Dear Colleagues, This post from Jim Hansen was shared on the NOAC list with a comment (thank you Clive!) and as I think it is of great importance, I’m forwarding it along to rest of our broader community.
One key take away: > However, it’s not the new equilibrium at +200 feet that’s of most concern, > it’s the chaos that ensues once ice sheet collapse begins in earnest. > > That chaos was the topic of our paper[1] “Ice Melt, Sea Level Rise and > Superstorms,” which was blackballed by IPCC (Intergovernmental Panel on > Climate Change). In that paper, we conclude that continuation of GHG > emissions along the path that the world is on will lead to shutdown of the > overturning (North Atlantic and Southern Ocean) circulations this century and > sea level rise of several meters on a time scale of 50-150 years. As yet, > little has changed to get us off that path. You would not know that from the > communications of the United Nations COPs (Conferences of the Parties) and > their scientific advisory body, the IPCC. Projected global warmings > continually rachet down as countries agree to more ambitious goals for future > emission reductions. If you take those plans plus $2.75 you can get a ride on > New York City’s subway (which, BTW, is safe and efficient, albeit ancient – > New York City is again a good place to visit). Best, Ron Sent from my iPhone Begin forwarded message: > > From: James Hansen <[email protected]> > Sent: Thursday, May 25, 2023 3:01 PM > To: Clive Elsworth <[email protected]> > Subject: Equilibrium Warming = Committed Warming? > > View this email in your browser > > A PDF of this Communication is available on my webpage, along with prior > Communications and other resources. > > > Tweet to your followers > > Share on your Facebook > > Forward to your friends > > > Fig. 28. Annual growth of climate forcing by GHGs including the part of O3 > forcing not included in the CH4 forcing. MPTG and OTG are Montreal Protocol > and Other Trace Gases. > > > Equilibrium Warming = Committed Warming? > > 25 May 2023 > James Hansen > > Some people on Twitter interpreted the statement: “Equilibrium global > warming including slow feedbacks for today’s human-made greenhouse gas (GHG) > climate forcing (4.1 W/m2) is 10°C, reduced to 8°C by today’s aerosols” in > our draft paper “Global Warming in the Pipeline” as indicating that the world > is committed to warming of 10°C. The word “committed” or “commit” does not > appear in our paper. If it had, it would have been in a statement such as > “the world needs to commit to global cooling of about 1°C for the sake of > young people and future generations.” > > Equilibrium warming is a useful concept employed for more than a century, > e.g., in the studies by Arrhenius in the 1890s and Charney in the 1970s. > Equilibrium response is the global temperature change after the climate > system restores energy balance following imposition of a climate forcing. One > merit of our analysis of Cenozoic (past 66 million years) climate is that it > reveals that the present human-made GHG (greenhouse gas) forcing is already > greater than the GHG forcing at the transition from a nearly unglaciated > Antarctica to a glaciated continent. Yes, if we leave atmospheric composition > as it is today, sea level will eventually rise about 60 m (200 feet). Of > course, none of us would be there to see it. However, it’s not the new > equilibrium at +200 feet that’s of most concern, it’s the chaos that ensues > once ice sheet collapse begins in earnest. > > That chaos was the topic of our paper[1] “Ice Melt, Sea Level Rise and > Superstorms,” which was blackballed by IPCC (Intergovernmental Panel on > Climate Change). In that paper, we conclude that continuation of GHG > emissions along the path that the world is on will lead to shutdown of the > overturning (North Atlantic and Southern Ocean) circulations this century and > sea level rise of several meters on a time scale of 50-150 years. As yet, > little has changed to get us off that path. You would not know that from the > communications of the United Nations COPs (Conferences of the Parties) and > their scientific advisory body, the IPCC. Projected global warmings > continually rachet down as countries agree to more ambitious goals for future > emission reductions. If you take those plans plus $2.75 you can get a ride on > New York City’s subway (which, BTW, is safe and efficient, albeit ancient – > New York City is again a good place to visit). > > Physics is a description of the real world. So, climate science should be > focused on data. That’s the way science is supposed to work. However, IPCC is > focused on models. Not just global climate models (GCMs), but models that > feed the models, e.g., Integrated Assessment Models (IAMs) that provide > scenarios for future GHG levels. These models are useful and even necessary > for analysis of the complex climate system, but sometimes the models contain > hocus-pocus. As we mention in our current paper, they can assume, in effect, > that “a miracle will occur.” So, the models need to be continually checked > against the real world. > > Our research is focused on real world data and comparison with models, with > the hope of gaining insights about how the climate system works and where the > real world is headed. Fig. 28 (lead figure) shows the annual increase of GHG > climate forcing based on real world data (which, BTW, is continually updated > and made available by Ed Dlugokencky of the NOAA Earth System Research > Laboratory; Ed is an unsung hero in the climate change story). Specifically, > Fig. 28 compares the real-world growth rate of GHG forcing with the RCP2.6 > scenario, which is used in IPCC’s AR5 report as a scenario that would limit > global warming to about 2°C. Figure 28 shows that an enormous gap has opened > between the real world and RCP2.6. The “miracle” in RCP2.6 is largely an > assumption of negative emissions via power plants that burn biofuels, > capturing and sequestering the CO2. Also beware of nations promising “net > zero” emissions without defining what they mean. As discussed in our paper, > the present policy approach is not working and it is not likely to work. For > example, the cost to close the gap in Fig. 28 via carbon capture and storage > is estimated as $3.4-7.0 trillion per year – that’s the annual, growing cost. > That miracle is not likely to happen. > > There’s no time to get involved in Twitter wars. It’s disappointing that > scientists who once contributed to research progress, but now enjoy > twittering, do not correct a nonscientist’s assumption that equilibrium > warming = committed warming but instead allow the misconception to persist > and then use it to insist that we are “wrong” in our assessment. Further, > their claim that current scientific literature points to eventual global > warming being kept “well below 2°C” as being consistent with real world > trends and policies is egregious, an uncritical acceptance of models and the > assumptions that went into them. > > > > Fig. 25. Global temperature relative to 1880-1920. > > Let’s end with another figure from our paper, Fig. 25 (above), which compares > the long-term global temperature trend with our prediction of accelerated > warming that accounts for declining atmospheric aerosols and an uptick in GHG > growth rates. As much as possible, the projection is based on data: measured > global energy imbalance and indirect indications of declining aerosol amount. > It has become popular to say that the emerging El Nino will cause global > temperature to soon exceed 1.5°C. We don’t know that for certain, but we can > expect it to reach at least +1.4-1.5°C. An El Nino spurred global temperature > close to +1.5°C will not provide a valid measure of what the world will be > like when the trend-line reaches +1.5°C, but the El Nino spurred peak > temperature will provide a first indication of whether there is a new, > accelerated trend line. If the 2024 temperature (peak global temperature lags > El Nino by several months) falls clearly above the yellow region in Fig. 25, > it will tend to confirm the acceleration. > > > [1] Hansen J, Sato M, Hearty P et al. Ice melt, sea level rise and > superstorms: evidence from paleoclimate data, climate modeling, and modern > observations that 2 C global warming could be dangerous. Atmos Chem Phys > 2016;16:3761-812 > > Donate to CSAS Columbia > Donate to CSAS, Inc. > FOLLOW US HERE > > > Subscribe to my future Communications > > CSAS EI Website > > CSAS, Inc. Website > > Dr. Hansen's Webpage > > Dr. Hansen's Facebook > > Dr. Hansen's Twitter > > CSAS YouTube > > > Copyright © 2023 Climate Science, Awareness and Solutions. All rights > reserved. > > > Want to change how you receive these emails? > > You can update your preferences or unsubscribe from this list. > > > > > > > This email was sent to [email protected] > why did I get this? unsubscribe from this list update subscription > preferences > Dr. James E. Hansen · Climate Science, Awareness and Solutions · 475 > Riverside Drive, Ste 401-O · New York, NY 10115 · USA > > > -- > You received this message because you are subscribed to the Google Groups > "NOAC Meetings" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/noac-meetings/0f6c01d98f17%24a91bee20%24fb53ca60%24%40EndorphinSoftware.co.uk. -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/geoengineering/E4360B66-1AB0-4958-88FC-10D8D3DA2C57%40gmail.com.
