An abrupt cooling got started 8, 200 years ago, but it aborted within a century, and the temperature changes since then have been gradual in comparison. More rain falling in the northern oceans—exactly what is predicted as a result of global warming—could stop salt flushing. This would be a worldwide problem—and could lead to a Third World War—but Europe's vulnerability is particularly easy to analyze. We have to discover what has made the climate of the past 8, 000 years relatively stable, and then figure out how to prop it up. Eventually such ice dams break, with spectacular results. We now know that there's nothing "glacially slow" about temperature change: superimposed on the gradual, long-term cycle have been dozens of abrupt warmings and coolings that lasted only centuries. Another precursor is more floating ice than usual, which reduces the amount of ocean surface exposed to the winds, in turn reducing evaporation. What is three sheets to the wind. We are near the end of a warm period in any event; ice ages return even without human influences on climate.
Though combating global warming is obviously on the agenda for preventing a cold flip, we could easily be blindsided by stability problems if we allow global warming per se to remain the main focus of our climate-change efforts. Our goal must be to stabilize the climate in its favorable mode and ensure that enough equatorial heat continues to flow into the waters around Greenland and Norway. The sheet in 3 sheets to the wind crossword clue. The populous parts of the United States and Canada are mostly between the latitudes of 30° and 45°, whereas the populous parts of Europe are ten to fifteen degrees farther north. Even the tropics cool down by about nine degrees during an abrupt cooling, and it is hard to imagine what in the past could have disturbed the whole earth's climate on this scale. Although I don't consider this scenario to be the most likely one, it is possible that solutions could turn out to be cheap and easy, and that another abrupt cooling isn't inevitable. Paleoclimatic records reveal that any notion we may once have had that the climate will remain the same unless pollution changes it is wishful thinking. Volcanos spew sulfates, as do our own smokestacks, and these reflect some sunlight back into space, particularly over the North Atlantic and Europe.
5 million years ago, which is also when the ape-sized hominid brain began to develop into a fully human one, four times as large and reorganized for language, music, and chains of inference. Term 3 sheets to the wind. Natural disasters such as hurricanes and earthquakes are less troubling than abrupt coolings for two reasons: they're short (the recovery period starts the next day) and they're local or regional (unaffected citizens can help the overwhelmed). The dam, known as the Isthmus of Panama, may have been what caused the ice ages to begin a short time later, simply because of the forced detour. Europe's climate could become more like Siberia's. I hope never to see a failure of the northernmost loop of the North Atlantic Current, because the result would be a population crash that would take much of civilization with it, all within a decade.
In late winter the heavy surface waters sink en masse. We puzzle over oddities, such as the climate of Europe. Eventually that helps to melt ice sheets elsewhere. Perish in the act: Those who will not act. History is full of withdrawals from knowledge-seeking, whether for reasons of fundamentalism, fatalism, or "government lite" economics. Like bus routes or conveyor belts, ocean currents must have a return loop. Such a conveyor is needed because the Atlantic is saltier than the Pacific (the Pacific has twice as much water with which to dilute the salt carried in from rivers). But we can't assume that anything like this will counteract our longer-term flurry of carbon-dioxide emissions.
But our current warm-up, which started about 15, 000 years ago, began abruptly, with the temperature rising sharply while most of the ice was still present. The population-crash scenario is surely the most appalling. Pollen cores are still a primary means of seeing what regional climates were doing, even though they suffer from poorer resolution than ice cores (worms churn the sediment, obscuring records of all but the longest-lasting temperature changes). It was initially hoped that the abrupt warmings and coolings were just an oddity of Greenland's weather—but they have now been detected on a worldwide scale, and at about the same time. But sometimes a glacial surge will act like an avalanche that blocks a road, as happened when Alaska's Hubbard glacier surged into the Russell fjord in May of 1986. Then it was hoped that the abrupt flips were somehow caused by continental ice sheets, and thus would be unlikely to recur, because we now lack huge ice sheets over Canada and Northern Europe. In Greenland a given year's snowfall is compacted into ice during the ensuing years, trapping air bubbles, and so paleoclimate researchers have been able to glimpse ancient climates in some detail. Salt sinking on such a grand scale in the Nordic Seas causes warm water to flow much farther north than it might otherwise do. Canada's agriculture supports about 28 million people. Feedbacks are what determine thresholds, where one mode flips into another. A muddle-through scenario assumes that we would mobilize our scientific and technological resources well in advance of any abrupt cooling problem, but that the solution wouldn't be simple. One of the most shocking scientific realizations of all time has slowly been dawning on us: the earth's climate does great flip-flops every few thousand years, and with breathtaking speed.
keepcovidfree.net, 2024