As the debate over the greenhouse effect and global warming has spread, the world's climate has become increasingly volatile. Aren't weather bureaus forecasting warmer winters? How was it then that just before the Lunar New Year several cold fronts struck Taiwan, forcing all those venturing outdoors to bundle up in heavy jackets, scarves and gloves? Isn't the world supposed to be getting warmer? The past summer's heat waves in the US caused many children and senior citizens to collapse, yet by November, North America, Europe and mainland China had all seen heavy snows and icy temperatures that caused thousands of homeless persons to die of exposure.

Global temperatures clearly demonstrate the warming trend. Although it may seem counterintuitive, global warming causes temperatures to swing back and forth between extremes of heat and cold, while precipitation levels also swing between severe drought and heavy precipitation.

Forest fires have struck in America, Asia, Australia, and Europe. A big fire in Taiwan on Yushan brought the issue of forest fire prevention into the public spotlight. (photo by Cheng Yuan-ching)

A global sauna

Temperatures in 1998 were the hottest on record. While the world cooled slightly in 1999, temperatures in that year were still among the top five ever recorded, and global temperatures in 2000 were second only to those in 1998. Scientists do not expect 1998's record to stand for long because the El Nino conditions that facilitated the record-setting temperatures are expected to return by the end of this year.

Scientists note that solar radiation also plays a role in temperature fluctuations. As the Earth orbits the Sun, its distance from the Sun varies, as does the amount of solar radiation it receives. Another factor is an orbital wobble measuring tens of thousands of years per cycle, thought by many scientists to be the cause of the earth's ice ages. From a glacial to an inter-glacial period, average global temperatures vary by 2-5°C. The Earth is currently in an inter-glacial period over which temperatures should be rising very gradually. However, since the 19th century temperatures have been rising at an abnormally fast, almost feverish rate.

In their efforts to understand what constitutes natural climatic variation, climatologists are examining glaciers, tree rings and other sources for data on ancient climates. They are also applying modern technology to create models of the natural factors affecting climate. Unfortunately, "Natural factors are insufficient to explain the rise in global temperatures since the 1950s," says Liu Chung-ming, the former director of National Taiwan University's Global Change Research Center. However, the higher temperatures can be explained if greenhouse gases such as carbon dioxide are incorporated into the models. Humans have been burning fossil fuels in quantity since the start of the industrial revolution, creating large volumes of greenhouse gases. These gases could well be the cause of the Earth's "fever."

From the examination of core samples taken from glaciers (which carry within them thousands of years of climatological data), paleoclimatologists have found evidence of a positive correlation between concentrations of carbon dioxide and global temperatures. "But whenever the natural concentration of carbon dioxide reaches a certain threshold, it falls again," says Wei Kuo-yen, a professor of paleoceanography and micropaleontology in NTU's geosciences department. In the relatively few years, geologically speaking, since the 19th century, carbon dioxide levels in the atmosphere have risen from 280 to 363 parts per million, the highest level seen in 160,000 years, and these levels are continuing to rise.

Climatologists look for clues to climate change by studying tree rings, ancient spores, and microfossils. The chemical composition of foraminifera ensconced in microfossils gathered from under the waters off Taiwan's coast offer scientists clues about Taiwan's paleoclimate. (courtesy of Wei Kuo-yen)

Abnormally rapid warming

As carbon dioxide levels have risen, the world's weather stations have marked one record-high temperature after another. Data from the United Nations' Intergovernmental Panel on Climate Change (IPCC) indicates that the current global rate of atmospheric warming is three times as fast as that seen in previous periods of warming in the Earth's history.

The effects of a warmer climate will be long term and very destructive. A number of nations have therefore come to a consensus on controlling emissions of greenhouse gases. However, because the nations of the world are at different levels of economic development and humanity remains highly dependent on fossil fuels, the reduction of greenhouse gas emissions continues to be a politically sensitive issue. (See pages 18-24.)

While greenhouse gases are perceived to be one of the major causes of global warming, climate is subject to a number of complex influences, including levels of solar radiation, evaporation of seawater and airflows between different latitudes. On a short-term, regional level, topography, bodies of water and even air pollution and the volume of airborne particles influence climate. Therefore, establishing the precise impact of greenhouse gases on climate is no easy task.

As the New Year rhyming couplet says, "Spring returns to greet the golden year." These kids are out having fun shopping with their mother on a sunny day during Taiwan's lunar new year holidays. (photo by Jimmy Lin)

Local warming

Many of the weather-related disasters of the last 20 years originate with the El Nino phenomenon in the eastern Pacific Ocean, which is now seen as a pump driving some of the ongoing climactic change.

In the 19th century, commercial shipping passing through the equatorial eastern Pacific off of Peru noted that every year there was an upwelling of plankton-rich cold water from the depths. These nutrient-rich waters attracted huge schools of fish, which turned the area into one of the world's largest fishing grounds. Occasionally, however, a warmer current would predominate, forcing the upwelling back below the surface. At these times, the plankton would sink back below the surface causing mass starvation of both fish and seabirds. This warmer current also had a major impact on agriculture. Because it usually appeared around Christmas, the Spanish-speaking people of the region christened it "El Nino," which means "the Christ-child."

The El Nino phenomenon always lasts for at least a year, and affects three continents. In normal years, the upwelling of cold water off the coast of Peru creates a region of high pressure in the area. The barometric pressure in the ocean off of Indonesia is lower, and the resulting pressure gradient draws air towards Indonesia from the high-pressure zone. When El Nino is active, however, this pressure gradient is reversed and Asia and nearby Australia experience devastating droughts. The 1997-1998 El Nino was the strongest of the 20th century and raised temperatures all over the world. It led to a deadly heat wave in the United States, raging forest fires in Australia, a long drought in Indonesia, and an exceptionally warm winter even in distant Taiwan.

The ocean, a huge system in itself, also interacts with the air currents that flow over the land. But the ocean reacts slowly to outside influences, making the ocean's trends more amenable to observation. Climatologists now attach critical importance to the study of El Nino, and see the ocean as being a key to climatological research.

As scientists have come to recognize some of the harbingers of El Nino, it has become possible to provide advance warning of its arrival, and make preparations. However, Liu Chung-ming notes another area of concern: "As the Earth has warmed in recent years, El Nino has become less regular; its cycle has become shorter and more erratic." Between 1982 and 1998, there were five El Ninos. This compares to a previous pattern of an El Nino occurring every 2-7 years and lasting for a year to a year and a half. "Science cannot yet explain the relationship between global warming and the changes in El Nino. However, as temperatures continue to rise, few doubt that El Nino will appear more frequently."

El Nino's power is beyond question, and its effects are far-reaching. Moreover, El Nino's links to global warming and its increasing impact make it impossible to ignore. However, El Nino is far more amenable to study than the greenhouse effect, which has an extremely complex impact upon global warming.

Knowing that interactions between solar radiation, the oceans and the atmosphere influence the climatic system, one expects that system to follow certain rules. However, climate is incredibly complex. Meteorologists are fond of saying that the atmosphere is not a linear system because a local climate depends upon so many area-specific and short-term factors. Snow accumulations and vegetation play a role, as do geographic factors such as mountains, deserts and bodies of water. Slight variations in any of these elements can result in very different local climates.

Global warming is causing extreme climate swings, including severe droughts and flooding. The Taipei area has seen flooding of historic proportions for the past several years running. The flood-prone district of Hsichih is shown here under water. (photo by Diago Chiu)

When Antarctica sneezes. . .

However, analysis of data gathered at weather stations around the world and insights derived from the development of models of climatic change have allowed scientists to identify some of the factors affecting long-term climate change. First, while average global temperature is rising, warming occurs at different rates and in differing degrees depending upon location. For example, the large "body" of the ocean is similar to that of an adult human in that it doesn't easily become "feverish." Land, on the other hand, more closely resembles a small child that catches a fever at the mere mention of the word. Therefore the Northern Hemisphere, which has more landmass than the Southern Hemisphere, will see a correspondingly greater increase in average temperature. Additionally, within a given hemisphere, the higher latitudes will see a greater increase in temperature than the lower latitudes. Consequently, over the last 100 years, the poles have seen an increase of 5°C in their average temperatures. Hence accelerated melting of the Antarctic ice sheet is one of the first symptoms of global warming.

But climate cannot be separated into discrete regional units. When changes take place in one part of the system, it affects the whole. One could almost say that a sneeze at high latitudes makes the whole world sick. For example, the melting of Antarctic ice raises sea levels, which has a disproportionate impact on the island nations at lower latitudes. But the rest of the world will not escape the effects of higher temperatures. Since the 1960s, the area of land worldwide covered by snow in winter has fallen by 10%. At this year's winter Olympics in Utah, the World Resources Institute told visitors that global warming has resulted in inconsistent snowfalls. In a warmer future, the US might be unable to host the winter games outside of Alaska due to insufficient snowpack. At tourist destinations ranging from the Himalayas to the Andes to Africa's Mt. Kilimanjaro, the snow is disappearing from peaks that were once snowcapped year round.

The greenhouse effect increases the amount of energy in the entire atmosphere. This makes atmospheric and oceanic oscillations more frequent. When cooking soup, the hotter the pot, the more vigorously the soup boils. Similarly, atmospheric and oceanic currents become more volatile when more energy is added to the system. According to Wu Ming-chin, a professor in NTU's Department of Atmospheric Sciences, warming acts as a catalyst which causes low- and high-pressure systems, and cold- and warm-air currents, to butt heads even more violently. This causes frontal boundaries to move, carrying cyclones and storm systems along with them.

As a result, a region that once had a very dry climate might experience frequent rains, or an area once known for its rains might cease to see any rainfall whatsoever. Under the influence of global warming, all kinds of strange meteorological phenomena might occur, including extreme cold alternating with extreme heat in one locale. At the South Pole, where temperatures are on the rise, scientists from the United States nonetheless discovered an ice gorge so cold that it froze their measuring equipment.

Average temperatures in Taiwan, 1901-2001

Two extremes

Extreme weather and unusual phenomena do not by themselves indicate that we are in the midst of long-term climate change. For example, Typhoon Nari may have dumped an incredible amount of rain and confounded meteorologists with the path it took, but it is difficult to link the storm directly to global warming. Liu Chung-ming explains that it is rather the repeated occurrence of extreme weather-when drought and flooding become more intense or temperatures continually hit record highs or lows-that indicates long-term climatic change is underway.

According to the IPCC: "Global warming is not a smooth, gradual shift. It is possible that just as at the end of the last ice age, there may be an unusual and dramatic jump, and a great increase in the frequency of disasters such as storms, tidal surges, torrential rainfall, drought and extensive forest fires, caused by aberrant weather."

The extreme weather that results from global warming is still more apparent when one examines changes in the volume of precipitation. According to Wu Ming-chin, who studies the links between climate change and water resources, in theory, when land-surface temperatures rise, both evaporation and rainfall should increase. However, in practice, when water vapor accumulates in one place, it pulls it from other places, which rapidly dry out. Moreover, the greenhouse effect accelerates the hydrological cycle, increasing the frequency of heavy downpours. Wu says, "It's not that average global rainfall increases, but that you get a more disparate distribution of that rainfall."

Out of all the many problems that global warming may create, scholars in Taiwan are most concerned about the impact on precipitation volume.

Burning of fossil fuels is the main source of increased carbon dioxide in the atmosphere. When companies establish new factories, their environmental impact studies ought to address the issue of greenhouse gas emissions. (photo by Vincent Chang)

Warming Taiwan

Some researchers have begun examining the potential regional or national impacts of warming in terms of water supplies, the frequency of storms and rising sea levels. Disaster prevention is a key concern.

Geographically, Taiwan is sub-tropical. Taiwan should therefore see a relatively small increase in its average temperature. A study of weather data from the last 100 years that the National Science Council commissioned from a number of local universities revealed that Taiwan's average temperature has increased by 1-1.4°C over the last century. While this increase was greater than the 0.6°C increase in average global temperature, it was in line with the increase in the average surface temperature on land. However, Taiwan's summer temperatures have risen more than its winter temperatures, indicating a trend towards the hot getting hotter.

To see the impact on the most common cause of disaster in Taiwan, typhoons, Associate Professor Tzeng Ren-yow of National Central University's atmospheric science department examined Pacific typhoon data from the last 100 years. Tzeng discovered that the average number of typhoons has risen from 17 per year in the early 20th century to 29 per year over the last 15 years. But Tzeng also noted, "The typhoons are taking a different course now, so Taiwan hasn't been struck any more often."

"The frequency of typhoons is not the issue; it's their course that matters." Tzeng explains that a typhoon's course is controlled by the general circulation of the atmosphere. In the past, a high-pressure system known as the Pacific High was dominant. High- and low-pressure systems quickly guided typhoons away from Taiwan. However, due to climate change, the circulations around Taiwan have become weaker. Without airflows to steer them, typhoons make their own strange course, sometimes even stalling completely and sitting in one place, spinning like a top.

In addition, an increase in temperature means that more water evaporates from the seas. Pacific typhoons pick up this additional water and release it when they strike the mountains of Taiwan, often in record-setting downpours that result in flooding. Lin Pay-liam remarks, "Over the last two typhoon seasons, rainfall volumes have risen steadily. This is consistent with the characteristics of long-term climatic change."

Could global warming bring on another episode of mass extinction? Modern humans, whose overuse of natural resources is spurring global warming, should take warning from the fate of the dinosaurs. The displays at the National Museum of Natural Science remind us that the dinosaurs left nothing to posterity but a bunch of bones. (photo by Hsueh Chi-kuang)

Greater Taipei into Waterworld

When students used to come from southern Taiwan to Taipei to study 20 years ago, they were warned about Taipei's gray and wet winters. Friends and relatives reminded them to carry a newspaper with them at all times to keep off the fine rain of the northeastern monsoon. Over the years, however, Taipei's winters have changed, becoming drier and less overcast.

Central Weather Bureau data shows that over the last 50 years, the average number of rainy days per year in Taipei has decreased. However, the volume of precipitation received by the damp northeast has continued to rise. Increased precipitation falling on fewer days means that there are more severe rainstorms, and rainfall intensity is increasing. According to Liu Chung-ming, "All of Taiwan's weather stations have recorded their highest-ever rainfall totals since 1990, and new records are being set all the time."

Looked at another way, more concentrated rainfall means more dry days. The flooding that Typhoon Nari brought to northern Taiwan is still fresh in people's memories, yet before Lantern Festival news broke of a water shortage affecting Hsinchu County. Factories in the Science-Based Industrial Park, already facing a decline in output value, are like cats on a hot tin roof, while farmers have been left fuming after being told to stop irrigating their land so that the water can be diverted to the high-tech plants.

The "rainy harbor" of Keelung provides an excellent example of this trend. In reviewing Pacific Ocean measurements, scientists from Columbia University in New York found that ocean temperatures off Taiwan's east coast were rising, and linked the trend to the weakening northeast monsoon. In fact, data showed that the water temperature off Taiwan's coast had shot up to 29°C, more than three degrees above the year-round average.

"Can you imagine water shortages in 'rainy' Keelung?" Lee Kuo-tien, Dean of Academic Affairs at Keelung's National Taiwan Ocean University, notes that water has the capacity to absorb a great deal of heat and wonders how much seawater must have evaporated to cause water temperatures off the northeast coast to rise by 3°C. While there is no guarantee that this enormous amount of water vapor will rain down on the location from which it evaporated, nearby Keelung will certainly feel the heat.

In addition to these observations, research into greenhouse gases and changes in the East Asian climate conducted by National Central University support the contention that climatic change is underway. According to Lin Pay-liam, "Today's simulation models take the carbon dioxide levels at the start of the Industrial Revolution as a baseline and model what will happen if levels double by 2050. Carbon dioxide levels currently stand at about 1.5 times the baseline level." Lin says that judging from the simulation results and observed atmospheric changes, "It turns out that the number of days of precipitation in Taiwan declines, but that the intensity of precipitation events increases and that extreme weather events occur more frequently. In the future, easterly air flows will predominate, the eastern part of Taiwan will receive more rain, and precipitation totals will decline in western Taiwan."

Severe drought in the south?

Scholars believe that while Taipei will become a "Waterworld" during typhoon season, the plains of western Taiwan will enter a long period of drought. Tzeng Ren-yow remarks, "Over the last two or three years, attention has been focused on flooding." However, Tzeng himself is far more concerned about the coming drought. "Droughts are more costly than floods. Fields lie fallow; reservoirs run short of water; factories have their water cut off; there is little water for residential use; rivers become less able to cleanse themselves. . . . Drought creates a whole series of interlinked problems."

Professor Wu Ming-chin of NTU's atmospheric science department has been tracking changes in Taiwan's undeveloped water catchment areas for many years. He notes, "The peak flood levels of most of Taiwan's rivers have risen. Peishih Creek, for example, which feeds the Feitsui Reservoir, rapidly reaches flood levels after any rain. On the other hand, the average flow of the rivers of central and southern Taiwan has fallen slightly." Wu says that if the trend continues, water supplies are going to become still tighter in the major cities of western Taiwan.

Although Taiwan's actual weather patterns match up pretty well with the weather patterns predicted by long-term climate change models, scholars remain cautious, and feel that much more research is needed before they can pinpoint the links with global warming adequately to provide useful information for policymakers. Hsu Huang-hsiung, a professor in NTU's Department of Atmospheric Sciences, believes that Taiwan must prepare for this eventuality by conducting more climate research. We must understand how much solar radiation the Earth receives, and how much is absorbed by land masses. We must learn the characteristics of various soils, and how all of these factors interact with the atmosphere. According to Hsu, we will not know how to best address the challenges of global warming without a solid grasp of the basics.

With the support of the National Science Council and the Environmental Protection Administration (EPA), more comprehensive plans on how to address climate change are being developed. In addition to the modeling data, experts have begun publishing research and reports on issues such as the impact of the greenhouse effect on sea levels, on the economy, and on agriculture and animal husbandry.

Strengthening the environment

Global warming has not yet struck at Taiwan's vitals, and many scholars do not believe that the recent floods are a consequence of climate change. Most regard Typhoon Nari's dumping of 1000 millimeters of rain on parts of northern Taiwan in one night-an amount equal to one-third of the area's annual rainfall-as an anomaly. An increasing number of heavy downpours in the north is not the point. Wu Ming-chin says, "the problem is not changes in the hydrological cycle, but rather overdevelopment of the land."

Wu explains that people tend to blame the inadequacies of the Keelung River levees in Taipei City on a lack of scientific data on flooding and levee construction when they were built, supposedly to cope with floods of a severity expected to occur once in 200 years. But, "The levees were built to meet the hydrological and geological conditions that existed at that time. In those days, there weren't any buildings in Hsichih and the river's course hadn't been straightened. The levees were built to handle a peak flow of 1000 cubic meters per second, which was more than enough at that time. Now, however, there has been excessive development of the land and the areas available for water to collect in have shrunk in size. As a result, 500 millimeters of rain results in flooding. That has nothing to do with the flood prevention standards the levees were designed to meet," says Wu Ming-chin with assurance.

According to Hsu Huang-hsiung, people are asking if the climate is changing and if such change will affect them. But in Hsu's eyes, what people should be asking is: Has the environment become more fragile? Is this related to people moving into run-off areas? Has development made the environment less able to adjust to climatic change?

A recent EPA report on rising sea levels also highlights how human activities exacerbate the effects of abnormal weather. The report states that if world sea levels continue to rise at the maximum rate currently estimated (0.9 centimeters per year), by the end of the 21st century they will have risen by at least 50 centimeters. For Taiwan, this means that the west coast will retreat by 10 to 100 meters. According to the report, Tainan City and County, Chiayi County, Yunlin County and Kaohsiung City and County are at high risk of flooding and of groundwater becoming saline.

The report also stresses that coastal fish ponds, reservoirs and the dredging of gravel from riverbeds combine to worsen the effects of global climate change. Considering the impact of the loss of Taiwan's coastal wetlands, it is clear that Taiwan could be doing much more to address climate change.

Liu Chung-ming cites several examples: Is infrastructure being built to withstand the extreme weather resulting from global warming? Can bridges withstand the flooding that occurs after extremely heavy downpours? Should bridge clearances be increased? Are drainage ditches capable of carrying sufficient volumes of water? Should some areas simply be reclassified as "recreational wetlands," rather than being developed? These are all partial solutions that can be implemented in the near term. Long term, the world must act together to reduce carbon dioxide emissions. Ultimately, however, it is individuals who must themselves curb their consumption, use less electric power and do whatever else it takes to lower carbon dioxide levels.

According to Wu Ming-chin, "All the models point to the same trend: global warming will only become more severe in the future." But Wu notes that global warming is like an illness that comes on slowly; if treated in its early stages, it can be controlled. It's up to us to do the right thing.