Thermal equilibrium for the last 10,000 years is shown as zero W/m2, ice ages around minus
six.
For the past million years, the natural cycle has oscillated between warm periods and ice
ages.
Milankovitch cycles initiate these natural changes.
Changes in the distribution of sunlight alter seasons,
greenhouse gas concentration,
ice cover, and ocean temperature.
Lately, natural cycle produces a warm period 'about' every hundred thousand years.
We came out of the last ice age 10,000 years ago.
In the natural cycle Earth should gradually cool,
descending ultimately into another ice age thousands of years from now.
Instead, we are warming.
Increased greenhouse gas concentrations, have increased climate forcing.
Total positive forcing is estimated around 3.6 W/m2 above thermal equilibrium.
Higher than it has been for millions of years.
The climate system has left the path of natural cycle,
we are warming,
and the warming is accelerating.
