Climate Change is the increase in Earth’s average temperature caused by human activity, mostly burning fossil fuels. The consequences are global – rising temperatures cause oceans and forests to heat up, melting polar ice caps and coral reefs, and drying up freshwater supplies. But it’s local too, affecting people, communities and the things they depend on for survival like food, water and jobs. From polar bears in the Arctic to marine turtles off Africa, every corner of the planet is at risk as the climate continues to change and natural disasters become more frequent.
The Earth has warmed and cooled before, and the science is clear. Over millions of years, the planet’s temperature has varied in lockstep with changes in solar energy, volcanic activity, and the amount of greenhouse gases in the atmosphere. But for the last 150 years, human activities have been adding to and accelerating those natural changes.
We know that Earth is warming because of long-term records from land and sea-based weather stations, ships at sea, satellite measurements, and other sources. While some skeptics have raised concerns about the accuracy of these data, they are regularly checked for accuracy and other factors. For example, weather stations located near cities tend to be hotter than those farther away, but this is taken into account by researchers.
Over the last century, Earth has warmed by 1.98degF offsite link (1.1degC) and is continuing to warm. This warming is caused mainly by human activities, particularly the emission of carbon dioxide from burning fossil fuels like coal, oil and gas. This is a large addition to the carbon dioxide that has naturally been cycling in and out of the air over many thousands of years as plants absorbed and released it during photosynthesis.
Other factors can influence climate as well, such as orbital variations and the growing or melting of ice sheets and glaciers. However, they are smaller and do not occur as frequently as the warming from humans.
Climate change is a global problem, but the people who are most affected by it live in low-income and disadvantaged countries and communities. They contribute least to its causes and are often the first to feel its effects – such as increased heat-related deaths from exposure to high temperatures, more disease outbreaks because of warmer conditions, and losses from flooding, droughts and wildfires. People who are most vulnerable to climate changes also have less access to resources to adapt or cope with them. These are the people who need help from others to protect themselves and their families, and to improve their living standards and economic opportunities. The best way to tackle climate change is through bold collective action. It’s time to stop business as usual.