donsutherland1

During the summer and early fall (early spring in the Southern Hemisphere), numerous daily and monthly high temperature records, including some all-time high temperature records, along with monthly mean temperature records were broken. A number of locations experienced their hottest summer on record. July 2020 was Phoenix’s hottest month on record. August 2020 was even hotter. Summer 2020 was, by far, Phoenix’s hottest summer on record. Parts of South America and Southern Africa are currently experiencing their most intense early spring heat on record. Research demonstrates that climate change has led to an increase in summertime high temperature records, which are tied to prolonged heat waves, by more than a factor of ten. There is approximately an 80% probability that the new records have been made possible by anthropogenic climate change. Further increases in such records are likely in coming decades as the world’s climate continues to warm. https://www.researchgate.net/publication/234114398_Global_increase_in_record-breaking_monthly-mean_temperatures

Under partly to mostly cloudy skies, temperatures rose mainly into the middle 70s across the region. In parts of South America, a historic early spring heatwave toppled monthly records. Some monthly records included: Asuncion, Paraguay: 108° Corrientes, Argentina: 109° Foz Do Iguacu, Brazil: 102° Pozo Hondo, Paraguay: 114° ***New all-time national high temperature record*** Meanwhile, in parts of Europe, early-season snows blanketed even the lower elevations of the Alps. Temperatures will likely remain at generally above normal levels for the remainder of September. A cool shot is likely during the opening week of October, but warmer readings could return during the following week. Phoenix has an implied 95% probability of recording just its 13th September on record with a mean temperature of 90° or above. The most recent such occurrence was 2018 with a mean temperature of 91.8°. Phoenix will very likely record its hottest June-September period on record with a four-month mean temperature of near 95.4°. That would exceed the previous June-August record of 95.1°, which was set in 2013 and tied in 2015. The existing record is 93.9°, which was set in 2011. October could be wetter than September in and around the New York City area. Since 1950, 10 of the 12 (83%) of the La Niña cases that followed an El Niño winter saw October receive more precipitation than September, including 7 of the 8 (88%) cases since 1980. October 1954 and October 1998 were the exceptions. The largest increase in precipitation occurred in 2005. September 2005 saw just 0.48" precipitation in New York City. October 2005 received 16.73" precipitation. The ENSO Region 1+2 anomaly was -0.4°C and the Region 3.4 anomaly was -0.8°C for the week centered around September 16. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.93°C and the ENSO Region 3.4 anomaly has averaged -0.68°C. La Niña conditions have developed and will likely prevail through the remainder of autumn. The SOI was +16.11. Today, the preliminary Arctic Oscillation (AO) figure was +0.683. On September 25, the MJO was in Phase 5 at an amplitude of 1.350 (RMM). The September 24-adjusted amplitude was 1.442. Since 1990, there have been 11 La Niña events, 6 of which followed an El Niño winter. 10/11 (91%) case saw warmer than normal September. All 6 following an El Niño winter were warmer than normal. September mean temperatures for New York City for those cases were: 11 cases: 69.9°; Subset of 6 cases: 70.8°; Entire 1990-2019 period: 69.0°. The September mean temperature for all La Niña and neutral-cool cases following an El Niño winter (1950-2019: n=13) was 69.9°. Since 1950, there have been five cases where a La Niña developed during June-July-August or afterward following an El Niño winter. 4/5 (80%) of those cases saw a predominant EPO+/AO+ winter pattern. The most recent such case was 2016-17. 9/10 (90%) of the La Niña winters that followed an El Niño winter featured a predominantly positive EPO. Based on sensitivity analysis applied to the latest guidance, there is an implied 85% probability that New York City will have a warmer than normal September. September will likely finish with a mean temperature near 68.6°.

Abstract: Extreme weather events in Asia have been occurring with increasing frequency as the globe warms in response to rising concentrations of greenhouse gases. Many of these events arise from weather regimes that persist over a region for days or even weeks, resulting in disruptive heatwaves, droughts, flooding, snowfalls, and cold spells. We investigate changes in the persistence of large-scale weather systems through a pattern-recognition approach based on daily 500 hPa geopotential height anomalies over the Asian continent. By tracking consecutive days that the atmosphere resides in a particular pattern, we identify long-duration events (LDEs), defined as lasting longer than three days, and measure their frequency of occurrence over time in each pattern. We find that regimes featuring positive height anomalies in high latitudes are occurring more often as the Arctic warms faster than mid-latitudes, both in the recent past and in model projections for the twenty-first century assuming unabated greenhouse gas emissions. The increased dominance of these patterns corresponds to a higher likelihood of LDEs, suggesting that persistent weather conditions will occur more frequently. By mapping observed temperature and precipitation extremes onto each atmospheric regime, we gain insight into the types of disruptive weather events that will become more prevalent as particular patterns become more common. https://www.nature.com/articles/s41598-020-71945-4

Morning thoughts... At 8:45 am, a shrinking area of moderate to heavy rain that had brought 0.66" rain to Wilmington was headed northward toward Allentown. Much of the rest of the region was cloudy with a few widely scattered light showers. Today will be mainly cloudy with perhaps a few additional showers. The sun could begin to break through the clouds during the afternoon. Temperatures will likely reach the lower to perhaps middle 70s across the region. Likely high temperatures around the region include: New York City (Central Park): 74° Newark: 75° Philadelphia: 75° The temperature will likely remain above normal through the remainder of the month.

@blizzard1024Tree rings at some locations had seemingly become a less reliable indicator of temperature. More recent research suggests that light (dimming) may have been responsible. https://phys.org/news/2014-05-arctic-tree-ring-divergence-problem.html

I’m not sure if the below paper has been posted here, but it allows for comparisons of Arctic sea ice volume during the first half of the 20th century, including the 1920-40 Arctic warming, and the rapid declines in volume today. The paper is: Arctic Sea Ice Volume Variability over 1901–2010: A Model-Based Reconstruction https://journals.ametsoc.org/jcli/article/32/15/4731/343909/Arctic-Sea-Ice-Volume-Variability-over-1901-2010-A

If the use of proxy data is the “weakest link,” how would you go about trying to compare today’s temperatures with those during the rest of the Holocene?

Tomorrow will be mainly cloudy with perhaps a few showers and a little cooler than today. In general, temperatures will likely remain at generally above normal levels for the remainder of September. A cool shot is possible in the opening week of October, but warmer readings could return during the following week. Phoenix has an implied 90% probability of recording just its 13th September on record with a mean temperature of 90° or above. The most recent such occurrence was 2018 with a mean temperature of 91.8°. Phoenix will very likely record its hottest June-September period on record with a four-month mean temperature of near 95.3°. That would exceed the previous June-August record of 95.1°, which was set in 2013 and tied in 2015. The existing record is 93.9°, which was set in 2011. The ENSO Region 1+2 anomaly was -0.4°C and the Region 3.4 anomaly was -0.8°C for the week centered around September 16. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.93°C and the ENSO Region 3.4 anomaly has averaged -0.68°C. La Niña conditions have developed and will likely prevail through the remainder of autumn. The SOI was +16.88. Today, the preliminary Arctic Oscillation (AO) figure was +0.613. On September 24, the MJO was in Phase 5 at an amplitude of 1.436 (RMM). The September 23-adjusted amplitude was 1.370. Since 1990, there have been 11 La Niña events, 6 of which followed an El Niño winter. 10/11 (91%) case saw warmer than normal September. All 6 following an El Niño winter were warmer than normal. September mean temperatures for New York City for those cases were: 11 cases: 69.9°; Subset of 6 cases: 70.8°; Entire 1990-2019 period: 69.0°. The September mean temperature for all La Niña and neutral-cool cases following an El Niño winter (1950-2019: n=13) was 69.9°. Since 1950, there have been five cases where a La Niña developed during June-July-August or afterward following an El Niño winter. 4/5 (80%) of those cases saw a predominant EPO+/AO+ winter pattern. The most recent such case was 2016-17. 9/10 (90%) of the La Niña winters that followed an El Niño winter featured a predominantly positive EPO. Based on sensitivity analysis applied to the latest guidance, there is an implied 79% probability that New York City will have a warmer than normal September. September will likely finish with a mean temperature near 68.6°.

The American Meteorological Society (AMS) just published the state of the climate report for 2019. Excerpts: All major greenhouse gases released into Earth’s atmosphere reached new record high concentrations in 2019. The annual global average carbon dioxide concentration at Earth’s surface was 409.8 ± 0.1 ppm, an increase of 2.5 ± 0.1 ppm over 2018, and the highest in the modern instrumental record and in ice core records dating back 800 000 years. Greenhouse gases, along with several halogenated gases, have contributed to a 45% increase in net forcing compared to 1990. Carbon dioxide is responsible for nearly two-thirds of this increase. A weak El Niño early in the year transitioned to ENSO-neutral conditions by mid-year, yet the annual global surface temperature across land and ocean surfaces was still among the three highest on record. July became the hottest month in records dating to the mid- to late-1800s. Each decade since 1980 is warmer than its preceding decade, with 2010–19 being around 0.2°C warmer than 2000–09. In 2019, there were a record high number of extreme warm days (temperatures above the 90th percentile) over global land surfaces. There were also a low number of extreme cool days (temperatures below the 10th percentile) compared to the last 70 years, but there were more cool days compared to the average of just the past decade. A new indicator introduced this year to the report—marine heat waves—indicates that the number of strong marine heatwaves surpassed the number of more moderate marine heat waves for the sixth consecutive year. Lake temperatures increased on average across the globe in 2019; observed Northern Hemisphere lakes were covered in ice seven days fewer than the 1981–2010 average, accord- ing to phenological records. Over land, the growing season was an average of eight days longer than the 2000–10 average in the Northern Hemisphere. In colder regions, alpine glaciers around the world continued to lose mass for the 32nd consecutive year, while record high permafrost temperatures were observed at many observing sites across the high northern latitudes. The complete report can be found here: https://www.ametsoc.org/ams/index.cfm/publications/bulletin-of-the-american-meteorological-society-bams/state-of-the-climate/

Climate Proxies: Some resources: Introduction to Climate Science: Paleoclimate: https://open.oregonstate.education/climatechange/chapter/paleoclimate/ What is Paleoclimatology? https://www.ncei.noaa.gov/news/what-is-paleoclimatology Data: Paleoclimatology data: https://www.ncdc.noaa.gov/data-access/paleoclimatology-data

Abrupt as in taking place in a matter of decades rather than the far longer geological timeframes such changes have typical (not always) occurred. Actually, I probably should have used a somewhat different term, as abrupt can infer an unexpected development when the warming is consistent with the latest understanding of climate change. Also, there’s no need to dismiss the work of paleoclimatologists who have pieced together climate records from various proxies. The proxies offer a reasonably consistent picture. They provide a lot of insight. The alternative is to pretend that what wasn’t recorded is unknown and unknowable. That’s not a scientific approach.

No climate scientist has published a paper that argues that the climate was "in almost complete stasis" since 1000 CE. Climate has always been dynamic due to changes in natural forcings, not to mention internal variability. There have been periods where it has been relatively more stable than at other periods. The big issue concerns the abrupt and sharp warming that commenced since the mid-20th century, predominantly on account of anthropogenic greenhouse gas emissions. That warming has occurred despite little change in solar irradiance and a long-term decline in summer solar insolation in the Arctic. The change in the atmospheric concentration of CO2 and the warming that has occurred in mere decades is remarkable, as such changes have typically (not always) occurred over geological timeframes, not decades.

Phoenix recorded its hottest summer (June 1-August 31) on record. Anthropogentic climate change has been driving an observed global warming. Within that global climate context, Phoenix has experienced both a warming of its summers and a lengthening of its summer-like temperatures. If one looks back at the climate model projections for the RCP 4.5 scenario, one finds that the climate model projections run in 2005 were very accurate in depicting what the summer 2011-2020 period would be like. Looking ahead, the summer 2021-2030 period will likely be even warmer under the RCP 4.5 scenario. Phoenix: Summer 2011-20 High Temperatures and Projected 2021-30 High Temperatures:

Morning thoughts... Today will be partly sunny and warm. The temperature will likely top out mainly in the upper 70s with a few lower 80s across the region. Likely high temperatures around the region include: New York City (Central Park): 78° Newark: 80° Philadelphia: 78° The temperature will likely remain above normal through the remainder of the month. Yesterday was Las Vegas' 157th consecutive day with no measurable precipitation. That is the longest such stretch on record for that city.

Those claims are aimed at dismissing climate scientists to circumvent the absence of scientific evidence to dismiss AGW. While we’re discussing independence or perceived independence of researchers, it should be noted that Lindzen cited above had been receiving funding from coal interests (Peabody Energy). https://www.theguardian.com/environment/2016/jun/13/peabody-energy-coal-mining-climate-change-denial-funding