Earth and Environment Atlas
Things this atlas does not know. Each entry is a question that specialists
have posed and not settled, recorded with what would actually resolve it and which
expertise the answer needs.
These are kept deliberately, rather than quietly omitted. An atlas that shows
only what it is sure of implies a confidence it has not earned, and the gaps are often where
the interesting work is. Several sit exactly where two fields fail to meet: identifying the
hyssop of the Hebrew Bible needs a botanist and a philologist of Biblical Hebrew, and neither
one settles it alone.
Grouped by the kind of thing the question is about, so you can go straight to the entity type you work on.
Concepts 6
Snowball Earth
Was Snowball Earth a full snowball or a slushball with an open equatorial band?
Open Snowball Earth
Why It Is Open Proponents argue that near-total glaciation best explains glacial deposits at tropical palaeolatitudes and other enigmatic features of the Cryogenian record, while opponents contest the geological evidence for global glaciation and the geophysical feasibility of an ice-covered or slush-covered ocean, and emphasize the difficulty of escaping an all-frozen state. Whether an equatorial band of open or seasonally open water persisted remains one of the hypothesis's named unanswered questions.
What Would Settle It Sedimentary or geochemical evidence that settles whether open water persisted at the Cryogenian equator during the Sturtian and Marinoan episodes, tested against climate models able to reproduce both entry into and escape from the frozen state.
Expertise Needed Paleoclimatology, Geology, Geochemistry
Question posed in
Snowball Earth (Wikipedia), Lead section.
Mantle Plume
Do deep mantle plumes feed volcanic hotspots such as Hawaii, or do shallower plate processes explain them?
Open Mantle Plume
Why It Is Open Since its introduction the plume hypothesis has been repeatedly adapted to fit observed hotspots rather than making firm predictions, and critics have developed a rival plate hypothesis; with the growing number of models the plume concept has been criticized as a weakly defined hypothesis that as a general term is currently neither provable nor refutable. Seismic tomography has produced evidence read as favoring a plume beneath Hawaii and, since 2011, beneath Yellowstone, but the general question stays contested.
What Would Settle It Seismic imaging of plume conduits from the core-mantle boundary to the surface at multiple hotspots, with resolution good enough that plume and plate explanations make distinguishably different predictions.
Expertise Needed Geophysics, Seismology
Question posed in
Mantle Plume (Wikipedia), Criticism section; Seismic tomography section.
Mantle Plume
Do Deep Mantle Plumes Explain Hotspot Volcanism, or Is the Plate Hypothesis Right?
Open Mantle Plume
Why It Is Open Whether anomalous volcanic hotspots such as Hawaii and Yellowstone are fed by narrow plumes rising from the core-mantle boundary, or are instead explained by shallow, plate-tectonic-driven processes, is contested as the Great Plume Debate; critics led by Don Anderson, Gillian Foulger and Warren Hamilton argue the plume hypothesis has not reliably predicted new hotspots since its 1971 introduction, while the rival plate hypothesis attributes the same volcanism to near-surface plate processes rather than a deep-mantle source.
What Would Settle It Direct seismic tomographic imaging that resolves a continuous, narrow, deep-sourced conduit beneath a disputed hotspot, or a plume-model prediction of a previously unknown hotspot later confirmed by observation, would settle the debate in the plume hypothesis's favor; a demonstrated shallow, plate-driven mechanism sufficient to explain the same hotspots without invoking a deep source would settle it the other way.
Expertise Needed Geophysics
Question posed in
Mantle Plume (Wikipedia), Alternative Hypotheses.
Anthropocene
Should the Anthropocene Be Formally Ratified as a Geological Epoch?
Open Anthropocene
Why It Is Open In 2024, after fifteen years of deliberation, the International Commission on Stratigraphy's Subcommission on Quaternary Stratigraphy voted down the Anthropocene Working Group's proposal to formally ratify the Anthropocene as a new epoch, owing largely to its shallow sedimentary record and its extremely recent, contested proposed start date, so the term remains widely used without a ratified place on the geologic time scale.
What Would Settle It A revised formal proposal addressing the 2024 objections, most likely with a different candidate start marker less exposed to the recency-bias criticism levelled at the 1950 Great Acceleration boundary, brought back to the International Commission on Stratigraphy and the International Union of Geological Sciences for a fresh vote, would resolve the question either way.
Expertise Needed Geochronology
Question posed in
Anthropocene (Wikipedia), Rejection in 2024.
Milankovitch Cycles
Why Does the 100,000-Year Ice Age Cycle Dominate When Its Orbital Forcing Is Weak?
Open Milankovitch Cycles
Why It Is Open Milankovitch's own theory identifies the roughly 41,000-year obliquity cycle as the strongest orbital forcing on high-latitude summer sunlight, yet ice age cycles over the last million years have paced at roughly 100,000 years, matching the far weaker eccentricity cycle instead. This mismatch between the strength of the forcing and the size of the climate response is known as the 100,000-year problem.
What Would Settle It A mechanism, such as an internal ice-sheet or carbon-cycle feedback, frequency modulation, or a stochastic-resonance effect, that amplifies the weak eccentricity signal into a full glacial cycle, confirmed against the detailed timing of the ice-core and ocean-sediment record.
Expertise Needed Paleoclimatology
Question posed in
Milankovitch Cycles (Wikipedia), The 100,000-year problem.
Environmental Health
When Did Environmental Health Emerge as a Distinct Field?
Open Environmental Health
Why It Is Open Environmental health's own encyclopedic source names two milestones that are often read as founding moments, Sir Edwin Chadwick's 1884 Association of Public Sanitary Inspectors and the World Health Organization's 1989 and 2016 definitional statements, but the first is the professionalization of sanitary inspection specifically, not the naming or founding of "environmental health" as a distinct concept, and the latter two are definitional updates to an already-existing term rather than its origin.
What Would Settle It A history-of-science source tracing when the term "environmental health" itself first came into use as a distinct field name, separate from the older sanitary and public health movement it grew out of.
Expertise Needed History of Public Health
Question posed in
Environmental Health (Wikipedia), Lead section and History section.
Processes 2
Plate Tectonics
When and how did plate tectonics itself begin on early Earth?
Open Plate Tectonics
Why It Is Open The rock and mineral record old enough to settle it is scarce and heavily altered: the Hadean and early Archean left almost no surviving crust to read directly, so estimates for when a single, stable, mobile-lid system of plates first organized range from roughly 4 billion to under 3 billion years ago, and some researchers argue the earliest crust moved under a different regime entirely before plate tectonics as it now works took over.
What Would Settle It Either a substantially larger surviving sample of Hadean and early Archean crust than currently exists, or a geochemical or isotopic proxy, read from what does survive, that can distinguish plate-tectonic from non-plate-tectonic crustal recycling with confidence.
Expertise Needed Geology, Geochronology
Question posed in
Plate Tectonics (Wikipedia), Onset and early history, disputed among specialists.
Thermohaline Circulation
Is the Atlantic Meridional Overturning Circulation Approaching a Tipping Point?
Open Thermohaline Circulation
Why It Is Open Direct measurement since the mid-2000s and proxy reconstructions suggest the Atlantic branch of the thermohaline circulation, the AMOC, has weakened, but as of the mid-2020s there is no scientific consensus on whether a consistent slowing has actually occurred, how much of any weakening reflects climate change versus natural multi-decadal variability, or whether an abrupt collapse could arrive within this century rather than the more gradual decline most comprehensive climate models project.
What Would Settle It A longer continuous observational record of the overturning circulation's strength, and climate models whose treatment of Atlantic freshwater transport can be tested against that record rather than relying on simulations some researchers argue understate collapse risk.
Expertise Needed Oceanography and Climatology
Question posed in
Thermohaline Circulation (Wikipedia), Weakening and collapse risk.
Eras 1
Pleistocene
What caused the mid-Pleistocene transition, when glacial cycles shifted from a roughly 41,000 year rhythm to the roughly 100,000 year rhythm still running today?
Open Pleistocene
Why It Is Open Milankovitch cycles predict a strong 41,000 year obliquity signal throughout, yet ice core and marine sediment records show glacial cycling shifted toward a dominant 100,000 year period around one million years ago, a change the orbital forcing itself does not obviously explain, since the eccentricity cycle it would need to track is a comparatively weak driver of incoming solar radiation on its own.
What Would Settle It A mechanism, most proposed candidates involve declining atmospheric carbon dioxide, thinning regolith on the continents changing how ice sheets respond, or some combination, that can be tested against the same ice core and sediment record well enough to be preferred over its rivals rather than merely consistent with the data.
Expertise Needed Climatology, Geochronology
Question posed in
Geologic Time Scale (Wikipedia), Approximately one million years ago, cycle-length shift.