Whatever you hear or read about "global warming" or "climate change" you should know something about the "solar sun-spot cycle" that happens on average every 11.2 years. The number and size of spots on the sun build up to a maximum and gradually diminish over a period of 11.2 years. Quite simply, sun-spots are whirlpools on the surface of the sun. The whirlpools draw in cooler surface material of the molten Sun, exposing the hotter underlayers. Vancouver has been, in my lifetime, in a position to see the effects of the sunspot cycle much more dramatically than most I suppose, since the 11.2 year variability of the sun is enough to either cause heavy snow in Vancouver's moist climate or rain fall.
Earth's distance to the Sun affects the amount of insolation received by the earth. The earth's orbit is an ellipse (an oval) around the Sun, not a circle. If you remember high school geometry you know that an ellipse has two foci. The Sun sits at one focus and the earth orbits around both foci. Therefore, the earth's distance to the Sun varies during the year. For a person's lifetime, the earth is very nearly the same distance to the Sun on the same date as preceding years. For much longer periods of time as the ellipse processes (rotates) around the Sun, the earth will be either closer or further from the Sun during the same season each year. Another thing is the tilt of the earth's axis varies a little bit, a few degrees, also over fairly long periods of time, but not on the same schedule. Without a tilt there wouldn't be any seasons at all. Too much tilt there would be extreme heating and cooling during the year. The other thing is that the land mass of the northern hemisphere is so much greater than that in the southern hemisphere. Snow can accumulate only on land and if these things conspire to make summers in the northern hemisphere cool enough, the snow won't melt and an "ice age" comes on from the northern hemisphere that affects the whole planet. Equally likely, these things can conspire to melt an ice age that some writers say that the earth is still in, since Antarctica and Greenland are in ice all year. On the longest schedule of all, the earth's continents drift about. Evidently there was a time when most of the land mass was around the equator. Was never any accumulation of snow and never any iceage at all for enormously long periods of time--hundreds of millions of years. In the recent past, currently about every 10,000 years.
An ice-age begins with snow remaining during summer months. The white snow reflect the Sun's heat preserving the snow. The snow pack builds up each year, compressing into icy glaciers. Melting glaciers strip landscape down to boulders and multiple lakes, as seen in northern Ontario and northern Manitoba. These days apparently, the Canadian arctic ocean is in retreat and the tree line is pushing north into the permafrost. As the temperature difference drops between the Arctic and where most everybody lives, the "Jet Stream" slows down. The Jet Stream is a fast current of air up about 10,000 metres usually traveling in nearly a straight line, west to east around the globe, dragging the changes of the weather along from day to day. However, as the Jet Stream slows with diminished temperature difference between the upper and mid latitudes, the Jet Stream meanders. At some longitudes going from north to south dragging cold air from the Arctic and at alternating longitudes dragging warm air northward, for example the Chinooks of Alberta. The meander may even stall unusually long periods bringing prolonged warmth to northern latitudes and cold to others. Recall that Toronto was playing golf all one December and by February in deep snow. On an entirely different schedule is the El Nino, the southern oscillation of warm and cold current in the Pacific Ocean that can bring either warm or cold air currents northward. Looks like quite a few folks in the NOAA, the National Oceanic and Atmospheric Administration in the United States have quite a career fitting all the different weather and climate parameters together to make a prediction without even looking at carbon.