As Earth’s climate warms, both the oceans and atmosphere are undergoing significant transformations. Observations from space reveal a range of phenomena, from shifts in oceanic hues due to phytoplankton blooms to atmospheric changes driven by dust storms and wildfire smoke. NASA’s upcoming Earth-observing satellite, PACE (Plankton, Aerosol, Cloud, ocean Ecosystem), scheduled for launch in February 2024, promises to advance our understanding of these complex interactions by providing unprecedented insights into the global changes associated with climate change.

Transformations in Ocean Color and Marine Life

The warming climate has profound impacts on ocean ecosystems, including rising sea levels, marine heatwaves, and biodiversity loss. One of the most visible signs of these changes is the alteration in ocean color, which is often linked to phytoplankton dynamics. Phytoplankton, microscopic plant-like organisms that form the foundation of the aquatic food web, thrive near the ocean’s surface and exhibit diverse species with distinct ecological roles. Their growth can create extensive blooms that are visible from space, often appearing green due to their chlorophyll content.

Recent studies utilizing over two decades of chlorophyll data from NASA’s Aqua satellite have shown a gradual shift towards greener oceans. The PACE satellite will enhance these observations with its Ocean Color Instrument (OCI), a hyperspectral sensor designed to differentiate phytoplankton species by their color signatures. This advancement allows scientists to remotely identify and monitor various phytoplankton types, offering insights into their ecological roles and responses to climate change. Some phytoplankton sequester carbon dioxide, contributing to climate regulation, while others release it back into the atmosphere.

Atmospheric Interactions and Nutrient Cycling

Phytoplankton do not exist in isolation; they are part of a broader environmental system influenced by atmospheric particles. PACE will monitor both phytoplankton and aerosols, the tiny particles suspended in the atmosphere that can affect oceanic nutrient levels. Aerosols, including dust and ash from wildfires, can be transported across continents and deposited into the ocean, where they act as fertilizers, stimulating phytoplankton growth.

This interaction between atmospheric particles and ocean ecosystems is a crucial component of the global nutrient cycle. The PACE satellite’s ability to track these interactions will provide valuable data on how increased atmospheric particles, potentially from more frequent wildfires or dust storms, impact phytoplankton communities and, by extension, ocean health.

Clouds, Aerosols, and Climate Uncertainty

Another key aspect of the climate system involves the relationship between aerosols and clouds. Aerosols can influence cloud formation by serving as nuclei around which water vapor condenses. This process affects cloud properties, including their brightness and longevity. For instance, certain aerosols can lead to brighter clouds that reflect more sunlight, potentially cooling the Earth’s surface, while others can contribute to warming by trapping heat in the atmosphere.

PACE will contribute to our understanding of these processes with its polarimetric instruments, SPEXone and HARP2, which will measure aerosol and cloud characteristics using light polarization techniques. By examining how aerosols affect cloud formation and properties, PACE aims to reduce the uncertainties surrounding the climate impacts of these interactions.

Conclusion

NASA’s PACE satellite represents a significant leap forward in climate science, offering new tools to explore the intricate relationships between the ocean and atmosphere. By providing detailed observations of phytoplankton, aerosols, and cloud dynamics, PACE will help scientists unravel the complexities of climate change and its effects on global ecosystems. As we face a warming planet, understanding these interactions is crucial for predicting and mitigating the impacts of climate change, ultimately guiding efforts towards a more sustainable future.

Radhika Garewal

University/College name : ACTRE-TMC, NAVI MUMBAI