CO₂: its impact is already all around us
How emissions change the climate, people's lives and ecosystems.
The mechanism
Human emissions of carbon dioxide increase its concentration in the atmosphere and intensify the greenhouse effect. This contributes to global warming. CO₂ absorbed by the oceans also takes part in chemical reactions that lower the water's pH, a process known as acidification.
Two numbers in context
The World Meteorological Organization reports that the global average temperature in 2025 was about 1.43 °C above the 1850–1900 average. This is an annual value, not the long-term average used for climate targets. The Global Carbon Budget 2025 estimates 38.1 billion tonnes of fossil CO₂ emissions in 2025; this figure does not cover all greenhouse gases.
The consequences
The IPCC documents the impacts of climate change on health, food and water security, biodiversity and population displacement. Effects vary across regions and also depend on exposure and the capacity to adapt. Ocean warming, acidification and sea level rise place different pressures on marine life and coastal areas.
Every reduction counts
Every increment of warming increases risks. Reducing emissions and preparing communities for impacts are complementary tasks. The scale of the problem calls for collective choices in energy, transport, production and land use systems, alongside individual choices.
Sources for this article
- World Meteorological Organization · State of the Global Climate 2025
- Friedlingstein and colleagues · Global Carbon Budget 2025
- IPCC · Climate Change 2023 Synthesis Report
- World Meteorological Organization · Climate and ocean indicators for 2025
Accessed on 7 October 2026. The data and dates refer to the publications listed. Personal proposals are identified in the text.