Atmospheric CO2 Crosses Danger Threshold, Risking Catastrophic Climate Change
Summary
Atmospheric CO2 levels surpassed 400 ppm last year, a danger threshold risking catastrophic climate change, with unabated emissions potentially leading to 9°C temperature rises by 2250, while even immediate emissions cuts would take millennia to restore pre-industrial CO2 levels.
Key Points
- Last year marked the first time in millions of years that atmospheric CO2 levels surpassed 400 parts per million, a symbolic threshold into a danger zone of climate change.
- If emissions continue unabated, CO2 levels could reach 500 ppm by 2050 and 2,000 ppm by 2250, causing catastrophic temperature rises of over 3°C and 9°C respectively.
- Even if emissions dropped to zero immediately, it would take around 10,000 years for atmospheric CO2 to return to pre-industrial levels of 280 ppm due to the slow natural carbon cycle processes.