Table 1.

Likelihood statistics, AIC, and BIC for different time series models (cf., Fig. 3) describing the sea ice extent (1979–2010)

Model	Mean	Std. Error	No. of parameters	−2log(L)	AIC	BIC
0	Constant	Constant	2	84.54	88.54	90.73
1	Linear	Constant	3	47.52	53.52	56.79
2	Linear	Linear	4	44.59	52.59	56.96
3	Segmented	Constant	5	37.21	47.21	52.67
4	Segmented	Segmented	7	35.72	49.72	57.36
5	Step change	Constant	4*	53.30	61.30	65.67
6	Linear	Step change	5*	42.34	52.34	57.80
7	Segmented	Step change	7*	31.76	45.76	53.39

The number of parameters in the step change models (Models 5, 6 and 7, marked with asterisk) included one parameter degrees of freedom for the year of the step change, although this year was not estimated as a free-floating parameter in the same manner as other parameters