Cluster 0

• Climate change
• History of climate change science
• Paleoclimatology
• Proxy (climate)
• Global temperature record
• Medieval Warm Period
• Little Ice Age
• Sea level rise
• Ice sheet
• Retreat of glaciers since 1850
• Glacier mass balance
• Arctic sea ice decline
• Climate change in the Arctic

Cluster 1

• Endangered species
• Critically endangered
• Holocene extinction
• IUCN Red List
• Effects of climate change on plant biodiversity

Cluster 2

• Intergovernmental Panel on Climate Change
• IPCC Second Assessment Report
• IPCC Third Assessment Report
• IPCC Fourth Assessment Report
• IPCC Fifth Assessment Report
• IPCC Summary for Policymakers

Cluster 3

• Human impact on the environment
• Environmental issue
• Environmental degradation
• Global warming
• Greenhouse gas
• Fossil fuel
• Carbon dioxide in Earth's atmosphere
• Representative Concentration Pathway
• Population growth
• Carbon footprint
• Pollution
• Ocean acidification
• Coral bleaching
• Coral reef protection
• Desertification
• Deforestation
• Deforestation and climate change
• Earth Summit
• Paris Agreement
• Kyoto Protocol
• United Nations Environment Programme
• United Nations Framework Convention on Climate Change
• United Nations Climate Change conference
• United States Environmental Protection Agency