Human activities and global warming: a cointegration analysis*

Using econometric tools for selecting I(1) and I(2) trends, we found the existence of static long-run steady-state and dynamic long-run steady-state relations between temperature and radiative forcing of solar irradiance and a set of three greenhouse gases series. Estimates of the adjustment coefficients indicate that temperature series is error correcting around 5e65% of the disequilibria each year, depending on the type of long-run relation. The estimates of the I(1) and I(2) trends indicate that they are driven by linear combinations of the three greenhouse gases and their loadings indicate strong impact on the temperature series. The equilibrium temperature change for a doubling of carbon dioxide is between 2.15 and 3.4 (C, which is in agreement with past literature and the report of the IPCC in 2001 using 15 different general circulation models.