The following graphs show that Earth is in a brief period of global warming called an interglacial. The longer time spans, the deep troughs are glacial periods. The line that runs across the graphs is the temperature in 1950 and listed as "0" on the left axis.
As can be seen in the last graph (Figure 1-5), Earth appears ready to move toward another ice age in the cycle.
I'm more concerned with sustaining global warming to offset global cooling and the next ice age.
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Ice Ages & Astronomical Causes |
This first graph looks bad, doesn't it -- steeper upward temperature trend. Horizontal red line is temperature at 1950.
Figure 1-1 Global warming
The second graph shows today's temperature isn't out of the norm. Horizontal blue line is temperature at 1950.
Figure 1-2 Climate of the last 2400 years
The next graph shows a downtrend in temperatures from 8,000 years ago to today. The down trend is steeper in the recent 2,000 years. From left to right the upper spikes have lower highs while the lower spikes have lower lows. (The same effect can be seen in Figure 1-2, above.)
Figure 1-3 Climate of the last 12,000 years
This graph shows that agriculture and stationary societies emerged 8,000 years ago during a time frame when global temperature was much higher than normal, or average.
Figure 1-4 Climate of the last 100,000 years
The next graph shows that the recent 8,000 years was one of five brief hot spikes when glaciers were at minimums. With much longer troughs when glacials (ice ages) were the norm most of the time.
Figure 1-5 Climate for the last 420 kyr, from Vostok ice
The graph below is reversed. That is, the left side is present day and the right side is 3 million years ago. It shows a 3 million year down trend toward widening extremes in the temperature cycle.
Figure 1-6 Climate for the last 3 million years