What is Climate Change?
Climate change refers to long-term shifts in global temperatures and weather patterns. While some climate change is natural, scientific consensus — supported by over 97% of climate scientists — confirms that human activities have been the primary driver since the mid-20th century.
The Science: How It Works
The Greenhouse Effect
The Earth’s atmosphere contains greenhouse gases (GHGs) that trap heat from the sun. Without this natural effect, Earth would be about 33°C colder. The problem is that human activities have dramatically increased GHG concentrations:
- Carbon dioxide (CO₂): Primarily from burning fossil fuels and deforestation; now at 425 ppm, the highest in 3 million years
- Methane (CH₄): From livestock, rice paddies, landfills, and natural gas leaks
- Nitrous oxide (N₂O): From fertilizers and industrial processes
- Fluorinated gases: From industrial applications and refrigerants
- More frequent and intense hurricanes, droughts, wildfires, and floods
- Heat waves becoming more common and deadly
- Changing precipitation patterns causing both floods and droughts
- Glaciers and ice sheets are melting
- Seas have risen ~20 cm since 1900; projected to rise another 30-90 cm by 2100
- Threatens coastal cities like Miami, New York, Mumbai, and Shanghai
- Coral reef bleaching (50% of Great Barrier Reef lost since 1995)
- Species shifting ranges or facing extinction
- Ocean acidification threatening marine food chains
- Increased heat-related illness and death
- Expanding range of vector-borne diseases (malaria, dengue)
- Air quality degradation from wildfires and increased ozone
- Food and water insecurity
- Reduce air travel — one transatlantic flight ≈ 1.5 tonnes CO₂
- Switch to an electric vehicle — saves ~1.5 tonnes CO₂/year
- Eat less meat — especially beef; plant-based diet saves ~0.5 tonnes/year
- Have one fewer child (long-term generational impact)
- Switch to renewable energy at home
- Improve home insulation and use efficient appliances
- Reduce, reuse, and recycle
- Choose public transit, biking, or walking
- Buy less, buy second-hand
- Support businesses with strong environmental commitments
- Paris Agreement: 196 nations committed to limiting warming to 1.5-2°C
- U.S. Inflation Reduction Act (2022): $369 billion for climate and clean energy
- EU Green Deal: Target of carbon neutrality by 2050
- Carbon pricing: 70+ countries have implemented carbon taxes or cap-and-trade systems
- Renewable energy: Solar and wind now the cheapest electricity sources in history
- Renewable energy costs have fallen 90% since 2010
- Electric vehicle adoption is accelerating rapidly
- More countries and companies are committing to net-zero emissions
- New technologies (direct air capture, green hydrogen) are advancing
- NASA Climate: climate.nasa.gov
- IPCC Reports: ipcc.ch
- Project Drawdown: drawdown.org (solutions ranked by impact)
- Climate Reality Project: climaterealityproject.org
Global Temperature Rise
The global average temperature has risen approximately 1.2°C above pre-industrial levels. The Paris Agreement aims to limit warming to 1.5°C — every fraction of a degree matters enormously.
Real-World Impacts
Extreme Weather
Sea Level Rise
Ecosystem Disruption
Human Health
What Can Individuals Do?
Highest Impact Actions
Everyday Actions
What Governments and Organizations Are Doing
Reasons for Optimism
Despite the challenges, there are positive trends: