But again, some metropolitan areas have more low - tuition private - school options than others, mainly due to historical variations in religious populations. (educationnext.org)
The climate is always changing - it's natural: The fact that there has been historical variation in temperature and greenhouse gas levels is well known in science. (treehugger.com)
Here too, one can expect that an increase of solar influence, based on historical variations of the last millennium, will lead to a decrease of the influence of CO2, again necessary to fit the temperature trend of the last century in the temperature equation. (realclimate.org)