Understanding how Earth's inner core (IC) develops and evolves, including fine details of its structure and energy exchange across the boundary with the liquid outer core, helps us constrain its age, relationship with the planetary differentiation, and other significant global events throughout Earth's history, as well as the changing magnetic field. Since its discovery in 1936 and the solidity hypothesis

Ongoing global warming due to anthropogenic climate change has long been recognized, yet uncertainties regarding how seasonal extremes will change in the future persist. Paleoseasonal proxy data from intervals when global climate differed from today can help constrain how and why the annual temperature cycle has varied through space and time. Records of past seasonal variation in marine temperatures

Dynamo magnetic fields are primarily generated by thermochemical convection of electrically conductive liquid metal within planetary cores. Convection can be sustained by secular cooling and may be bolstered by compositional buoyancy associated with core solidification. Additionally, mechanical stirring of core fluids and external perturbations by large impact events, tidal effects, and orbital precession

Carbon is among the most abundant substances in the universe; although severely depleted on Earth, it is the primary structural element in biochemistry. Complex interactions between carbon and climate have stabilized the Earth system over geologic time. Since the modern instrumental CO2 record began in the 1950s, about half of fossil fuel emissions have been sequestered in the oceans and land ecosystems

Light hydrocarbons (LHs) are an important component of natural gas whose chemical and isotopic compositions play a vital role in identifying gas genetic type, thermal maturity, gas–gas correlation, gas–source correlation, migration direction and phase, and secondary alterations (such as evaporative fractionation, biodegradation, and thermochemical sulfate reduction) experienced by the gas pool. Through

Geoscientists have generally been at the leading edge of predicting the challenges society faces from hazards both natural and anthropomorphic. As geoscientists, we have been less successful in devising the solutions to those problems to ensure a habitable planet for ourselves and future generations because often the solutions lie in creating novel partnerships with other researchers, including engineers

Volcanic eruptions impact climate, subtly and profoundly. The size of an eruption is only loosely correlated with the severity of its climate effects, which can include changes in surface temperature, ozone levels, stratospheric dynamics, precipitation, and ocean circulation. We review the processes—in magma chambers, eruption columns, and the oceans, biosphere, and atmosphere—that mediate the climate

Water ice Ih exhibits brittle behavior when rapidly loaded. Under tension, it fails via crack nucleation and propagation. Compressive failure is more complicated. Under low confinement, cracks slide and interact to form a frictional (Coulombic) fault. Under high confinement, frictional sliding is suppressed and adiabatic heating through crystallographic slip leads to the formation of a plastic fault

Volcanoes play a key role in the cycling of volatile metals (e.g., chalcophile elements such as Tl, Pb, and Cu and metalloids such as As, Te, and Se) on our planet. Volatile metals and metalloids are outgassed by active volcanoes, forming particulate volcanic plumes that deliver them in reactive form to the environment, where they may be nutrients (e.g., Cu and Zn) or pollutants (e.g., Hg, As, Pb)

This review examines the current understanding of the global coastal ocean carbon cycle and provides a new quantitative synthesis of air-sea CO2 exchange. This reanalysis yields an estimate for the globally integrated coastal ocean CO2 flux of −0.25 ± 0.05 Pg C year−1, with polar and subpolar regions accounting for most of the CO2 removal (>90%). A framework that classifies river-dominated ocean margin

Just as glaciers worldwide left a record of past advances and retreats that shifted latitudinally in response to oscillating Quaternary climate changes, so too have cold-climate conditions and permafrost left topographic and sedimentary signatures in former periglacial environments. This review documents widespread occurrence of past permafrost and intense frost action that led to rock fracturing,

Large igneous provinces (LIPs) represent some of the greatest volcanic events in Earth history with significant impacts on ecosystems, including mass extinctions. However, some fundamental questions related to the eruption rate, eruption style, and vent locations for LIP lava flows remain unanswered. In this review, we use the Cretaceous–Paleogene Deccan Traps as an archetype to address these questions

Northeast Japan is a typical island arc related to the Pacific plate subduction. The 2011 Mw 9.0 Tohoku-oki earthquake provided a unique opportunity to analyze crustal deformation with different boundary conditions, similar to a gigantic rock deformation experiment. We review findings obtained through various observations and data analyses in Northeast Japan, focusing on the crustal deformation in

Melt extraction from the partially molten mantle is among the fundamental processes shaping the solid Earth today and over geological time. A diversity of properties and mechanisms contribute to the physics of melt extraction. We review progress of the past ∼25 years of research in this area, with a focus on understanding the speed and style of buoyancy-driven melt extraction. Observations of U-series

Paleoanthropologists have long speculated about the role of environmental change in shaping human evolution in Africa. In recent years, drill cores of late Neogene lacustrine sedimentary rocks have yielded valuable high-resolution records of climatic and ecosystem change. Eastern African Rift sediments (primarily lake beds) provide an extraordinary range of data in close proximity to important fossil

Rocks in Earth's crust are formed, modified, and destroyed in response to myriad interactions between the solid Earth (tectonics, geodynamics), the fluid Earth (ocean-atmosphere, cryosphere), and the living Earth (evolution, biochemistry). As such, the geological record is an integrator of geological, biological, and climatological processes and their histories. Here we review contrasting perceptions

The Mammoth Steppe was the dominant terrestrial biome of the Northern Hemisphere during the late Pleistocene. It encompassed a nonanalog community of animals living in a cold and treeless steppe-tundra landscape. The high diversity of species, including megafauna, could be supported by a productive environment. The carbon-13 and nitrogen-15 abundances in bone collagen confirmed that the coexistence

The response of the terrestrial biosphere to warming remains one of the most poorly understood and quantified aspects of the climate system. One way to test the behavior of the Earth system in warm climate states is to examine the geological record. The abundance, distribution, and/or isotopic composition of source-specific organic molecules (biomarkers) have been used to reconstruct terrestrial paleoenvironmental

The Cenozoic Colorado Plateau physiographic province overlies multiple Precambrian provinces. Its ∼2-km elevation rim surrounds an ∼1.6-km elevation core that is underlain by thicker crust and lithospheric mantle, with a sharp structural transition ∼100 km concentrically inboard of the physiographic boundary on all but its northeastern margin. The region was uplifted in three episodes: ∼70–50 Ma uplift

Carbonatites are igneous rocks formed in the crust by fractional crystallization of carbonate-rich parental melts that are mostly mantle derived. They dominantly consist of carbonate minerals such as calcite, dolomite, and ankerite, as well as minor phosphates, oxides, and silicates. They are emplaced in continental intraplate settings such as cratonic interiors and margins, as well as rift zones,

Polygenetic volcanoes and calderas produce eruptions of a wide variety of magnitudes, chemistries, and recurrence times. Understanding the interplay between long- and short-term and deep and shallow processes associated with accumulation and transfer of eruptible magma is essential for assessing the potential for future eruptions to occur and estimating their magnitude, which remains one of the foremost

Molar-tooth structure (MTS) is an unusual carbonate fabric that is composed of variously shaped cracks and voids filled with calcite microspar. Despite a century of study, MTS remains enigmatic because it juxtaposes void formation within a cohesive yet unlithified substrate with the penecontemporaneous precipitation and lithification of void-filling carbonate microspar. MTS is broadly restricted to

One of the pillars of geomorphology is the study of geomorphic processes and their drivers, dynamics, and impacts. Like all activity that transfers energy to Earth's surface, a wide range of geomorphic process types create seismic waves that can be measured with standard seismic instruments. Seismic signals provide continuous high-resolution coverage with a spatial footprint that can vary from local

Paleogeography is the study of the changing surface of Earth through time. Driven by plate tectonics, the configuration of the continents and ocean basins has been in constant flux. Plate tectonics pushes the land surface upward or pulls it apart, causing its collapse. All the while, the unrelenting forces of climate and weather slowly reduce mountains to sand and mud and redistribute these sediments

Jupiter's Galilean satellite Io is one of the most remarkable objects in our Solar System. The tidal heating Io undergoes through its orbital resonance with Europa and Ganymede has resulted in a body rich in active silicate volcanism. Over the past decades, Io has been observed from ground-based and Earth-orbiting telescopes and by several spacecraft. In this review we summarize the progress made toward

Throughout Earth's history, CO2 is thought to have exerted a fundamental control on environmental change. Here we review and revise CO2 reconstructions from boron isotopes in carbonates and carbon isotopes in organic matter over the Cenozoic—the past 66 million years. We find close coupling between CO2 and climate throughout the Cenozoic, with peak CO2 levels of ∼1,500 ppm in the Eocene greenhouse

The Cassini-Huygens mission that explored the Saturn system during the period 2004–2017 revolutionized our understanding of Titan, the only known moon with a dense atmosphere and the only body, besides Earth, with stable surface liquids. Its predominantly nitrogen atmosphere also contains a few percent of methane that is photolyzed on short geological timescales to form ethane and more complex organic

Most tsunamis are generated by earthquakes, but in 1998, a seabed slump offshore of northern Papua New Guinea (PNG) generated a tsunami up to 15 m high that killed more than 2,200 people. The event changed our understanding of tsunami mechanisms and was the forerunner to two decades of major tsunamis that included those in Turkey, the Indian Ocean, Japan, and Sulawesi and Anak Krakatau in Indonesia

The budget of reactive nitrogen (Nr; oxidized and reduced inorganic and organic forms of nitrogen) has at least doubled since the preindustrial era due to human activities. Excess Nr causes significant detrimental effects on many terrestrial and aquatic ecosystems; less is known about the impact on the open ocean. Nr deposition may already rival biological N2 fixation quantitatively and will likely

Central America has a rich mix of conditions that allow comparisons of different natural experiments in the generation of arc magmas within the relatively short length of the margin. The shape of the volcanic front and this margin's architecture derive from the assemblage of exotic continental and oceanic crustal slivers, and later modification by volcanism and tectonic activity. Active tectonics of

Inclusions of basaltic melt trapped inside of olivine phenocrysts during igneous crystallization provide a rich, crystal-scale record of magmatic processes ranging from mantle melting to ascent, eruption, and quenching of magma during volcanic eruptions. Melt inclusions are particularly valuable for retaining information on volatiles such as H2O and CO2 that are normally lost by vesiculation and degassing

Organic molecules are key components of the Earth-life system. Their stable isotope composition provides information on various problems such as past climate, energy resources, or the synthesis of prebiotically relevant molecules on Earth and elsewhere. Organic molecules are made of isotopologues, molecules differing in the number and/or position of isotope substitution. Recent years have witnessed

Knowledge of how and why oxygenic photosynthesis, eukaryotes, metazoans, and humans evolved on Earth is important to the search for complex life outside our Solar System. Hence, one grand challenge for modern geoscience research is to reconstruct the story of how Earth's environment and life coevolved through time. A critical part of the effort to understand Earth's story is the use of geochemical

The Cascadia subduction zone (CSZ) is an exceptional geologic environment for recording evidence of land-level changes, tsunamis, and ground motion that reveals at least 19 great megathrust earthquakes over the past 10 kyr. Such earthquakes are among the most impactful natural hazards on Earth, transcend national boundaries, and can have global impact.Reducing the societal impacts of future events

The rise of molecular oxygen (O2) in the atmosphere and oceans was one of the most consequential changes in Earth's history. While most research focuses on the Great Oxidation Event (GOE) near the start of the Proterozoic Eon—after which O2 became irreversibly greater than 0.1% of the atmosphere—many lines of evidence indicate a smaller oxygenation event before this time, at the end of the Archean

Distributed acoustic sensing (DAS) is an emerging technology that repurposes a fiber-optic cable as a dense array of strain sensors. This technology repeatedly pings a fiber with laser pulses, measuring optical phase changes in Rayleigh backscattered light. DAS is beneficial for studies of fine-scale processes over multi-kilometer distances, long-term time-lapse monitoring, and deployment in logistically

Higher boreal summer insolation in the early to middle Holocene drove thousands of years of summer warming across the Arctic. Modern-day warming has distinctly different causes, but geologic data from this past warm period hold lessons for the future. We compile Holocene temperature reconstructions from ice, lake, and marine cores around Greenland, where summer temperatures are globally important due

Hydrogen and deuterium isotopic evidence indicates that the source of terrestrial water was mostly meteorites, with additional influx from nebula gas during accretion. There are two Earth models, with large (7–12 ocean masses) and small (1–4 ocean masses) water budgets that can explain the geochemical, cosmochemical, and geological observations. Geophysical and mineral physics data indicate that the

Accelerating global climate change drives new climate risks. People around the world are researching, designing, and implementing strategies to manage these risks. Identifying and implementing sound climate risk management strategies poses nontrivial challenges including (a) linking the required disciplines, (b) identifying relevant values and objectives, (c) identifying and quantifying important uncertainties

Iran is a remarkable geoscientific laboratory where the full range of processes that form and modify the continental crust can be studied. Iran's crustal nucleus formed as a magmatic arc above an S-dipping subduction zone on the northern margin of Gondwana 600–500 Ma. This nucleus rifted and drifted north to be accreted to SW Eurasia ∼250 Ma. A new, N-dipping subduction zone formed ∼100 Ma along ∼3

Understanding the evolution and processes that shape our planet critically depends on the robustness of the absolute ages and process durations obtained from rocks and crystals. Two main aspects of...

The Laurentian Great Lakes are vast, spatially heterogeneous, and changing. Across these hydrologically linked basins, some conditions approach biogeochemical extremes for freshwater systems anywhe...

Pluto and Charon are strikingly diverse in their range of geologies, surface compositions, and crater retention ages. This is despite the two having similar densities and presumed bulk compositions...

The martian surface preserves a record of aqueous fluids throughout the planet's history, but when, where, and even whether such fluids exist at the contemporary surface remains an area of ongoing ...

The influence of the continental lithosphere and its root (or keel) on the continental drift of Earth is a key element in the history of plate tectonics. Previous geodynamic studies of mantle flow ...

Minoru Ozima describes important influences in his scientific life, from the trauma of World War II during adolescence to studying with such giants of Earth science as J. Tuzo Wilson. He benefited ...

Mars is the nearest planet that potentially harbors life and that can be explored by humans, so its history of water is of considerable importance. Water was abundant on early Mars but disappeared ...

Volatile elements (water, carbon, nitrogen, sulfur, halogens, and noble gases) played an essential role in the secular evolution of the solid Earth and emergence of life. Here we provide an overvie...

The atmosphere is the synthesizer, transformer, and communicator of exchanges at its boundaries with the land and oceans. These exchanges depend on and, in turn, alter the states of the atmosphere, land, and oceans themselves. To a large extent, the interactions between the carbon cycle and climate have mapped, and will map, the trajectory of the Earth system. My quest to understand climate dynamics

The strong ground motions, large crustal deformation, and tsunami generated by the 2011 Tohoku-oki earthquake (Mw 9.1) reveal that a large coseismic slip likely propagated to shallow depth in the J...

The Human System is within the Earth System. They should be modeled bidirectionally coupled, as they are in reality. The Human System is rapidly expanding, mostly due to consumption of fossil fuels...

Carbonate sediments and rocks are valuable archives of Earth's past whose geochemical compositions inform our understanding of Earth's surface evolution. Yet carbonates are also reactive minerals a...

The connection between the geological record and dynamic topography driven by mantle convective flow has been established over widely varying temporal and spatial scales. As observations of the pro...

Melanin and other pigments are now well known to be important in exceptional preservation of soft tissues in vertebrates and other animals. Because pigments confer coloration and even structural co...

As the world overheats—potentially to conditions warmer than during the three million years over which modern humans evolved—suffering from heat stress will become widespread. Fundamental questions...

Climate extremes threaten human health, economic stability, and the well-being of natural and built environments (e.g., 2003 European heat wave). As the world continues to warm, climate hazards are...

The sinking of organic matter to the deep ocean leaves extremely low concentrations of major and trace nutrients for photosynthetic organisms at the sunlit surface. As a result, marine phytoplankto...

Jupiter is in the class of planets that we call gas giants, not because they consist of gas but because they were primarily made from hydrogen-helium gas, which upon gravitational compression becom...

Groundwater is a crucial resource for current and future generations, but it is not being sustainably used in many parts of the world. The objective of this review is to provide a clear portrait of...