We are presently living in an ice age - The Ice Age. The earth has been in it for at least 2 and a half million years. Glacial ice has covered the northern latitudes some 80 percent of this time with only a few brief interludes every 80,000 to 11,0000 years. This present brief warming interlude we are in now, the Holocene, has already lasted 12,000 years, already a bit longer than the few others. When it ends, the earth is in for thousands of years of glaciers covering New York, Chicago, Scotland and similar latitudes.
Doing the wrong thing (such as pumping cooling chemicals into the atmosphere) could easily trigger this to start. Something always has. It may not affect you, but maybe your grandchildren.