Take away most of the atmosphere and the heating and cooling become extreme, just like on the moon. When the sun shines its hot and when there is shade it is cold. The globe is kind of a heat engine.

I searched Google for some data on global air temperatures, and came up with some interesting facts.
The information is from a Journal of Geophysical Research, VOL. 108, NO. D14, 4407, doi: 10.1029/2002JD002670, 2003

If you can get to the beginning of the report, scroll down to the fourth page, you will see two graphs indicating north and south hemisphere ice concentration.
What is very interesting is that there is a very sharp disruption/decrease in the concentration before the year 1950.
It is also interesting that several nuclear bombs were detonated in the atmosphere before the year 1950, and the total amount of radioactive material that such activity dispersed into the atmosphere must have been less than what we now get from leaking nuclear power plants.

Nuclear tests:

http://www.onlinenevada.org/1942_1950:_nuclear_testing_before_nevada

Journal of Geophysical Research:

https://docs.google.com/viewer?a=v&q=cache:B8azutPE96cJ:citeseerx.ist.psu.edu/viewdoc/download?doi%3D10.1.1.172.4502%26rep%3Drep1%26type%3Dpdf+global+air+temperature&hl=en&gl=ca&pid=bl&srcid=ADGEESjywMvI72oyGT-L10FYHpKV7Vg-J8IJjFLtGfHzhnzr1QVzKxxy6gJyEhA5lxh8GS8OlIvEu7Doy5YM3jZCO7dkhE1I1XnBoO_aYhMXO11GdgtmPq6JkfficnbLMaqspd_mwM1F&sig=AHIEtbQh8eJeYj4GHi1eJctYnH6rdHwdOA

Can I say I told you so.