The availability of climate data in many forms is crucial in the quest
to understand, simulate, and predict the climate system and how it might
change in the future. Such data provide the basics for our characterizations
of the time-averaged climate states of various statistics of temperature,
pressure, wind, water amounts, cloudiness, and precipitation as a function
of geographical location, time, and altitude. Most importantly, such data
provide invaluable information on the natural variability of climate, ranging
from seasons to decades.
These data sets have empowered important direct insights on how the climate
system works. For example, the observed average daily and seasonal ranges
of mean temperature provide valuable evaluations of our theoretical understanding
of how the climate changes in response to changed radiative circumstances
(e. g. day to night, summer to winter). On longer timescales, indirect
inferences (or proxy measures) provide valuable information on how ice
ages and warm epochs appear to depend sensitively on subtle changes to
the heating of Earth due to seemingly small variations in the precession
of Earth's orientation toward the sun and in Earth's elliptical orbit around
the sun. Interestingly, the onset of ice ages and their terminations appear
to respond more sensitively to these small solar heating changes than are
calculated by our current climate models. For example, the ice core records
show that atmospheric CO2 lowers as the
climate cools, a positive feedback effect that we do not expect to be relevant
over the next century. However, such observations of prehistoric climates
are ambiguous enough that they do not justify any confident conclusions
that our current climate models may be underestimating the century-scale
global temperature increase due to added greenhouse gases.
For the atmosphere, there are thousands of places on earth that collect
information daily for the primary purpose of weather forecasting. Fortunately,
all the information collected for weather purposes are also central to
the needs to characterize longer-term climate. Unfortunately, many kinds
of key atmospheric information are not readily available from the weather
networks. These include vertical velocity, radiative heating/ cooling,
cloud characteristics, evaporation, and properties of critical trace species
such as particles containing sulfate and carbon.
For the land surface, many local sites provide information on snow, water
storage, runoff, and soil moisture. Unfortunately, the spatial coverage
is far from adequate, and most stations provide little information on the
state of the vegetative cover and its role in governing surface water budgets
and reflectivity of solar radiation.
For the world ocean, the data coverage is spotty and episodic relative
to the need to characterize the state of the ocean and its role in climate
variability and climate change. For example, we are still waiting to see
the first instantaneous "weather map" of the internal ocean's
waves, jets, and vortices, a privilege that is taken for granted by atmospheric
scientists. Fortunately, the ocean's surface is partly accessible to measurements
from earth-orbiting satellites. This allows remote measurements of ocean
surface temperatures, sea state, and ocean height, a measure of integrated
density over a fairly deep layer that allows some inferences about ocean
currents.
For all parts of the climate system, the ability to characterize long-term
trends of key climate variables is minimally adequate at best and nonexistent
at worst. Few climate measurement systems currently in place are configured
to address what I call the climate monitoring requirement.
Climate monitoring is defined here as the systematic, long-term collection
of key climate measurements, with careful attention paid to maintenance
of calibration and continuity of records for very long time intervals,
and with a strong focus on interpretation of the data gathered. Very few
current climate measurement systems satisfy these stringent requirements.
This mainly is because of the fact that almost all climate-relevant measurements
are gathered for shorter-term purposes such as weather forecasting, and
for efforts to understand specific processes such as clouds or El Niño.
So, why should we care about this climate monitoring deficiency? Who actually
has a stake in improved climate monitoring? Climate data scientists do
because their goal is to use the data to learn about how climate and climate
change actually work. Climate theorists and modelers do because the current
anthropogenic greenhouse warming projections are theoretically based, as
manifested in the mathematical climate models (making climate change projections
without attempting to evaluate them against the evolving real world is
counter to the ethic of science). Policymakers do because they are already
in the process of making policy (or nonpolicy) in the face of an imperfectly
understood, but potentially very serious, global environmental threat.
Policymakers, like scientists, always need to evaluate their conclusions
against new information.
In spite of the compelling needs for improved climate monitoring, not much
is now being done nationally or internationally about the current monitoring
deficiencies. Even worse, many critical capabilities are deteriorating
in the United States and elsewhere because of budgetary pressures. Why
is this so? This is a question that continues to baffle me. I suspect the
answer lies mainly in the unwillingness of top officials to make firm commitments
to a problem that requires sustained focus for many decades.10
Also, the problem suffers from its apparent lack of glamour. "What?
No immediate payoff?" It is also possible that some may not feel much
need to get the right answer if their minds are already made up, a phenomenon
not unheard of at both ends of the political spectrum.
This summary of some of the barriers to better climate monitoring reveals
a serious challenge that is currently producing a net reduction in the
global climate monitoring capability at the same time that international
policy negotiators are taking the greenhouse warming problem seriously.
Clearly, improved information is required to guide the dauntingly tortuous
mitigation (or lack thereof) of greenhouse gas emissions over the next
century. The emerging climate monitoring information can reveal that our
greenhouse warming projections were either too high or too low. Given this
information, future mitigation decisions can be strongly affected. Without
this key information, we will be flying in the dark much longer.
10It is
a personal privilege to acknowledge the pioneering efforts of Charles D
Keeling to ensure the presence of today's impressive CO2
record (this volume). He has taught us that proper climate monitoring is
difficult, and invaluable. Perhaps soon the world will begin to take his
message seriously.
Next: Role of Controversy