How can global warming lead to an ice age, can anyone help me?

The cooler summer temperatures are responsible for ice-age.

Now let's examine how this can occur.

These drastic climate changes occurs when Earth distances away from the sun, decreasing the amount of solar radiation Earth is exposed to.

Q: What happens in summer?
A: Summer temperatures are at a low, and snow from the winter piles on the ground annually as there is insufficient solar radiation to melt the snow.

Q: How does the accumulation of snow affect the climate?
A: More snow on the ground will lead to colder climates, as snow will reflect heat & light. Eventually, layers of ice-sheets will form. This marks the beginning of ice-age.