"I'm wondering how that lower heating bill will look when crops start failing globally and you can't afford food?"

A way to look at lowering heating bills is that a people are either lowering the amount fuel they using {and btw, reducing a significant source of CO2 emission] Or there is more availiblity of supply of the heating source [and therefore unit cost is usually at a lower price].

And if one uses the scientific meaning of global warming then global warming is a very essential element that allows a significant amount of the crops to be grown at the present time.

If it were humanly possible to cut a significant amount of CO2 in the atmosphere and therefore humans were to somehow remove more than 1/2 of the CO2 from the atmosphere, the result would that plants would be starved from the lack of CO2- plant growth in general would be significantly stunted- crops would "start to fail" [as though crop failure weren't part of very long history and it was something that was going be "started"].
Conversely if it were humanly possible to significantly increase the amount of global CO2 and therefore humans were to somehow more than double the present level of CO2, then plant growth would increase- there would still be instances of crop failure, but annual average crop yield would increase.

Now, there is absolutely no basis to link the present global warming with amount of global CO2- sea level hasn't risen over 100 meters over the last hundreds of centuries because of increasing or decreasing levels of global CO2.
I mentioned CO2 only because the public in general has been given a lot of misinformation that attempts to connect increasing levels of CO2 with "Global WARMING".

When talking about global or regional average temperature increase or decreases the most significant variance is nite time and winter temperature. In other words if the nites are cooler and winters are cooler, then that reflects a cooling trend. If nites and winter are warmer, this is said to be a warming trend. It doesn't need to be said, but in last 10,000 year the nites and winter have been warmer than compared to the earlier 10,000 year period. And the biggest difference is in the temperate and arctic regions of the world- global warming or cooling is NOT "about" differences in summer and daytime temperatures, Or changes of average temperatures in the Tropics

When you are farmer in Kansas or any other temperate region in the world, the factor determining when you plant a crop in related to how cold the nite will be- generally the eariler in the year you plant your crop the better, as long as it's not so earier that the frost kills your crop. Therefore generally speaking, global warming results in longer growing season for temperate regions, and global cooling would result in shorter growing seasons or areas in which is too cold to commerically grow crops [which aren't in a greenhouse]. E.g Southern California is a great place to grow crops because it's warmer than most places in the US and has a long growing season- allowing 2 or more crops to grown per year.

The tropics are not affected much by swings in global temperature [long term cooling or warming treads] but it's likely that the region of the tropics has much to do with causing global temperature changes- because it's the region in which gets most of the sun's energy.
The most significant part of the tropics [in terms of global temperature] is it's ocean area- which recieve, absorb, and retains the majority of the sun's energy, and distributes this energy globally.
In comparison between land and ocean, the ocean is far greater factor in regards to warming the planet. In regards to the atmosphere, water in the air is the most significant greenhouse gas- but the oceans of the world is a bigger factor in global air temperature than the earth's atmosphere.
The combination of high humidy and the tropical oceans is the earth's furnace.