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Issues for the 21st century
The environmental issues that may become priorities in the 21st century can be clustered in the following groups:
Unforeseen events and scientific discoveries
The huge increase in environmental research over recent decades has made the possibility of sudden and unexpected surprises about the environment less probable. Many hypotheses on possible future problems have already been analysed in detail or are under continuous investigation. However, the northern bias of this research means that an environmental issue that no one has predicted, foreseen or studied could emerge in the less developed regions. The best guarantee against unforeseen events is the stimulation of scientific research and the application of current knowledge through policy-oriented assessments.
In the past, several unforeseen environmental issues have been brought to light by the scientific community. The best known recent example is probably stratospheric ozone depletion caused by emissions of CFCs and other ozone-depleting substances. The phenomenon was not discovered until 1974 and it took until 1985 - when the presence of the Antarctic ozone hole was discovered - for it to be accepted as a major international issue. Similarly, acid rain was not foreseen as one of the results of industrial expansion, and its discovery in the 1960s - including the first observations of its impact - was one of the critical events that led to the Stockholm Conference on the Human Environment in 1972.
The oceanic flip-flop theory suggested by several scientists since the early 1960s (see, for example, Broecker 1987) is another example. Global warming, it is argued, could interrupt the system by which cold, salty water in the North Atlantic periodically sinks to the ocean floor, a mechanism that is vital to the general circulation of the oceans and particularly to the Gulf Stream that warms much of Europe. If global warming caused increased rainfall or reduced wind speeds over the North Atlantic or led to the melting of freshwater glaciers in Greenland, salt concentrations in surface waters could fall, leading to less mixing of surface and deep waters. This would interrupt the flow of the Gulf stream, bringing a cooler climate to northern Europe. More recently, Broecker (1997) has suggested that these effects could turn off the deep-ocean conveyor belt completely, triggering an ice age. Evidence for such flip-flops has been found in geological records obtained from ice cores and deep-sea sediments. Of particular concern is the fact that these events have occurred over time periods as short as four years. Broecker refers to the oceans as the Achilles' heel of the climate system.
Current research may well bring to light other unexpected consequences of the increasing human manipulation of nature and biological processes. The possible effects of accidentally or intentionally introducing genetically-modified organisms (GMOs) on the gene pools, survival and overall health of wild populations of cultured species is an active area of research. While GMOs are expected to be widely used in the United States by the year 2000 in crops such as soya and maize, in other regions there is serious concern about the risks involved, and their commercialization has been postponed until more is known about possible impacts.
The rapid evolutionary nature of microbes, viruses and some insects is another area where surprises could be in store. Similarly, the enormous disruption that chemicals can have on ecosystems and human health is now well known. But every year many new chemicals are brought into circulation. The fact that many are introduced without sufficient research into their impacts is a major worry, as is the potential impact of mixtures of chemicals of which we currently have little understanding. More research into the whole range of chemical issues, including recently recognized topics such as endocrine disrupters, is needed.
Unexpected transformations of old issues
Many of the issues that will require priority attention in the next century will be aggravated forms of today's issues. Many of these continue to evolve and broaden in response to changing socio-economic, cultural and environmental conditions, although they are becoming better understood through increasing scientific and technical knowledge.
A classic example is the chemical time bomb (Stigliani 1991). Chemicals, either produced naturally or as a result of industrial and agricultural activities, tend to accumulate slowly and harmlessly over many years in soils, sediments, lakes and other environmental reservoirs. However, when the carrying capacity of the receiving ecosystems is finally exceeded, there can be a sudden release of the chemical. Alternatively, the chemical may be released because of changed environmental conditions, as happens when harbours are dredged and wetlands drained. The environmental consequences of chemical time bombs can be severe, as the following examples show:
Another recent example of a 'transformation in action' is the current surge in number and severity of forest fires and natural disasters. Forest fires have raged periodically throughout history. However, in the last couple of years, due to a variety of factors, including human activities, the prevailing weather and severe degradation of natural resources, their frequency and intensity seems to have increased (see page 31), particularly in the Amazon and Southeast Asia. Addressing these and other disasters, such as flooding, may well become an environmental priority in the decades to come.
A further example of a contemporary issue becoming more serious is coral bleaching. First described nearly 80 years ago, coral bleaching occurs when corals expel the symbiotic algae that live in their tissues. This is a response to environmental stress, in particular high sea temperatures but also high solar radiation, fluctuating salinities, extremely low tides and often a combination of these factors (ISRS 1999, Pomerance 1999 and ITMEMS 1998).
In the mid-1980s, coral bleaching began to occur on a large scale. In 1998, coral bleaching was more severe than ever before and occurred in at least 60 countries (ISRS 1999 and ITMEMS 1998). Although the links between global climate change, El Niño phenomena and extensive coral bleaching are still subject to debate (ISRS 1999), it has been suggested that only global warming could have induced such extensive bleaching simultaneously throughout the disparate reef regions of the world (Pomerance 1999). What permanent effect the alarming 1998 event will have remains to be seen.
Similarly, the incidence of biological invasions by non-indigenous species seems to be on the increase. First identified as a problem in the 1950s when the mesquite tree was introduced into Sudan with quite unexpected agricultural results, more recent and even more costly effects have resulted from the inadvertent introduction of the zebra mussel into the Great Lakes area of North America (see page 145) and the water hyacinth which now clogs many of Africa's waterways (see page 61), and for which no solution is yet in sight. Invasive species are the second leading cause of biodiversity loss after habitat destruction (UNEP 1995). Continued globalization, and increases in travel and trade, might well make such invasions more common in the future and in need of even greater international attention.
Most issues that will require policy attention in the next century are, however, issues that are currently existing and well known. As time goes on they will become more severe and pose major local and global challenges. If these challenges are not addressed, they will give rise to major environmental crises in the 21st century. As such, they are emerging due to lack of avoiding actions. More effort is also needed to understand the mechanisms through which emerging issues become issues for policy. Social and political processes, science and the trend towards public involvement all have a role to play, at least in some countries.
There are numerous examples from the past. Increased and accelerating emissions of carbon dioxide have led to the climate change issue; the continued intensification of fishing activities has led to the collapse of fisheries in many seas, and the relentless pace of urbanization has creating a series of problems for local authorities in developing and developed countries alike. A classic example of an environmental disaster caused by lack of action is the fate of the Aral Sea. Policy makers were well aware that continued and uncontrolled water abstraction for irrigation would lead to the death of the Aral Sea. They could, however, find no other way of meeting the economic imperatives of the time than through ignoring the problem.
In GEO-1, a list of fundamental global issues that threaten long-term sustainability was derived from the analysis of regional and global trends. These issues still stand and will, if not urgently addressed, become even bigger problems in the 21st century:
GEO-2000 draws attention to additional global and regional trends that are likely to get worse in the next century. These issues are summarized in the box above. Many of these environmental problems result from the continuous unfolding of socio-economic processes that have yet to be properly controlled or managed. The continued poverty of the majority of the planet's inhabitants and the excessive consumption by the minority are the two major underlying causes of continued environmental degradation. These causes, combined with rapidly changing political, social, institutional, financial and technological developments, present policy makers with intractable problems without easy or obvious solutions. The complexity and magnitude of the problems at hand should, however, not be a reason for complacency. We must not baulk at designing and implementing preventive policies today. Even if the costs seem high, they will be small in relation to the enormous risks and irreversible damage in the future associated with inaction or 'business-as-usual' paths.
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