evidence: The interconnections between these cycles used to make it hard to show that human-caused climate change was statistically significant and not just another lurch of natural variability. But anthropogenic climate change has since gone well beyond natural variability in weather and seasonal temperatures. The U.S. National Climate Assessment in 2017 concluded that there’s "no convincing evidence for natural cycles in the observational record that could explain the observed changes in climate." [...] Earth’s orbit wobbles as the sun, the moon and other planets change their relative positions. These cyclical wobbles, called Milankovitch cycles, cause the amount of sunlight to vary at middle latitudes by up to 25% and cause the climate to oscillate. These cycles have operated throughout time, yielding the alternating layers of sediment you see in cliffs and road cuts. [...] Today Earth is approaching another minimum of northern sunlight, so without human carbon dioxide emissions we would be heading into another ice age within the next 1,500 years or so.