The interglacial period almost 100,000 years ago, with height maybe 4 degrees C warmer than the 20th century was, significantly (but did not completely) melt Greenland's icecap / "ice sheet".
Forecasts only mildly on the alarmist side of AGW projections are that we will get that warm again or a bit worse within a couple centuries, and urban/industrialized areas having a lot of industry and at least a couple hundred million people will have to move inland/uphill to extent of maybe
6-7 meters uphill.Should Antarctica thaw out (more far-fetched, likely requiring global warming by 6 maybe 7 degrees C), sea level rises much more - something like 180 meters.
If Greenland thaws out while Antarctica does not (or does not do so until much later), or even if sea ice and snow cover decrease bigtime and do so disproportionately in the Northern Hemisphere, zonal weather trend zones especially the "intertropical convergence zone" (ITCZ) shift northward. In a more extreme case, summertime "monsoon" of Yucatan gets more extreme and moves northward to late-summer position anywhere from Mexico City latitude to Rio Grande area (and westward). South Texas in such more extreme case becomes like northern India. Precipitation increase in semiarid-to-desert areas in central/northern Mexico and nearby parts of SW USA may allow new agricultural opportunities. Canada and other northern nations stand to gain increase of agricultural opportunities due to shorter/milder winters. Southern Europe and similar regions of Asia could get a bit more semi-arid and/or more heatwave-prone, and southern/western portions of USA's "breadbasket" region could long-term become more like what befell much of central USA around 1931-1936 or so.
I would suggest that the USA "states" of Texas and New Mexico look into agricultural opportunities for increased rainfall and humidity in semi-arid to arid areas farther south and southwest where weather pattern shifts from Arctic-concentrated global warming have "some fair chance of accomplishing such" (my words).
- Don Klipstein ( snipped-for-privacy@misty.com)