donsutherland1

In its coverage of the extreme heat, the Los Angeles Times had a fairly lengthy discussion of climate change. https://www.latimes.com/california/story/2020-09-05/heat-health-risks This linkage to climate change provides important context for the newspaper’s readers and the general public. The Washington Post also provide climate change-related context when discussing California’s fires and extreme heat. The New York Times did not, depriving its readers of important insight into the events.

2020 was the 11th summer on record with a mean temperature above 94.5 degrees in Phoenix. It also became the 6th out of those 11 summers to see the 9/1-6 period wind up warmer than the entire summer average. All of those six summers with a warmer start to September occurred 2000 or later and four occurred 2010 or later. What this means is that the intense heat of exceptionally warm summers now has a tendency to last a little longer than had been the case in the past.

It’s not hubris. It’s a conclusion based on the evidence. Here’s one study that shows historical temperature trends, the trends that would have occurred only with natural forcings, and those that would have occurred only with anthropogenic forcings. The relevant charts are on page 8 of the paper. https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1002/jgrd.50239

When greenhouse gases are omitted, the observed ongoing warming cannot be replicated. Only when such gases are included can the observed warming be replicated. Gavin Schmidt, director of National Aeronautics and Space Administration’s Goddard Institute for Space Studies, said that scientists look at a lot of different things at once. “We have a very, very clear understanding that the amount of heat in the ocean is increasing—the ocean heat content is going up by a lot,” said Schmidt. “That implies that there must be an external change in the radiation budget of the earth—more energy has to be going in than leaving... To understand this rapid change in climate, scientists look at data sets and climate models to try to reproduce the changes that have already been observed. When scientists input only natural phenomena such as the sun’s intensity, changes in the Earth’s orbit and ocean circulation, the models cannot reproduce the changes that have occurred so far. “We have independent evidence that says when you put in greenhouse gases, you get the changes that we see,” said Schmidt. “If you don’t put in greenhouse gases, you don’t. And if you put in all the other things people think about—the changes in the earth’s orbit, the ocean circulation changes, El Niño, land use changes, air pollution, smog, ozone depletion—all of those things, none of them actually produce the changes that we see in multiple data sets across multiple areas of the system, all of which have been independently replicated.” In other words, only when the emissions from human activity are included, are the models and data sets able to accurately reproduce the warming in the ocean and the atmosphere that is occurring. https://blogs.ei.columbia.edu/2017/04/04/how-we-know-climate-change-is-not-natural/

There is literature about the lags namely where increasing solar insolation kicked off warming in the Northern Hemisphere and subsequent warming led to increases in CO2, which, in turn, amplified further warming. That humanity has engineered a “short cut” of sorts by dramatically and rapidly increasing atmospheric CO2 does not mean that (1) this increased CO2 won’t drive warming (CO2's properties found in physics and other empirical literature suggests that it should; the ongoing observed warming demonstrates that the expected warming is taking place) and (2) that one assumes the climate system is linear. No serious climate scientist has made such claims that I can find. The real question is why atmospheric CO2 levels consistent with the Pliocene should not produce warming perhaps of a similar magnitude? Global temperature are rising. The 2010s was the warmest decade of the instrument record (all major data sets). The 2020s will likely exceed that level of warmth.

A basic primer in slides by Paleoclimatologist Jessica Tierney: https://www.agci.org/sites/default/files/pdfs/lib/main/19s1_05_08_1800_Tierney_WOR_Aspen2019.pdf Dr. Tierney has done extensive research on earlier climate regimes e.g., the Eocene warming. She is the co-author of newly published paper on temperatures during the last ice age.

Two papers: https://iopscience.iop.org/article/10.1088/1748-9326/10/1/014005 https://www.nature.com/articles/s41467-018-05256-8.epdf

There is some research indicating that Arctic Amplification also has an impact on the summer weather pattern in addition to that of the fall. In general, one line of thought is that it is leading to greater persistence of events due to a wavier and slowing jet stream.

Actually, the UAH has had documented issues. RSS, RATPAC, etc., are better tools. That UAH is an outlier highlights its issues. One paper: https://journals.ametsoc.org/jtech/article/34/1/225/342433

It’s tough to know. But some of the studies suggest that New York City will have a climate similar to Virginia Beach by 2050.

Back last year, Eric Blake of the National Hurricane Center tweeted about Miami’s record 42nd day with a high temperature of 93 degrees or above. 2019 went on to finish with 44. Through September 4, 2020 has had 48 such days. 2019 also went on to record an annual mean temperature of 79.1 degrees, which tied 2017 for the second warmest year on record 2015, with an annual mean temperature of 79.2 degrees, is Miami’s warmest year on record.

The issue isn’t whether humans can “overpower” such past events, but whether humans can have a significant impact on the climate. The science is unambiguous. Human greenhouse gas emissions are now the main driver of the rapid observed warming. Moreover, humans are releasing CO2 at a rate 10 times faster than has occurred at any other time over the past 66 million years. https://www.sciencedaily.com/releases/2016/03/160321123656.htm

Those are over millions of years not hundreds of years.

Yes, but that’s well before the Holocene. Nevertheless, what one is witnessing today is highly unusual.

The rate of warming has been unprecedented for the Holocene. For a graph that goes well beyond the Holocene for even greater perspective: https://www.sciencemag.org/news/2019/05/500-million-year-survey-earths-climate-reveals-dire-warning-humanity Sea levels are rising as ice caps and glaciers are melting. Finally, the scientists have already demonstrated that anthropogenic factors are responsible for most of the recent warming.

Mann’s paper laid out the basis for the “hockey stick.” The basic findings and the temperature reconstruction (aka the hockey stick) were validated. Thus the reconstruction is not a “fraud.”

Scientific understanding advances through research. That research is published in peer-reviewed journals. The topic at hand concerns anthropogenic climate change. No other alternative explanation can explain the recent dramatic warming that has occurred since 1950. Mann’s research has contributed to a solid scientific understanding. If anthropogenic climate change is “fraud,” one should have credible scientific research to expose it. Such credible research does not exist, because the scientific basis is sound. Earlier, I provided a link to subsequent research that validated Mann’s paper. No one has provided a link to any paper that overturns it. That’s where things stand. Finally, the reference to policy was an illustration to show that the world is moving to applying the scientific understanding. The scientific question, with the exception of some nuances, residual uncertainties, and details about feedbacks is largely settled on the cause of the ongoing observed warming.

Hopefully, others who read these pages will realize that, notwithstanding erroneous Social Media claims, Mann’s “Hockey Stick” has been validated by subsequent research. The good news is that the world has largely moved on from the past debate over whether climate change is occurring (it is) and whether it is principally driven by anthropogenic activities (it is). Those who reject the now near unequivocal consensus among climate scientists have had decades to provide a plausible and empirically robust alternative to AGW. They have not. Among the Millennials and Generation Z, the fundamental basis of climate change is widely understood. The urgency of addressing that great global challenge is also well understood. It’s those generations that will, as their political influence and participation grows, put an end to efforts to thwart the policy making necessary to address climate change.

His paper did not reach conclusions “regardless to which set of numbers was used.” As a result, the paper has largely withstood the test of time. Today, at least in the scientific field, it is considered among the breakthrough works that have informed the evolution of understanding of climate change. If you can point me to peer-reviewed research that finds his basic conclusion was wrong, please share it. The studies that followed largely upheld the paper with some revisions for the 1400-1500 period. The most important part concluding that the warming during the late 20th century (which has now been exceeded in the early 21st century) was greater than anything that had occurred during the prior 600 years was reaffirmed in the follow-up research. Today, there is no serious debate that the current global temperatures are unprecedented during the current 1,000 years. Within a few decades or less, they will likely be the warmest of the entire Holocene Interglacial Period. Moreover, the warming is more abrupt and rapid than anything that took place in the Holocene. Taking potshots at modeling to evade the largely sound conclusions of Dr. Mann’s paper is the “strawman.” Moreover, the modeling from the 1970s and 1980s, even as it was fairly rudimentary at that time, has proved quite accurate.

Mann created his landmark temperature chart from multiple lines of proxy data and the instrument record.

Article on Phoenix’s historic summer by The Washington Post’s Capital Weather Gang: https://www.washingtonpost.com/weather/2020/09/01/phoenix-hottest-summer

Here is the extended information that includes the 30-year periods ending in 1930 and 1940 for Phoenix. Average Summer Temperatures (30-Year Moving Average):

I have confidence in the large and growing body of peer-reviewed research on the matter. Further, there is no alternative explanation that even begins to account for the observed warming that has occurred since 1950. Models that rely solely on natural forcings cannot reliably reproduce the warming. Those that include anthropogenic greenhouse gases do very well.

Initially, one could make a compelling argument that Phoenix’s warming was being driven by growing urbanization. But that has changed. During the 1990-2020 period, the 30-year moving average for summer temperatures rose 2.7° at Phoenix but 1.4° at Tombstone (current population 1,330). However, if one excludes the 1990s, the increases were 1.5° and 1.0° respectively. Since 2010, Tombstone actually saw greater warming than Phoenix, even as its population fell slightly from 1,382. In addition, as with Phoenix, a disproportionate share of Tombstone’s 10 warmest summers have occurred since 2000. In fact, 9 of Tombstone’s 10 warmest summers have occurred since 2010. In sum, the recent data is consistent with what the overwhelming body of scientific research shows overall: Most of the recent warming is related to anthropogenic climate change, not location-specific factors such as the Urban Heat Island (UHI) effect. Not surprisingly, IPCC is considering raising the level of confidence about the role of anthropogenic factors leading to most of the recent warming to 99%-100% for the Sixth Assessment Report that will be published next year.

Urbanization was cited as one of three factors by the National Weather Service. Climate change was another. Moreover, the idea that urbanization is responsible for the outcome was addressed by NWS Phoenix which stated, "The record summer heat wasn't just in Phoenix, or solely due to Urbanization. A large chunk of the SW saw exceptional heat and all-time records. Some other locations w/ all-time summer records: Lost Dutchman SP, Carefree, Tombstone, Tucson, & Nogales."