Dear Thomas,

unfortunately, the increased use of the concept of "tipping points" in the Earth system over the past few years has led to some misunderstandings. Although often characterized as such, crossing the "magic" 1.5 K mark of anthropogenic warming as such does not constitute a fundamenral regime shift. It is simply a rough estimation of a line above which many Earth system components are believed to change in ways that would proove dangerously difficult for humans to adapt to with reasonable means. Physical tipping points do exist in several Earth system components such as the AMOC, Greenlandic and Antarctic ice sheets (to name some prominent examples). However, it is not the case that they will suddenly be triggererd, as it were, when the 1.5 K mark is crossed. However, they do constitute potential future tipping elements that one should keep watching with increasing concern. It is not possible, though, to give one single date or figure for a singular global tipping point (so to speak) in the Earth system triggered by anthropogenic warming. 1.5 °C is a rather arbitrary number when comparing the impacts in a 1.5 K world with that of a + 1.49 or 1.51 K Earth...

Best,

Julius

Keep burning fossil fuels without planting trees and native plants to sequester that carbon before it is burned, like Saudi Arabia and the other 24 countries that on Nov. 7 at COP27 formed the "Middle East Green Initiative" to plant 50 billion trees to sequester carbon, and we could easily keep going past 10 deg. C. Each country needs to start its own Green Initiative, and plant enough native trees and native grasses and wildflowers, to offset their annual fossil fuel AND methane production.

I could see you help get started the "Swiss Green Initiative" and not only planting trees in Europe, and also fund that planting to offset your own carbon burning, for plantings in North Africa to help them increase their rainfall, as the Saudis are doing after they adopted my proposal in 2010 to set aside 200 million hectares as Ecological Restoration Preserve in Arabia and replant with native plants at https://www.ecoseeds.com/cool.html

Hi, the last temperature jump during the El-Nino was different than the ones before in so far as other climate modes contributed to the jump in global temperatures. Especially some ocean regions other than the equatorial Pacific had been involved and the northern latitudes. The main question will be when the next extreme El-Nino will occur and what climate modes, ocean regions, and albedo developments will contribute to the jump.

My personal view is, that temperature jumps by extreme El-Ninos will be increasingly reinforced by regime shifts in other physical and ecological systems. Thus the next jump will be highly interesting. How much will other system changes contribute to it? The date of the next extreme ENSO event will determine how much we will cross the 1.5°C mark.

From then on things will get truly ugly for humanity as the increase in extreme events was non-linear after the temperature jump of 2012-2016. Thus it becomes only reasonable that the next increase will be even more non-linear as the couplet circulation modes of Earth are now increasingly producing synergistic compound events beyond anything we imagined possible! Marine heatwaves, a drying out atmosphere, and higher variability of high-pressure systems (several increasing in size and/or intensity) fueled by increasing deep convection from the tropics will be at the forefront of our problems...

All the best

Jan

Thx Jan for your take. Would be interesting to hear a number, such as straight through in a few years to 2.0 for a temporary equilibrium. Agree the surge will most likely be highly nonlinear.

Unfortunately, such "straightforward" predictions are not possible. The global climate system is a highly complex and - in the sense of chaos theory - chaotic system. It is very unlikely, that the system will reach any kind of "equilibrium" state in the near future (apart from the fact that "equilibria" stages are very hard to define meteorologically/climatologically). Climate scientists generally refrain from issuing "predictions" or "forecast" (unlike - quite rightfully so - meteorologists in short- to mid-term weather forecasting), instead they like to lay out "scenarios" or "pathways" (such as the IPCC does). Even they, however, usually give numbers for expected radiative forcing (RF) based on different socio-economic scenarios. Note that it is far from trivial to translate RG figures into figures for average global warming such as + 1.5 / 2.0 K etc. Having said all that, I deem it quite likely that the 2.0 K/°C threshold will be crossed in the not too distant future. Given the current emission behavior it is almost already "built into" the system.

Best,

Julius

Sorry - we are, indeed, on RG, but, of course, I meant to write "RF" for "radiative forcing" :-)

Here is a post of James Hansen and co. on the matter - 1.4-1.5°C could be reached in 2024 - i go with them - as not only our SOx emissions are declining, but also methane levels are increasing now insanely fast. They base their assumption on the next El-Nino which should happen end of 2023. But it could be also a year or two later. http://www.columbia.edu/~jeh1/mailings/2023/Temperature2022.12January2023.pdf

Another sign is the amount of warm water accumulating in the Westpacific which is now off the charts - and its this water, that is needed for an El-NIno, as it is driven eastward during an El-Nino. https://www.pmel.noaa.gov/elnino/upper-ocean-heat-content-and-enso - you are interested in West Anomalies

And last we will have a sun maximum the following years https://www.esa.int/ESA_Multimedia/Images/2022/07/Solar_cycle_25_prediction_NOAA_July_2022 which weakens the Walker Circulation, which would be another hint, that we will get more El-Ninos the coming years. The elephant in the room are extreme eruptions (the tonga likely prolonged the current La Nina event) and summer sea ice in the Arctic - could now vanish any year due to a freak chain of events as it is now nearly gone end of summer - we lost all multiyear sea ice the last years. SO our chances are in my opinion higher than 50% that we will reach 1.5 °C of warming till 2026 as the WMO predicts it. But beyond that it gets difficult but a significant acceleration of global warming is now possible with all the feedbacks now kicking in.... Arctic summer sea ice gone will be a game changer...