The sun's maximum declination is responsible for Earth's seasons. It has been continuously decreasing. In 515BC it was measured by Pythagoras to be 24.0 degrees. The Nautical Almanac for 1984 shows the maximum declination to be 23.442 degrees, while by 2016 it had decreased to 23.435 degrees. The global warming people are trying to blame on carbon emissions is actually the result of a decreasing axis tilt which is causing Earth to become more tropical.