Climate Change: Detection and impacts

Although global warming has been ongoing for decades, monitoring and detecting climate change remain important task, as evidenced by the abrupt warming of 2023/2024 that caught even scientists by surprise. When will we reach 1.5 °C of global warming above pre- -industrial levels? How unusual is the current temperature from a long-term perspective, and how unusual are current climate extremes? This paper summarizes the challenge of climate change detection over the past 50 years as well as the past 300 years. The paper addresses recent global trends in thermodynamic quantities, as well as longer-term regional trends in temperature and in atmospheric circulation, highlighting the difference between dynamic and thermodynamic quantities with respect to trends. The paper briefly presents historical climate reconstructions that could help in climate change detection and summarizes the global impacts of climate change.