Tag

Paleoclimatology

All articles tagged with #paleoclimatology

science2 days ago•13 min saved

The Green Sahara’s 20,000-year rhythm: how orbital cycles once turned North Africa lush

Earth’s orbital precession creates a roughly 19,000–23,000-year cycle that can pull monsoons deep into North Africa, turning the Sahara into grasslands, wetlands and lakes and even hosting hippos and crocodiles. The last humid phase occurred in the Holocene (about 14,500–5,000 years ago) as a mosaic landscape, not a rainforest, ending gradually as conditions dried. Evidence comes from lake sediments, sapropels, river records and archaeology. Future green periods are not guaranteed and depend on multiple factors, including ice sheets, dust, sea temperatures and human warming—proving the Sahara is not permanently dry.

via Space Daily|

#green-sahara #holocene #orbital-precession

earth-science7 days ago•16 min saved

Ancient Ocean Heatwaves Hint at Today’s Warming Danger

A new study links the Permian-Triassic 'Great Dying' to warming oceans with expanding oxygen-poor waters, showing species most vulnerable to higher temperatures and low oxygen died off at higher rates; the findings serve as a warning that contemporary human-driven warming could trigger a similar marine crisis if carbon emissions aren’t curbed.

via Gizmodo|

#earth-science #global-warming #great-dying

science17 days ago•12 min saved

Mantle Waves Helped Antarctica Freeze Ahead of the Arctic

A new study argues that deep-Earth mantle waves, triggered during the Gondwana breakup, uplifted East Antarctica around 45 million years ago. This uplift raised elevations high enough for snow to persist, allowing the East Antarctic ice sheet to form by about 34–35 million years ago and contribute to global cooling. The Arctic, lacking similar high terrain, lagged behind by roughly 25 million years, with climate and CO2 declines later driving ice-age conditions. The work suggests geology helped set the stage for ice sheets long before climate alone made the poles cold.

via The Conversation|

#antarctica #geology #ice-sheets

science27 days ago•6 min saved

Could Distant Planetary Flybys Have Triggered Earth's Mass Extinctions?

A conference-backed hypothesis by Daniele Fargion suggests gravitational tides from flybys of planetary-mass bodies or outer Solar System dwarfs near Earth could have driven major extinctions by triggering huge tides, volcanism, climate shifts, and altered meteoritic delivery. Citing correlations with known extinctions (including the Permian/Triassic) and clues in the Earth–Moon system, the idea is speculative and not yet dated or widely validated, but it frames tidal encounters as a possible common cause alongside impacts and volcanism.

via Universe Today|

#mass-extinctions #outer-solar-system #paleoclimatology

science3 months ago•9 min saved

Ancient Coccoliths Reveal a Cooler Miocene North Atlantic Than Expected

A Nature Communications study applies clumped-isotope geochemistry to exceptionally well-preserved fossil coccoliths to reconstruct 16 million years of North Atlantic temperatures, finding temperatures about 9°C cooler than previous alkenone-based estimates and closer to climate model simulations, challenging the view of extreme Miocene warmth and highlighting the need to re-evaluate climate proxies.

via SciTechDaily|

#clumped-isotope-geochemistry #coccolithophores #miocene

science5 months ago•4 min saved

Ancient Ocean Hidden Under West Antarctica Revealed by Deep Ice Drill

A multinational team drilled beneath the West Antarctic Ice Sheet, reaching 523 meters of ice and 228 meters of ancient rock and sediment, and found marine organisms and shell fragments that indicate parts of the region were once open ocean. These findings shed light on past warmer climates over the last roughly 23 million years and could help improve predictions of future sea-level rise as the ice sheet retreat cycles are better understood.

via The Daily Galaxy|

#antarctica #climate-change #ice-sheet

science5 months ago•3 min saved

Deep Antarctic Drill Uncovers Ancient Open-Ocean Clues

Scientists drilled 523 meters through the Crary Ice Rise on the Ross Ice Shelf and recovered 228 meters of sediment, finding evidence that parts of West Antarctica were once open ocean as recently as about 23 million years ago. The findings help decode past ocean temperatures and environmental conditions to improve predictions of future ice loss and sea‑level rise; samples are being analyzed in New Zealand after transport from Antarctica.

via ScienceAlert|

#antarctica #ice-shelf #ocean-history

science5 months ago•13 min saved

Ancient Collisions Carved the Wallace Line, Explaining a Biodiversity Boundary

A computer-model study links the Wallace Line to a 35-million-year-old continental collision and subsequent climate swings, explaining why Bali’s Asian fauna abruptly shifts to Australian forms on Lombok and nearby islands—and how tectonics and climate history have shaped biodiversity across the region, with nearby lines like Weber’s and Lydekker’s also noted as regional boundaries.

via ZME Science|

#australia-asia-fauna #biogeography #paleoclimatology

science8 months ago•4 min saved

Ancient Ice and Hidden Canyons Reveal Antarctica's Climate Secrets

Scientists have discovered 6-million-year-old ice in Antarctica's Allan Hills, providing unprecedented insights into Earth's past climate and long-term cooling trends, which could help understand natural climate variability and future changes.

via Phys.org|

#allan-hills #antarctica #climate-change

science10 months ago•21 min saved

Climate Extremes Define the Age of Animals

Earth's climate has experienced a vast range of temperatures and conditions over the past half-billion years, driven primarily by atmospheric CO2 levels, with periods of extreme heat and cold that have shaped the evolution and survival of animal life. Modern climate change, caused by rapid CO2 emissions, risks pushing the planet beyond its historical bounds, threatening the biosphere.

via Quanta Magazine|

#carbon-dioxide #climate-extremes #earth-climate-history

science10 months ago•2 min saved

Dinosaur Teeth Unveil Ancient Earth's Climate and CO2 Levels

Scientists analyzed dinosaur tooth enamel to reconstruct Mesozoic atmospheric CO2 levels and photosynthesis, revealing that Earth's atmosphere contained significantly more CO2 and had higher plant productivity during that era, providing new insights into ancient climate dynamics.

via Sci.News|

#carbon-dioxide #climate-reconstruction #dinosaur-teeth

science1 year ago•4 min saved

Ancient Africa's Rainy Climate Challenges Traditional Views of Human Origins

A new study challenges the long-held belief that northern Africa became arid around 3 million years ago, showing evidence that rainfall remained stable during a critical period of human evolution, which may prompt a reevaluation of theories linking climate change to early human development.

via SciTechDaily|

#africa #climate-change #human-evolution

science2 years ago•3 min saved

The Frozen Fate of Europe's First Humans: A Sudden Freeze 1.1 Million Years Ago

Europe's first humans, Homo erectus, likely went extinct about 1.1 million years ago due to an extreme cooling event. Fossils and stone tools indicate that Homo erectus arrived in Europe from Asia between 1.8 million and 1.4 million years ago but disappeared around 1.1 million years ago. The cooling event, supported by evidence from marine sediment cores, caused a significant drop in temperature and may have led to the extinction of archaic humans in Europe. The cold climate made it difficult for them to find food, and their lack of adaptations for the cold likely contributed to their demise. This study highlights the impact of climate variability on early human populations and its relevance to understanding modern climate change.

via Livescience.com|

#climate-change #europe #extinction

climate-change3 years ago•4 min saved

Unprecedented Heat: Earth's Hottest Temperatures in Millennia

Observations from satellites and weather stations confirm that the Earth has been rapidly warming over the past 44 years, and data from as far back as 1850 shows a clear rise in average temperatures. While it is challenging to precisely determine temperatures from thousands of years ago, paleoclimatologists are confident that the current warming trend is exceptional compared to any period since before the last ice age, about 125,000 years ago. Although it is difficult to pinpoint the hottest day in the past 100,000 years, scientists estimate that temperatures during a warm period 6,000 years ago were likely similar to current conditions. However, the current heat is unprecedented due to its rapidity and the fact that it is caused by human activities, particularly the burning of fossil fuels and greenhouse gas emissions.

via The Washington Post|

#climate-change #climate-history #fossil-fuels