Global climate change alters Earth’s energy balance, raising average temperatures and reshaping the cryosphere and coasts. These connected impacts create environmental stress and increasing human vulnerability, especially for communities concentrated near shorelines.

9.5.2 Key Impacts of Global Climate Change

Warming: rising temperatures as a driver of change

Rising temperatures are a central, measurable impact of climate change and a trigger for many secondary effects.

• Warmer average conditions increase the frequency of heat extremes, stressing organisms and human systems.

• Higher temperatures shift the timing of seasonal events (e.g., earlier spring conditions), disrupting agriculture and ecosystem synchrony.

• Warming increases evaporation and can intensify drought conditions in some regions, reducing freshwater availability for people and ecosystems.

• Hotter conditions can lower labour productivity and increase energy demand for cooling, raising costs and health risks during heatwaves.

Ice melt: melting permafrost and sea ice

Warming affects multiple types of ice, with major consequences for landscapes, ecosystems, and people.

Melting permafrost destabilises once-frozen ground, changing hydrology and damaging built infrastructure.

This diagram illustrates key mechanisms of permafrost degradation, emphasizing both thermal thaw (energy input) and physical erosion along coasts. It helps connect permafrost thaw to real-world consequences such as ground instability, erosion, and increased risk to nearby infrastructure. Source

• Thawing can cause ground subsidence, cracking roads, pipelines, and building foundations.

• Landscapes may shift toward wetter conditions in some areas as ice within soils melts, altering drainage patterns and habitat conditions.

• Thaw can increase erosion and slope failure, raising hazards for Arctic and sub-Arctic settlements.

Sea ice melt reduces floating ice cover in polar oceans, reshaping habitat and food webs.

These NSIDC visualizations map monthly sea ice extent and compare it to a historical median baseline, making sea-ice decline and variability easy to interpret. The accompanying graphs and anomaly views help students link warming to shrinking sea-ice coverage and downstream impacts on polar ecosystems and human travel routes. Source

• Ice-dependent species lose platforms for hunting, resting, and breeding, and the timing of seasonal ice formation/breakup can disrupt life cycles.

• Reduced sea ice can change local conditions for coastal communities that rely on ice for travel routes and access to fishing or hunting grounds.

Unlike land ice, sea ice does not directly raise sea level when it melts, but it is still a major indicator of warming and strongly affects coastal and marine systems.

Sea-level rise: expanding coastal risk

Rising sea levels amplify coastal hazards and can permanently transform low-lying environments.

This satellite-based graph shows the long-term increase in global mean sea level since the early 1990s. It highlights that sea-level rise is a persistent, measurable trend driven by ocean warming (thermal expansion) and the addition of water from melting land ice. Source

• Higher baseline sea level increases the reach and damage potential of storm surge and coastal flooding.

• Chronic high-tide flooding becomes more frequent, damaging roads, sewage systems, drinking-water infrastructure, and ports.

• Saltwater can intrude into coastal groundwater and soils, reducing the productivity of farmland and contaminating freshwater supplies.

• Coastal wetlands may drown if they cannot build elevation fast enough, reducing natural flood buffering and habitat availability.

Displacement: movement of coastal populations

As climate impacts accumulate, displacement of coastal populations becomes more likely, ranging from temporary evacuation to permanent relocation.

• Homes and critical services (hospitals, schools, wastewater treatment) may become too costly to protect or repair after repeated flooding.

• Loss of land, housing, and livelihoods can drive internal migration from exposed coasts to inland cities, increasing pressure on housing, jobs, and public services.

• Cultural displacement can occur when communities lose ancestral lands, historic sites, or place-based subsistence practices.

• Inequities often intensify because low-income households may have fewer resources for insurance, relocation, or rebuilding, even when risks are similar.

Connecting the impacts: why they compound

These impacts often reinforce one another in practical, real-world ways.

• Warming increases the likelihood of ice melt (permafrost thaw and reduced sea ice).

• Ice-related changes can increase coastal vulnerability, while sea-level rise raises the frequency of damaging floods.

• As risks rise and recovery costs accumulate, displacement becomes an adaptive response for some communities and an unavoidable outcome for others.