Ocean Acidification, Aerosols, and Climate Change: Key Concepts for Environmental Science

What is ocean acidification?

A decrease in ocean pH caused by the absorption of atmospheric CO₂.

What percentage of human-emitted CO₂ have oceans absorbed since the Industrial Revolution?

Approximately 40%.

What happens when CO₂ dissolves in seawater?

It forms carbonic acid (H₂CO₃), which reduces carbonate ions (CO₃²⁻) needed for shell formation.

What is the saturation state (Ω) in relation to shell growth?

Ω > 1 indicates water is supersaturated, allowing shells to grow normally; Ω < 1 indicates undersaturation, leading to shell dissolution.

What factors affect CO₂ solubility in water?

CO₂ solubility is higher in cold, fresh water and lower in warm, salty water.

How does ocean acidification impact shell-forming species?

Species like corals, oysters, and pteropods struggle to calcify due to reduced carbonate ions.

What is the definition of atmospheric aerosols?

Tiny solid or liquid particles suspended in air, ranging from 10 nm to 10 µm.

What are the two main types of aerosols?

Natural aerosols (e.g., dust, sea salt, volcanic ash) and human-made aerosols (e.g., soot, industrial emissions).

What are the four processes of aerosol behavior?

Emission, chemical transformation, coagulation, and deposition (wet and dry).

What is the planetary boundary for aerosol optical depth (AOD)?

A difference of 0.1 AOD between hemispheres.

What are the impacts of reflective aerosols on Earth's climate?

They increase Earth's albedo, which helps reduce warming.

What is the role of the Intertropical Convergence Zone (ITCZ)?

It is a low-pressure band where Hadley cells converge at the equator, affecting rainfall patterns.

What is a keystone species?

A species that has a disproportionately large effect on its environment relative to its abundance.

What is the current status of global forest cover compared to Holocene levels?

Approximately 60% of original forest remains, indicating the boundary has been crossed.

What are the main drivers of forest loss?

Agricultural expansion, urbanization, logging, and wildfires exacerbated by climate change.

What does REDD+ stand for?

Reducing Emissions from Deforestation and Forest Degradation.

What are novel entities?

Human-made substances that can harm Earth systems, often persistent and irreversible.

What are some examples of novel entities?

Plastics, PFAS (forever chemicals), persistent organic pollutants (POPs), and nuclear waste.

Why are microplastics a concern?

They do not degrade, can bioaccumulate, and are found in ecosystems and human bodies.

What is the thermohaline circulation?

A density-driven global ocean conveyor belt that is affected by warming and freshwater input.

What is the significance of biodiversity metrics?

They measure genetic diversity and ecosystem health, with current extinctions exceeding safe boundaries.

What are ecosystem services?

Benefits provided by ecosystems, including provisioning, regulating, supporting, and cultural services.

What is the impact of climate change on the hydrological cycle?

Warming affects precipitation patterns, ice cover, and ocean currents.

What does the Keeling Curve represent?

It shows the increase of atmospheric CO₂ levels over time.

What are Nationally Determined Contributions (NDCs)?

Emission reduction targets set by countries as part of climate agreements.

What is the 'Right to Be Cold' in the context of environmental justice?

It refers to the human rights issues faced by Arctic communities due to climate change impacts.