Seems there's some debate about that and the article didn't actually cite any resources to back it up. According to the end of this National Science Foundation

Seems there's some debate about that and the article didn't actually cite any resources to back it up. According to the end of this National Science Foundation article [1], it depends on the type of cloud. Contrails are maybe analogous to cirrus clouds, which block more thermal energy from the ground than they reflect back into space. [1] https://www.nsf.gov/news/special_reports/clouds/question.jsp https://www.nsf.gov/news/special_reports/clouds/question.jsp