A Major Ocean Current May Be Hurtling Towards Collapse
S E E D E D C O N T E N T
The ocean may have less time than we thought before massive, irreversible shifts take place. A new study finds that a crucial ocean system may reach its "tipping point" sooner than predicted if the rate of climate change continues at a breakneck pace.
When we talk about climate change, the concept of tipping points is basically adding fuel to the already nightmare fire. Scientists now agree that climate changes could drive crucial systems on our planet to change so much that they reach a tipping point where recovery is impossible and change is inevitable.
One of the most pressing worries scientists have when it comes to tipping points lies underwater. Specifically, the Atlantic meridional overturning circulation, known as the AMOC, which helps shepherd warmer water to the North Atlantic. Among other things, it helps ensure Europe has relatively mild winters given its high latitude. Messing with it could be one of the fastest ways to make not just the region's but the world's weather run amok.
In the new study published Monday in the Proceedings of the Natural Academy of Sciences, scientists considered not just the amount of change to the oceans that could precede a tipping point, but also the rate of change. Think of it as the difference between pouring a cup of hot water very slowly into a bucket of cold water versus dumping it in all at once. While the same amount of water is being added both times, the rate at which water is being added is quite different.
To measure the impact the rate of change may have on the AMOC, the new study ran several experiments on a global ocean model. The current has been under intense scrutiny in recent years because cold, fresh water from melting Greenland glaciers has essentially been causing the current to slow down, though not stop.
"The AMOC is at risk of collapsing when a certain level of freshwater flow into the North Atlantic from increasing ice melt in Greenland is reached," Johannes Lohmann, one of the authors of the study, said in an email. "These tipping points have been shown previously in climate models, where meltwater is very slowly introduced into the ocean. In reality, increases in meltwater from Greenland are accelerating and cannot be considered slow."
The study modeled the increase in freshwater flowing. Lohmann said using "a large ensemble of simulations, we systematically varied the rate of change and the ocean's initial conditions, and investigated how the collapse of the AMOC depended on these factors."
The models ended up showing that in some cases with a more rapid rate of change, the AMOC actually collapsed before previous predictions indicated it would. If we stick to the cup of water analogy, previous studies essentially found a full cup of hot water needed to be added to the bucket for collapse, but the new findings show dumping in the water faster means you need less than a cup to trigger the collapse. The study shows that "the safe levels of global warming before such a collapse occurs may be smaller than previously thought, and may also be difficult to predict with certainty," Lohmann said.
This study isn't the final word on how fast the AMOC may change. Some of the modeling Lohmann and his coauthors use may merit a closer and more critical look, Dave Sutherland, an associate professor in the department of Earth sciences at the University of Oregon, who was not involved in the study, said over email. Sutherland pointed out that the study does not account for some of the specifics of the location of freshwater in Greenland, even as the findings are "important and timely" to help determine the fate of the AMOC.
"Bottom line is I think this study is important and points out the complex dynamics inherent in our climate system," Sutherland said. "I'm worried by the details (though I'm sure some reviewers were, too), and think there could be other climate feedbacks or unresolved processes that might change their results, if not their ultimate conclusions."
Lohmann said that the study's findings do need to be tested further, but pointed out that the possibility of a rapid AMOC collapse should sound an alarm bell.
"Due to the potentially increased risk of abrupt climate change in parts of the Earth system that we show in our research, it is important that policymakers keep pushing for ambitious short- and mid-term climate targets to slow down the pace of climate change, especially in vulnerable places like the Arctic," Lohmann said.
Tags
Who is online
322 visitors
This is very troubling...... Those that understand the concepts of mass and inertia in systems will know how difficult it will be to stop and reverse the current quantified trend.
What the article does not mention in regards to the AMOC is the effect of the ACC or Antarctic Circumpolar Currents that are also shifting and affecting the Southern Hemisphere's climate. Icebergs are calving off Antarctic glaciers at a greater rate than in previous years. When I was at McMurdo Station, Antarctica in the late 80's and early 90's this was already beginning to be noticed.
Very good point to add Ed.
It'll likely be awhile. Current sea level rise is....
Long-term measurements of tide gauges and recent satellite data show that global sea level is rising, with the best estimate of the rate of global-average rise over the last decade being 3.6 mm per year (0.14 inches per year). The rate of sea level rise has increased since measurements using altimetry from space were started in 1992; the dominant factor in global-average sea level rise since 1970 is human-caused warming. The overall observed rise since 1902 is about 16 cm (6 inches) [Figure 6].
Global sea level has been rising over the past century, and the rate has increased in recent decades. In 2014, global sea level was 2.6 inches above the 1993 average—the highest annual average in the satellite record (1993-present). Sea level continues to rise at a rate of about one-eighth of an inch per year. Is sea level rising? (noaa.gov)
So using both sets of data Greg, the rate of change is accelerating, which only enhances the problem. Your 1902 average comes in at .05"/yr. The stated average since 1993 yields .09"/year, and current rate from NOAA looks to be .125"/yr.
Even if we started now, I doubt we could reverse the current trend in the next 100 years....
We're doomed!
We're doomed!
Sorry you think that way Greg. Some of us think it is worth the effort to try and save humanity despite those that who couldn't care less.
Odd, some people can believe nonsense such as 'Trump won the election' or 'the Earth is only 6,000 years old' yet will categorically reject all findings of anyone doing research on climate change.
If we stopped emitting GHGs today, it would take 50 years for the atmospheric CO2 to return to pre-industrial levels.
Would it cause the climate in Europe to become colder? There was a article I read once where the French Revolution was spurred on by a poor harvest caused by a mini ice age.
As would our winters in the North East Trout. The way I read it is that the AMOC brings warm water from the equator into the North Atlantic on a clockwise rotation. Without that warm water, colder weather would be the result. The amount of snow may drop in both those areas as well as there is less moisture laden air accompanying the current. Just a supposition though as I'm not a climatologist by any stretch of the imagination.
The basics (not the box office hype ) of the movie "Day after Tomorrow" was based upon this theory.
I was just thinking about that movie. The colder the air gets, the less moisture it holds, so I could understand less snow. In the Interior of Alaska, it got very cold (-82 F and that was ambient) but we didn't get major snow fall, at least not all at once. It just didn't melt which is why we skiied all the time. And the snow was very light and fluffy, not the dense, snowball packing kind we got in PA.
Nailed it Trout!
Thank-you!
From an article in 2018 - The Gulf of Main is actually warming 99% faster than the rest of the Atlantic because of the slowing of the AMOC. Instead of a fast moving stream of water that warm water just spreads and sits. It's already affected fisheries from Cape Hatteras to the Gulf of Main. Cold water species like lobsters are moving further off coast to avoid the warmer water. Warm water species are moving further north.
Source
Antarctica. Technically the largest desert on Earth because it get so little precipitation (and that is how deserts are measured).
Yep. When I was at McMurdo Station, there was one particular phenomena the freaked out newcomers and took some getting used to. Every now and then under the right conditions, minute ice crystals would form and float suspended in the air. Sunlight would refract through said crystals forming a slightly golden colored shimmering haze. First time I saw it I thought something was wrong with my eyes!
The result of the Tambora eruption in 1815. Not a Super Volcanic Eruption, but big enough to plunged the entire planet into a yearlong winter that devastated harvests around the globe but especially in Europe. The volcano is located in Indonesia.
Or the Krakatoa eruption of 1883 as well, also in Indonesia.
How do we begin to address the terrifying problems before us when half of the U S Senate denies there are any problems. The deadenders in the damn gop!