The big picture
Five connected climate challenges
Climate change is not one isolated problem. Warming interacts with oceans, ecosystems, food systems, water, health, infrastructure and livelihoods.
01
Warming & emissions
Rising greenhouse-gas concentrations
The problem: Human activities have increased concentrations of heat-trapping greenhouse gases, warming the atmosphere, ocean and land. The physical evidence for human-caused warming is extensive.
Why it matters: More warming raises the likelihood and intensity of many climate hazards and reduces the ability of people and ecosystems to adapt.
Impacts: More extreme heat, changing rainfall, glacier and ice loss, sea-level rise, ecosystem disruption and risks to health and livelihoods.
Action: Cut fossil-fuel use and methane emissions, improve energy efficiency, expand low-emissions energy, protect carbon sinks and support effective climate policies.
02
Extreme events
Climate hazards and cascading impacts
The problem: A warmer climate changes the conditions that influence heatwaves, heavy precipitation, drought, wildfire weather and other hazards.
Why it matters: Climate hazards can compound existing vulnerabilities and disrupt health systems, food production, water supplies, homes, infrastructure and economies.
Impacts: Heat stress, flood damage, crop losses, displacement, infrastructure disruption and higher risks for vulnerable communities.
Action: Combine rapid emissions cuts with adaptation: early-warning systems, heat plans, flood management, climate-resilient infrastructure, water planning and locally appropriate risk reduction.
03
Nature & carbon sinks
Deforestation and ecosystem degradation
The problem: Forests and other ecosystems are under pressure from land-use change, degradation, fire and other disturbances. Losing healthy ecosystems can weaken biodiversity and carbon storage.
Why it matters: Forests support biodiversity, water regulation, livelihoods and climate resilience while storing carbon.
Impacts: Habitat loss, biodiversity decline, reduced ecosystem services, carbon emissions and greater vulnerability to climate hazards.
Action: Protect high-value ecosystems, reduce deforestation and degradation, restore native ecosystems where appropriate, strengthen sustainable land management and use reliable forest monitoring.
04
Energy transition
Decarbonizing energy, transport and industry
The problem: Modern economies still use large quantities of fossil fuels, producing substantial greenhouse-gas emissions. Transitioning systems requires technology, infrastructure, finance, policy and social participation.
Why it matters: Energy-system choices influence long-term emissions and can also affect air quality, energy security and economic development.
Impacts: Persistent emissions, air pollution, energy insecurity and transition challenges for workers, communities and industries.
Action: Deploy renewable electricity and storage, improve efficiency, electrify suitable end uses, expand clean transport, modernize grids and plan just transitions.
05
Resilience & justice
Adapting to unavoidable climate impacts
The problem: Some climate impacts will continue because the climate system responds over time to past and present emissions. Communities therefore need to reduce vulnerability while mitigation continues.
Why it matters: Adaptation can reduce harm, but its effectiveness depends on finance, institutions, information, infrastructure, technology and local conditions.
Impacts: Unequal exposure to heat, floods, drought, sea-level rise and food or water stress can deepen existing social and economic vulnerabilities.
Action: Use climate-risk information in planning, strengthen early warnings, climate-proof infrastructure, protect water and food systems, and center locally led and equitable adaptation.