There are many of us that think the ocean currents are the primary cause of the climate changes in the north hemisphere. a long cycle of 1000 to 1100 years and a short cycle of 60 to 70 years. These cycles match up with the medieval warm period, the little ice age and current swings of 60 years. If a small amount is added for CO2 using the more current 1.0 degree C doubling almost all the current temperature movements shown by NASA.NOAA can be modeled. .