A new study analyzed Greenland ice core oxygen-18 data, and nitrogen data, indicating past abrupt heating -- to create a climate model that matches historical abrupt warming events.
L.C. Sime, Peter O. Hopcroft, and Rachael H. Rhodes found that loss of Arctic sea ice corresponded to the Southwest region of Greenland getting around 16°C warmer within a few decades. Both moisture source (ocean evaporation further north in the Labrador Sea) and temperature increase were involved in the oxygen isotope changes which signaled abrupt regional warming. Here's what an ice core signal for abrupt warming looks like by examining amounts of oxygen-18..
There's a lot I didn't understand in this technical paper. During the melting (interstadial) stage, more snow fell in Winter because seawater evaporated further north, closer to land. This made Winter snow carry more oxygen-18 isotope.
They used 32 simulations of Dansgaard-Oeschger (abrupt warming). During the freezing (stadal) stages, salt is lost from the North Atlantic. Presumably more dense salty water was being drawn down and out of the North Atlantic by thermohaline circulation. Then when climate switches to the melting stage, "... salt returns to the North Atlantic from the tropical Atlantic Ocean and the wider global ocean. This causes the onset of an abrupt warming DO event." Abrupt Greenland warming seems to have something to do with thermohaline circulation weakening, but I wasn't clear how that worked.
Three sites are shown from different locations in Greenland, in green, blue, and pink. You can see that the ice core oxygen-18 ratios signal temperature (vertical rise). The vertical dotted lines are past abrupt warming events, each identified by a number along the bottom. These aren't simulations. You can tell that warming is instantaneous at this scale, while returning to cooler temperature takes thousands of years. So plenty of time for rapid melting to proceed for each event.
The authors suggest that their model would allow future quantitative forecasts of impacts on Greenland from Arctic sea ice melt if more current data is collected.
What this tells me is that sea level rise is being underestimated from around 2030 on. Remember the excitement when all of Greenland had a day or two above freezing not too long ago? Now imagine above freezing being the Greenland norm all Summer, every Summer, starting in a few decades.
It doesn't matter whether going up or down in temperature, the change is very often abrupt and without warning. Just look at the chart above, the sudden change in direction of temperature from one to the other occurs very fast, too fast for the human lifestyle or any lifestyle to adapt. If you read the sociological studies that accompany these changes, one has often seen the fast deterioration of culture at best and extinction at worst. Look at geology records, these often reveal this trend.
1. End Ordovician, 444 million years ago, 86% of species lost
2. Late Devonian, 375 million years ago, 75% of species lost.
3. End Permian, 251 million years ago, 96% of species lost.
4. End Triassic, 200 million years ago, 80% of species lost.
5. End Cretaceous, 66 million years ago, 76% of all species lost.
Some scientists state we are in the midst of the 6th great extinction. “We don’t always know what caused them but most had something to do with rapid climate change”,
~ Melbourne Museum palaeontologist Rolf Schmidt.
If we are in the 6th great extinction, will we lose 75%, or 96%, or who knows how many % of species? How will Homo sapiens cope? Whatever problems we face now, what will future generations face with such rapid change?
I worry for my descendants and wonder how I can prepare them for the worst while hoping for the best?
Faced with a failed president, confronted by a weak legislature, and throttled by a corrupt judicial, citizen action that is based on conflicted values leaves inhabitants of the nation vulnerable to even worse governments.