02 - Greenhouse Effect

1. Positive Feedback Loop

A positive feedback loop is a process where the effects of a small change in a system are amplified, leading to further changes and potentially significant impacts. In the context of climate change, this often involves interactions that exacerbate warming or climatic shifts.

2. Melting Ice and Northern Warming

As temperatures rise due to climate change, ice in polar regions melts, exposing more water, which has a lower albedo compared to ice. Unlike ice, which reflects solar energy, water absorbs more heat. This increase in absorbed heat leads to further temperature rises and more ice melting, creating a cycle where the northern regions warm faster than the global average due to this positive feedback loop.

3. Thawing Permafrost and Feedback

Thawing permafrost contributes to a positive feedback loop because it releases stored organic matter, which decays and emits greenhouse gases such as carbon dioxide (CO₂) and methane (CH₄). This release of gases further increases global temperatures, leading to more permafrost thawing, resulting in a self-reinforcing cycle of warming.

4. Melting Land Ice vs. Sea Ice on Water Levels

Melting land ice, such as glaciers or ice sheets, contributes to rising sea levels because it adds freshwater to the oceans. In contrast, melting sea ice does not raise sea levels significantly because it displaces an amount of water equivalent to its ice form. If all land ice were to melt, sea levels could rise by approximately 70 meters, which would drastically alter coastlines and habitats.

5. Impact of Rising Sea Levels on Cities and Human Populations

Rising sea levels threaten coastal cities with flooding, increased erosion, and the potential for saltwater intrusion into freshwater supplies. This could lead to significant displacement of populations, loss of property, and increased costs related to infrastructure repair and adaptation measures.

6. Addition of Freshwater to Ocean Currents

The addition of large quantities of freshwater from melting ice can disrupt ocean currents, such as the thermohaline circulation, which relies on salinity and temperature gradients. Disruption of these currents can affect global weather patterns and climate, which can have dire consequences for agriculture, fisheries, and overall human livelihoods.