Arguments
Video: Climate, Sea Level, and Superstorms
Posted on 21 November 2017 by greenman3610
This season’s disasters in the Caribbean and Gulf of Mexico re-started the conversation around climate and extreme weather. Several recent studies shine a light on this:
I thought a recent study determined that a storm the size of Sandy could have moved that boulder to where it is, given the special topograph of the location mentioned in the film. Is it deceptive a bit to still use it as a backdrop? Or should we say, hey, we're already at that point, and it's gonna get worse from here!"?
These superstorms in the past appear many orders of magnitude greater than even worst case scenario of increasing hurricane intensity (which is bad enough). Yet these superstorms appear to have occured in period of CO2 concentrations similar to where we are heading.
So assuming evidence for superstorms is convincing, is the current scientific modelling too conservative? Or has it missed some unusual weather / climate phenomenon? Could something cause radical regional ocean warming like a hot spot, at just right time of year to cause incredibly intense storms in some locations? Maybe change in ocean currents. Because what else could it possibly be?
".. a recent study..." How about some references to which study?
#3:
This is probably one of them:
Ice melt, sea level rise and superstorms by James Hansen et al.
#2:
One of the points made in the study referred to above is that increased freshwater flux into the North Atlantic and Southern Ocean from melting ice sheets in Greenland and Antarctica will cool the sea surface. This will increase the temperature contrast between high and low latitudes and thus cause more intense storms. The surface cooling will also reduce the heat loss from these oceans and lead to a higher global energy imbalance (possibly as much as 3 or 4 watts/m2) and more deep ocean warming since the elevated GHG level continues to pump heat into the oceans at lower latitudes.
HK thanks, sounds slightly like that movie "a day after tomorrow".
Yes, thanks HK.
"... We focus attention on the Southern Ocean’s role in affecting atmospheric CO2 amount, which in turn is a tight control knob on global climate.
The millennial (500-2000 year) time scale of deep ocean ventilation affects the time scale for natural CO2 change, thus the time scale for paleo global climate, ice sheet and sea level changes. This millennial carbon cycle time scale should not be misinterpreted as the ice sheet time scale for response to a rapid human-made climate forcing. ..."
Tell that to the GOP. (sic)
#5:
In his book Storms of my Grandchildren James Hansen described that movie as "highly unscientific" as it greatly exaggerates the global cooling caused by the shutdown of the Gulfstream. The lead climate scientist in the movie – portrayed by Dennis Quaid – claimed that the storms would continue until the balance was restored, but I doubt that the movie makers really understood the global energy imbalance the way climate scientists define it.
HK @7 yes fair comments. The movie the day after tomorrow was obviously fantasy, and things like a change in the gulf stream and cooling Northern ocean cannot cause such a deep ice age and certainly not that fast, or generate superstorms of that ferocity and also covering the entire northern hemisphere. That is Hollywood hype and dramatic licence, like numerous other disaster movies. Virtually everyone realises this is fantasy. However I quite enjoy these movies, and it's interesting to contemplate why we enjoy disaster movies.
However its interesting that the day after tomorrow got a little bit partly right that changes to gulf stream and thus cooler northern oceans leads to more intense storms as you pointed out. I wonder if that was accident or a little bit of science input.
The more accurate scenario is a warming climate could cause a change in gulf stream, but low probability at this stage. It would potentially cause a semi ice age in Europe and parts of N America with significant drop in temperatures over decades to centuries, that would be very damaging, although not kilometre thick ice sheets. Although the probability is low, the consequences are still serious enough so we should pay strong attention.
Nigelj,
I would look more carefully at the Gulf Stream system.
This RealClimate post reviews two reasons that current models are biased toward a more stable Gulf Stream. It describes collapse of the Gulf Stream over 100-300 years. It has several additional links at the end.
This Real Climate post #2 describes slowing of the Gulf Stream since 1930.
Fig. 3 Index of the strength of the overturning circulation in the Atlantic (AMOC), calculated from the temperature in the subpolar Atlantic minus the mean temperature of the Northern Hemisphere (red and blue curves). The green curve shows the coral data of Sherwood and colleagues. Source: Rahmstorf et al, Nature Climate Change 2015.
The Gulf Stream flow is a little higher than its lowest point around 1980. It is not catastrophic but not a "low probability" that it could get worse. The currently measured slow down is greater than predicted by models.
The cold patch just below Greenland on many global temperature graphs is caused by the slowing of the Gulf Stream. This patch set a record for the coldest measured (over the entire record) during 2015, a record hot year worldwide.
Fig. 1 Linear temperature trends from 1901 to 2013 according to NASA data. Source: Rahmstorf et al, Nature Climate Change 2015.
about 285ppm#2 Nigelj writes … Yet these superstorms appear to have occured in period of CO2 concentrations similar to where we are heading.
It is well established that during the Eemian thermal naximum (~129,000 to 124,000 years ago), CO2 concentration in the atmosphere reached a maximum of about 285ppm, while present concentration is around 406ppm, a level unprecedented over the last 800,000 ears.
#9 Mr Sweet writes … The cold patch just below Greenland on many global temperature graphs is caused by the slowing of the Gulf Stream.
In fact, the opposite occurs. Discharge of cold water from Greenland ice sheet melt is likely to cause Gulf Stream slowing by pushing warmer water deeper.
Riduna,
The key point is that observing the cold patch shows that the Gulf Stream has already begun to slow. The size and temperature of the cold patch can be used to calculate how much the Gulf Stream has slowed.
The superstorms are powered by the difference in temperature between the tropics and the arctic. If the cold patch continues to grow Hansen claims that will provide the power for superstorms.