When Ice Extent on Earth is low, when the oceans are warm, when Polar Oceans are thawed, much more water is exposed to the fierce Polar Winds and becomes available for clouds, rain and snow.
When fierce winds make the water surface turbulent, the effective water surface area exposed to the atmosphere is multiplied many times. The snowfall and the ice accumulation is huge in these times. Ice advances after this and this increasing Albedo does cool the Earth.
When the oceans are cold and Polar Oceans are covered with ice, much less water is exposed to the fierce Polar Winds and does not become available for clouds, rain and snow. The snowfall in these times does not replace the ice that is melted by the sun in every warm season. Ice retreats after this and this decreasing Albedo does warm the Earth.
This simple explanation shows why temperature has been tightly bound in the same bounds for ten thousand years and why A Roman Warm Period was followed by a cold period and why that was followed by the Medieval Warm Period and why that was followed by the Little Ice Age and why that was followed by this Modern Warm Period and why this warm period will be followed by another cold period. This cycle is between 800 to 1000 years and has repeated for ten thousand years in the same bounds.
This is what the data does show did happen before and is happening now.
The oceans are warm, the Polar Regions did open, and the snow has started falling. This increased snowfall will continue until the oceans cool and the Polar Oceans do freeze and turn off the increased snowfall.
You should not look at and curve fit a century of data and use that to predict a climate that has a thousand year cycle that you ignore.
A lot of effort has gone into identifying the cycles of sixty years and less.
Very little effort has gone into identifying the cycles of more than sixty years.
The Little Ice Age Happened after the Medieval Warm Period. The sun did not change that much. The CO2 did not Change much. Ice Extent changed a lot. It did not get cold and start snowing. It started snowing when it was and because it was warm and Polar Oceans were thawed.
It did get cold after that snow piled up and advanced.
It really is that simple.