What Is The Maximum Extent Of Pleistocene Ice In North America

When the northern hemisphere was locked in the throes of the last ice age, what was the climate in the equatorial and southern regions of the earth?

We’re still in an ice age, so checking out the what the weather generally is at some place during some season on the current Earth gives at least one indication of how things would have been in a similar environmental at some time in the recent past, a few million years.Otherwise, the answer depends in large part on if we were looking at things during an interglacial, like we’re in now. (Average globally, +4 °C or thereabout, depending on where in the thousands of years one was looking) Or if we were in a glacial period, unlike now. (Average globally, -8 °C or thereabouts, depending on when in the tens of thousands of years one was looking)In general, much of the time in the last few million years has no direct data. Although some would argue proxies are direct. Yet either way what we have are mostly not measured at the time they occur or nearly so, in the ways a thermometer would. Beyond such nuances, anything before about fifty thousand years ago would have been made by humans that were not behaviorally modern. Either way there’s not much in the way of measurements or photographs etc.However, there are those proxies (ocean sentiment, ice cores, tree rings, etc) that suggest things. That the equator and for some amount of latitude north and south, it would have been “warmer”, and farther north and south “colder” during a glacial period to give that planetary average of some 6 °C or so. Then when in an interglacial period, the warmer would go farther north and south, and the colder less far towards the equator, than it was, to give that planetary average of some 18 °C.A simpler answer is that when it’s colder overall, the area of warmer doesn’t extend as far in upper latitudes. Warmer and colder being comparative terms. Upper latitudes being higher numbers either north or south.

What's the evidence for either past gradual or relatively rapid climate change from glacial to interglacial periods? How does that evidence compare to the current rates of change? I read that today's rates are unprecedented, is this true empirically?

Climate Change is both natural and man-made. It is part of the earth’s natural rhythm. For example, the glacial-interglacial cycles that we generally refer to as ice ages are result of minute shifts in the earth’s orbit. These climate change cycles are very slow. In contrast, the current human-caused warming is happening rapidly.Take the latest ice age, the cooling period (the glacial period) started about 125,000 years ago and lasted until 22,000 years ago, when there was the maximum extent of ice cover. Then the warming period (the interglacial period) began and the Earth is at its warming maximum now.The average cooling rate during this last glacial period—about 10 degrees Celsius over 100,000 years—is about 0.01 degree of cooling per century. The average warming rate during the interglacial period—about 10 degree Celsius over 22,000 years—is about 0.045 degree of warming per century.For the current human-caused warming, the warming rate for the past 30 years and the projected warming rate for the next century is about 2.5 degree Celsius per century—that is over 250 times the cooling rate in the glacial period and 50 times of the warming rate in the interglacial period. This current human-caused warming is working against the slow natural cooling trend and this warming rate has completely overwhelmed the natural climate change cycle.

Would the human race survive another Ice Age?

Good news! Ice ages come only every 155 million years. Another is not due until around the year 155,002,016.The real worry is whether there is another glaciation left in our present Quaternary glaciation. If there is any scientist out there with a prediction as to whether our present Holocene epoch is an interglacial, that is, a warmer lull between two glacial periods, or the exit from our ice age, I haven’t heard a peep.If we are due another major glacial event or even a series of Stadials, or minor glaciations, they arrive with great rapidity, last a good long time and change things tremendously, as in a sheet of ice a mile thick over present-day Chicago and three miles thick over present-day Montreal. So much for civilization as we know it.But there’s good news and bad news about a possible coming major glaciation. Our species has been around for an estimated 200 millennia, and all but the last 12 millennia have been lived in glacial periods, a few other interglacials lasting 12 to 15 millennia apart. We’re adapted. The 34,400 generations of Homo before the start of our present epoch were known as Paleolithic man, and paleolithic man partied!Major glaciations tend to be populated by large, lumbering, meaty and fatty beasts, relatively easy to stalk and take down. The streams were thick with salmon. Snow and ice lasted almost all the year. Packing away enough salmon, mastodon, walrus and ground sloth in ice banks to last the long winter was easy-peasy. It’s thought to be the reason our species is so sexually versatile and inclined—long winters by the fire in a cave on a high-protein diet with nothing to do but cook and lounge around on plush fur beds. Good times!*The bad news—we existed as clans of twenty or fifty people scattered thinly around the world.* Good thing we didn’t evolve hibernation instead.