State Indicators

Global CO₂ concentration

CO₂ occurs naturally in the atmosphere; however, its concentration has increased significantly (IPCC, 2007). This increase promotes global warming and thus climate change (Houghton et al., 2000; WRI, 2005; IPCC 2007). The Global atmospheric CO₂ concentration reflects the state of the atmosphere and is an indirect indicator of CO₂ emissions. This indicator is used, among other initiatives, by the OECD and the European Environment Agency (OECD, 2005; EEA, 2009).

Global temperature

Although climate varies naturally, the records and climate models developed suggest that the increase in mean temperature observed since the mid-twentieth century to date is very likely due to higher anthropogenic GHG levels (IPCC, 2007). The IPCC concluded that the total temperature rise for 1850-1899 was 0.76 °C compared to 2001-2005. Eleven of the twelve warmest years since 1850 occurred between 1995 and 2006, 2005 being the warmest year recorded so far (IPCC, 2007). The temperature rise associated with climate change has affected hydrological systems and terrestrial and marine ecosystems in many parts of the world, including Mexico. Some of its effects are: increased frequency, persistence and intensity of the El Niño phenomenon; occurrence of hurricanes and heat waves; increased precipitation in mid and high latitudes in the northern hemisphere; more intense and prolonged droughts in the tropics and subtropics; contraction or expansion of the distribution ranges of a number of invertebrate, fish, insect, bird and plant species; bleaching of coral reefs; earlier onset of flowering in many plant species; and earlier arrival and reproduction of migratory birds, among others (NAS, 2001; Townsend et al., 2002; CBD, 2003; Webster et al., 2005; IPCC 2007). In this context, the indicator Global temperature changes shows the historical changes in one of the climate variables most important  for regulating the general climate; this indicator is supplemented by the indicator Global atmospheric CO₂ concentrations. The former indicator is proposed by the European Environment Agency (EEA, 2009).