Earth’s climate has changed naturally throughout history, leaving evidence in tree rings, glaciers, ocean sediments, coral reefs, and rock layers. Scientists analyze air bubbles trapped in glacial ice to understand past greenhouse gas levels and temperatures, creating a historical record spanning 800,000 years.
Graph showing temperature anomalies from the EPICA ice core in Antarctica.
This paleoclimate data reveals past ice ages and warmer periods, but the current warming trend is significantly faster than previous events. Over the past million years, global temperatures rose 4-7 degrees Celsius over 5,000 years as the Earth emerged from ice ages. However, in the last century alone, the temperature has increased by 0.7 degrees Celsius, about ten times faster than the average ice-age recovery rate.
Modern instrument data combined with paleoclimate records show that current global temperatures are higher than in the past 1,000 years, possibly even longer. Climate models project a 2-6 degree Celsius warming in the next century. Historically, it took the planet approximately 5,000 years to warm 5 degrees. The projected rate for the coming century is at least 20 times faster, representing an exceptionally rapid change. This accelerated warming trend raises concerns about its potential impact on the planet.
