New research shows Earth's moving surface plays a much larger role in shaping global climate than previously understood. The way tectonic plates spread apart, rather than just volcanoes, drove major climate shifts over the past 540 million years. This finding challenges long-held scientific views about the planet's natural carbon cycle.[ndtv+3]
Tectonic Plates Reshape Climate History
A recent study, published in the journal Communications, Earth and Environment, highlights how Earth's tectonic plates regulate carbon flows. Scientists from the Universities of Melbourne and Sydney led this work. They found that mid-ocean ridges and continental rifts, where plates pull away from each other, significantly influenced Earth's climate.[ndtv+3]
Previously, experts thought volcanic arcs, formed where plates collide, were the main natural source of atmospheric carbon. The new findings challenge this view. Carbon gas released from spreading tectonic plates likely triggered major transitions between ancient ice ages and warm periods.[ndtv+2]
Dr. Ben Mather, a lead researcher from the University of Melbourne, explained the importance of this shift. He said their findings show carbon gas from deep under the ocean, where tectonic plates move, likely drove major climate changes for most of Earth's history. Dr. Mather added that carbon from volcanic arcs only became a major source in the last 100 million years.[unimelb]
Uncovering the Deep Carbon Cycle
The research reconstructed how carbon moved between volcanoes, oceans, and deep within the Earth. This process happened over the last 540 million years. It offers new insights into how Earth's natural carbon cycle works.[unimelb+1]
Professor Dietmar Müller from the University of Sydney's School of Geosciences contributed to the study. He said the team used global plate tectonic reconstructions and carbon-cycle modeling. This allowed them to trace how carbon was stored, released, and recycled as continents moved.
These geological processes operate over millions of years. They influence the amount of carbon dioxide in the atmosphere. This long-term "deep carbon cycle" plays a vital role in regulating the planet's climate.
Mountains Also Impact Carbon Levels
Beyond plate spreading, mountain formation and erosion also affect the planet's carbon balance. Mountains can either remove carbon dioxide from the atmosphere or release it. This depends on factors like erosion rates and the types of rocks present.
For example, when rainwater dissolves carbon dioxide to form carbonic acid, it reacts with certain minerals in rocks. This process, called chemical weathering, can pull CO2 out of the atmosphere. Siliceous rocks, common in mountains, contribute to this carbon removal at moderate erosion rates.
However, if mountains have sulfur-bearing minerals and experience high erosion rates, they can release CO2. Microbes in mountain soils also contribute by breaking down ancient organic carbon trapped in rocks, producing carbon dioxide.
Jeremy Rugenstein, an assistant professor of geosciences at Colorado State University, explained this balance. He said, "Whether a mountain range is a source or sink of carbon dioxide depends on how fast the landscape is eroding."
Volcanic Activity and Climate
Volcanoes also contribute to the carbon cycle, but their impact on climate varies greatly by timescale. Large explosive eruptions inject gases like sulfur dioxide into the stratosphere. This can lead to temporary global cooling for a few years by reflecting sunlight.
However, volcanoes also release carbon dioxide, a greenhouse gas. Over millions of years, long periods of intense volcanic activity have contributed to warming periods in Earth's history. This happens when volcanoes emit CO2 faster than oceans and plant life can remove it.
Today, the CO2 released by human activities far exceeds volcanic emissions. All studies show that present-day volcanoes release less than one percent of the carbon dioxide that humans emit.
Lessons for Future Climate Models
Understanding these ancient geological processes helps scientists create better future climate models. These models can more accurately predict how the Earth system will respond to ongoing changes. The new research provides important context for today's rapidly changing climate.
Earth has experienced dramatic climate shifts between "icehouse" and "greenhouse" states throughout its history. Scientists have long linked these shifts to atmospheric carbon dioxide levels. The new findings emphasize that the drivers of this carbon are more complex than previously thought.
Human activities currently release carbon dioxide at an alarming rate. This rate is about 100 to 200 times faster than natural increases seen after the last ice age. This rapid increase overwhelms Earth's natural carbon cycle.
The planet's average surface temperature has risen by about 2 degrees Fahrenheit (1 degree Celsius) since the late 19th century. This warming is largely due to increased carbon dioxide emissions from human activities.
The study highlights that Earth's climate stability depends on long-term carbon storage as much as emissions. This understanding reinforces the importance of protecting natural carbon sinks.
