“The Carnian Pluvial Event: Investigating the Million-Year Duration of Rainfall That Altered Earth’s Climate”

### Earth’s Longest Rainstorm: The Carnian Pluvial Event and Its Impact on Life

While the Pacific Northwest is renowned for its persistent rainfall, the modern rains are no match for a prehistoric occurrence that transformed the Earth millions of years ago. Approximately 232 million years ago, during the Late Triassic Period, our planet experienced a remarkable climatic episode referred to as the **Carnian Pluvial Event (CPE)**—a ceaseless rainstorm that persisted for an estimated one to two million years. This extraordinary period of relentless rainfall led to significant environmental transformations and paved the way for the emergence of dinosaurs and other contemporary ecosystems.

#### **What Was the Carnian Pluvial Event?**

The Carnian Pluvial Event signified the conclusion of a protracted dry period in Earth’s timeline. It was an era when the supercontinent **Pangea** reigned over the planet, with various geographical and climatic dynamics fostering a turbulent environment. During this time, **sea surface temperatures climbed to unprecedented levels**, prompting humid air masses to condense and release incessant rainstorms.

Geological records indicate that this extended wet phase was instigated, at least partly, by colossal volcanic eruptions in the **Wrangellia Large Igneous Province**, which currently includes areas of Alaska and British Columbia. These massive volcanic events emitted greenhouse gases, notably carbon dioxide and water vapor, into the atmosphere, exacerbating the hydrological cycle. This, in turn, led to a marked and prolonged rise in worldwide precipitation.

Simultaneously, oceans ingested these gases, causing **acidification** that severely disrupted marine habitats. As continents faced unending rainfall and land environments became waterlogged, Earth’s ecosystems underwent dramatic shifts.

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#### **The Geological Evidence Behind CPE**

The identification of the Carnian Pluvial Event was pioneered by geologists such as Alastair Ruffell and Michael Simms, who explored rock formations in the UK. While scrutinizing the **red sandstone of Lipe Hill in Somerset**, they identified a band of gray material indicative of a sudden shift from dry to humid conditions. This was a global event, supported by discoveries in **Alpine regions** and other global locales.

These sudden environmental transitions were documented in rock layers as alterations in sediment makeup. For instance, during the CPE, extensive deposits from rivers and lakes supplanted previously desert-dominated rocks, providing a clear geological indication of a wetter climate. These formations not only illustrate the severity of the rainfall but also the biological disruptions that accompanied it.

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#### **The Dual Impacts:** Extinction and Evolution

The Carnian Pluvial Event instigated a **mass extinction event**, comparable to other significant die-offs throughout Earth’s timeline. Across one to two million years, approximately **one-third of marine species** faced extinction. The resulting ocean acidification and breakdown of food webs devastated marine ecosystems, while terrestrial environments battled to cope with overwhelming humidity and flooding. Numerous plant and animal forms—particularly those adapted to dry conditions—perished during this tumultuous period.

However, despite the bleakness of this scenario, the Carnian Pluvial Event also represented a **crucial turning point in Earth’s evolutionary narrative**. The sudden climatic changes opened avenues for adaptive radiation, wherein new species diversified and evolved to occupy abandoned ecological roles. This era witnessed the emergence or rapid evolution of many contemporary organisms, including:

– **Dinosaurs**: Though their inception predates the CPE, dinosaurs began to flourish and dominate ecosystems by the period’s conclusion, overshadowing other reptiles as key predators and herbivores.
– **Frogs, turtles, and lizards**: The roots of today’s amphibians and reptiles can be traced back to species that first emerged during or soon after the CPE.
– **Modern coral reefs and plankton**: In the marine environment, coral systems and plankton populations commenced their recovery and diversification, laying the groundwork for the marine ecosystems we recognize today.

Geology professor **Jacopo Dal Corso**, a prominent researcher of the CPE, remarked that this damp phase effectively heralded the **”dawn of the modern world.”** The ecological disruptions prompted by extinction events frequently act as catalysts for evolution, and the CPE was no outlier. Many of the dominant life forms in current ecosystems can trace their ancestry back to this tumultuous epoch.

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#### **What We Can Learn from the Carnian Pluvial Event**

Investigating the Carnian Pluvial Event equips scientists with crucial knowledge about the interconnections among climate, geology, and biology. This event exemplifies the profound impact volcanic activity can have on atmospheric conditions, leading to swift environmental transformations. It also underscores the resilience and adaptability of life on Earth, as organisms evolved to navigate new and demanding circumstances.

Gaining insights from historical climate events like the CPE holds particular significance today, as humankind confronts the severe ramifications of global warming and ocean acidification. By understanding how