Responding to climate change requires both mitigation — actions to reduce or prevent greenhouse gas emissions — and adaptation — adjustments that minimize harm from climate impacts already underway. Mitigation strategies include transitioning to renewable energy, improving energy efficiency, and protecting forests, while adaptation includes building sea walls, developing drought-resistant crops, and improving early warning systems. Carbon capture and storage (CCS) is a technology that captures CO₂ from industrial sources or the atmosphere and stores it underground in geological formations. Market-based approaches such as a carbon tax (a fee on burning carbon-based fuels designed to internalize the cost of emissions) and cap-and-trade systems (which set a total emissions cap and allow companies to buy and sell emission allowances) create economic incentives to pollute less. Nature-based solutions use ecosystems to sequester carbon and build resilience, including reforestation, wetland restoration, and sustainable agriculture.
Internationally, the United Nations Framework Convention on Climate Change (UNFCCC), established in 1992, provides the foundational framework for climate negotiations. Its 2015 Paris Agreement, signed by 196 parties (195 countries plus the EU), committed nations to limit global warming to well below 2°C, preferably 1.5°C, above pre-industrial levels. Each country submits Nationally Determined Contributions (NDCs) outlining how it will reduce emissions and adapt. The goal of net-zero emissions — achieving a balance in which the amount of greenhouse gases emitted equals the amount removed from the atmosphere — is now a central target for many governments and companies. Companies also classify their emissions into Scope 1 (direct emissions), Scope 2 (indirect from purchased energy), and Scope 3 (all other indirect emissions in their value chain). The Intergovernmental Panel on Climate Change (IPCC), a UN body, assesses the science of climate change and publishes comprehensive reports guiding these efforts.
The energy transition underpins all of these solutions. Solar photovoltaic (PV) systems generate electricity by using solar cells that convert sunlight directly into electrical current via the photovoltaic effect. Wind turbines generate electricity when their blades, turned by moving air, spin a generator. Hydroelectric power uses the kinetic energy of flowing or falling water to spin turbines, typically at dams or run-of-river installations. Geothermal energy taps heat within the Earth, while biomass energy uses organic materials such as wood, crop waste, or animal manure through combustion, gasification, or anaerobic digestion. Compared with fossil fuels, renewables offer lower greenhouse gas emissions, an inexhaustible supply, reduced air pollution, energy independence, and declining costs. The principal challenge is intermittency, because the sun does not always shine and the wind does not always blow, making technologies such as batteries, pumped hydro, and hydrogen-based energy storage essential for grid reliability. Importantly, the ozone hole and the greenhouse effect, although both involve atmospheric chemistry, are separate issues: the ozone hole is a thinning of stratospheric O₃ caused by CFCs, while the greenhouse effect involves heat trapping by CO₂, methane, and related gases.