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Original English Version--
Title:"The 10 Questions Shaping 21st-Century Earth Sciences"
Although plate tectonic theory is well established, scientists wonder why
Earth has plate tectonics and how closely it is related to other aspects of
Earth, such as the abundance of water and the existence of the continents,
oceans, and life.
--by Staff Writers
Washington DC (SPX) Mar 13, 2008
Ten questions driving the geological and planetary sciences were identified
today in a new report by the National Research Council. Aimed at reflecting
the major scientific issues facing earth science at the start of the 21st
century, the questions represent where the field stands, how it arrived at
this point, and where it may be headed.
"With all the advancements over the last 20 years, we can now get a better
picture of Earth by looking at it from micro- to macro-perspectives, such as
discerning individual atoms in minerals or watching continents drift and
mountains grow," said Donald J. DePaolo, professor of geochemistry at the
University of California at Berkeley and chair of the committee that wrote
the report. "To keep the field moving forward, we have to look to the past
and ask deeper fundamental questions, about the origins of the Earth and
life, the structure and dynamics of planets, and the connections between life
and climate, for example."
The report was requested by the U.S. Department of Energy, National Science
Foundation, U.S. Geological Survey, and NASA. The committee selected the
question topics, without regard to agency-specific issues, and covered a
variety of spatial scales -- subatomic to planetary -- and temporal scales --
from the past to the present and beyond.
The committee canvassed the geological community and deliberated at length
to arrive at 10 questions. Some of the questions present challenges that
scientists may not understand for decades, if ever, while others are more
tractable, and significant progress could be made in a matter of years, the
report says. The committee did not prioritize the 10 questions -- listed with
associated illustrative issues below -- nor did it recommend specific
measures for implementing them.
1.HOW DID EARTH AND OTHER PLANETS FORM? While scientists generally agree that
this solar system's sun and planets came from the same nebular cloud, they do
not know enough about how Earth obtained its chemical composition to
understand its evolution or why the other planets are different from one
other. Although credible models of planet formation now exist, further
measurements of solar system bodies and extrasolar objects could offer
insight to the origin of Earth and the solar system.
2.WHAT HAPPENED DURING EARTH'S "DARK AGE" (THE FIRST 500 MILLION YEARS)?
Scientists believe that another planet collided with Earth during the latter
stages of its formation, creating debris that became the moon and causing
Earth to melt down to its core. This period is critical to understanding
planetary evolution, especially how the Earth developed its atmosphere and
oceans, but scientists have little information because few rocks from this
age are preserved.
3.HOW DID LIFE BEGIN? The origin of life is one of the most intriguing,
difficult, and enduring questions in science. The only remaining evidence of
where, when, and in what form life first appeared springs from geological
investigations of rocks and minerals. To help answer the question, scientists
are also turning toward Mars, where the sedimentary record of early planetary
history predates the oldest Earth rocks, and other star systems with planets.
4.HOW DOES EARTH'S INTERIOR WORK, AND HOW DOES IT AFFECT THE SURFACE?
Scientists know that the mantle and core are in constant convective motion.
Core convection produces Earth's magnetic field, which may influence surface
conditions, and mantle convection causes volcanism, seafloor generation, and
mountain building. However, scientists can neither precisely describe these
motions, nor calculate how they were different in the past, hindering
scientific understanding of the past and prediction of Earth's future surface
environment.
5.WHY DOES EARTH HAVE PLATE TECTONICS AND CONTINENTS? Although plate tectonic
theory is well established, scientists wonder why Earth has plate tectonics
and how closely it is related to other aspects of Earth, such as the
abundance of water and the existence of the continents, oceans, and life.
Moreover, scientists still do not know when continents first formed, how they
remained preserved for billions of years, or how they are likely to evolve in
the future. These are especially important questions as weathering of the
continental crust plays a role in regulating Earth's climate.
6.HOW ARE EARTH PROCESSES CONTROLLED BY MATERIAL PROPERTIES? Scientists now
recognize that macroscale behaviors, such as plate tectonics and mantle
convection, arise from the microscale properties of Earth materials,
including the smallest details of their atomic structures. Understanding
materials at this microscale is essential to comprehending Earth's history
and making reasonable predictions about how planetary processes may change in
the future.
7.WHAT CAUSES CLIMATE TO CHANGE -- AND HOW MUCH CAN IT CHANGE? Earth's surface
temperature has remained within a relatively narrow range for most of the
last 4 billion years, but how does it stay well-regulated in the long run,
even though it can change so abruptly" Study of Earth's climate extremes
through history -- when climate was extremely cold or hot or changed quickly
-- may lead to improved climate models that could enable scientists to
predict the magnitude and consequences of climate change.
8.HOW HAS LIFE SHAPED EARTH -- AND HOW HAS EARTH SHAPED LIFE? The exact ways
in which geology and biology influence each other are still elusive.
Scientists are interested in life's role in oxygenating the atmosphere and
reshaping the surface through weathering and erosion. They also seek to
understand how geological events caused mass extinctions and influenced the
course of evolution.
9.CAN EARTHQUAKES, VOLCANIC ERUPTIONS, AND THEIR CONSEQUENCES BE PREDICTED?
Progress has been made in estimating the probability of future earthquakes,
but scientists may never be able to predict the exact time and place an
earthquake will strike. Nevertheless, they continue to decipher how fault
ruptures start and stop and how much shaking can be expected near large
earthquakes. For volcanic eruptions, geologists are moving toward predictive
capabilities, but face the challenge of developing a clear picture of the
movement of magma, from its sources in the upper mantle, through Earth's
crust, to the surface where it erupts.
10.HOW DO FLUID FLOW AND TRANSPORT AFFECT THE HUMAN ENVIRONMENT? Good
management of natural resources and the environment requires knowledge of the
behavior of fluids, both below ground and at the surface, and scientists
ultimately want to produce mathematical models that can predict the
performance of these natural systems. Yet, it remains difficult to determine
how subsurface fluids are distributed in heterogeneous rock and soil
formations, how fast they flow, how effectively they transport dissolved and
suspended materials, and how they are affected by chemical and thermal
exchange with the host formations.
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