Table 2. Result of the principal factor analysis for 91 economies.

		Factor loadings‡
Variables†		1	2	3	4
Gross domestic product		0.971	−0.113	0.023	−0.133
Imports of goods and services		0.961	−0.048	−0.052	−0.162
Services, etc., value added		0.960	−0.167	0.013	−0.138
Industry, value added		0.956	0.023	0.042	−0.144
Energy use		0.945	0.244	0.065	0.145
Railway		0.922	0.050	0.072	0.309
International tourism, receipts		0.917	−0.116	−0.038	−0.130
International migrant stock, total		0.917	−0.202	−0.079	0.172
CO2 emissions		0.908	0.337	0.068	0.140
Exports of goods and services		0.898	0.039	−0.075	−0.169
Roadway		0.889	0.081	0.218	0.084
International tourism, expenditures		0.885	−0.091	−0.103	−0.186
Other greenhouse gas emissions, HFC, PFC and SF6		0.874	0.331	−0.022	0.116
Airports		0.856	−0.265	0.194	0.186
Energy production		0.803	0.319	0.091	0.430
Net migration		0.742	−0.482	−0.260	0.122
Nitrous oxide emissions		0.705	0.526	0.363	0.150
Methane emissions		0.681	0.542	0.273	0.350
Agricultural land		0.569	0.380	0.413	0.396
Population, total		0.392	0.852	0.223	0.091
Agriculture, value added		0.677	0.691	0.211	0.017
Plant species (higher); total known		0.204	0.132	0.872	0.185
GEF benefits index for biodiversity		0.465	0.080	0.817	0.213
Species, total known		0.410	0.341	0.795	0.074
Forest area		0.410	−0.021	0.245	0.828
Land area		0.508	0.147	0.253	0.772
Waterway		0.461	0.512	0.204	0.610
Rotated sums of squared loadings§	Eigenvalues	15.981	3.145	2.902	2.631
	% of variance	59.190	11.649	10.748	9.746
	Cumulative %	59.190	70.839	81.587	91.333

^†Refer to Table S2 for details and units.

^‡Extraction method was Principal component analysis.

^§Rotation method was Quartimax with Kaizer Normalization.