34 Comments

Could a sudden climagte shift be caused by the Hunga Tonga-Hunga Haʻapai volcano eruption, a large, undersea eruption that released enormous amounts of water vapor into the atmosphere?

Expand full comment

This thoughtful nuance is exactly why I read this page.

Another example: I never knew what RCP 8.5 was before coming here. Now I know it's the most important thing I didn't know on the subject (and what rarely if ever gets explained in regime media reports on climate and energy policy).

Expand full comment

I am a bit concerned about the consistency of your argument. If we do not know abrupt climate change then how do we know we are increasing the likelihood of it? Or this the elsuive precautionary principle again: prepare even if we dont know it will make a differenece?

Expand full comment

Since there has not been a September as warm as 2023 since 1940, doesn’t that mean the temperature range from September 1940 had to be very similar to the temperature range from September 2023? And if I am not mistaken the CO2 levels were much lower in 1940 than today, and not a truck or SUV in sight.

Expand full comment
founding

Are Hausfather and Dessler a team now? They seem to have a joint Substack.

Expand full comment

The unusual and warm, completely unpredicted weather of the summer illustrates that the climate scientists simply don't know what they don't know and are only fooling themselves into thinking that they do know about climate and climate change.

As is often stated here and elsewhere, climate is a dynamic and chaotic system. There is no way that mankind's continual and gentle increase in CO2 can cause such a stepwise increases in temperatures. As important as we think we are, mankind is not in the bigger picture of climate. Clearly, natural forces are at work and sadly because the study of natural climate change has been displaced by the feeding frenzy of anthropogenic climate change (ie funding) we are no closer to finding out why these events happen.

Expand full comment

"Are We Seeing Abrupt Climate Change?" No, Abrupt Climate Change refers to very specific events that are characterized by rapid warming or cooling that may persist thousands of years. About two dozen such events (such as Dansgaard–Oeschger events) have been recorded over the last 100,000 years. There is no indication that a rise or fall in greenhouse gases triggered these events. The warming that we are experiencing now may be do to increases in atmospheric carbon dioxide and/or natural variability but is unlike the truly rapid rise and fall that characterizes Abrupt Climate Change. Yes, sudden climate change is a feature of our planet's history for millions of years and not just a recent happening.

Expand full comment

In my view many climate scientists have been crying wolf for some decades. It's worth noting that a stopped clock is right twice a day. There is a possibility of human forcings inducing rapid change

This would validate at least part of the emotional distress that people (including scientists) have become accustomed to feeling about climate. However what it would not do is fundamentally alter the policy direction

As Roger states, abrupt change can and has happened naturally. This would seem to make adaptation to potential extremes relatively more important than a singular focus on CO2 output. This is already the case with current policy that fails to properly implement adaptive measures, including promoting economic growth to enable greater resilience

Because a human triggered shift should be more likely at higher temperature rises policies with long time horizons that can have the largest long term impact are more important. Researching tomorrow's fuel source is better than subsidizing today's Tesla

Expand full comment
founding
Oct 8, 2023Liked by Roger Pielke Jr.

We look at the need to consider risk more broadly in our paper

Pielke, Sr. R.A., J. Adegoke, F. Hossain, and D. Niyogi, 2021: Environmental and social risks to biodiversity and ecosystem health – A bottom-up, resource-focused assessment framework. Earth, 2, 440–456. https://doi.org/10.3390/earth2030026

Expand full comment
founding
Oct 8, 2023Liked by Roger Pielke Jr.

Also

Pielke Sr., R.A., R. Wilby, D. Niyogi, F. Hossain, K. Dairaku, J. Adegoke, G. Kallos, T. Seastedt, and K. Suding, 2012: Dealing with complexity and extreme events using a bottom-up, resource-based vulnerability perspective. Extreme Events and Natural Hazards: The Complexity Perspective Geophysical Monograph Series 196 © 2012. American Geophysical Union. All Rights Reserved. 10.1029/2011GM001086.

http://pielkeclimatesci.files.wordpress.com/2012/10/r-3651.pdf

Expand full comment

This is worth remembering:

"We cautioned against subsuming the issue of abrupt climate change to human-caused climate change — the issue is much broader:"

Thank you, Roger, for reminding us all..

Expand full comment

Yes

But the issue is the IPCC charter only directs them to look for human causes.

When all you have is a hammer everything looks like a nail.

Expand full comment

Yes

But the issue is the IPCC charter only directs them to look for human causes.

When all you have is a hammer everything looks like a nail.

Expand full comment

Feel really sorry for your reader who sent you the note referenced at the beginning. That guy is going to need serious mental health supports, I wonder if the “other scientists” he refers to includes the loony Kalmus? As long as he is employed by NASA it’s not possible to take it seriously as scientific organization.

As to September, as there is no known mechanism whereby the slightly increasing co2 year by year causes a sudden step change in temps I look forward to seeing some real science figure it out.

I just hope that occurs before I die around 2055

Expand full comment
founding
Oct 8, 2023Liked by Roger Pielke Jr.

Climate has always involved sudden transitions even on decadal and shorter time periods, and without human involvement. Here are two papers we published on this subject.

Sveinsson, O.G.B., J.D. Salas, D.C. Boes, and R.A. Pielke Sr., 2003: Modeling of long-term variability of hydroclimatic processes. J. Hydrometeor., 4, 489-505

http://pielkeclimatesci.wordpress.com/files/2009/10/r-255.pdf

Rial, J., R.A. Pielke Sr., M. Beniston, M. Claussen, J. Canadell, P. Cox, H. Held, N. de Noblet-Ducoudre, R. Prinn, J. Reynolds, and J.D. Salas, 2004: Nonlinearities, feedbacks and critical thresholds within the Earth's climate system. Climatic Change, 65, 11-38.

http://pielkeclimatesci.wordpress.com/files/2009/10/r-260.pdf

Expand full comment

Solid evidence shows the the warming by CO2 is too small to measure. The Sun controls the Earth's temperature. We have no control over the Sun. We should be more concerned about the coming winter in the Northern hemisphere. Maybe it will be as brutal as the recent winter in the southern hemisphere. Then we will need lots of fossil fuels to keep warm.

Expand full comment

Personally, I find "global average temperature" a rather crude metric for "abrupt change." To me, long-term changes in temperature patterns are better indicators. For example, over the last few years, our summers in SC have been cooler than average; tending to surplus rainfall. Not of much meaning by itself. But our more temperate temperatures indicate someone else got blasted. Change in pattern?

Further, unless we go back and include the 1930's, I can't get too excited.

Expand full comment

Yes, funny how the Copernicus data chart starts at 1940.

As it’s fall I love cherries, cherry pie remains my favorite thing that comes from cherry picking.

Expand full comment
Oct 8, 2023Liked by Roger Pielke Jr.

Excellent analysis.

Expand full comment

Roger

I assume you saw Antonis Christofides et al post on Judith Curry’s blog showing data that suggests CO2 increase is a consequence of rising temperatures, not the other way around. Do you buy this causality reversal from consensus thinking?

Secondly, could this be forewarning of the state change you discussed here, where we have reached the tipping point and temperature increase now is leading to a runaway cycle of more CO2 thus even higher temperatures etc. ?

Appreciate your thoughts on this one!

Expand full comment