The yellow bars are interglacial periods. The larger white regions in between are glacial cycles, aka ice ages.
These cycles are driven by slow variations in the Earth's orbit.
These glacial–interglacial cycles have waxed and waned throughout the Quaternary Period (the past 2.6 million years). Since the middle Quaternary, glacial–interglacial cycles have had a frequency of about 100,000 years (Lisiecki and Raymo 2005). In the solar radiation time series, cycles of this length (known as “eccentricity”) are present but are weaker than cycles lasting about 23,000 years (which are called “precession of the equinoxes”).Here are my amateur observations from the chart.
Long-term cosmological cycles are much more important that what humans have done so far.
We are overdue for another ice age.
Current CO2 levels are high, but the biggest increases were 10-15k years ago, long before humans could have influenced the climate.
As these slow variations appear to be exceptionally important for glaciation, climate, and life on Earth, the Earth's orbit must be finely-tuned for human life.
If the long-term trends hold up, we have more to fear from cooling than warming. However, if catastrophic greenhouse gas emissions cause runaway warming, then this chart tells us nothing about the future.
I am not a climate expert, and I do not know whether greenhouse gases are a problem. They probably are. I just want to understand the physics. It seems possible to me that the Industrial Revolution put out just enough CO2 to postpone an ice age.