re: NYC was drowned in snow today, some global warming huh?

One of the warnings we have been bombarded with is that once the glaciers and snowpack start to melt and retreat, less sunlight is reflected back into the atmosphere thereby increasing the warming of the planet. This is due to the fact that white reflects and dark absorbs heat. It does not matter how "deep" the white objects (glaciers and snowpacks) are, merely their extent. If more of the northern hemisphere is covered with snow, does that not lower the prospective temperature? Is there a tipping point that we do not understand because we have not been around on the planet all that long in historical terms? The Great Lakes are only about 11,000 years old. Around the dawn of civilization in a geological sense . Are we missing something important? I mean it may only take less than a century of unusual snowfall to bring about radical cooling. Winter only has to be below 32 degrees for it to happen. Who knows?