Evidence For A Warming Trend

Model predictions indicate that the major impact of global warming will be felt in the arctic. Temperatures in the arctic have risen almost twice as fast as those in the rest of the world. Models have certainly been correct on this. Although most of the sun's energy hits the tropics, the atmosphere and oceans redistribute the tropical energy north and south to the poles. In the tropics, much of the energy ends up as evaporation. In the arctic, the energy warms the atmosphere. In November 2004, the Arctic Council, an organization of eight northern countries, plus indigenous-peoples organizations, issued a report estimating that by late in the century, average arctic temperatures will rise by some 4-10°C over land and 7-10°C over the oceans, leading to severe changes by century's end. But currently the Inuit people of Canada -s northern provinces report that shrinking ice cover and a consequent shortened hunting season is responsible for the emaciated look of increasing numbers of polar bears. Many fiords, formerly covered with hard ice between October and July, are now frozen only between December and May. The walrus have changed their hunting grounds, moving further north, where it is colder [ 30]. These changes are the harbingers, and as the permafrost uncovers, CO2 and CH4 are released into the atmosphere, contributing additional GHGs. We may just be seeing the emergence of a feedback loop, which will speed up warming faster than model predictions. Not a good omen. With warmer temperatures, permafrost underlying the soil surface softens and coastal erosion increases. The arctic warms quickly because as ice melts, which normally is highly reflecting, the now darker seawater and land areas reflect less of the incoming solar radiation, causing the remaining ice to melt ever faster.

In Austria, the Pasterze, its largest glacier, is shrinking at the rate of 13-26 feet a year. But all of Austria's 925 glaciers, these rivers of ice, are also shrinking rapidly [31]. Glaciers in Tibet and China are shrinking along with them. In eastern Tibet the normally massive 27-square-mile glacier, Zepu, has lost 300 feet of its thickness in the last three decades because of rising temperatures in the region [32]. Puddles of melted ice water at 20,000 feet in the Himalayas have replaced ice that covered the mountaintops for thousands of years; and in Peru, the Quelccaya ice cap retreated at a rate of more than 600 feet a year between 2002 and 2004, leaving an 80-foot-deep lake where none had existed before. On Mount Kilimanjaro in Kenya, an 11,700-year-old ice cap that measured 43 square miles in 1912, had shrunk to 0.94 square miles by 2000. "When you see the big picture from many sites, the evidence of drastic climate change becomes quite compelling" [33]. Indeed, the evidence from both the Northern and Southern hemispheres and from continents across the planet the evidence speaks clearly to such a conclusion.

Retreat of the glaciers is only part of the concern. Scientists have warned that lakes forming behind glaciers because of melting ice could burst through cracks in the glaciers and cause tsunami-like devastation to towns below. With the shrinkage, towns depending on seasonal glacial melting could lose their natural water supplies [32].

In Antarctica, on the opposite side of the planet, "which is competing with the Yukon for the title of the fastest warming place on the globe," the Larson A ice shelf, the size of Rhode Island, disintegrated in 1995, followed in 1998 by the collapse of the neighboring Wilkins ice shelf. Over a month in January 2002, at the end of the Southern Hemisphere summer, Larsen B, a 1200-squareimile ice shelf of floating sea ice 722 feet thick, suddenly shattered, losing more than 25% of its total mass and over 35 days setting thousands of icebergs adrift in the Weddell Sea [33] . Then, in just a month, an area twice that size crashed into the sea with its 72 billion tons of ice. Clearly, when greenhouse gases go up, the ice sheets go down.

In Europe's intensively fished North Sea, warming waters over the past 25 years have driven fish populations further north and deeper, making it more difficult for commercial fisherman to locate and land their normal catch [34]. British scientists have reported that increasing levels of carbon dioxide are turning the oceans acidic, which will be harmful to marine life and coral reefs. Acidity does not require computer modeling; it is measured on a pH scale in which 1 is the most acidic and 14, the most alkaline. One unit on the pH scale reflects a change by a factor of 10. With the 25 billion metric tons of carbon dioxide going into the air yearly, and a third of that being absorbed by the oceans, producing carbonic acid, it's anticipated that should this level of CO2 continue, the pH of ocean water would drop to 7.7 by 2100—lower than at any time in the last 420,000 years [35].

Warmer and acidic seas are only part of the concern. An 11-year study by researchers at the International Rice Research Institute in the Philippines, found a 10% drop in rice crop yields for every 1.8°F increase in nighttime temperature. They believe that warmer nights speeds up plant respiration, causing the rice plants to work harder and waste energy. With Asian populations increasing, and yields flattening, prospects of future food shortages are a growing concern [36].

It is not yet known whether Hurricane Katrina is linked to global warming, but the available evidence suggests that it is highly likely that this warming trend is making hurricanes more destructive and of greater frequency. Hurricanes derive their power in part from warm water, and models show future hurricanes becoming more severe as sea-surface temperatures rise. Professor Emmanuel Kerry of MIT informs us that "The large upswing in the last decade is unprecedented, and probably reflects the effect of global warming." He goes on to say that "any results suggest that future warming may lead . . . to a substantial increase in Hurricane-related losses in the 21st century" [37]. A warmer world also makes hurricanes more destructive by raising sea levels, which means more flooding. Paradoxically, developing countries especially island nations that are not major emitters of CO2 will be the most severely affected. Rising seas will displace hundreds of thousands, perhaps millions, flooded out of their island homes. How will they be dealt with? Recall the upheaval spawned by Hurricanes Katrina and Rita, and the hundreds of thousands of individuals from Louisiana, Mississippi, and Texas who had to be evacuated to other cities and states with all the stresses attendant on leaving their homes, possessions, family, friends, and jobs. Consider now the displacement of millions of people from islands and shore communities around the world who would need to be resettled in foreign countries with different languages, customs, and food. Such shifting of populations is currently considered as leading to conflicts over living space, food and water, which could easily lead to potential disruption of global security and stability requiring military intervention. This is a nightmare scenario. On the other hand, as noted earlier, global warming's effects will not be felt equally around our planet. The effect of shifting climates is exemplified in the accompanying cartoon, Figure 5.8, suggesting that opportunities and benefits may be the obverse side of the global warming coin.

If, as evidence suggests, climate is changing, and at an unprecedented rate, what impacts can be expected on our health, our food supply, and our lives generally?

Food production is a critical and essential renewable resource. No more than 25 food crops feed the world's population. The most definitive factor in food production is climate, and the lack of water is the single greatest impedi-

Figure 5.8. This cartoon speaks directly to the issue of rising sea levels.

ment to crop growth and production. According to the UNFCCC, degrading soils and water resources will place enormous strains on food production for growing populations. They believe that a warming of less than 2.5°C could reduce food supplies and contribute to higher prices. Assuming prediction of a warming of 1.4-5.8°C over the coming 100 years, evaporation and precipitation will increase along with rainfall intensity. Some regions may become wetter; others will suffer loss of soil moisture and increased erosion. Soil moisture is expected to decline in some midlatitude continental regions in summer, while rain and snow, models predict, will increase in high latitudes during the winter [38] .

It is widely believed that increased CO2 emissions will stimulate photosynthesis in wheat, rice, barley, cassava, and potato plants. Experiments based on a 50% increase in CO2 concentrations have found that "CO2 fertilization " can increase yields by 15% under optimal conditions. But new studies suggest that increased CO2 levels may be a mixed blessing, as there appears to be a tradeoff between quantity and quality. Researchers at Ohio State University have found that nutritional quality declines because "while plants produce more seeds under higher CO2 levels, the seeds contain less nitrogen" [39]. As the quality of food decreases, you' ve got to eat more of it to obtain the same benefit. Under the rising CO2 scenario, livestock and humans would have to increase their intake of crops to compensate for the loss. Echoing the work at Ohio State, Chinese scientists at the Nanjing Institute of Soil Sciences, part of the Chinese Academy of Sciences, found that rising levels of CO2 could result in increased growth rate but decreased nutritional value of rice and wheat. They maintain that the protein level will decrease by 10% by the year 2050, and elements such as iron and zinc will also decline. These scientists spent 3 years studying the impacts of greenhouse gas emissions on the growth of rice and wheat. Providing the plants with a 50% higher level of CO2 increased the rice crop yield by 15% and 14% for wheat, and both plants grew faster. But protein levels in both dropped by 10%. They also predict that if air temperatures continues to increase by 0.04°C yearly, the amount of organic matter derived from decaying animal and plants in rice fields will decline by 7% by 2050 [40] .

Similar results were obtained by scientists at the USDA's Agricultural Research Service. They reported that elevated temperature and CO2 levels decreased the food quality of soybeans; total oil, carbohydrate, nitrogen (protein), and phosphorous concentrations decreased with increasing temperature [41].

At a conference on climate change impacts on agriculture, held at the University of Florida, a group of researchers from the Universities of South Carolina and Florida also found that increased levels of CO2 reduce nutritional content of crops by 10-20%. But they also reported that climate change will affect agriculture via its impact on pest management. Cold and freezing weather are natural pest control mechanisms; as temperatures rise, pest central will decrease. A participant from Oregon State University indicated that an increasing temperature may also increase the need for pesticides, may reduce pesticide effectiveness, and may increase residues, which will raise food safety issues [42] .

It has also been widely noted, and accepted, that trees would become CO2 sinks, absorbing and sequestering much of the increased CO2 emissions. But that has remained an open question as there was little solid evidence supporting such a contention. Recently, however, researchers at the University of Basel - s (Switzerland) Institute of Botany, appeared to have answered this question. They set up a 140-foot -tall construction crane in the middle of a forest of oaks, lindens, maples, and pines, and used it to run a network of porous plastic tubes through the forest canopy and pumped CO2 through it for 4 years. Indeed, the trees grew vigorously, but did not add biomass. For the investigators, this study "does not support expectations of greater carbon bonding in tree biomass in such deciduous trees" [43]. This study suggests that large trees will be of little help in storing excess carbon dioxide. From a purely agricultural view, climate change does not appear to bode well for either human or animal populations.

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