by René van Westen, Utrecht University; Henk A. Dijkstra, Utrecht University, and Michael Kliphuis, Utrecht University
Used with permission.
Superstorms, abrupt climate shifts and New York City frozen in ice. That’s how the blockbuster Hollywood movie “The Day After Tomorrow” depicted an abrupt shutdown of the Atlantic Ocean’s circulation and the catastrophic consequences.
While Hollywood’s vision was over the top, the 2004 movie raised a serious question: If global warming shuts down the Atlantic Meridional Overturning Circulation, which is crucial for carrying heat from the tropics to the northern latitudes, how abrupt and severe would the climate changes be?
Twenty years after the movie’s release, we know a lot more about the Atlantic Ocean’s circulation. Instruments deployed in the ocean starting in 2004 show that the Atlantic Ocean circulation has observably slowed over the past two decades, possibly to its weakest state in almost a millennium. Studies also suggest that the circulation has reached a dangerous tipping point in the past that sent it into a precipitous, unstoppable decline, and that it could hit that tipping point again as the planet warms and glaciers and ice sheets melt.
Read the full article on The Conversation.
German theoretical physicist Sabine Hossenfelder's Youtube "I wasn't worried about climate change. Now I am," with over a million views in the past six days, shows results if James Hansen's warnings of climate sensitivity are correct. She said at 13:14 on the timeline, "It just blows my mind how mind-fucking stupid it is that the lives of all people on this planet depend on an obscure discussion about the properties of supercooled water droplets in a type of cloud whose name I can't even rememeber [ . . . . ] At 12:44 she noted, "If the climate sensitivity is [ . . . as high as James Hansen's recent paper suggests with a climate sensitivity of 4.8 C plus or minus 1.2 C for doubled CO2' . . . ] then we have maybe 20 years or so until our economies collapse." [ . . . . ] At 15:08 she adds, "People in the developed world will somehow cope with the hotter conditions by fertilizing and irrigating the hell out of any agricultural areas they have. But in many countries around the equator, crop yield will substantially drop. This will most affect countries that are already prone to famine, and at the same time, some of the poorest countries in the world will be hit very hard by heat waves and drought. [ . . . . ] We're talking about some hundred millions of people who have nothing left to lose, suddenly beginning to migrate. [ . . . . ] That's going to cause a lot of tensions at the Southern borders of Europe, Russia, and Mexico, for just to mention a few. Someone somewhere will make a lot of money by selling weapons. Drones will be deployed. Some of them will shoot. Innocent people will die." She also added concerns about pandemics, and for those in the developed world, movement inland to avoid rising seas, huge economic problems, and "every-day products will become more and more expensive, until most of us simply can't afford them. And then they'll disappear. Need a new iPhone? That'll be 50 thousand dollars. Internet connection at home? 8 thousand a month [ . . . . ]"
I wrote June 5, 2023, Michael Mann was quoted by Bob Berwyn's May 26, 2023 Inside Climate News article, "James Hansen Warns of a Short-Term Climate Shock Bringing 2 Degrees of Warming by 2050," "Hansen has 'ignored a decade of new science,' and that the incorrect claims about climate sensitivity 'won’t survive peer review.'" However, I added, "Even though Mann is well-known for his 1998 'Hockey Stick' graph, I agree with Zeke Hausfather and Andrew Dessler's point in Berwyn's article. Considering that Jim Hansen’s predictions have often proven correct, it’s important that we pay close attention to what he’s saying.”
With what's at stake, I thought it would be good to dig deeper into the cloud issue as it relates to climate sensitivity. I found concerning news about this in a Nov 2, 2022 YouTube "Deep Dive: Climate Modeling with Nick Lutsko" published by Scripps Oceanography. Assistant Professor of Oceans and Climate Nick Lutsko said at 6:19 on the timeline, "So climate sensitivity is just a measure of how much our surface temperature will warm up in response to increases in CO2 concentrations, and normally we define it per doubling of CO2 so let's say we went from like roughly 400 parts per million today to 800 parts per million. How much would the climate system warm up? [ . . . . ] The reason I think it's important is because so many of the impacts of climate change scale with global mean surface temperature. You know we already see this in COP or we know it's much worse to have 2 degrees of warming versus 1.5 degrees of warming and so we think that earth's climate sensitivity is somewhere between let's say two and four and a half degrees Celsius. [ . . . . ]
At 9:21 on the timeline, Lutsko continued, "Joel Norris and I at Scripps [ . . . ] call these [low clouds] 'hot spots' because if you look at maps [ . . . ] of cloud cover they kind of pop up as being important [ . . . . ] At 13:01 Lutsko noted, "Just having more CO2 in the atmosphere, even if you keep the [sea and land] temperatures the same, has an impact on clouds [ . . . . ] At 13:52 he added, "Basically the CO2 sits above the clouds and it absorbs radiation that the clouds emit, and so you can think of it as there's this little bit of warming right above the clouds or extra warming where the CO2 is absorbing radiation."
Interviewer Margaret Leinen, Scripps Director, said at 14:11 "So it's a little blanket on top of the cloud," and Lutsko said "Exactly."
At 18:06 Lutsko said regarding the also concerning role of aerosols, "We think that [the forcing is] actually on the high end of, for example, the range that the IPCC gives. We think that historically aerosols have provided more cooling than was previously thought and the implication of course is that the climate system is more sensitive than maybe people thought."
As I noted above, Hossenfelder said, "If the climate sensitivity is [ . . . as high as James Hansen's recent paper suggests with a climate sensitivity of 4.8 C plus or minus 1.2 C for doubled CO2' . . . ] then we have maybe 20 years or so until our economies collapse."
At 18:30 Leinen said, "So if we clean up more pollution in the atmosphere and remove that cooling that we would see a much more sensitive climate response," and Lutsko said, "Yeah, this is a big irony. Of course we want to clean up all this air pollution but that's also going to lead to more warming."
It's worth noting ClimateAdam, aka climate scientist Adam Levy with a PhD from Oxford in atmospheric physics, had a much different response to the climate sensitivity issue than Sabine Hossenfelder's Youtube. He said, "The real story here is that 'Climate models that have shown themselves to be bad at simulating climate change get weird results when asked to simulate future climate change, and climate scientists aren't taking those results so seriously.'" While I agree with most of what ClimateAdam says in his videos, I disagree with him about the IPCC writing "really authoritative reports." My reasons are: 1) Keah Schuenemann's excellent May 19, 2015 YouTube showing "the role of the IPCC and their tendency to underestimate climate impacts"; and 2) Dahr Jamail, author and winner of a Martha Gellhorn Prize for Journalism, said in May 15, 2019 YouTube "Climate Change & The End of Ice - Presentation at GERC2019," at 36:19 on the timeline, "[Regarding the IPCC] there was a peer-reviewed study that was published on this [that showed the IPCC] is extremely over-conservative. I have talked to several IPCC authors [ . . . ], some of them in this book [The End of Ice], that have said the IPCC's projections are watered down. It's a heavily politicized organization, and in short it's not science. So another person from within the IPCC, it was passed on to me, said you can basically take the IPCC's worst case predictions and double them." In an August 20, 2018 truthout.org article, "Sixth Mass Extinction Ushers In Record-Breaking Wildfires and Heat," Jamail wrote, "I’ve spoken to prestigious scientists both on and off the record who believe that sooner rather than later, global population will be reduced to around 1 billion humans."
It therefore seems wise to use the precautionary principle at this time.
Didier Bourguignon, Head of Citizens’ Enquiries Unit (AskEP) who serves as an adviser at European Parliament, wrote "The precautionary principle enables decision-makers to adopt precautionary measures when scientific evidence about an environmental or human health hazard is uncertain and the stakes are high. It first emerged during the 1970s and has since been enshrined in a number of international treaties on the environment, in the Treaty on the Functioning of the European Union and the national legislation of certain Member States. The precautionary principle divides opinions. To some, it is unscientific and an obstacle to progress. To others, it is an approach that protects human health and the environment. Different stakeholders, experts and jurisdictions apply different definitions of the principle, mainly depending on the degree of scientific uncertainty required for the authorities to take action. Although most experts agree that the precautionary principle does not call for specific measures (such as a ban or reversal of the burden of proof), opinions are divided on the method for determining when to apply precautionary measures. The application of the precautionary principle presents many opportunities as well as challenges. The precautionary principle is closely linked to governance. This has three aspects: risk governance (risk assessment, management and communication), science-policy interfaces and the link between precaution and innovation."
I'm grateful my August 24, 2013 post "Metabolism of Stars" had recent interest.
