Surface observations made at weather stations and onboard ships, dating back over a century, provide the longest available records of cloud cover changes. (ipcc.ch)
In the tropics, the prime reason for the diversity of response is associated with the models» cloud cover changes as climate warms. (giss.nasa.gov)
Resolving how much each contributed to ongoing cloud cover changes is an area for future work, he says. (sciencemag.org)