Human industrial and agricultural activity, CO2 is increasing 100 times faster than at any time in the past 800,000 years, because humans in the modern day are burning fossil fuels and forests and are producing cement which all emit CO2.
The orbit has an effect on climate by determining the amount of incoming sunlight. The cycle of ice ages are linked to changes in the earth's orbit, so they are important to the long-term climate variability of the earth. Using this model we can predict the future of earth's climate based off of data.