donsutherland1

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."

Another tweet from the Phoenix office of the National Weather Service: https://twitter.com/NWSPhoenix/status/1300795549499756544?s=20

From the NWS Phoenix forecast office:

If the idea that Phoenix’s climate will resemble that of Baghdad is reasonably accurate, then there could be some nights with lows at or above 100 (Phoenix’s lows are higher than those in Baghdad) and highs in the lower and middle 120s during periods of extreme heat.

Phoenix concluded, by far, its hottest summer on record. During June-August 2020, Phoenix had a mean temperature of 96.7°. That smashed the old record of 95.1°, which was set in 2013 and tied in 2015. Table 1: Summer 2020 Average Temperatures Since 2009, every summer has ranked among the 20 warmest summers on record. In addition, 2015, 2016, 2019 and 2020 have ranked among the 10 warmest summers. Table 2: 20 Warmest Summers Monthly Mean Temperatures: June: 92.0° (21st warmest June on record) July: 98.9° (warmest July on record; old record: 98.3°, 2009) August: 99.1° (warmest August on record; old record: 98.3°, 2011) July 2020 set a new monthly mean temperature. August 2020 surpassed that record. Just 3 (15%) of the 20 warmest months were recorded prior to 2000. 17 (85%) of the warmest months occurred 2000 or later and 10 (50%) of the warmest months occurred 2010 or later. There were three cases where both July and August ranked among the 20 warmest months: 2007, 2019 and 2020. Table 3: 20 Warmest Months Table 4: Record High Minimum Temperatures Table 5: Record High Maximum Temperatures Select Monthly Heat Thresholds: Highs 110° or above: 22 days, August 2020 (old record: 19 days, July 2020; prior old record: 18 days, June 1974) Highs 115° or above: 7 days, August 2020 (tied record set in June 1974) Lows: 90° or above: 16 days, July 2020 (old record: 11 days, July 2006); August 2020 had 12 such days. Select Summer Heat Thresholds: Highs 110° or above: 48 days (old record: 31 days, 2007 and 2011) Highs 115° or above: 13 days (old record: 7 days, 1974) Lows: 90° or above: 28 days (old record: 15 days, 2003 and 2013) Climate Change: Anthropogenic climate change is driving a warming of Phoenix's summers. The warming has accelerated in recent decades. The observed global warming since the 1950s is unequivocal with anthropogenic greenhouse gas emissions being the dominant driver of that warming (IPCC Climate Change Synthesis Report 2014). The warming is a global phenomenon with 98% of the world having experienced its warmest 51 years during the current 2,000 years (Neukom, et al. 2019). Recent research suggests that Phoenix's climate will resemble that of Baghdad by 2050 (Bastin, et al. 2019). During the summer, Baghdad typically receives no rainfall. Baghdad's average high temperatures (Weather Atlas 2002-2020) during the summer months are: June: 105.8° July: 111.2° August: 109.4° Summer Average High Temperature: 108.8° Until summer 2020, the highest mean summer maximum temperature was 107.0°, which was set in 1978 and tied in 1989. The highest monthly summer maximum temperature was 109.8°, which was set in July 1989 and tied in July 2020. August 2020 surpassed that record with an average high temperature of 110.7°. As recently as 2000, Phoenix's average low temperature during the summer was 79.8°. Since 1999, Phoenix has had no summer with an average low temperature below 80.0°. Prior to 2020, the highest average monthly minimum temperature was 87.5°, which was set in August 2011. July 2020 had an average minimum temperature of 88.0°. Based on the above research findings, summer 2020 provides a glimpse of what a typical Phoenix summer will be like by 2050. Table 6: Average Summer Temperatures (30-Year Moving Average) Climate change is also resulting in an increase in the frequency of days on which the low temperature stays at or above 90° and the high temperature reaches 100° or above, 110° or above, and 115° or above. Table 7: Average Annual Days at Set Thresholds (30-Year Moving Average) According to the Fourth National Climate Assessment, Phoenix saw 60 to nearly 100 100° days per year at the 5th and 95th percentiles. Under the RCP 4.5 scenario, those figures are projected to increase to 110-141 days per year during the 2070-2099 period. During the 1950-1999 period, 9 (18%) of years saw the number of 100° days fall within the projected RCP 4.5 interval (U.S. Global Change Research Program, 2017). From 2000-2019, 11 (55%) of years fell within that interval. 2020 is all but certain to become the 12th case since 2000 to meet that higher interval. Moreover, through August 31, the 30-year moving average is just above 110 days per year. During the summer, 48 days saw high temperatures 110° or above. The previous summer record was 31 days, which was set in 2007 and tied in 2011. During 2020, there have been 50 such days vs. the prior record of 33 days, which was set in 2011. There were also 28 days on which the minimum temperature was 90° or above, which eclipsed the previous record of 15, which was set in 2003 and tied in 2013. In addition, the number of very hot (high temperature of 110° or above) and super hot (high temperature of 115° or above) days has been increasing as a share of the increasing number of 100° days. For the 30-year period ending in 1980, 12.6% of 100° days had high temperatures of 110° or above and 1.0% saw temperatures reach 115° or above. For the 30-year period ending in 2000, those figures increased to 15.7% and 1.7% respectively. For the period ending in 2020 (through August 31), those figures increased further to 18.8% and 2.0% respectively. Overall, the frequency and intensity of compound summertime hot extremes (events that combine daytime and nighttime heat where such temperatures are above their 90th percentile for their calendar) has been increasing especially in geographic locations that include the U.S. Southwest (Wang 2020). The increase in forcing associated with anthropogenic greenhouse gases is the dominant driver of this outcome. (Wang 2020). During summer 2020, 15 record high minimum temperatures were tied or broken in Phoenix and 14 record high maximum temperatures were tied or broken. On 7 days, both record high minimum and maximum temperatures were tied or broken. Summary: Summer 2020 saw Phoenix record its highest summer temperature on record. It also saw Phoenix experience its two hottest months on record. In addition, Phoenix easily surpassed records for the most days on which the temperature reached 110° or above and on which minimum temperature was 90° or higher. Anthropogenic climate change, which has turned hot patterns hotter and increased pattern persistence, is largely responsible for this exceptional warmth. Based on the latest research, the extreme heat of summer 2020 will likely become the "new normal" by 2050. Updates: September 1-7: https://www.americanwx.com/bb/topic/53697-phoenix-records-its-hottest-summer-on-record/?do=findComment&comment=5650331 Summer High Temperatures: Climate Model Projections and Actual Outcomes: https://www.americanwx.com/bb/topic/53697-phoenix-records-its-hottest-summer-on-record/?do=findComment&comment=5661632 Phoenix Records a 90° Mean Temperature for September: https://www.americanwx.com/bb/topic/53697-phoenix-records-its-hottest-summer-on-record/?do=findComment&comment=5664607 Phoenix Experiences its Hottest Week in October: https://www.americanwx.com/bb/topic/53697-phoenix-records-its-hottest-summer-on-record/?do=findComment&comment=5668129 Phoenix Sets New Annual Record for 100° Days: https://www.americanwx.com/bb/topic/53697-phoenix-records-its-hottest-summer-on-record/?do=findComment&comment=5672012 A Very Warm October Concludes in Phoenix: https://www.americanwx.com/bb/topic/53697-phoenix-records-its-hottest-summer-on-record/?do=findComment&comment=5684211 Phoenix Experiences its Warmest 5-Day November Period on Record: https://www.americanwx.com/bb/topic/53697-phoenix-records-its-hottest-summer-on-record/?do=findComment&comment=5687553 Phoenix Experiences Latest 90° Days on Record: https://www.americanwx.com/bb/topic/53697-phoenix-records-its-hottest-summer-on-record/?do=findComment&comment=5698629

Arctic sea ice extent fell to 3.995 million square kilometers on JAXA. That makes 2020 the second consecutive year that will have a minimum extent below 4.000 million square kilometers and the third such year on record.

Unfortunately, based on 2010-19 melt rates, it is very likely that 2020 will finish solidly with the second lowest minimum extent on record. It will also be the second consecutive year with a minimum extent below 4 million square kilometers and third such year on record.