleutian goose was soon considered extinct until a few pairs were found on 3 fox-free islands. Humans embarked on programs to eradicate introduced foxes allowing seabirds and geese to recover. The Aleutian goose recovery has been so rapid, that along the coast of northern California where the geese winter, they are now considered a pest in local parks.

Arctic Fox

Lost habitat has caused many extinctions, especially species dependent on rapidly disappearing wetlands. For centuries wetlands were being drained and converted to croplands and pastures. However, in the United States that trend is being reversed. Due to more efficient farming methods, the extent of land covered by crops decreased 18% between 1938 and 1992, allowing most of that land to return to more natural habitat. Due to improved wildlife management and incentives to conserve wetlands, wetland-dependent birds have increased by over 30% since 1968. Unfortunately, the incentives to protect wetlands have been counteracted by misguided government subsidies for biofuels in the name of fighting climate change. As a result, some farmers have been enticed to drain their wetlands to grow corn.

The probability of extinction by chance is greatly enhanced when a species’ range is extremely small, and their original abundance is low. Minor habitat disturbances can then cause extinctions. For example, most extinct plant species in California were found in only one or two counties, and due to low abundance were known only from one or two collections.

Nonetheless people are still striving to restore wetlands. We preserve habitat by establishing land trusts. My research prompted restoration of a Sierra Nevada watershed that was initially degraded over 100 years ago. Meadows then stayed wetter during California’s 3-year drought than had been the case before the drought and before restoration. Furthermore, bird populations significantly increased. Colleagues are now restoring other meadows as are several other non-profit organizations. 

The United Nations’ report hyping one million extinctions in the near future should be regarded with extreme suspicion. It engages in fearmongering that only evokes a sense of helplessness. It repeatedly argues their environmental goals for 2030 and beyond “may only be achieved through transformative changes across economic, social, political and technological factors.” Their proposed remedy smells of a hidden political agenda. It ignores the tremendous strides humans have taken towards being better environmental stewards. 

Bald Eagle

Our situation is not hopeless. Simply funding the eradication of invasive species on islands would save a significant number of threatened species. America’s regulations have promoted the recovery of several endangered species now listed as species of “least concern”: bald eagleshumpback whalesbrown pelicans and many more. Improved agricultural practices and our efficient economy have allowed more land to convert from cropland back to natural habitat despite feeding a growing human population. Learning from past mistakes, we are now on a trajectory to create win-win situations for both humans and the environment.

Humpback Whale

Jim Steele is retired director of the Sierra Nevada Field Campus, SFSU

Wednesday, June 26, 2019

How Cold Air Caused a Heatwave

From What’s Natural? Column

published in Pacifica Tribune June 26, 2019

Worst Heatwaves During the 1930s Dust Bowl Years

I was recently asked if the record June 2019 heat in the San Francisco Bay Area validated CO2 driven climate models. Surprisingly climate scientists have now demonstrated the heat wave was largely due to an intrusion of record cold air into the Pacific Northwest. How?

Basically, the winds’ direction controls the San Francisco Bay Area’s weather. In summer, California’s inland regions heat faster than the ocean, so the winds blow inland from the cooler ocean. Those onshore winds bring cooling fog, our natural air conditioner. Later, as the sun retreats southward in the fall, the land cools faster than the ocean. Seasonal winds then reverse and blow from the cooling land out to sea. Those winds keep the fog offshore. Without fog, San Franciscans finally enjoy pleasantly warm days in September and October. In northern California those strong offshore winds are called the Diablo winds. Although Diablo winds bring welcome warmth, those winds also increase wildfire danger.

Typically, inland California heats up in June drawing in the fog. But that temporarily changed when a surge of record cold air briefly entered Washington state and then moved down into northeastern California and Nevada. Dr. Cliff Mass, a climate scientist at the University of Washington, studies the Diablo winds. On his popular weather blog,  he discussed how that intruding cold air created an unseasonal burst of Diablo winds that then kept the fog offshore. Without cooling fog, solar heating increased temperatures dramatically. According to Accuweather, San Francisco’s maximum temperature on Friday June 7th was 67 °F, skyrocketed to a record 97 °F by Monday and then fell to 61 °F three days later as onshore winds returned. 

Such rapid temperature change is never caused by a slowly changing greenhouse effect.  Nevertheless, the media asks if rising CO2 concentrations could have contributed to the higher temperatures or made the heatwave more likely? 

Although definitions vary, the World Meteorological Organization defines a heat wave as 5 or more consecutive days of prolonged heat in which daily maximum temperatures are 9+ °F higher than average. Assuming the rise in CO2  concentration increased all temperatures relative to the 20thcentury average, it is believed maximum temperatures are more likely to exceed that 9 °F threshold. But heatwaves are not caused by increasing greenhouse gases.

The science is solid that greenhouse gases can intercept escaping heat and re-direct a portion of that heat back to earth. That downward directed heat reduces how quickly the earth cools, and thus the earth warms. However, heat waves typically occur when greenhouse gas concentrations are greatly reduced.  Eighty percent or more of our greenhouse effect is caused not by CO2, but by water vapor. Satellite data shows the dry conditions that accompany a heat wave actually reduce the greenhouse effect because drier air allows more infrared heat to escape back to space. However, like less fog, less water vapor and less clouds allow more solar heating. So despite the increase in escaping heat, increased solar heating dominates the weather and temperatures rise. 

The important contribution of dryness to heat waves helps explain why the USA experienced its worst heat waves during the 1930s Dust Bowl years (see EPA Heatwave Index above). Furthermore, the EPA’s heat wave index appears totally independent of rising CO2 concentrations.  Dryness also helps to explain why the hottest air temperature ever recorded anywhere in the world happened over a century ago in Death Valley on July 10, 1913; a time of much lower CO2 concentrations.

To summarize, an intrusion of record cold air into the Pacific Northwest generated unseasonal Diablo winds in northern California.  Those offshore winds prevented the fog from reaching and cooling the land. In addition, because the Diablo winds are abnormally dry, solar heating of the land increased. Those combined effects caused temperatures to temporarily jump by 30 °F. 

Lastly, not only can Diablo winds cause heatwaves, Diablo winds will fan small fires into huge devastating infernos such as the one that destroyed Paradise, California. Fortunately, there were few wildfire ignitions during this heat wave. To be safe, Pacific Gas and Electric had shut off electricity to areas predicted to have high wind speeds. So Dr. Mass mused, that because colder temperatures generate the destructive Diablo winds, climate warming may have some benefits.

Jim Steele is retired director of the Sierra Nevada Field Campus, SFSU

Wednesday, June 12, 2019

Fear Mongering Floods

published in the Pacifica Tribune June 12, 2019

What’s Natural

Politics Distorts the Science of Floods

At the confluence of the Missouri and Mississippi Rivers, native American “mound builders” built Cahokia, the largest city in pre-Columbus America. The purpose of their mounds is still debated. Were the mounds refuges from frequent floods, strategic defenses from hostile attacks, or monuments to ruling elites? I suspect all of the above. During warmer and more arid times with minor flooding, Cahokia’s population expanded. By 1250 AD its population equaled contemporary London or Paris. Charles Mann wrote about Cahokia in his superb book  1491 , “the kings who gained their legitimacy from claims to control the weather, would face angry questions from their subjects” when the catastrophic floods returned.  Indeed, as severe flooding increased, Cahokia was eventually abandoned.

Great Flood of 1927 Mississippi River

Eerily, in the wake of the 2019 Mississippi River Valley flooding, politicians are similarly telling flood victims that their climate policies can also control the weather. Washington’s Governor Inslee tweets, “For the people of Davenport, Iowa, climate change is personal. It’s destroying their homes, harming their communities, and hurting their livelihoods. We must defeat the climate crisis to protect our fellow Americans.” Senator Warren tweeted, “the consequences of climate change are severe, and they are already affecting places like Burlington, Iowa. We have a moral responsibility to act.”  But these politicians ignore the science and long history of the Mississippi’s floods. 

Investigating causes of Cahokia’s abandonment, scientists uncovered natural climate cycles 
governing the region’s flooding. Large floods were common between 300 AD and 600 AD.  Then between 600 AD and 1200 AD more arid conditions prevailed. But after 1200 AD severe flooding returned. Natural ocean oscillations can explain alternating patterns of dry and wet periods. So accordingly, the Intergovernmental Panel on Climate Change (IPCC) expresses low confidence regards any global warming effect on modern flooding.

Over the Atlantic Ocean exists a large and somewhat permanent atmospheric pressure system named the North Atlantic Subtropical High (NASH), or Bermuda High. Its clockwise rotation critically effects the climate of the eastern United States. NASH is the reason the eastern United States experiences very humid summers in contrast to the dry west because on NASH’s western edge, warm moist air from the south is pumped northward. More importantly, NASH regulates regional droughts and floods. NASH naturally shifts locations over decades driven by natural ocean oscillations like El Nino. When NASH shifts further to the west, more moisture from the Gulf of Mexico is pumped into the Great Plains causing more floods. When shifted further east, the Midwest suffers more droughts. 

Non-scientific journalists and media talking heads falsely insinuate recent extreme flooding is due to global warming. They parrot a single fact that “warmer air can hold more moisture”. Although true, that fact is grossly misapplied. The earth’s warmest air temperatures happen over deserts, but there the air is bone dry. The key to extreme rainfall is not temperature, but how much moisture is transported from the oceans to the land. During cooler times, severe Mississippi Valley floods were observed in 1809, 1829, 1844, 1851, 1874 and 1882. The Great Flood of 1927 is considered the Mississippi Valley’s greatest modern flood. Due to the transport of excessive moisture from the Gulf, average rainfall nearly doubled in 1927. 

In contrast to global warming predictions, the Mississippi River Valley also experienced below average winter temperatures and above average snowfall in early 2019. The National Weather Service issued early warnings that the melting snow could cause flooding. They further warned the frozen ground and saturated soils wouldn’t absorb the excess water, additionally swelling streams and rivers. 

So many farmers are rightfully rejecting the politicians’ climate claims. Instead farmers blame the Army Corps of Engineers for breached levees and improperly managing levee systems. Levees had seduced people to move into the flood plains. People assumed those levees would always be maintained. But worse, the levee systems unintentionally elevated flooding probabilities.

Each year high water levels from snowmelt and spring rains cause rivers to approach flood stage. Excess water would normally get stored on natural floodplains, minimizing downstream floods. But when levees deny a river’s access to its flood plains, higher volumes of flood water get shunted downstream. Instead of allowing flood waters to spread out, levees narrow a river’s channel width, forcing the river to rise much higher than normal. Thus researchers had warned, “river engineeringhas elevated flood hazard on the lower Mississippi to levels that are unprecedented within the last five centuries.”  

Blaming CO2climate change only misguides attention from these real problems. If politicians sincerely hope to promote wise flood protection, they better educate themselves regards natural climate cycles and the unintended consequences of separating rivers from their flood plains.

Jim Steele is retired director of the Sierra Nevada Field Campus, SFSU

Wednesday, May 29, 2019

Cycles of Rapid Climate Warming

Published in the Pacifca Tribune May 28, 2019

What’s Natural

Cycles of Rapid Climate Warming

The globally averaged temperature rose 1.5°F from 1880 to today. Various narratives suggest the rise since 1950 was driven by increasing concentrations of CO2. The rising temperature before 1950 was considered natural. Since 1990, Arctic temperatures rose 2 to 3 times faster than the global average. So, are rapidly rising Arctic temperatures evidence of an impending climate crisis? 

Astute students of climate history recall rapid Arctic warming has happened often and naturally. During the last Ice Age when COconcentrations were just half of today’s, 25 abrupt warming eventshappened. Arctic temperatures rose 9°F, and sometimes as much as 14°F in just 40 years. These rapid warming episodes are now called Dansgaard–Oeschgerevents (D-O events) in honor of the researchers who first detected them in Greenland’s ice cores. These D-O episodes affected global climate, changed ocean currents along California’s coast and altered the range of European forests.

What caused such abrupt warming? Basic physics dismisses changes in greenhouse gases or solar insolation because neither radiative effect induces such rapid warming. The most reasonable explanation suggests episodes of ventilating heat, that had accumulated in the Arctic Ocean, rapidly warmed the air. 

The notion of stored heat in a freezing Arctic Ocean seems unfathomable to many laypeople. But it is scientifically well documented.Tropical Atlantic waters experience intense heating and evaporation. This results in warm salty water that is relatively dense. The Gulf Stream and its branching currents then transport that warm water northward. Because the water is salty and dense it sinks below colder and fresher surface waters as it approaches the Arctic Ocean. As a result, there is a layer of warm Atlantic water stored at depths between 300 and 2,700 feet below the Arctic Ocean’s surface.Arctic researchers report, “the total quantity of heat is substantial, enough to melt the Arctic sea ice cover several times over.”

Warm Atlantic Water in the Arctic Ocean

Sea ice and a layer of cold fresh water normally inhibit subsurface heat from ventilating to the atmosphere. But as the incoming heat increases and accumulates, the warm Atlantic Waters can eventually melt the overlying ice cover. Other times, changes in the direction of Arctic winds will blow sea ice out into the Atlantic, as it did in the late 1990s. Either way, without insulating ice, a burst of heat ventilates from the ocean and warms the atmosphere. 

Recently, anthropologists studying past Arctic cultures found the pre-Dorsett culture periodically abandoned then recolonized the Arctic coast as changes in sea ice affected temperatures. When sea ice covered coastal waters for 2 months longer than today, temperatures became 3-7°F cooler. Arctic people then abandoned the coast and moved south. A few hundred years later they re-colonized the coast when periods of open water, lasting 4 months longer than today, allowed heat to ventilate and raise temperatures 10°F warmer than today.  Such changes alternated over several hundred years. And that raises the question, is the Arctic still experiencing similar cyclical warming?

Over the past several hundred years, melting Arctic sea ice corresponds with observed periods of increased intrusions of warm Atlantic waters. The dramatic Arctic warming during the 1920s and 1930s corresponded with increased intrusions of warm water accompanied by Atlantic fish species normally found further south. As the 1922 newspaper clipping reveals (see above), the warming of the Arctic was so dramatic it raised concerns the frigid Arctic would soon be converted to a warmer “temperate zone”. 

Arctic 1922

When warm water inflows began retreating around 1950 so did the Atlantic fish. Sea ice then increased.  Such cycles have been recorded infishery data for hundreds of years. The most recent cycle of melting Arctic sea ice likewise coincided with intruding warm Atlantic waters with patterns of invading fish very similar to the 1920s-1930s warming episode.

So, we are now in the midst of an instructive natural experiment. If the loss of Arctic sea ice and warmer temperatures are due to rising CO2concentrations, we should soon see a total loss of Arctic sea ice as predicted by some climate scientists. In contrast, if natural oscillations are controlling intrusions of warm Atlantic waters, Arctic sea ice will soon rebound. Indeed, a recent shift in ocean oscillations is now decreasing warm water intrusions. Temperatures should fall as less heat ventilates into the atmosphere. Based on earlier 20thcentury patterns when lost sea ice rebounded in the 1960s and 70s, Arctic sea ice should begin rebounding by the year 2030. But then again, warmer temperatures did last for 300 years during cycles a few thousand years ago. Either way, natural climate cycles predict Arctic temperatures will not experience further accelerated warming. We will soon see which theory is most accurate within the coming decade.

Jim Steele is retired director of the Sierra Nevada Field Campus, SFSU

Saturday, May 25, 2019

The $1000 Student Climate Challenge Award

Is there a climate crisis??  

 Currently children are being asked to lead a political charge for “climate change action”. Climate is very complex, and most adults have a very poor understanding of all the factors affecting climate change.  Thus, many people believe our children must have a far inferior understanding of climate change and are just being used as pawns in the politics of climate change. Many adults see student strikes as silly political theater, not validation of any climate theory or proof of an impending climate crisis.

But perhaps I underestimate the knowledge and intelligence of our student “climate strikers”. So, I am offering a $1000 award to the student who unequivocally outlines why 1) rising concentrations of CO2 are the cause of recent climate change, and 2) why that change is catastrophic. 

I warn participants, I devoted my whole professional career towards scientific research and education that promotes wise environmental stewardship. Nonetheless I became a climate skeptic. I observed too many people eager to blame climate change for environmental problems that were caused by other factors and had real remedies. So, I suspect no adult, never mind a child, can meaningfully determine that recent weather or recent changes in a species abundance have been driven by rising greenhouse gases. 

But you may prove me wrong. 

Furthermore, to encourage good scientific thinking, if there is no winner in this climate challenge, I will still guarantee a $500 “runner-up” prize to the student who demonstrates the best scientific thinking, even if their conclusions are wrong.

Here are the requirements:

1.    The student must be 21 years or younger. Nonetheless I encourage each student to discuss climate change with your parents, teachers and friends as well as contacting scientists.

2.    The student must email their arguments in a document that is no larger than 5000 words. They must state their name and age and type “The $1000 Student Climate Challenge Award” in the subject line. Email the document by December 1, 2019 to

3.    The student must use the foundation of scientific inquiry, the “null hypothesis.   In other words, the student must show that current weather/climate reflects a change that exceeds natural climate change. That requires choosing the appropriate time frames for discussion.

4.    Students must go beyond simple correlations. Correlation is notcausation. Although CO2 concentrations are higher today than they were 200 years ago, higher concentrations are not evidence of causation. 

5.     Students must address relevant alternative hypothesesFor example, why is Arctic warming the result of CO2 warming and not the result of natural oscillations that drive warmer waters into the Arctic?

6.    Students must address why warming is catastrophic. If warming is caused by rising CO2, why would a longer growing season be catastrophic? Or if there is less sea ice why would the resulting increase in photosynthesis be catastrophic? Or what is the evidence of a trend in larger or more tornados?

7.    Consensus is not evidence.  Consensus is merely political theater. Arguments must be based on evidence. Politically motivated scientists tried to refute Albert Einstein’s theory of relativity using a “consensus” argument and writing “100 Authors Against Einstein”. The consensus was still wrong.

8.    Avoid arguments from authority. As Carl Sagan wisely advised “arguments from authority carry little weight  - authorities have made mistakes in the past.” For example, John Muir’s ideas were published in popular papers and magazines regards the formation of Yosemite Valley by glaciers. The geological authority from Harvard, Josiah Whitney, suggested otherwise and tried to smear Muir as just an “ignorant shepherd”. But Muir was mostly correct! Likewise, I warn that using the word “denier” will not make your arguments more correct.

9.    Students can enter as many times as they want. You may want to change your arguments when new information comes to light. Simply note that your new entry replaces your last.

As student essays roll in, I will periodically report in my What’s Naturalnewspaper column, and on my blog, regards failed common arguments and why it will disqualify your essay from the award.  That will allow every student to improve their argument and re-submit.

I wish every student the best and hope their sincere essays will promote better scientific discourse and understanding.

Sincerely Jim Steele

Director emeritus, Sierra Nevada Field Campus, San Francisco State University

Wednesday, May 15, 2019

Our Urban “Climate Crisis”

Published in Pacifica Tribune  May 14, 2019

What’s Natural 
Our Urban “Climate Crisis”

Based on a globally averaged statistic, some scientists and several politicians claim we are facing a climate crisis. Although it’s wise to think globally, organisms are never affected by global averages. Never! Organisms only respond to local conditions. Always! Given that weather stations around the globe only record local conditions, it is important to understand over one third of the USA weather stations report a cooling trend.  Cooling trends have various local and regional causes, but clearly, areas with cooling trends are not facing a “warming climate crisis”. Unfortunately, by averaging cooling and warming trends, the local factors affecting varied trends have been obscured. 
It is well known as human populations grow, landscapes lose increasing amounts of natural vegetation, experience a loss of soil moisture and are increasingly covered by heat absorbing pavement and structures. All those factors raise temperatures so that a city’s downtown area can be 10°F higher than nearby rural areas. Despite urban areas representing less than 3% of the USA’s land surface, 82% of our weather stations are located in urbanized areas. This prompts critical thinkers to ask, “have warmer urbanized landscapes biased the globally averaged temperature?”  (Arctic warming also biases the global average, but that dynamic must await a future article.)
from Wickham 2013
Satellite data reveal that in forested areas the maximum surface temperatures are 36°F cooler than in grassy areas, and grassy areas’ maximum surface temperatures can be 36°F cooler than the unvegetated surfaces of deserts and cities. To appreciate the warming effects of altered landscapes, walk barefoot across a cool grassy lawn on a warm sunny day and then step onto a burning asphalt roadway.
In natural areas like Yosemite National Park, maximum air temperatures are cooler now than during the 1930s. In less densely populated and more heavily forested California, maximum air temperatures across the northern two thirds of the state have not exceeded temperatures of the 1930s. In contrast, recently urbanized communities in China report rapid warming of 3°F to 9°F in just 10 years, associated with the loss of vegetation.

Although altered urban landscapes undeniably raise local temperatures, some climate researchers suggest warmer urban temperatures do not bias the globally averaged warming trend. They argue warming trends in rural areas are similar to urbanized areas. So, they theorize a warmer global temperature is simply the result of a stronger greenhouse effect. However, such studies failed to analyze how changes in vegetation and wetness can similarly raise temperatures in both rural and urban areas. For example, researchers reported overgrazing had raised grassland temperatures 7°F higher compared to grassland that had not been grazed. Heat from asphalt will increase temperatures at rural weather stations just as readily as urban stations.
To truly determine the effects of climate change on natural habitats requires observing trends from tree ring data obtained from mostly pristine landscapes.  Instrumental data are overwhelmingly measured in disturbed urbanized areas. Thus, the difference between instrumental and tree ring temperature trends can illustrate to what degree landscapes changes have biased natural temperature trends.  And those trends are strikingly different!
The latest reconstructions of summer temperature trends from the best tree ring data suggest the warmest 30-year period happened between 1927 and 1956. After 1956, tree rings recorded a period of cooling that lowered global temperatures by over 1°F. In contrast, although tree rings and instrumental temperatures agreed up to 1950, the instrumental temperature trend, as presented in NASA graphs, suggests a temperature plateau from 1950 to 1970 and little or no cooling. So, are these contrasting trends the result of an increased urban warming effect offsetting natural cooling?

from Schneider 2015

After decades of cooling, tree ring data recorded a global warming trend but with temperatures just now reaching a warmth that approaches the 1930s and 40s. In contrast, instrumental data suggests global temperatures have risen by more than 1°F above the 1940s. Some suggest tree rings have suddenly become insensitive to recent warmth? But the different warming trends are again better explained by a growing loss of vegetation and increasing areas covered by asphalt affecting temperatures measured by thermometers compared with temperatures determined from tree ring data in natural habitats.
Humans are increasingly inhabiting urban environments with 66% of humans   projected to inhabit urban areas by 2030. High population densities typically reduce cooling vegetation, reduce wetlands and soil moisture, and increase landscape areas covered by heat retaining pavements. Thus, we should expect trends biased from urbanized landscapes to continue to rise. But there is a real solution to this “urban climate crisis.” It requires increasing vegetation, creating more parks and greenbelts, restoring wetlands and streams, and reducing heat absorbing pavements and roofs. Reducing CO2concentrations will not reduce stifling urban temperatures. 

Jim Steele is the retired director of San Francisco State University’s Sierra Nevada Field Campus and authored Landscapes and Cycles: An Environmentalist’s Journey to Climate Skepticism