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contemporary analogues of future climate changes and studies
that are based on scenarios generated by numerical models can be
useful. Studies are needed of such subjects as water and
ecosystems, and they should be integrated to create a larger,
coherent picture. Social, demographic, economic, and ecological
data for both the United States and other countries need to be
improved to aid impact assessments and adaptations.
Although estimates of impact and suggestions of adaptation
abound, many suffer from four shortcomings. First, they may assess,
say, the fall in yield of 1990 wheat caused by a 1°C warming in
2030, ignoring the proven adaptability of farmers, who will not
behave in 2030 just as they do in 1990 if their environment has
changed. Second, the studies may ignore technological changes, such
as improved wheat strains. Third, the assessments are usually made
without regard for the background of other changes that will affect
impacts, for example, how markets for food products are changing
and how production is shifting around the world from one region to
another because of changes in comparative advantage. Fourth,
suggestions of adaptations may fail to anticipate such side effects
as salinity from irrigation.
Similar issues arise in impact studies of unmanaged ecosystems,
which often study the response of a single species, neglecting the
impact of other blows, such as chemical pollution, and amidst the
competition and contributions of other species that grow with it.
How will one species succeed another as the system adjusts at a
place? How will a system of plants and animals migrate if climatic
zones shift over half a century?
Many studies of adaptation must be conducted outdoors and in the
current climate. The need for specialized research and development
concerned with changing climate is moderated by the fact that the
climates that may be experienced in 2030 are, for the most part,
climates that are today being experienced somewhere, probably
nearby. If the climate of Nebraska is going to become like that in
Oklahoma today, experiments in Oklahoma fields now help later
adaptation in Nebraska. Nevertheless, keeping in mind knowledge
from simplified and controlled experiments and searching for global
principles rather than catalogs of empiricisms, scientists must
learn how disparate, entire systems of species live and
reconstitute themselves outside as the environment, especially the
concentration of CO2, changes.
Analysis must include so-called pests whose depredations depend on
the quality of the host and environment and alter the outcome
outdoors. For crop varieties a sound strategy continues to be
maintaining diverse strains and adapting them to the weather of the
current decade, because the climate of the next decade will not be
vastly different, even if climate is changing over a century, and
because the useful economic life of a cultivar is only about a
decade. It will be useful to demonstrate in the reality of outdoors
how to shorten long renewal times so that man-made things can be,
and natural things will be, promptly adapted to climate.