How do we know humans cause global warming?

Deadly heatwaves, devastating floods, droughts, and record-low Arctic and Antarctic ice levels make 2023 the hottest year in the 174-year observational record and likely the hottest in 125,000 years.

There are myths and confusion about climate change despite the overwhelming scientific consensus. This part addresses core climate change topics, science, and impacts and asks if "we humans are causing global warming?

Earth has experienced natural cycles of cooling and warming due to solar energy variations and ocean circulation changes, but these causes cannot explain the recent rapid warming, especially in recent decades. For example, volcanic action can send out gases and dust that cool the Earth for a short time, but this has little long-term effect.

Increased greenhouse gas concentrations are the main cause of global warming. Greenhouse gases like CO2, CH4, and water vapor trap the Sun's energy, warming Earth. Since the Industrial Revolution, burning fossil fuels like coal, oil, and gas has boosted greenhouse gas emissions.

For example, CO2 concentration has increased from 280 ppm pre-industrial to around 410 ppm today. CO2 levels are at an 800,000-year high, according to ancient ice cores. This greenhouse gas emissions increase has caused fast warming, especially since the 1950s.

The UN's Intergovernmental Panel on Climate Change (IPCC) and other studies confirm human influence on the climate system is expanding. The IPCC says people are the main driver of global warming, affecting all continents and oceans. Scientists are 95% sure humans caused recent global warming.

A 2014 study stresses the high chance that human-caused greenhouse gas emissions are causing present warming. Less than 1 in 100,000 chances of warming without human impact. These outcomes highlight the necessity for global climate change mitigation and its effects.