Pluvial Karnia
Tauhid Nur Azhar
Sunday is the day I switch professions to become the family driver, always ready to follow orders from Ibu Maharatu.
Ibu Ratu’s agenda on Sundays is usually well-planned, involving searching for unique dining spots found on social media, followed by visits to coffee shops and dessert places. Typically, on the way home, we make a stop at another eatery to buy takeaway food, serving as a light snack while watching TV shows at our hillside home.
Last Sunday was no different. After attending a community service event in the southern part of the city, we met up to embark on our culinary adventure. However, given the season, last Sunday was marked by overcast skies, lightning, and thunder.
Not long after midday, the sky seemed to pour water. Cumulonimbus clouds unleashed liters of water from evaporation and condensation back to the earth.
As a result, several locations experienced severe flooding. The drainage systems were overwhelmed, leading to traffic congestion in various areas. Many vehicles, including ours, were stuck in long queues due to the inability of the cars in front to move forward. Meanwhile, the rain continued to pour relentlessly.
Stuck in traffic, with the rain continuously pounding, my mind began to wander, imagining various phenomena from millions of years ago. I recalled the intense rainfall event known as the Pluvial Karnia, which occurred during the Triassic period.
The Pluvial Karnia was a phenomenon that took place during the late Triassic period, the final epoch of the Mesozoic era, spanning from about 237 million to 201.3 million years ago. This period marked a significant transition in Earth’s history, characterized by dramatic changes in climate, geography, and life forms. It paved the way for the rise of dinosaurs as the dominant land group and set the stage for the Jurassic era.
During the late Triassic, Earth was dominated by the supercontinent Pangea, surrounded by the global ocean Panthalassa. This configuration created extreme climatic conditions. Much of Pangea was arid with vast deserts, while coastal regions experienced more humid conditions. The initial fragmentation of Pangea began towards the end of this period, triggering massive volcanic activity in regions like the Central Atlantic Magmatic Province (CAMP).
During this period, several major animal groups that would dominate the Mesozoic began to emerge and diversify rapidly. Archosaurs, the ancestors of dinosaurs, pterosaurs, and modern crocodilians, dominated the land. The first dinosaurs, such as Eoraptor and Herrerasaurus, appeared in South America and began to diversify quickly.
Meanwhile, the first mammals, originating from synapsid groups like therapsids, also emerged, although they remained small and overshadowed by large reptiles. Ammonites, ichthyosaurs, and plesiosaurs ruled the oceans. Coral reefs, composed of hexacorals, began to flourish after recovering from the end-Permian extinction.
Gymnosperms, including conifers, dominated the land, providing habitats for large herbivores.
However, the end of the Triassic was also marked by the Triassic-Jurassic mass extinction, which resulted in the disappearance of about 76% of species on Earth. The primary cause of this event was the intense volcanic activity from CAMP, which released vast amounts of carbon dioxide and sulfur dioxide, leading to climate change and ocean acidification.
During the late Triassic, around 232 million years ago, our planet experienced one of the most extreme climate episodes in its history, known as the Pluvial Karnia. This period was characterized by intense and prolonged rainfall lasting over a million years. The phenomenon was triggered by massive volcanic activity in the Central Atlantic Magmatic Province (CAMP), one of the largest volcanic systems ever, which altered landscapes, ecosystems, and the course of evolution on Earth.
The volcanic activity of CAMP released vast amounts of carbon dioxide (CO₂) and sulfur dioxide (SO₂) into the atmosphere. Research from the Geological Society of America (2020) shows that the release of CO₂ in large quantities caused global warming, leading to increased evaporation of seawater. The resulting water vapor intensified rainfall in extensive coastal areas, particularly in the supercontinent Pangea. The combination of global warming and extreme rainfall created an unstable climate cycle.
The supercontinent Pangea, with its vast land configuration, exacerbated this effect. According to a study by Benton (2022), the extensive landmass created strong seasonal winds, concentrating rainfall into heavy, continuous downpours.
The Pluvial Karnia significantly altered Earth’s landscape. Intense rainfall eroded the land surface, forming new river networks, deltas, and lakes. Geological evidence from sediment formations in Northern Italy, analyzed by Simms et al. (2019), indicates massive sediment deposition from river systems that emerged due to intense erosion.
However, the impact was not limited to the landscape. The dramatic climate change triggered the Carnian Pluvial Event, one of the five major mass extinctions in Earth’s history. Some organism groups, such as therapsids and aquatic reptiles, could not adapt to these drastic changes. On the other hand, this extinction event paved the way for the diversification of new species, including the rise of dinosaurs, which dominated terrestrial ecosystems for the next 150 million years.
The Pluvial Karnia provides valuable lessons about the impact of volcanic activity and climate change on Earth’s ecosystems. Although the timescales differ, the global warming we are experiencing today shares similarities with the conditions created by CAMP. Greenhouse gases released by human activities, particularly CO₂, can trigger similar climate changes, with domino effects on global ecosystems.
According to a report by the Intergovernmental Panel on Climate Change (IPCC, 2021), a temperature increase of 1.5°C to 2°C in the coming decades could intensify extreme rainfall patterns, floods, and soil erosion, resembling the geological dynamics observed during the Pluvial Karnia.
This phenomenon also highlights how climate change can drive or hinder biodiversity. Just as dinosaurs thrived after the Pluvial Karnia, modern species that can rapidly adapt to changing environments may become evolutionary winners in the future. However, many species lacking the time to adapt will face extinction risks.
Geomorphologically, sustained intense rainfall can accelerate the formation of new geomorphic features, such as river deltas, floodplains, and lakes, and even hasten land degradation. This phenomenon can increase the risk of disasters such as landslides and major floods in densely populated areas.
My thoughts began to race, and my brain started to fantasize. Could the super heavy rain that caused total flooding on Sudirman Street in the heart of my city be a model of the extreme rainfall that will initiate the onset of extreme climate phenomena altering the geomorphology of Java Island and the Nusantara archipelago? This seems to be a thought whose level of sophistication has exceeded the boundaries of reasonable imagination, right?
But who knows, perhaps the geological cycles of millions of years can indeed recur through various phenomena. Isn’t Java Island, where I am currently stuck, a result of a series of continuous and sustained geotectonic and volcanic dynamics?
Java Island and the Nusantara archipelago originated from fragments of the supercontinent Gondwana, which began to break apart around 200 million years ago during the Mesozoic era. These fragments, including the plate that is now part of Southeast Asia, moved northward due to plate tectonic dynamics.
The Indo-Australian, Eurasian, and Pacific plates are the key players in the formation of this region. The northward movement of the Indo-Australian plate, colliding with the Eurasian plate, created a subduction zone along the southern edge of the Eurasian plate. This subduction zone played a crucial role in the formation of the islands in Indonesia, including Java.
Around 65 million years ago, during the Tertiary period, the subduction zone in southern Nusantara became highly active. The subduction of the Indo-Australian plate beneath the Eurasian plate triggered intense volcanic activity, forming a volcanic arc stretching from Sumatra, Java, Bali, to Nusa Tenggara.
Java Island was formed as part of this volcanic arc. Continuous volcanic activity produced lava deposits, volcanic ash, and pyroclastic material, forming highlands and mountains. Volcanoes such as Merapi, Semeru, and Krakatau are results of this process and remain active to this day.
Besides volcanic activity, sedimentation played a significant role. Materials carried by rivers from the Asian mainland and erosion of volcanic areas accumulated in sedimentary basins around the volcanic arc. Over time, tectonic pressure and uplift resulted in the formation of new land.
During the Quaternary period (the last 2.5 million years), ongoing tectonic activity caused the uplift of Java and Nusantara, forming mountains, highlands, and alluvial plains we see today.
The rise and fall of sea levels during glacial and interglacial periods over the last 2.5 million years also shaped the Nusantara archipelago. During ice ages, sea levels were lower, connecting much of Nusantara as a landmass known as Sundaland. When the ice melted and sea levels rose, this landmass broke apart into the islands we see today.
Thus, it cannot be denied that the archipelago, located at the convergence of the three major plates — Indo-Australian, Eurasian, and Pacific — and experiencing the consequences of subduction zones, faults, and active volcanic zones, is part of an active geodynamic process that continues to this day.
Just like the super heavy rain I experienced on Sunday, those brief fragments might be tiny parts of a phenomenon that can last millions of years, much like the Pluvial Karnia. Similarly, our lifespans are partial and can only capture a few changes in the extremely short human life cycle compared to the age of the Earth and the universe.
And just like the weather on that Sunday, after an hour of waiting under the pouring rain, the sky began to clear, and the stagnant traffic started to flow. The drainage system began to work, reducing the flooding, and although slow, the queue of vehicles could move forward.
I quickly took the first opportunity to turn right. I knew that right turn well; it led to Kelenteng Street, where there was an antique coffee shop in the middle.
A cup of pletok beer accompanied by a plate of warm, sweet, and delicious Pofertjes dusted with powdered sugar had made me fully aware that what we can do together is to preserve nature, as best and as much as we can, which has been entrusted to us and cannot be taken for granted. Therefore, no matter how small our contribution and role, what matters most is the intention to safeguard what has been bestowed upon us, manifesting in time and space.
