[PAPER REVIEW] Can Urban Greenery Bring People Together?

Authors
Yookyung Lee, Seungwoo Han

Journal
npj Urban Sustainability

Year
2025

Volume / Article
Vol. 5, Article 6

DOI
10.1038/s42949-025-00194-z

1. Background

Urban green spaces have been widely associated with reduced stress, improved mental health, and greater life satisfaction. However, much of the existing literature has focused primarily on the effects of natural environments on individual well-being.

This study takes a broader perspective by asking:

Can greener urban environments reduce loneliness, and can reduced loneliness in turn strengthen people's perceptions of social cohesion?

The authors therefore conceptualize loneliness not merely as a personal emotional state, but as a social-psychological mechanism that may influence how individuals perceive trust, support, and cohesion within society.

2. Research Question

“If people live in greener environments, do they feel less lonely and perceive society as more cohesive?”

Urban Greenness
↓
Reduced Loneliness
↓
Reduced Perceived Social Fragmentation
↓
Greater Social Cohesion

3. Hypotheses

H1. Vegetation Conditions → Loneliness

Better vegetation density and health in residential environments are associated with lower levels of loneliness.

H2. Loneliness → Perceptions of Societal Fragmentation

Individuals experiencing greater loneliness are more likely to perceive society as fragmented, distrustful, exploitative, and indifferent.

4. Methodology

A key methodological strength of the study is its combination of environmental and individual-level data.

Vegetation conditions were objectively measured using satellite-based remote sensing indices, including:

• NDVI: Normalized Difference Vegetation Index

• EVI: Enhanced Vegetation Index

Rather than relying solely on participants' subjective perceptions of neighborhood greenery, the researchers used actual satellite-derived vegetation measures.

These district-level environmental data were then integrated with individual-level responses from the Korean Happiness Survey, collected during 2020 and 2021 amid the COVID-19 pandemic.

The researchers applied multilevel analysis to examine relationships across individual and district levels and additionally used path analysis to examine the pathway linking vegetation, loneliness, and perceived societal fragmentation.

5. Key Findings

Result 1. Greener environments were associated with lower levels of loneliness.

Both NDVI and EVI showed statistically significant negative associations with loneliness.

In other words: Higher levels of neighborhood vegetation → Lower levels of loneliness.

Result 2. Greater loneliness was associated with stronger perceptions of societal fragmentation.

Higher levels of loneliness were associated with stronger perceptions of:

Distrust
Exploitation
Indifference

This suggests that loneliness may extend beyond an individual's emotional experience and influence broader perceptions of society and community relationships.

6. Central Finding

The key contribution is not simply that greenery directly makes communities more cohesive.

Rather,

Greener environments may reduce loneliness, and reduced loneliness may subsequently strengthen social cohesion.

Thus, the study proposes the mechanism:

🌳 Green Environment

→ 👤 Less Loneliness
→ 🤝 Greater Social Cohesion

Loneliness therefore functions as an important mediating mechanism connecting the physical environment with social outcomes.

7. Significance

The major contribution of this study is that it links the physical urban environment to both psychological and social outcomes.

Previous approaches often emphasized: Green Space → Stress Reduction → Mental Health

This study extends the pathway to: Green Environment → Loneliness → Social Perception → Community Cohesion

Another important strength is its integration of objective satellite-based environmental data with individual survey data.

Consequently, urban greening can be understood not merely as an environmental or aesthetic policy, but potentially as part of a broader strategy for reducing social isolation and strengthening community well-being.

8. Limitations

First, the data were collected during the unusual social conditions of the COVID-19 pandemic, meaning that the findings may not be fully generalizable to ordinary periods.

Second, although significant associations were identified, the study does not establish definitive causal relationships.

Third, NDVI and EVI objectively capture vegetation conditions but do not directly measure how frequently individuals actually use or interact with green spaces.

9. Key Summary

Urban greenery may function not merely as an environmental amenity, but as social infrastructure that reduces loneliness and potentially strengthens social trust and community cohesion.