The Weekend Wonk: Jason Box on 5 Factors Behind the Global Heat Wave
Jason Box has been doing some good explainers in recent months, focusing recently on some of the most important indicators of the record El Nino cycle we are living.
Above, one suggested cause of current high Atlantic Sea Surface Temps is of some unintended consequences, actually an example of inadvertent geo-engineering.
The Atlantic Ocean is running a fever. Waters off Florida have become a hot tub, bleaching the third-largest barrier reef in the world. Off the coast of Ireland, extreme heat was implicated in the mass death of seabirds. For years, the north Atlantic was warming more slowly than other parts of the world. But now it has caught up, and then some. Last month, the sea surface there surged to a record 25°C—nearly 1°C warmer than the previous high, set in 2020—and temperatures haven’t even peaked yet. “This year it’s been crazy,” says Tianle Yuan, an atmospheric physicist at NASA’s Goddard Space Flight Center.
The obvious and primary driver of this trend is society’s emissions of greenhouse gases, which trap heat that the oceans steadily absorb. Another influence has been recent weather, especially stalled high-pressure systems that suppress cloud formation and allow the oceans to bake in the Sun.
But researchers are now waking up to another factor, one that could be filed under the category of unintended consequences: disappearing clouds known as ship tracks. Regulations imposed in 2020 by the United Nations’s International Maritime Organization (IMO) have cut ships’ sulfur pollution by more than 80% and improved air quality worldwide. The reduction has also lessened the effect of sulfate particles in seeding and brightening the distinctive low-lying, reflective clouds that follow in the wake of ships and help cool the planet. The 2020 IMO rule “is a big natural experiment,” says Duncan Watson-Parris, an atmospheric physicist at the Scripps Institution of Oceanography. “We’re changing the clouds.”
Crisscrossing clouds known as ship tracks can be seen off the coast of Spain in this 2003 satellite image. With the phasing out of high-sulfur ship fuel, these reflective clouds have become scarcer, leading to ocean warming.ACQUES DESCLOITRES/MODIS LAND RAPID RESPONSE TEAM; MARK GRAY/MODIS
By dramatically reducing the number of ship tracks, the planet has warmed up faster, several new studies have found. That trend is magnified in the Atlantic, where maritime traffic is particularly dense. In the shipping corridors, the increased light represents a 50% boost to the warming effect of human carbon emissions. It’s as if the world suddenly lost the cooling effect from a fairly large volcanic eruption each year, says Michael Diamond, an atmospheric scientist at Florida State University.
The natural experiment created by the IMO rules is providing a rare opportunity for climate scientists to study a geoengineering scheme in action—although it is one that is working in the wrong direction. Indeed, one such strategy to slow global warming, called marine cloud brightening, would see ships inject salt particles back into the air, to make clouds more reflective. In Diamond’s view, the dramatic decline in ship tracks is clear evidence that humanity could cool off the planet significantly by brightening the clouds. “It suggests pretty strongly that if you wanted to do it on purpose, you could,” he says.
The influence of pollution on clouds remains one of the largest sources of uncertainty in how quickly the world will warm up, says Franziska Glassmeier, an atmospheric scientist at the Delft University of Technology. Progress on understanding these complex interactions has been slow. “Clouds are so variable,” Glassmeier says.
This has sparked a bit of discussion among Climate experts on Social Media, with Michael Mann in particular taking issue with the Marine sulfates theory:
This more detailed and updated estimate from Forster et al (2023) shows a small steady decrease in (negative) aerosol forcing of ~0.1W/m^2 per decade over past two decades. The total anthropogenic radiative forcing was +0.8W/m^2 per decade (dominated by GHGs) (h/t @ABrailove) https://t.co/yEZqbfFqxZpic.twitter.com/fygZNlEULo
— Prof Michael E. Mann (@MichaelEMann) June 27, 2023
It's not sulphate aerosols. It's not the Tonga eruption. It's not unicorns or fairy dust.
3 thoughts on “The Weekend Wonk: Jason Box on 5 Factors Behind the Global Heat Wave”
One of the early jokes about addressing global warming was to repeal the The Clean Air Act which, among other things, cut the SOx and NOx associated with acid rain.
Regarding human-induced negative forcings on the Earth’s temperature, as opposed to the major greenhouse gas warming we’re doing, a recent paper claims that a significant part of the iron in the ocean is from human sources, and that it tends to be more bio-available than the usual natural sources, mostly rock dust from the Sahara or from glacial weathering. https://pubs.acs.org/doi/10.1021/acs.est.3c01084
Addition of iron to parts of the ocean where it’s the limiting nutrient for plankton has been proposed as a way to draw down carbon. A trial using a hundred tons of iron sulfate put into an eddy off British Columbia resulted in the biggest salmon run in decades. Another test in the Southern Ocean, involving the German scientific vessel Polarstern, did cause a brief flush of plankton, but they were rapidly gobbled up by mini-carnivores, with little carbon sequestration. If silicates were added as well, diatoms could form their glassy shells from it, and survive long enough to sink into deeper water.
Before humans wiped out about ninety percent of the whales, the latter probably kept the oceans much better fertilised with micronutrients like iron, by bringing up prey from deep water, and excreting at the surface.
Till the whale population rebounds to pre-19th century levels, it would seem prudent to increase our already significant additions to oceanic iron levels, and do it in areas where it might be most effective. Not everyone agrees – before the Polarstern could conduct its fairly small trial, it faced court action from a slew of NGOs, and a ban on doing it anywhere within 200 miles of every speck of land with a post-colonial claimant to it.
Deliberate injection of cloud nucleation particles, sulfate, salt, or whatever works, to replace the hundreds of tons lofted gratis from ships’ filthy bunker fuels, should also be tested. Low level would have the same effect as the ship trails, stratospheric would be more like a volcanic eruption. Having some data on this, instead of having every trial blocked by litigation, would have been handy. The foil helmet brigade think they’re all getting contrailed already, anyway. (Which they are, but commercial aircraft could be directed to choose routes and times that maximised their existing cooling effect.)
One of the early jokes about addressing global warming was to repeal the The Clean Air Act which, among other things, cut the SOx and NOx associated with acid rain.
I saw this last night on the PBS News Hour:
https://www.pbs.org/newshour/show/gop-presidential-candidates-avoid-discussing-climate-change-on-campaign-trail
which blames the millions of dollars in campaign money from the fossil fuel interests according to site https://www.opensecrets.org/
Regarding human-induced negative forcings on the Earth’s temperature, as opposed to the major greenhouse gas warming we’re doing, a recent paper claims that a significant part of the iron in the ocean is from human sources, and that it tends to be more bio-available than the usual natural sources, mostly rock dust from the Sahara or from glacial weathering.
https://pubs.acs.org/doi/10.1021/acs.est.3c01084
Addition of iron to parts of the ocean where it’s the limiting nutrient for plankton has been proposed as a way to draw down carbon. A trial using a hundred tons of iron sulfate put into an eddy off British Columbia resulted in the biggest salmon run in decades. Another test in the Southern Ocean, involving the German scientific vessel Polarstern, did cause a brief flush of plankton, but they were rapidly gobbled up by mini-carnivores, with little carbon sequestration. If silicates were added as well, diatoms could form their glassy shells from it, and survive long enough to sink into deeper water.
Before humans wiped out about ninety percent of the whales, the latter probably kept the oceans much better fertilised with micronutrients like iron, by bringing up prey from deep water, and excreting at the surface.
Till the whale population rebounds to pre-19th century levels, it would seem prudent to increase our already significant additions to oceanic iron levels, and do it in areas where it might be most effective. Not everyone agrees – before the Polarstern could conduct its fairly small trial, it faced court action from a slew of NGOs, and a ban on doing it anywhere within 200 miles of every speck of land with a post-colonial claimant to it.
Deliberate injection of cloud nucleation particles, sulfate, salt, or whatever works, to replace the hundreds of tons lofted gratis from ships’ filthy bunker fuels, should also be tested. Low level would have the same effect as the ship trails, stratospheric would be more like a volcanic eruption. Having some data on this, instead of having every trial blocked by litigation, would have been handy. The foil helmet brigade think they’re all getting contrailed already, anyway. (Which they are, but commercial aircraft could be directed to choose routes and times that maximised their existing cooling effect.)