SCIENCE / MEDICINE : Climate vs. the Volcano : Weather: Physicist Paul Handler says America’s dry periods, corn production in the Midwest and the level of Lake Michigan can be determined by volcanic activity.
California’s 4-year-old drought will not ease until a volcano erupts at latitudes near the Equator, according to University of Illinois physicist Paul Handler.
Volcanic eruptions in that region produce stratospheric dust and sulfur dioxide gas that prevent a small portion of sunlight from reaching the Earth’s surface, thereby altering climate in what Handler believes to be highly predictable ways.
He has linked volcanic eruptions--or their absence--to corn production in the Midwest, water levels of the Great Salt Lake and Lake Michigan, warming of the Pacific Ocean, the colonization of Greenland, the “little ice age” that afflicted Europe in the middle of this millennium and even the disappearance of the Mesa Verde Indians in the Southwest and the Kahoki Indians in Illinois.
Handler’s theory is controversial and not widely accepted, and most climatologists consider him an outsider whose ideas are too simplistic.
But he is one of the few who forecast continuing drought in California this winter and the return of rainfall to the drought-stricken Sahel Desert in North Africa in 1988.
“I’m a little skeptical, but I’m not ruling him out,” said meteorologist Kenneth Bergman of the National Academy of Sciences in Washington. “I think it is worth (further study). If he is correct, it has strong implications for climate prediction.”
“We think of Paul Handler’s work as being rather innovative and interesting,” said solar physicist Kenneth Schatten of the National Aeronautics and Space Administration in Greenbelt, Md. “But I think it has yet to be really accepted by the scientific community. It’s research on the forefront of our knowledge, and thus there may be both some good and some bad in it. I wouldn’t believe everything is 100% correct . . . but he has done a lot of positive work.”
Handler came to climatology late in life after 23 years working with microelectronics. He first became interested in the subject in the early 1970s while he was working with data bases on agricultural production and began to perceive correlations between crop production and volcanoes.
In particular, he noted a link between corn production in the American Midwest and volcanic eruptions in the low latitudes, roughly between 25 degrees south and 25 degrees north.
Whenever an eruption occurred in the low latitudes, corn yield in the states of Indiana, Iowa and Illinois was always above average the following year. Conversely, when no eruption occurred for a period of time, corn yields plummeted because of drought.
Handler’s reasoning:
Volcanic eruptions spew ash and sulfur dioxide into the stratosphere, the upper layer of the Earth’s atmosphere. The ash can block sunlight dramatically, but it is washed out by rain in days or weeks. But the sulfur dioxide is converted to sulfuric acid, which condenses with water to form extremely small particles called aerosols.
The aerosols are rained out of the stratosphere over a two- to five-year period. But while they are present, they absorb a small fraction of the sunlight reaching Earth and prevent it from reaching the surface. After the eruption of the Mexican volcano El Chichon in April, 1982, for example, the low-latitude solar radiation was reduced by more than 7.7% for many months.
When temperatures are reduced near the Equator because of decreased sunlight, the two Northern Hemispheric high-pressure systems adjacent to the continental United States, the California High and the Bermuda High, become weaker and are displaced south of their normal positions and farther from land.
The strength and position of these highs are two of the major factors that determine the path of the jet stream, the mile-thick, 60-mile-wide body of air that flows over the United States at a height of 10 miles and speeds of up to 200 m.p.h., carrying storm systems with it. This means that when volcanic eruptions have introduced aerosols into the stratosphere, the jet stream--and its associated storms--will flow farther south over the United States.
In the Northern Hemisphere, the effect of the decrease in low-latitude radiation is to prolong the spring and fall seasons, while decreasing the intensity and duration of summer.
For the summer period, the jet stream will be located in the northern United States rather than Canada, which should bring more rain and cloudiness to the north-central United States than normal. In effect, the volcanic aerosols would prolong the higher rainfall of May and June into July and August, which normally are drier.
In the absence of volcanic eruptions, the opposite occurs. The jet stream moves farther north, and rainfall is reduced in the United States.
Handler notes that “there was very little stratospheric aerosol during the 1930s. The stratosphere was just very, very clear, and that may be a possible explanation of why there was a drought then. The same was true during the 1950s.”
That is the situation Southern California finds itself in now. The stratosphere is very clear, and most of the winter storms that normally bring rain and snowfall have passed north of California, leaving a large water deficit.
Handler has shown a strong relationship between volcanic eruptions and the levels of Lake Michigan and the Great Salt Lake extending from 1819, when lake levels were first recorded, to the present. His correlation shows that levels of the lakes always rise after volcanic eruptions, beginning one to two years after the presence of aerosols. The lag time, he said, is caused by the need for rainfall to replenish ground water reservoirs before excess water begins flowing into the lakes.
He noted that the highest levels of the lakes, historically, occurred after the massive eruptions of the Indonesian volcano Krakatoa in 1883 and El Chichon in 1982. “No one has ever been able to explain variations in the lake levels before,” he said.
Handler has been able to extend his observations on climate and volcanoes as far back as AD 550, using data on stratospheric acidity extracted from ice cores drilled in Greenland by several researchers. (The approximate location of the volcanoes can generally be determined by examining the chemical composition of the ash and aerosols.) The data suggest some intriguing possibilities.
He noted, for example, a sharp drop in volcanic activity beginning about AD 850 and lasting until about AD 1300, which resulted in a greater amount of radiation striking the Earth’s surface and warming the Northern Hemisphere (he hasn’t studied the Southern Hemisphere). During that period, colonization increased dramatically in Greenland and Iceland, trees grew profusely and agricultural colonies were established.
Those colonies prospered between AD 1100 and 1250 and the population of Greenland reached 80,000, a figure it would not attain again until the 20th Century. But when volcanic eruptions became more common again after AD 1350, the colonies began withering away. “Archeological excavations show that the people got shorter and looked sicker,” he said. By 1410, the colonies had either disappeared or lost contact with the outside world.
But the same conditions that benefited Greenland must have wreaked havoc in the U.S. Midwest and Southwest. The climate there would have become much more arid, making it almost impossible to raise corn and other food crops, which most likely led to the disappearance of both the Kahoki and Mesa Verde tribes. “It got so dry that there was no human habitation in the plains around 1200,” he said.
From about 1350 to 1750, volcanic activity was higher than normal. This activity correlates with the “little ice age” in Europe, a period when glacier movement increased dramatically in the Alps and average temperatures were an estimated 5 degrees cooler than now.
Although there was a brief period of volcanic activity in the late 19th Century, volcanic activity has been relatively low throughout the 20th Century, leading to an overall warming. That warming, Handler cautions, is superimposed on the warming caused by the greenhouse effect, which results from the release of carbon dioxide into the atmosphere from burning of fossil fuels.
“I think volcanoes are an important source of climate change over the last 100 years,” said climatologist Allan Robock of the University of Maryland in College Park. “The data indicate that the greenhouse warming was observed, but was masked to some extent by volcanoes. . . .That implies that greenhouse warming will continue into the future.”
Most of Handler’s correlations have been retrospective, but they do have some predictive value as well. Geochemist Mary Jo Spencer of the University of New Hampshire in Durham has been studying ice cores, extending back 800 years, obtained in Greenland from a site near a U.S. radar installation.
Spencer noted that in Handler’s initial studies, based only on literature reports of volcanic eruptions, “he was missing some events.” That is, he had climatic events for which there were apparently no volcanic eruptions. “Now we have much more complete information over the period he is looking at. Lo and behold, in most cases where he was missing events, we now have one.”
Handler’s correlations are not restricted to the United States and Europe. He has also linked volcanoes to El Ninos, a recurring Pacific Ocean phenomenon whose name--a reference to the Christ Child--was coined by Spanish fisherman because the phenomenon typically begins around Christmas.
El Nino is a huge mass of warmer-than-normal water off the coast of Peru extending far out into the Pacific. It has previously been linked to a variety of weather events around the world, including drought in the United States and weaker-than-normal monsoons in the Indian subcontinent.
“From 1870 to the present, over 80% of all El Nino events can be shown to have occurred after the appearance of low-latitude stratospheric aerosols,” Handler said. “The conventional wisdom is that those 20 or so El Nino events occurring directly after a volcanic eruption were all coincidences. I don’t think so.”
But how does decreased sunlight striking the Equator induce warming of the ocean? Handler says that evaporative cooling--the same phenomenon by which sweating cools the body--is the dominant factor. The decreased sunlight leads to a decrease in Equatorial winds. The decreased winds lead to decreased evaporative cooling and, hence, to increased water temperatures--El Nino. The El Nino reinforces the changes in the jet stream that affect U.S. weather.
One outspoken critic of Handler is atmospheric scientist Clifford F. Mass of the University of Washington in Seattle, whose views probably represent those of most climatologists.
According to Mass, “The big problem is that he uses extremely weak eruptions, many of which never put significant aerosol into the stratosphere, so they couldn’t have had any climatic impact.”
Mass also argues that the use of data from ice cores “gives him a huge number of events. If he has an El Nino, he can always find some kind of event the year before.”
In Mass’ own research, he looked at only the largest volcanic eruptions and found “no correlation at all.”
For his part, Handler recognizes the reluctance of climatologists to accept his conclusions. But he has some questions for them: “Can you explain why the monsoons of 1942 to 1949 were above normal? Why Lake Michigan and Salt Lake hit peaks in 1986? Why the Sahel had rainfall again in 1988? My theory can.”
HOW VOLCANIC ERUPTIONS AFFECT WEATHER
1. Sulfer-dioxide gas causes long-range changes. Once in the stable stratosphere, it is converted to sulfuric-acid droplets which can persist for years.
2. As the sulfuric-acid cloud spreads, it disrupts normal weather patterns by reflecting sunlight, decreasing the amount of radiation striking the Earth.
Large dust particles block out sunlight but the effect is local and brief. The dust soon falls back to Earth or is washed out in the rain.
The Jet Stream: When temperatures are reduced near the Equator because of decreased sunlight, the two Northern Hemispheric high-pressure systems become weaker and are displaced south. This, in turn, affects the path of the jet stream, the thick body of air that flows above the U.S., carrying storm systems with it. This means that after volcanic eruptions, the jet stream--and its associated storms--will flow farther south.
