Increase of Methane

University of Bristol, University of London, Department of Geology, Palaeontology Dept Lead Authors: Richard D. Pancost, David S. Steart, Luke Handley
Where Published: Nature

if the processes occurring at Cobham were widespread, then the increase in
methane emissions could have caused further warming, amplifying the climate
change at this time.

article

abstract

Methane Fueled Ancient Global Warming

University of Bristol
Lead author: Richard Pancost
Where published: Nature

Huge belches of methane from bogs in what is now Britain likely contributed to global warming some 55 million years ago ... The finding adds weight to the idea that methane being released from wetlands today may accelerate modern global warming.
...
Methane already appears to be seeping out of once frozen bogs in Siberia.

article

Increase In Atmospheric Moisture Tied To Humans

Lawrence Livermore National Laboratories
Lead author: Benjamin Santer
Where published: Proceedings of the National Academy of Sciences

The atmosphere's water vapor content has increased by about 0.41 kilograms per square meter (kg/m²) per decade since 1988, and natural variability in climate just can't explain this moisture change. The most plausible explanation is that it's due to the human-caused increase in greenhouse gases.
...
More water vapor -- which is itself a greenhouse gas -- amplifies the warming effect of increased atmospheric levels of carbon dioxide.

article