Easterling & Wehner (2009)
Also: Easterling & Wehner 2009
Is the climate warming or cooling?
Easterling, D. R., & Wehner, M. F. (2009). Is the climate warming or cooling?. Geophysical Research Letters, 36(8). Link to paper
DOI: 10.1029/2009GL037810
References
All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.