New Study Reveals Ancient CO2 Levels and Their Influence on Climate
A groundbreaking study conducted by a consortium of over 80 researchers from 16 nations has provided a comprehensive review of ancient atmospheric carbon dioxide (CO2) levels and their corresponding temperatures. This study, which covers geologic records spanning the past 66 million years, has put present-day atmospheric CO2 concentrations into context with deep time, offering valuable insights into the Earth’s climate.
One of the key findings of the research is that the last time atmospheric CO2 consistently reached today’s human-driven levels was a staggering 14 million years ago. This discovery pushes back the timeframe much further than previously believed. Moreover, the study suggests that long-term climate is highly sensitive to greenhouse gases, with cascading effects that may evolve over many millennia.
While mainstream estimates predict that every doubling of atmospheric CO2 will drive average global temperatures 1.5 to 4.5 degrees Celsius (2.7 to 8.1 degrees Fahrenheit) higher, recent studies argue that the current consensus underestimates planetary sensitivity, indicating warming rates of 3.6 to 6 degrees Celsius per doubling. All estimates, however, put the planet dangerously close to or beyond the 2-degree warming threshold that many scientists agree we must avoid.
The research highlights that current CO2 levels have already surpassed those of the late 19th century, resulting in a rise of approximately 1.2 degrees Celsius (2.2 degrees Fahrenheit) in global temperatures. By analyzing published studies and recalibrating others using the latest analytical techniques, the researchers have calculated a new 66-million-year curve of CO2 versus temperatures. Their analysis concludes that a doubling of CO2 is predicted to warm the planet by 5 to 8 degrees Celsius.
Furthermore, the study emphasizes that Earth system sensitivity goes beyond the immediate greenhouse effect of CO2, taking into account factors such as melting ice sheets, changes in plant cover, and atmospheric aerosols. This comprehensive approach provides crucial observations for climate modelers trying to predict future climate, aiding in distinguishing between short-term and long-term processes.
The study also confirms that CO2 concentrations were high during the distant period from about 66 to 56 million years ago, indicating that variations in CO2 affect not only climate but ecosystems as well. Notably, CO2 levels were last consistently higher than they are today around 16 million years ago. Around 14 million years ago, they dropped to today’s human-induced levels. This decline continued, and approximately 2.5 million years ago, CO2 levels reached a point that initiated a series of ice ages.
The researchers underline that regardless of the exact degree of temperature change, the planet is currently experiencing conditions never seen by our species before. This calls for reflection and consideration of the path forward. As the study provides robust observations and insights into climate changes over hundreds of thousands of years, it will undoubtedly prove invaluable for climate modelers attempting to predict future climate patterns.
In conclusion, this groundbreaking study sheds light on the intricate relationship between CO2 levels and their impact on global temperatures throughout history. With current CO2 concentrations surpassing those of the late 19th century, urgent action is required to mitigate further warming and preserve the planet for future generations.
“Infuriatingly humble tv expert. Friendly student. Travel fanatic. Bacon fan. Unable to type with boxing gloves on.”