Geological evidence indicates that Earth's current rate of temperature increase is faster than any period in the planet's history, excluding the aftermath of the asteroid impact 66 million years ago.
Key facts
- •Atmospheric carbon dioxide levels have risen faster in the last two centuries than at any time since the asteroid impact 66 million years ago.
- •The current rate of temperature increase is at least 20 times faster than the warming observed at the end of the last glacial period.
- •A return to Late Pliocene conditions would involve CO2 levels between 330 and 400 ppm and sea levels 15 to 25 metres higher than today.
- •Miocene-era conditions, occurring 15 to 17 million years ago, featured temperatures 6ºC to 8ºC above 1800s levels.
- •Satellite data confirms a rapidly escalating energy imbalance on Earth, supporting the possibility of extreme long-term warming.
Earth is currently experiencing a rate of climate heating that exceeds any documented in the geological record, according to analysis of sediments, ice sheets, and ancient life. While the planet has been hotter in its 4.6-billion-year history, the unprecedented speed of the current temperature rise poses a unique challenge. This rate of change is estimated to be 10 times faster than the Palaeocene-Eocene Thermal Maximum and at least 20 times faster than the end of the last glacial period.
By the numbers
Comparing current trends to deep time
Researchers use geological records to identify potential climate analogues for the future. Over the last 50 million years, the planet generally followed a cooling trend, which is now being reversed. If emissions peak by 2040 and decline, models suggest the climate could shift to a Late Pliocene state, characterized by temperatures 2.5ºC to 4ºC above pre-industrial levels and sea levels 15 to 25 metres higher. Pliocene-like conditions could emerge in continental heartlands as early as the 2030s.
Risks of higher emissions and feedback
Failure to control emissions or the influence of natural feedback loops could drive the climate back to conditions seen 15 to 17 million years ago during the Miocene. During that era, temperatures were 6ºC to 8ºC above 1800s levels, with sea levels potentially 50 metres higher than today. Satellite observations of Earth's energy imbalance suggest that even more extreme scenarios, such as a return to the early Eocene hothouse conditions, remain within the bounds of possibility, which would render much of the world uninhabitable for humans.
Advertisement
This article was independently rewritten by ManyPress editorial AI from reporting originally published by New Scientist.
