June 9, 2014
#1379: 4.5 Degrees
Without prompt, aggressive limits on CO2 emissions, the Earth will likely warm by an average of 4°-5°C by the century’s end.
How big a change is that?
[[The panel shows a temperature scale.]]
In the coldest part of the last ice age, Earth’s average temperature was 4.5°C below the 20th century norm.
Let’s call a 4.5°C difference one “Ice Age unit.”
((These are along the time line, spaced out for clarity.))
-2 IAU
<– snowball Earth (-4 IAU)
-1 IAU
20,000 years ago
((There’s an inset panel, showing a picture of a glacier.))
My neighborhood:
Half a mile of ice
0
Average during modern times
((Another inset panel.))
[[A character is in the foreground of a green field with a skyline in the distance.]]
My neighborhood:
Character: Hi!
0.20
Where we are today
+1 IAU
Where we’ll be in 86 years
((Another inset panel.))
My neighborhood:
?
+2 IAU
Cretaceous hothouse
+200m sea level rise
No glaciers
Palm trees at the poles