The temperature of Earth is greatly influenced by tiny ocean shells.

Unbeknownst to us, marine life that forms microscopic calcium carbonate shells contributes to climate regulation. Researchers discovered that existing climate models under-represent the calcifying plankton, which includes coccolithophores, foraminifers, and pteropods, which are plankton-based shell builders.

We probably underestimate important mechanisms of the ocean's carbon cycle and climate change responses as a result of this absence.

Knowing the Earth system

An international team from the Universitat Autònoma de Barcelona's Institute of Environmental Science and Technology (ICTA-UAB) carried out the review. According to the scientists, these creatures influence the chemistry of saltwater and direct the flow of carbon from the atmosphere into the deep ocean.

Understanding their distinct functional characteristics and how they differ amongst groups is important for comprehending the functioning of the Earth system.

Massive climate role, tiny shells

Ocean creatures that precipitate calcium carbonate (CaCO3) are known as signature shell-builders. These calcifying plankton use minerals to create tiny shells. Their shells affect ocean alkalinity, the movement of carbon into abyssal depths, and consequently the global climate as they live, die, and sink.

According to Patrizia Ziveri, the study's principal author, "plankton shells are tiny, but together they shape the chemistry of our oceans and the climate of our planet."

"We risk overlooking fundamental processes that determine how the Earth system responds to climate change" if these species are excluded from climate models, the researchers caution.

Ocean blind spots for climate change

The heterogeneous collection of calcifying plankton is frequently simplified or left out of ordinary Earth System Models (such those used in the Coupled Model Intercomparison Project).

Processes such as shallow dissolution, in which CaCO3 dissolves close to the surface instead of solely in deep water, are under-represented, according to the experts.

A significant number of the shells never reach the ocean floor. Rather, they dissolve in the upper ocean, altering the dynamics of the carbon cycle and local and global alkalinity.

Models may miss the amount, rate, and location of carbon storage if they ignore the "particle journey" from the surface to the deep and the variations among plankton groups.

Not every shell-builder is created equal.

Not all calcifying plankton is created equal. According to the review, pteropods, foraminifers, and coccolithophores all have unique characteristics. Their susceptibility, ecology, and carbon cycle influence are all impacted by these characteristics.

One of the biggest sources of CaCO3 in the open ocean is found in coccolithophores. However, because they lack the pumps that safeguard their internal acid-base balance, they are especially vulnerable to acidification.

Pteropods and foraminifiers behave differently, but they both have systems in place to control acidity. Pteropods are particularly susceptible to low pH environments because they depend on the more soluble aragonite form of CaCO3. Warming and decreased oxygen levels are also threats to foraminifiers.

Climate modellers lose nuance and run the risk of biassing predictions when they disregard this variation and treat them as a single generic "calcifier" group.

The invisible carbon freeway

The review highlights that the number of shells sinking and the amount of carbon exported are actively changed by shallow disintegration, aggregation, predation, and microbial respiration.

The amount of carbon that escapes the surface ocean and returns to circulation or the deep sea is determined by these dynamics. We might underestimate the ocean's capacity to absorb CO2 or release it back into the atmosphere if we don't take those processes into consideration.

The study's authors advise immediate action to improve estimates of calcium carbonate production, dissolution, and export by these various plankton taxa.

Consequently, Earth System Models would be able to more accurately interpret sediment records, capture ocean-atmosphere feedback, and project not only atmospheric carbon flows.

Clues about the climate in ancient shells

The results of this study have two benefits. First, we can make more accurate forecasts about how the ocean will react to stressors like heat and acidification by incorporating calcifying plankton dynamics into climate models.

Second, reinterpreting old sediment records is made easier by improving the biological aspect of the "carbon pump." Layers of calcium carbonate can help us better understand historical plankton populations and climates.

According to the assessment, in order to improve future estimates, these microscopic organisms that created the fossil record now merit consideration.

Creating models from research

The experts suggest many avenues of work to fill in the gaps. It is essential to better quantify export efficiency and group-specific production rates.

The responses of each group to climatic changes like as acidification, heat, and oxygen depletion must be documented in laboratory and field investigations.

The next step is for researchers to convert such findings into climate model parameterizations. In such case, biology would no longer be a supplementary subject but rather a fundamental one.

"We might miss important climate dynamics if we ignore the smallest organisms in the ocean," Ziveri stated.

According to her, adding calcifying plankton to climate models "could offer deeper insights into how ecosystems and societies may be affected and sharper predictions."

The smallest voices in the water are important.

This overview serves as a reminder that climate systems encompass biology in addition to physics and chemistry. The tilt of large-scale systems can be caused by microscopic creatures.

Although plankton builders' shells might not look like much, taken as a whole, they control sedimentation, alkalinity, carbon export, and climatic feedback. Before we rely on faulty assumptions, it is vital that we incorporate their contributions into our models.

We can only assess the resilience or vulnerability of our oceans by doing this. Consequently, this will demonstrate the performance of our climate system in the upcoming decades.