1
$\begingroup$

We are living in a historical period of global warming since about 20,000 years ago. This global warming period is one of about ten in human history. Those periods may very well be forced to start by optimal orbital conditions, but seems to develop rapidly by amplifying feedback from carbon dioxide and other greenhouse gases. Typically, the warming peek is very spiky at a rate of carbon dioxide slightly below 300 ppm. The probability that this peek is correlated to actual orbital forcing seems to me therefore very low.

Strong extratropical cyclones are known since before the extraordinary ppm values of today, at lower warming rates than the typical warming peaks. The enormous amount of energy from (historical) global warmings did partly result in kinetic energy in storms. I think this is demonstrated in the increasing damage from tropical storms and my question is if there are reasons why extratropical cyclones in future, nearer the peek, not could change the albedo by clouds and snow/ice to a rate that turn global warming into cooling?

My question isn't about the actual rate of carbon dioxide, but about the cycles that preceded our glacial period. Neither the question concern orbital forcing as such, but the possibility that a period of very bad weather with much snow in the north at least for some time (centuries) can cause global cooling.

enter image description here

Below the extratropical cyclone Oratia in western Europe in October 2000:

enter image description here

Improve this question
$\endgroup$
8
  • 2
    $\begingroup$ While clouds may have a negative impact on global irradiation due to their albedo, this is strongly countered by their reflectiveness when it comes to infrared/thermal radiation. E.g.: A cloudy night is warmer than a cloudless one, since without clouds the warmth "bleeds into space". $\endgroup$
    – Erik
    Commented May 6, 2019 at 8:50
  • $\begingroup$ @Erik: yes but global cooling seems to be a "chaotic" process in progress of up to 100,000 years. The "termos effects" at nights just slower the process down, while the increasing albedo decrease the insolation. $\endgroup$
    – Lehs
    Commented May 6, 2019 at 9:07
  • $\begingroup$ Re The probability that this peek is correlated to orbital forcing seems therefore very low. Exactly the opposite. It is very high. You are leaping to conclusions. $\endgroup$
    – David Hammen
    Commented May 6, 2019 at 10:49
  • 2
    $\begingroup$ The southern hemisphere is mostly water. It's the northern hemisphere that counts with regard to whether a glaciation will start or stop. Glaciations start when summertime temperatures (the standard proxy is the mean temperature at 60° north latitude in July) drop low enough for snow to last through the summer in northern Eurasia and northern North America. Once this happens the Earth begins to switch from an unglaciated to a glaciated state. $\endgroup$
    – David Hammen
    Commented May 6, 2019 at 10:57
  • 1
    $\begingroup$ The transitions have multiple positive feedbacks. Positive feedbacks in general are a bad thing. (Think of the squealing loudspeaker when the announcer says "Testing, testing".) The increased snow cover increases the Earth's albedo, reducing the amount of heat absorbed from the Sun. The colder temperatures increase the oceans' ability to dissolve carbon dioxide, reducing the greenhouse effect. Both result in even more snow, and eventually more ice. When orbital conditions revert so the July temperature at 60° N rise above 0° C, the reverse happens, but even more quickly. $\endgroup$
    – David Hammen
    Commented May 6, 2019 at 11:05

0

Reset to default

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.