Earth and its atmosphere orbit the Sun within a zone of solar radiation intensity halfway between too cold, the temperatures at which water turns to ice, and too hot, the temperatures at which water turns to steam. Most non-microscopic Earthly life cannot long survive average temperatures if they swing too far outside the comfort zone.
Earth’s neighbors are not so lucky. Water on Mars is frozen and exists only beneath the polar caps. Mars’ atmosphere is thin and incapable of retaining enough heat for liquid water. Water on Venus is superheated steam in solution with sulfuric acid likewise superheated and gaseous. Venus’ atmosphere is thick, nearly opaque, and the volcanically hyperactive surface is estimated to run about 900 degrees fahrenheit, the same temperature as a tandoori oven and 400 degrees hotter than most home ovens will get, except in the cleaning cycle.
Both Mars and Venus serve as warnings of what can happen to Earth if the Earthly climate slides out of its comfort zone.
If Earth heats up a little, some ice deposits will melt, far northern latitudes will become more habitable and agriculturally productive, and equatorial regions become slightly warmer. Arctic and Antarctic animals will thrive, as fewer will die in the extreme cold. More people die every year around the world from cold than die from heat, so death rates would fall. Greenland and other icy lands will become inhabitable, and farming will even be possible along Greenland’s coasts. When a slight warming trend happened during the medieval warm period Europe’s population doubled. Populations would probably rise during a new warming trend. Sea levels might rise another foot, maybe a foot and a half.
In other words, it sounds like a vacation at the beach. What is so terrible about this possibility again?
If Earth heats up a lot, things get much more uncomfortable, desertification increases, and eventually, if it gets hot enough and enough steam gets into the atmosphere at some point temperature and water vapor would go into a self-reinforcing positive feedback loop that turns Earth into a terribly hot planet (though cooler than Venus). But to be honest this is reaching. Even if subject to a rampant greenhouse effect Earth will never reach Venus’ temperature because it’s too much farther out from the Sun, but the average surface temperature might reach two hundred or three hundred degrees. That’s in the uninhabitable range. The atmosphere would be filled with superheated steam that would scrub the flesh right off your bones as it cooked you. Long before that comes to pass, mankind will be unable to live on Earth and our descendants will need to have made the jump to space if they do not choose to become extinct.
If things get cooler then they get bad very quickly. Winter death rates rise rapidly even with a small temperature drop. Northern latitudes become less fertile. Arctic and antarctic species die off. Crops become unproductive. The price of food would double, then double again, then again. Population growth would stop, then reverse.
If they get even colder then it gets yet worse. Ten thousand years ago North America and much of Europe were covered with enormous sheets of ice a mile thick. Mankind could not survive in those temperatures. The northern latitudes are abandoned and all people crowd into the tropics, there to make war upon each other.
At a far more moderate level of cooling than the one required for all the fresh and salt water on Earth to freeze the toll of human suffering will be enormous. Migrations from the North to the South will reverse the population migrations of the 20th century. People will pray and beg for a warmer climate, just like the old days in the 21st century. They will curse the name of Al Gore and other Global Warming celebrities.
The Independent talks about weather, and evidence that Sunspot activity affects temperature.
Sunspots can be long or short, weak or strong and sometimes they can go away altogether. Following the discovery of the cycle, astronomers looked back through previous observations and were able to see it clearly until they reached the 17th century, when it seemed to disappear. It turned out to be a real absence, not one caused by a lack of observations. Astronomers called it the “Maunder Minimum.” It was an astonishing discovery: our Sun can change. Between 1645 and 1715 sunspots were rare. About 50 were observed; there should have been 50,000.
Ever since the sunspot cycle was discovered, researchers have looked for its rhythm superimposed on the Earth’s climate. In some cases it’s there but usually at low levels. But there was something strange about the time when the sunspots disappeared that left scientists to ponder if the sun’s unusual behaviour could have something to do with the fact that the 17th century was also a time when the Earth’s northern hemisphere chilled with devastating consequences.
Scientists call that event the “Little Ice Age” and it affected Europe at just the wrong time. In response to the more benign climate of the earlier Medieval Warm Period, Europe’s population may have doubled. But in the mid-17th century demographic growth stopped and in some areas fell, in part due to the reduced crop yields caused by climate change. Bread prices doubled and then quintupled and hunger weakened the population. The Italian historian Majolino Bisaccioni suggested that the wave of bad weather and revolutions might be due to the influence of the stars. But the Jesuit astronomer Giovanni Battista Riccioli speculated that fluctuations in the number of sunspots might be to blame, for he had noticed they were absent.
h/t: Tarnsman at Belmont Club