Climate change is a global phenomenon, but it affects people differently. Wealthy nations, which have produced the most emissions historically, can afford to spend more on climate-related investments and take steps to reduce their own pollution. But they cannot shield themselves from the impacts of warming. The world’s poorest countries will suffer most and have fewer resources to cope with the climate crisis. They will struggle to access healthy food and treatment for respiratory illnesses caused by wildfire smoke. Their homes will be less comfortable and they will have fewer options for moving to safer ground when a hurricane is headed their way.
Human activities are the primary cause of global warming. When fossil fuels are burned, they release greenhouse gases – especially carbon dioxide (CO2) — into the air. These gases act like a blanket, trapping extra heat in the atmosphere and warming the planet. Carbon dioxide has increased to levels not seen in the Earth’s recent history, and other greenhouse gases such as methane and nitrous oxide are also increasing.
The increase in greenhouse gases warms the planet, altering weather patterns, and changing ocean conditions. Temperatures rise around the world, melting polar ice and raising sea levels. The frequency and intensity of extreme heat events is growing, and droughts are becoming more common.
Scientists use data from modern instruments to study the climate, and can also look back further using records such as tree rings and ice cores. These data show that our current climate has become warmer and we are on track for the highest temperatures in a millennium.