Do natural climate cycles disprove that modern global warming is caused by humans?
During Earth’s last glacial period between 120,000 and 11,500 years ago, a number of approximately 1,500-year temperature cycles occurred. Also known as Dansgaard-Deschger events, the cycles caused a transfer of heat between the northern and southern hemispheres, producing a “seesaw effect”: when one hemisphere cooled, the other warmed.
The climatic change of modern times is not a heat transfer within our climate, but an overall temperature increase across the globe. It has been understood since the 19th century that atmospheric gases such as carbon dioxide trap heat. After not exceeding 300 parts per million for 800,000 years, atmospheric CO2 has spiked due to human activities since the Industrial Revolution, reaching 416 parts per million in February 2021. Temperatures have climbed also: the global average temperature has risen one degree Celsius since 1880.
