The search for a living atmosphere on other planets is an ongoing and advancing effort, yet it remains a formidable challenge.

Mars, a focal point of study, has a thin atmosphere mainly composed of carbon dioxide, with trace amounts of water vapor and oxygen. Although inhospitable, the discovery of liquid water beneath its surface and signs of past water presence suggests the possibility of microbial life.

Venus, with its thick atmosphere of carbon dioxide and sulfuric acid clouds, appears hostile to life as we know it. However, some speculate about the potential for life in its more temperate upper cloud layers.

Exoplanet exploration has significantly expanded the search. Missions like Kepler and TESS have identified thousands of exoplanets, some located in the habitable zones of their stars where liquid water could exist. Future missions, such as the James Webb Space Telescope (JWST) and ground-based observatories like the Extremely Large Telescope (ELT), aim to analyze exoplanet atmospheres for biosignatures—indicators of life.

Additionally, moons like Europa (orbiting Jupiter) and Enceladus (orbiting Saturn) possess subsurface oceans beneath their icy crusts, which could potentially harbor microbial life. Missions such as the Europa Clipper are set to explore these intriguing possibilities.

Despite these significant efforts, definitive evidence of a living atmosphere on another planet remains elusive. The pursuit of this discovery is a top priority in astrobiology, and technological advancements alongside new missions will continue to enhance our chances of success in the near future.

Ocean acidification is the process where the ocean becomes more acidic due to the absorption of carbon dioxide (CO₂) from the atmosphere. When CO₂ dissolves in seawater, it forms carbonic acid, which then breaks down into bicarbonate and hydrogen ions, increasing the water’s acidity.

### Consequences for Marine Ecosystems

1. **Calcifying Organisms**: Species like corals, mollusks, and some plankton need calcium carbonate to build their shells and skeletons. Higher acidity reduces carbonate ion availability, making it difficult for these organisms to maintain their structures.

2. **Coral Reefs**: Coral reefs are highly sensitive to acidification. Weakened coral skeletons result in less stable reef ecosystems, which serve as crucial habitats for a wide variety of marine species.

3. **Food Web Disruption**: Many marine animals depend on calcifying organisms for food. A decline in these primary producers and prey items can disrupt the entire food web, affecting fish, marine mammals, and human industries that depend on seafood.

4. **Behavior and Physiology Changes**: Increased CO₂ levels can alter the behavior and physiology of marine life. For instance, some fish show a reduced ability to detect predators and navigate, impacting their survival.

5. **Marine Plants and Algae**: Some marine plants and algae might benefit from higher CO₂ levels due to enhanced photosynthesis. However, this benefit does not outweigh the broader ecological disruptions caused by acidification.

6. **Biodiversity Loss**: Struggling to adapt to more acidic conditions, various marine species may decline, leading to reduced biodiversity. This loss can make ecosystems more vulnerable to other stressors like overfishing and climate change.

7. **Economic Impact**: Human communities relying on the ocean for their livelihoods, particularly through fishing and tourism, may face significant economic challenges as marine ecosystems degrade, fish stocks dwindle, and coral reefs suffer damage.