Similarly to the PETM, we are now seeing an increase in atmospheric greenhouse gas concentrations. In the figure below, taken from the Climate Trends learning tool, the large spike in methane concentrations in recent years is barely visible. You can, however, clearly see a correlation between temperature and methane concentrations.

To better see this spike, open the Climate Trends learning tool and select methane from the graph options. Click and drag a section of the graph to zoom in so that you are viewing data for the past 250 years. You can see the concentration of methane is much higher in recent years than any historical concentrations on record!

This tool does not extend all the way back to the PETM. However, we can still use it to compare the rate of temperature increase during the PETM with that of today.

Question: Which has a greater rate of temperature increase, the current period of warming or the warming of the PETM?

During the PETM, temperature increased by about 6°C over a 20,000 year period. To determine the rate of change, divide 6°C by 20,000 years to get 0.0003°C/yr.

Open the Climate Trends learning tool again. Go to the last 250 years and click on the calculate slope option at the top to access the slope tool. Use this to determine the rate of temperature change over the past 250 years. The approximate rate of change is 0.004 - 0.008°C/ yr. This is over ten times the rate of temperature change during the PETM!