Marine Heatwaves Leading To Rapid Hurricane Intensification Before Landfall

[bluewave]

https://www.disl.edu/about/news/marine-heatwaves-and-hurricanes-study-examines-compounding-impact-of-severe-weather

Several coastal communities are picking up the pieces after being ravaged by hurricanes in the past month. Hurricane Laura, a category 4, and Hurricane Sally, a category 2, seemed to meander their way across the Gulf of Mexico constantly shifting forecasts and keeping meteorologists on their toes. In the hours before these storms struck land, they seemed to explode in intensity. 

Researchers at the Dauphin Island Sea Lab with support from the Jet Propulsion Laboratory can offer insight into why these storms intensified quickly as they moved across the continental shelf. 

“Surprisingly, both Hurricane Laura and Hurricane Sally appeared to have similar setups to Hurricane Michael with both storm events being preceded by smaller storms (i.e. Hurricane Hanna and Marco, respectively),” Dr. Brian Dzwonkowski explained. “This pre-storm setup of the oceanic environment likely contributed to the intensification prior to landfall.  Importantly, this pre-landfall intensification was not well predicted by hurricane models or forecasts, which as you can imagine is critical information for evacuation  and disaster preparation.”

Dzwonkowski and his team’s publication, “Compounding impact of severe weather events fuels marine heatwave in the coastal ocean”, outlines how one storm could impact the intensity of another storm by restructuring the thermal properties of the water column. Nature Communications published the findings in its September issue.

The research focuses on Hurricane Michael which devastated Mexico Beach, Florida, and the surrounding communities, on October 10, 2018. The category 5 storm intensified hours before making landfall. 

Dzwonkowski, a physical oceanographer with the Dauphin Island Sea Lab and Associate Professor at the University of South Alabama in the Department of Marine Sciences, and his team tracked down the key events and processes that pushed the coastal waters in the Gulf of Mexico to an extremely warm state (i.e. a marine heatwave), likely contributing to the intensification of a storm so close to shore. 

Unlike the deep ocean, the continental shelf has a shallow bottom that limits how much cold water can be mixed up to the surface, cooling the sea surface temperature and weakening approaching storms. Dzwonkowski and his team focused on how a strong mixing event pushes surface heat downward and clears the bottom water of its cold water reserve.  If this mixing is followed by a period of rewarming, such as an atmospheric heatwave,  the shelf’s oceanic environment could be primed for the potential generation of extreme storm events, i.e. Hurricane Michael.

This work shows that understanding the preceding weather conditions in a region where a storm is going to make landfall can improve interpretation of hurricane model forecasts  and what the storm is likely to do prior to landfall,” says Dr. Dzwonkowski 

In mapping out heat flux and mixing, the team focused on the Mississippi Bight in late summer and early fall with data gathered by a mooring site off Dauphin Island’s coastline. The mooring site collects data throughout the water column allowing for the full heat content of the shelf to be determined. The period prior to the landfall of Hurricane Michael turned out to be the warmest ocean conditions during this time period in the 13-year record. 

 “Turns out hurricanes and atmospheric heatwaves will be getting stronger in a warming world which would indicate the identified sequence of events that generate these extreme conditions may become more frequent,” Dzwonkowski said.   “The occurrence of extreme heat content events, like marine heatwaves has significant implications for a broad range of scientific management interests beyond hurricane intensity.”Importantly, the mechanisms that generated this marine heatwave are expected to be more frequent and intense in the future due to climate change, increasing the likelihood of such extreme conditions.  

For example, coral reefs and hypoxia-prone shelves are already stressed by long-term warming trends. These temperature-specific benthic communities and habitats are typically of significant societal and economic value. As such, the newly identified sequence of compounding processes is expected to impact a range of coastal interests and should be considered in management and disaster response decisions. 

This research was funded by the NOAA RESTORE Science Program and NOAA NGI NMFS Regional Collaboration network. 

https://www.nature.com/articles/s41467-020-18339-2

 

Abstract

Exposure to extreme events is a major concern in coastal regions where growing human populations and stressed natural ecosystems are at significant risk to such phenomena. However, the complex sequence of processes that transform an event from notable to extreme can be challenging to identify and hence, limit forecast abilities. Here, we show an extreme heat content event (i.e., a marine heatwave) in coastal waters of the northern Gulf of Mexico resulted from compounding effects of a tropical storm followed by an atmospheric heatwave. This newly identified process of generating extreme ocean temperatures occurred prior to landfall of Hurricane Michael during October of 2018 and, as critical contributor to storm intensity, likely contributed to the subsequent extreme hurricane. This pattern of compounding processes will also exacerbate other environmental problems in temperature-sensitive ecosystems (e.g., coral bleaching, hypoxia) and is expected to have expanding impacts under global warming predictions.

[donsutherland1]

Excerpts from Penn State climate scientist Michael Mann’s Newsweek column:

My colleagues and I have just published an article in the journal Nature Climate Change showing that the oceans are not only becoming more stable, but are doing so faster than was previously thought. Led by Guancheng Li of the Institute of Atmospheric Physics in China, our team (which also includes Lijing Cheng, Jiang Zhu, Kevin Trenberth and John P. Abraham) analyzed a quantitative measure of stability known as "stratification". We found that the stratification of the world oceans is not only increasing, but is doing so at a greater rate than estimated in previous studies. Our study uses more comprehensive data and a more sophisticated method for estimating stratification changes, and we found a nearly 6 percent increase in the stratification of the upper 200 meters (~650 feet) of the world oceans over the past half century....

That's bad for a number of reasons. As we currently watch the most active Atlantic hurricane season on record play out, a key underlying factor is the anomalous surface warmth of the tropical Atlantic. The increasingly intense and damaging hurricanes we've seen in recent years have fed off warmer surface waters. More stably stratified waters tend to inhibit the wind-driven mixing up of cold deeper waters that often serves as a sort of release-valve, shutting off the source of energy at the surface that intensifies these storms. A more stably stratified ocean potentially favors more intense, destructive hurricanes.

Warmer waters absorb less atmospheric carbon dioxide (just as warm soda loses its carbonation faster when you open the top.) Less ocean mixing also means that less of the atmospheric carbon dioxide gets buried beneath the ocean surface. So carbon pollution accumulates even faster in the atmosphere, causing yet more warming.

The paper can be found here:

https://psu.app.box.com/s/2j7cynrci6xlkkoe70cnbqn04dpbr2bd

Here’s a simplified summary:

https://news.psu.edu/story/633153/2020/09/28/research/increasing-stability-decreases-ocean-productivity-reduces-carbon#

 

[blizzard1024]

On 9/25/2020 at 9:27 AM, bluewave said:

https://www.disl.edu/about/news/marine-heatwaves-and-hurricanes-study-examines-compounding-impact-of-severe-weather

Several coastal communities are picking up the pieces after being ravaged by hurricanes in the past month. Hurricane Laura, a category 4, and Hurricane Sally, a category 2, seemed to meander their way across the Gulf of Mexico constantly shifting forecasts and keeping meteorologists on their toes. In the hours before these storms struck land, they seemed to explode in intensity. 

Researchers at the Dauphin Island Sea Lab with support from the Jet Propulsion Laboratory can offer insight into why these storms intensified quickly as they moved across the continental shelf. 

“Surprisingly, both Hurricane Laura and Hurricane Sally appeared to have similar setups to Hurricane Michael with both storm events being preceded by smaller storms (i.e. Hurricane Hanna and Marco, respectively),” Dr. Brian Dzwonkowski explained. “This pre-storm setup of the oceanic environment likely contributed to the intensification prior to landfall.  Importantly, this pre-landfall intensification was not well predicted by hurricane models or forecasts, which as you can imagine is critical information for evacuation  and disaster preparation.”

Dzwonkowski and his team’s publication, “Compounding impact of severe weather events fuels marine heatwave in the coastal ocean”, outlines how one storm could impact the intensity of another storm by restructuring the thermal properties of the water column. Nature Communications published the findings in its September issue.

The research focuses on Hurricane Michael which devastated Mexico Beach, Florida, and the surrounding communities, on October 10, 2018. The category 5 storm intensified hours before making landfall. 

Dzwonkowski, a physical oceanographer with the Dauphin Island Sea Lab and Associate Professor at the University of South Alabama in the Department of Marine Sciences, and his team tracked down the key events and processes that pushed the coastal waters in the Gulf of Mexico to an extremely warm state (i.e. a marine heatwave), likely contributing to the intensification of a storm so close to shore. 

Unlike the deep ocean, the continental shelf has a shallow bottom that limits how much cold water can be mixed up to the surface, cooling the sea surface temperature and weakening approaching storms. Dzwonkowski and his team focused on how a strong mixing event pushes surface heat downward and clears the bottom water of its cold water reserve.  If this mixing is followed by a period of rewarming, such as an atmospheric heatwave,  the shelf’s oceanic environment could be primed for the potential generation of extreme storm events, i.e. Hurricane Michael.

This work shows that understanding the preceding weather conditions in a region where a storm is going to make landfall can improve interpretation of hurricane model forecasts  and what the storm is likely to do prior to landfall,” says Dr. Dzwonkowski 

In mapping out heat flux and mixing, the team focused on the Mississippi Bight in late summer and early fall with data gathered by a mooring site off Dauphin Island’s coastline. The mooring site collects data throughout the water column allowing for the full heat content of the shelf to be determined. The period prior to the landfall of Hurricane Michael turned out to be the warmest ocean conditions during this time period in the 13-year record. 

 “Turns out hurricanes and atmospheric heatwaves will be getting stronger in a warming world which would indicate the identified sequence of events that generate these extreme conditions may become more frequent,” Dzwonkowski said.   “The occurrence of extreme heat content events, like marine heatwaves has significant implications for a broad range of scientific management interests beyond hurricane intensity.”Importantly, the mechanisms that generated this marine heatwave are expected to be more frequent and intense in the future due to climate change, increasing the likelihood of such extreme conditions.  

For example, coral reefs and hypoxia-prone shelves are already stressed by long-term warming trends. These temperature-specific benthic communities and habitats are typically of significant societal and economic value. As such, the newly identified sequence of compounding processes is expected to impact a range of coastal interests and should be considered in management and disaster response decisions. 

This research was funded by the NOAA RESTORE Science Program and NOAA NGI NMFS Regional Collaboration network. 

https://www.nature.com/articles/s41467-020-18339-2

 

Abstract

Exposure to extreme events is a major concern in coastal regions where growing human populations and stressed natural ecosystems are at significant risk to such phenomena. However, the complex sequence of processes that transform an event from notable to extreme can be challenging to identify and hence, limit forecast abilities. Here, we show an extreme heat content event (i.e., a marine heatwave) in coastal waters of the northern Gulf of Mexico resulted from compounding effects of a tropical storm followed by an atmospheric heatwave. This newly identified process of generating extreme ocean temperatures occurred prior to landfall of Hurricane Michael during October of 2018 and, as critical contributor to storm intensity, likely contributed to the subsequent extreme hurricane. This pattern of compounding processes will also exacerbate other environmental problems in temperature-sensitive ecosystems (e.g., coral bleaching, hypoxia) and is expected to have expanding impacts under global warming predictions.

Hurricanes have been ravaging the Gulf Coast for eons. How do we know that all of the sudden now they are getting stronger before landfall? How did we measure that 100 years ago?  It's not just ocean heat content that drives Hurricanes. Interaction with the westerlies, wind shear and frictional effects all are important before landfall. You can't say that global warming causes this. The warmer ocean waters can't even be proven to be related to global warming from CO2. This is all hype right before a presidential election. They want voters to believe the weather is getting more severe because of CO2 levels. This is insanity. CO2 levels have little to do with storm severity. Climate scientists want there to be a link so all this research is coming out trying to tie severe weather events to global warming. And Michael Mann is not even an atmospheric scientist. He basically is a climate activist and that is what passes for academia now in atmospheric science departments at major universities. sad. 

[bluewave]

10 minutes ago, blizzard1024 said:

Hurricanes have been ravaging the Gulf Coast for eons. How do we know that all of the sudden now they are getting stronger before landfall? How did we measure that 100 years ago?  It's not just ocean heat content that drives Hurricanes. Interaction with the westerlies, wind shear and frictional effects all are important before landfall. You can't say that global warming causes this. The warmer ocean waters can't even be proven to be related to global warming from CO2. 

 

https://www.nature.com/articles/d41586-018-05978-1

Ocean heatwaves will become more frequent and extreme as the climate warms, scientists report¹ on 15 August in Nature. These episodes of intense heat could disrupt marine food webs and reshape biodiversity in the world’s oceans. 

Scientists analysed satellite-based measurements of sea surface temperature from 1982 to 2016 and found that the frequency of marine heatwaves had doubled. These extreme heat events in the ocean's surface waters can last from days to months and can occur across thousands of kilometres. If average global temperatures increase to 3.5 °C above pre-industrial levels by the end of the century, as researchers currently project, the frequency of ocean heatwaves could increase by a factor of 41. In other words, a 1-in-100-day event at pre-industrial levels of warming could become a 1-in-3-day event.

Marine heatwaves have already become more long-lasting, frequent, intense and extensive than in the past,” says lead study author Thomas Frölicher, a climatologist at the University of Bern in Switzerland. He adds that these changes are already well outside what could be expected on the basis of natural swings in Earth’s climate: the study’s analysis determined that 87% of heatwaves in the ocean are the result of human-induced global warming.

Going global

Scientists have studied heatwaves on land for decades. But it wasn’t until researchers faced episodes of extreme heat in the ocean in the past several years that they started paying more attention to the issue at sea. Those episodes included the massive warm water ‘blob’ in the northeastern Pacific Ocean that killed off sea otters (Enhydra lutris) in Alaska and sea lions (Zalophus californianus) in California, and disrupted fisheries off North America from 2014 to 2015. They also included the massive 2015–16 El Niño that ravaged coral reefs around the world.

The emphasis on marine heatwaves is really motivated by the recognition that the same kinds of extremes can happen in the ocean as on land,” says Noah Diffenbaugh, a climatologist at Stanford University in California. He adds that this latest study takes global perspective on these regional issues. 

The study provides a useful framework for disentangling short-term temperature spikes from long-term warming trends in the oceans, says Kris Karnauskas, a physical oceanographer at the Cooperative Institute for Research in Environmental Sciences at the University of Colorado Boulder. He says that marine heatwaves could be the result of natural temperature swings that become more extreme owing to a warming ocean. Or they could be a signal that global warming is changing how the ocean functions — thus altering the likelihood and intensity of marine warming events. 

Frölicher says current models suggest that more frequent and intense ocean heatwaves are largely a result of warming oceans. And now, he and his team are working to develop models that can explore marine heatwave trends and their ecological impacts at local and regional levels.

https://www.nature.com/articles/s41586-018-0383-9

 

https://www.nature.com/articles/s41467-019-08471-z#ref-CR7

Tropical cyclones that rapidly intensify are typically associated with the highest forecast errors and cause a disproportionate amount of human and financial losses. Therefore, it is crucial to understand if, and why, there are observed upward trends in tropical cyclone intensification rates. Here, we utilize two observational datasets to calculate 24-hour wind speed changes over the period 1982–2009. We compare the observed trends to natural variability in bias-corrected, high-resolution, global coupled model experiments that accurately simulate the climatological distribution of tropical cyclone intensification. Both observed datasets show significant increases in tropical cyclone intensification rates in the Atlantic basin that are highly unusual compared to model-based estimates of internal climate variations. Our results suggest a detectable increase of Atlantic intensification rates with a positive contribution from anthropogenic forcing and reveal a need for more reliable data before detecting a robust trend at the global scale.

[blizzard1024]

How can we be certain this is related to CO2 levels and not natural variability?  What about the warmth of the 1930s? Did we really know what the ocean heat content was back then? Plus this site in Hawaii that is on this guys twitter only has data back to 1954. This is not long enough to make such sweeping conclusions that manmade greenhouse gases are causing this. 

A recent paper actually is showing continued declines the upper tropospheric absolute humidity even the ERA5 data at 200 mb... see

https://friendsofscience.org/assets/documents/TPW-and-GHE.pdf

This suggests that CO2 is not the driver of the current warming trend. So to blame all this on CO2 levels is a stretch.  

[donsutherland1]

1 hour ago, blizzard1024 said:

How can we be certain this is related to CO2 levels and not natural variability?  What about the warmth of the 1930s? Did we really know what the ocean heat content was back then? Plus this site in Hawaii that is on this guys twitter only has data back to 1954. This is not long enough to make such sweeping conclusions that manmade greenhouse gases are causing this. 

A recent paper actually is showing continued declines the upper tropospheric absolute humidity even the ERA5 data at 200 mb... see

https://friendsofscience.org/assets/documents/TPW-and-GHE.pdf

This suggests that CO2 is not the driver of the current warming trend. So to blame all this on CO2 levels is a stretch.  

Scientists have a very high level of confidence that the ongoing warming, including heating of the oceans is related to anthropogenic greenhouse gas emissions. The earth's energy imbalance has persisted despite fluctuations in solar irradiance. Consistent with the rise in atmospheric greenhouse gases, oceanic heat has been increasing. No credible alternative theories to the consensus AGW position have emerged, especially in the recent scientific literature.

What about the 1930s? Excerpts from a relevant paper that looked at longer periods of time:

Daily in situ measurements of ocean temperature at century-long monitoring sites were used to examine MHW properties over multi-decadal time scales. We selected six stations for which centennial-scale records (89–111 years) of daily ocean temperatures were available: Arendal (Norway), Port Erin (UK), Race Rocks (Canada) and Pacific Grove, Scripps Pier, and Newport Beach (USA; Table 1). Changes over time were calculated between early and late 30-year periods shared across all stations (1925–1954 and 1984–2013, respectively). All stations, except Newport Beach, exhibited annual mean SST warming of between 0.37 °C and 0.78 °C (p < 0.05); Newport Beach exhibited a non-significant change in SST (−0.003 °C, p > 0.05). There was clear centennial increase in annual MHW frequency at all stations (Fig. 4a–f, black lines).

https://www.nature.com/articles/s41467-018-03732-9

Greenhouse gases explain most of the warming that has occurred since the mid-20th century and especially in recent decades. During the most recent period, natural forcings would have suggested a slight cooling.

 

[donsutherland1]

3 hours ago, blizzard1024 said:

Hurricanes have been ravaging the Gulf Coast for eons. How do we know that all of the sudden now they are getting stronger before landfall? How did we measure that 100 years ago?  It's not just ocean heat content that drives Hurricanes. Interaction with the westerlies, wind shear and frictional effects all are important before landfall. You can't say that global warming causes this. The warmer ocean waters can't even be proven to be related to global warming from CO2. This is all hype right before a presidential election. They want voters to believe the weather is getting more severe because of CO2 levels. This is insanity. CO2 levels have little to do with storm severity. Climate scientists want there to be a link so all this research is coming out trying to tie severe weather events to global warming. And Michael Mann is not even an atmospheric scientist. He basically is a climate activist and that is what passes for academia now in atmospheric science departments at major universities. sad. 

Michael Mann has degrees in applied mathematics and physics, physics, and geology and geophysics. He is eminently qualified to research climate and has had breakthrough work related to proxies and temperatures.

The atmosphere is a single part of the earth's climate system. One does not need a degree in atmospheric science or meteorology to study climate. Meteorology is a different field. Over his career, Mann has published or co-published more than 400 peer-reviewed articles. To dismiss him as a "climate activist" rather than the serious researcher he is, is absurd. He is taking a visible role in educating and informing the public about the climate change, its causes, its implications, etc. At the same time, he is continuing to research and publish.

[skierinvermont]

4 hours ago, blizzard1024 said:

 What about the warmth of the 1930s? Did we really know what the ocean heat content was back then?

I’ll add to what don already said. As I have explained before and you have ignored, one of the ways scientists know ocean heat content back then is sea level rise. The primary cause of sea level rise has been thermal expansion, thus far. Go read some papers if you have concerns about how scientists measure ohc back then. You’re not the first person to think of this. Far from it.

[bdgwx]

2 hours ago, blizzard1024 said:

This suggests that CO2 is not the driver of the current warming trend. So to blame all this on CO2 levels is a stretch.  

If CO2 is not a significant contributing factor then what is?

[chubbs]

7 hours ago, blizzard1024 said:

This suggests that CO2 is not the driver of the current warming trend. So to blame all this on CO2 levels is a stretch.  

 

[forkyfork]

stop engaging him

[rclab]

2 hours ago, forkyfork said:

stop engaging him

No Forky, the silence would be worse. As long as the discussion is civil let it continue and prove its own points. Those of us that have less between the Ears than many of the prime poster benefit by being able to read and appreciate the passion. Even if the saltwater is up to our ankles. Besides it would be like someone telling you to stop trolling which would be sad because when it comes from you it’s fun to reply. Let the talk continue, As always ....

[blizzard1024]

10 hours ago, skierinvermont said:

I’ll add to what don already said. As I have explained before and you have ignored, one of the ways scientists know ocean heat content back then is sea level rise. The primary cause of sea level rise has been thermal expansion, thus far. Go read some papers if you have concerns about how scientists measure ohc back then. You’re not the first person to think of this. Far from it.

Sea levels have been rising well before mass burning of fossil fuels. What caused this? The climate supposedly was in a perfect stasis before man made fossil fuel burning began en-masse mid 20th century. Plus according to many of you the Little Ice Age was just a regional phenomenon?  So I have never heard a good explanation for why sea levels and presumable OHC has risen since the mid 1800s. 

[blizzard1024]

5 hours ago, chubbs said:

 

Proxy data that ignores known roman, medieval warm periods and the dark age and little ice age cold periods and then stitched higher resolution observations at the end. The Hockey Stick. There is no way the Earth's climate has been this steady for almost 2000 years.  CO2 never lead temperatures in the past, why now?  explain. You need a strong water vapor feedback too. There is plenty of evidence that this is not the case. 

[chubbs]

30 minutes ago, blizzard1024 said:

Sea levels have been rising well before mass burning of fossil fuels. What caused this? The climate supposedly was in a perfect stasis before man made fossil fuel burning began en-masse mid 20th century. Plus according to many of you the Little Ice Age was just a regional phenomenon?  So I have never heard a good explanation for why sea levels and presumable OHC has risen since the mid 1800s.

The timing in the sea-level chart is the same as the temperature+CO2 chart. Increases in all three started in the late 1700s.

 

[donsutherland1]

39 minutes ago, blizzard1024 said:

Sea levels have been rising well before mass burning of fossil fuels. What caused this? The climate supposedly was in a perfect stasis before man made fossil fuel burning began en-masse mid 20th century. Plus according to many of you the Little Ice Age was just a regional phenomenon?  So I have never heard a good explanation for why sea levels and presumable OHC has risen since the mid 1800s. 

High solar activity was very likely the main cause. But in the background, fossil fuel consumption had begun to gradually increase starting around 1750. Such consumption would increase dramatically by the 20th century.

http://lasp.colorado.edu/lisird/data/historical_tsi/

 

[donsutherland1]

41 minutes ago, blizzard1024 said:

Proxy data that ignores known roman, medieval warm periods and the dark age and little ice age cold periods and then stitched higher resolution observations at the end. The Hockey Stick. There is no way the Earth's climate has been this steady for almost 2000 years.  CO2 never lead temperatures in the past, why now?  explain. You need a strong water vapor feedback too. There is plenty of evidence that this is not the case. 

As noted previously, the MWP and LIA were regional events. The chart in question concerns global, not regional temperatures. As previously posted, three papers and the abstract of another (the full copy of which can be requested from the authors):

https://www.nature.com/articles/ngeo1797.epdf?sharing_token=Pm1NFtFxqxcwIUqtvBVOsdRgN0jAjWel9jnR3ZoTv0OXdKps0x-mydYxlxY1CTS2FraCgd_SIOyFr3Frnr2wB7rEiUt5oncmTKp32KflJCHeITcA-EqP5p3xfWpkUotuN0E3ir4Us_bcTtsZ27MrFmdPv9A4iznKkWIxs3GlY8t2zgJ1RqKr1SMAGJNtp3FZCGkf9OhfrosIZ6HA_48P3A%3D%3D&tracking_referrer=www.realclimate.org

http://www.meteo.psu.edu/holocene/public_html/shared/articles/MannetalScience09.pdf

https://advances.sciencemag.org/content/1/11/e1500806

https://www.researchgate.net/publication/334662695_No_evidence_for_globally_coherent_warm_and_cold_periods_over_the_preindustrial_Common_Era

[bdgwx]

2 hours ago, blizzard1024 said:

Proxy data that ignores known roman, medieval warm periods and the dark age and little ice age cold periods and then stitched higher resolution observations at the end. The Hockey Stick. There is no way the Earth's climate has been this steady for almost 2000 years.  CO2 never lead temperatures in the past, why now?  explain. You need a strong water vapor feedback too. There is plenty of evidence that this is not the case. 

The data says the Earth's climate was that steady for almost 2000 years on a global scale. Global/hemisphere proxy data temperature reconstructions do not ignore the MWP or LIA. Remember, the MWP and LIA were names given to periods of climatic shifts primarily in the North Atlantic periphery area (see Lamb 1982) though most scientist do accept some global influence albeit by a smaller amount. These North Atlantic sites are included in Holocene temperature reconstructions regardless.

CO2 did lead temperatures in the past. The PETM is probably the best analog. Nevermind that an agent does not have to lead a variable for it to be a significant contributing factor to the trajectory of that variable anyway.

CO2 is leading now because it is being released in huge quantities independent of any climate modulation. 

[skierinvermont]

3 hours ago, chubbs said:

The timing in the sea-level chart is the same as the temperature+CO2 chart. Increases in all three started in the late 1700s.

 

Yes I was going to point out the same thing. He's straight contradicting himself. And as he well knows, the radiative forcing of CO2 is logarithmic and so just because the large majority of CO2 emissions occurred after 1945, doesn't mean the large majority of the forcing did (still a majority, but there was significant CO2 forcing before 1945).

[chubbs]

8 hours ago, blizzard1024 said:

Proxy data that ignores known roman, medieval warm periods and the dark age and little ice age cold periods and then stitched higher resolution observations at the end. The Hockey Stick. There is no way the Earth's climate has been this steady for almost 2000 years.  CO2 never lead temperatures in the past, why now?  explain. You need a strong water vapor feedback too. There is plenty of evidence that this is not the case. 

1) Pages2k the best compilation of data available. There are are wide range of sources including ice cores. Note the range in time resolution below, some of the series have relatively fine time resolution.  If you have any information that is not included please provide.

2) There are plenty of instances of CO2 leading temperatures. The PETM for a start and many others. Our recent ice ages only started after CO2 had dropped low enough for orbital cycles to trigger.

3) There is plenty of data supporting water vapor feedback, as discussed in the other thread. 

 

[blizzard1024]

8 hours ago, donsutherland1 said:

As noted previously, the MWP and LIA were regional events.

This drives my crazy. How can this be? This is NOT how the atmosphere works! You don't have centuries of persistent intense anomalies in one part of the world that don't eventually change due to basic fluid dynamics. It is a cop out for the climate alarmists. So basically Greenland was warmer and habitable for centuries as well as Europe and North America and these same areas got much colder during the LIA. The rest of the planet got colder during the MWP to balance the warmth out and then got warmer in the LIA to balance the cold out? I know a geologist who specializes in tree rings proxies in Alaska and he clearly can see both MWP and LIA in his data.   Here are some examples...

https://journals.sagepub.com/doi/10.1191/095968399672825976    clearly warm periods and cold periods coincident with MWP and LIA. 

Lüning, S., M. Gałka, F. Vahrenholt (2019): The Medieval Climate Anomaly in Antarctica. Palaeogeogr., Palaeoclimatol., Palaeoecol., doi: 10.1016/j.palaeo.2019.109251

Lüning, S., M. Gałka, F. García-Rodríguez, F. Vahrenholt (2019): The Medieval Climate Anomaly in Oceania. Environmental Reviews, online Just-IN, doi: 10.1139/er-2019-0012

Lüning, S., M. Gałka, F. P. Bamonte, F. García-Rodríguez, F. Vahrenholt (2019): The Medieval Climate Anomaly in South America. Quaternary International, 508: 70-87. doi: 10.1016/j.quaint.2018.10.041.

Lüning, S., M. Gałka, F. Vahrenholt (2017): Warming and cooling: The Medieval Climate Anomaly in Africa and Arabia. Paleoceanography 32 (11): 1219-1235, doi: 10.1002/2017PA003237.

On 29 June 2019, a paper by Lüning et al. 2019 on the Medieval Warm Period in Antarctica appeared in the trade journal Palaeogeography, Palaeoclimatology, Palaeoecology. Here is the abstract:

The Medieval Climate Anomaly in Antarctica
The Medieval Climate Anomaly (MCA) is a well-recognized climate perturbation in many parts of the world, with a core period of 1000–1200 CE. Here we are mapping the MCA across the Antarctic region based on the analysis of published palaeotemperature proxy data from 60 sites. In addition to the conventionally used ice core data, we are integrating temperature proxy records from marine and terrestrial sediment cores as well as radiocarbon ages of glacier moraines and elephant seal colonies. A generally warm MCA compared to the subsequent Little Ice Age (LIA) was found for the Subantarctic Islands south of the Antarctic Convergence, the Antarctic Peninsula, Victoria Land and central West Antarctica. A somewhat less clear MCA warm signal was detected for the majority of East Antarctica. MCA cooling occurred in the Ross Ice Shelf region, and probably in the Weddell Sea and on Filchner-Ronne Ice Shelf. Spatial distribution of MCA cooling and warming follows modern dipole patterns, as reflected by areas of opposing temperature trends. Main drivers of the multi-centennial scale climate variability appear to be the Southern Annular Mode (SAM) and El Niño-Southern Oscillation (ENSO) which are linked to solar activity changes by nonlinear dynamics.

  So here is peer reviewed papers on the MWP and LIA in other parts of the world that are probably ignored because it is very inconvenient to mainstream climate folks.  How do we not know that we are just rebounding from the LIA with some added CO2 forcing and of course UHI effects which are often ignored too. 

[blizzard1024]

5 hours ago, skierinvermont said:

And as he well knows, the radiative forcing of CO2 is logarithmic

It is logarithmic. This is from the climate activist blog realclimate   RF = 5.35 ln(CO₂/CO₂_orig).  In math "ln" means natural logarithm in case you didn't know this. So indeed lower amounts of CO2 have more of an influence so the statement that CO2 was too low so other effects dominated the climate system and now it is dominating the system is false mathematically.  

[blizzard1024]

14 hours ago, forkyfork said:

stop engaging him

Yep. That is what climate scientists typically do, they shut down or ignore "the other side" when they are confronted with inconvenient facts. Even though at times one or two posters have been rude, the majority of them have not and it has been interesting and informative.  

[skierinvermont]

4 hours ago, blizzard1024 said:

It is logarithmic. This is from the climate activist blog realclimate   RF = 5.35 ln(CO₂/CO₂_orig).  In math "ln" means natural logarithm in case you didn't know this. So indeed lower amounts of CO2 have more of an influence so the statement that CO2 was too low so other effects dominated the climate system and now it is dominating the system is false mathematically.  

You just repeated what I said. I know what ln means lol. Who do you think you are?

Make up your mind. Was there significant CO2 forcing before 1945, or not? The graph you posted said that the warming before 1945 can't be CO2 because almost all the CO2 was after 1945. Now you're saying the opposite. Such a joke. The reality is significant CO2 forcing occurred before 1945.

[bdgwx]

5 hours ago, blizzard1024 said:

It is logarithmic. This is from the climate activist blog realclimate   RF = 5.35 ln(CO₂/CO₂_orig).

This actually comes from Myhre 1998. Well...the 5.35 sensitivity parameter anyway. Myhre used radiative transfer models (LBL, NBM, BBM) using data from the well known HITRAN database. The logarithmic behavior was first diagnosed by Arrhenius 1896 so he usually gets credit for this mind numbingly simple back-of-the-envelope model of the climate system's response to changes in CO2 concentration. This model is so well know that it is typically regarded as common knowledge and is referenced ubiquitously often without citations in the climate community. BTW...Arrhenius' final computation (which is said have been very laborious) from 1908 using his more complex 1896 model yields 4C of warming for 2xCO2 (see Worlds in the Making by Arrenhius 1908). It is interesting that this falls comfortably within the official IPCC range and despite his primitive (by today's standards) understanding of the climate system. Wouldn't that be a remarkable feat of brilliance if his 4C estimate turns out to be close to the observed value? 

[bdgwx]

6 hours ago, blizzard1024 said:

How do we not know that we are just rebounding from the LIA with some added CO2 forcing and of course UHI effects which are often ignored too. 

Indeed, we are "rebounding" from the LIA. But "rebounding" is a NOT a cause. It is an observation. That rebound happened for a reason that likely includes many contributing factors. CO2 is certainly among those factors and its significance became most acute after 1950.

UHI effects are NOT ignored. Every conventional surface based database I'm aware of gives the UHI effect its well deserved consideration. Berkeley Earth has a great publication detailing how much the UHI bias impacts global mean temperatures (see Rohde 2013). 

"We observe the opposite of an urban heating effect over the period 1950 to 2010, with a slope of -0.10 ± 0.24°C/100yr (2σ error) in the Berkeley Earth global land temperature average.. The confidence interval is consistent with a zero urban heating effect, and at most a small urban heating effect (less than 0.14°C/100yr, with 95% confidence) on the scale of the observed warming (1.9 ± 0.1°C/100 yr since 1950 in the land average from Figure 5A)."

As you can see their conclusion is that the UHI effect is more likely to have a negative bias than a positive bias on global mean temperature trends after 1950 when the warming became most acute. The observed trends in the global mean surface temperature datasets is NOT a result of the UHI effect. It is a result of the planet actually warming.

 

[bdgwx]

6 hours ago, blizzard1024 said:

This drives my crazy. How can this be? This is NOT how the atmosphere works! You don't have centuries of persistent intense anomalies in one part of the world that don't eventually change due to basic fluid dynamics.

That is absolutely how the atmosphere works. Just considering ocean circulations alone is enough to explain persistent anomalies in atmospheric temperature. For example, if the AMOC slows down  some regions will likely cool while others warm as the poleward heat movement is impeded. Sure, tropical cyclone activity (among other mechanisms) may increase and work to pull this heat poleward via atmospheric circulation as opposed to ocean circulation, but the distribution of that heat would almost certainly not be exactly the same as before. The paleoclimate record is convincing...climatic shifts do not work in perfect harmony between regional and global scales. The global mean temperature can warm while specific regional mean temperatures cool and vice versa.

[donsutherland1]

13 hours ago, blizzard1024 said:

This drives my crazy. How can this be? This is NOT how the atmosphere works! You don't have centuries of persistent intense anomalies in one part of the world that don't eventually change due to basic fluid dynamics. It is a cop out for the climate alarmists. So basically Greenland was warmer and habitable for centuries as well as Europe and North America and these same areas got much colder during the LIA. The rest of the planet got colder during the MWP to balance the warmth out and then got warmer in the LIA to balance the cold out? I know a geologist who specializes in tree rings proxies in Alaska and he clearly can see both MWP and LIA in his data.   Here are some examples...

https://journals.sagepub.com/doi/10.1191/095968399672825976    clearly warm periods and cold periods coincident with MWP and LIA. 

Lüning, S., M. Gałka, F. Vahrenholt (2019): The Medieval Climate Anomaly in Antarctica. Palaeogeogr., Palaeoclimatol., Palaeoecol., doi: 10.1016/j.palaeo.2019.109251

Lüning, S., M. Gałka, F. García-Rodríguez, F. Vahrenholt (2019): The Medieval Climate Anomaly in Oceania. Environmental Reviews, online Just-IN, doi: 10.1139/er-2019-0012

Lüning, S., M. Gałka, F. P. Bamonte, F. García-Rodríguez, F. Vahrenholt (2019): The Medieval Climate Anomaly in South America. Quaternary International, 508: 70-87. doi: 10.1016/j.quaint.2018.10.041.

Lüning, S., M. Gałka, F. Vahrenholt (2017): Warming and cooling: The Medieval Climate Anomaly in Africa and Arabia. Paleoceanography 32 (11): 1219-1235, doi: 10.1002/2017PA003237.

On 29 June 2019, a paper by Lüning et al. 2019 on the Medieval Warm Period in Antarctica appeared in the trade journal Palaeogeography, Palaeoclimatology, Palaeoecology. Here is the abstract:

The Medieval Climate Anomaly in Antarctica
The Medieval Climate Anomaly (MCA) is a well-recognized climate perturbation in many parts of the world, with a core period of 1000–1200 CE. Here we are mapping the MCA across the Antarctic region based on the analysis of published palaeotemperature proxy data from 60 sites. In addition to the conventionally used ice core data, we are integrating temperature proxy records from marine and terrestrial sediment cores as well as radiocarbon ages of glacier moraines and elephant seal colonies. A generally warm MCA compared to the subsequent Little Ice Age (LIA) was found for the Subantarctic Islands south of the Antarctic Convergence, the Antarctic Peninsula, Victoria Land and central West Antarctica. A somewhat less clear MCA warm signal was detected for the majority of East Antarctica. MCA cooling occurred in the Ross Ice Shelf region, and probably in the Weddell Sea and on Filchner-Ronne Ice Shelf. Spatial distribution of MCA cooling and warming follows modern dipole patterns, as reflected by areas of opposing temperature trends. Main drivers of the multi-centennial scale climate variability appear to be the Southern Annular Mode (SAM) and El Niño-Southern Oscillation (ENSO) which are linked to solar activity changes by nonlinear dynamics.

  So here is peer reviewed papers on the MWP and LIA in other parts of the world that are probably ignored because it is very inconvenient to mainstream climate folks.  How do we not know that we are just rebounding from the LIA with some added CO2 forcing and of course UHI effects which are often ignored too. 

Thank you for posting those papers. I will clarify my language to be somewhat more precise.

Both the MCA (aka MWP) and LIA were largely regional events with a degree of global synchronicity. The magnitude of standardized temperature anomalies were nowhere near as uniform as they are today.

The papers, if one reads closely to consider lags and areas covered (differences in Australia, parts of South America, parts of Antarctica), are still reasonably consistent with the temperature anomalies found by Mann et al.

Here are the charts from the Mann paper:

The Neukom et al., 2019 paper addresses the latest scientific understanding of past warm and cool epochs during the last 2,000 years and contrasts those periods with the ongoing anthropogenic warming. It explains:

No preindustrial epoch shows global coherence in the timing of the coldest or warmest periods. There is, however, regional coherence. For example, there are almost continental-scale patterns during many of the periods, and there is a coherent pattern in the tropical Pacific in the RWP, DACP and LIA periods, reminiscent of the El Niño–Southern Oscillation—the most dominant mode of interannual variability in the climate system.

In contrast to the spatial heterogeneity of the preindustrial era, the highest probability for peak warming over the entire Common Era is found in the late twentieth century almost everywhere (98% of global surface area), except for Antarctica, where contemporary warming has not yet been observed over the entire continent. Thus, even though the recent warming rates are not entirely homogeneous over the globe, with isolated areas showing little warming or even cooling, the climate system is now in a state of global temperature coherence that is unprecedented over the Common Era...

Against this regional framing, perhaps our most striking result is the exceptional spatiotemporal coherence during the warming of the twentieth century. This result provides further evidence of the unprecedented nature of anthropogenic global warming in the context of the past 2,000 years.

The underlining is mine.

Here are the charts from the Neukom paper:

[blizzard1024]

6 hours ago, bdgwx said:

That is absolutely how the atmosphere works. Just considering ocean circulations alone is enough to explain persistent anomalies in atmospheric temperature. For example, if the AMOC slows down  some regions will likely cool while others warm as the poleward heat movement is impeded. Sure, tropical cyclone activity (among other mechanisms) may increase and work to pull this heat poleward via atmospheric circulation as opposed to ocean circulation, but the distribution of that heat would almost certainly not be exactly the same as before. The paleoclimate record is convincing...climatic shifts do not work in perfect harmony between regional and global scales. The global mean temperature can warm while specific regional mean temperatures cool and vice versa.

For hundreds of years parts of the Earth stay warmer and are compensated by colder parts of the Earth for a very balanced climate state. That is not how the atmospheric works. Ocean currents transport warm and cold across the hemispheres over times scales of decades. The Earth stuck in different "modes" for centuries it just off. It doesn't jive with fluid dynamics, thermodynamics, convection, cloud cover or even radiative transfer. Somehow today everything is different now because of a minor GHG CO2 which needs amplifying effects of H20 to really impact the climate. This is just not logical. So by this logic, insolation increases a little bit, cloud cover decreases a little bit by natural causes which warms the Earth a little, then more evaporation takes places and enhances this warming. The enhanced warming, then leads to more evaporation and more H20 which further warms the planet and so on. What is the breaking mechanism? There has to be something or the Earth's climate goes off the rails. Anyway, a minor GHG with a small absorption band, CO2 does not drive the climate.  Total solar output,  convection, cloud cover, water vapor and ocean currents do. CO2 is a small component. Without climate models, you can't prove that it does.  The paleo studies assume a larger role of CO2 which is unproven. The tiring fact that CO2 did not drive the climate back then based on ice core data should have put this all to rest more than a decade ago. But the climate change gravy train had too much momentum and money to stop so it continues today. The insanity grows more and more so that all weather, and anomalies are basically now affected by this minor trace gas through a feedback mechanism. But this narrative is working...the politicians are listening and this could fundamentally change the western world into a socialist hell. Cheap energy is good for the environment. Again, look at Haiti where there is barely a tree standing because they use charcoal and wood for cooking and heat. Life expectancies are very low. Poverty means destruction of the environment. In Venezuela, they are poached wild animals, birds and even eating their own pets to survive. Again, extreme poverty because of socialism is decimating their environment. People live shorter brutal lives. We don't want that in America. Going to renewables by 2035 would destroy our economy. And if you like the fact that countries like Haiti have minimal carbon emission why don't you move there? In fact, why do you folks even drive cars? You shouldn't use electricity either, or heat your home. I bet you can find a cave to live in and go back to the stone age. That would help and make you guys FEEL better.  

[donsutherland1]

1 hour ago, blizzard1024 said:

For hundreds of years parts of the Earth stay warmer and are compensated by colder parts of the Earth for a very balanced climate state. That is not how the atmospheric works. Ocean currents transport warm and cold across the hemispheres over times scales of decades. The Earth stuck in different "modes" for centuries it just off. It doesn't jive with fluid dynamics, thermodynamics, convection, cloud cover or even radiative transfer. Somehow today everything is different now because of a minor GHG CO2 which needs amplifying effects of H20 to really impact the climate. This is just not logical. So by this logic, insolation increases a little bit, cloud cover decreases a little bit by natural causes which warms the Earth a little, then more evaporation takes places and enhances this warming. The enhanced warming, then leads to more evaporation and more H20 which further warms the planet and so on. What is the breaking mechanism? There has to be something or the Earth's climate goes off the rails. Anyway, a minor GHG with a small absorption band, CO2 does not drive the climate.  Total solar output,  convection, cloud cover, water vapor and ocean currents do. CO2 is a small component. Without climate models, you can't prove that it does.  The paleo studies assume a larger role of CO2 which is unproven. The tiring fact that CO2 did not drive the climate back then based on ice core data should have put this all to rest more than a decade ago. But the climate change gravy train had too much momentum and money to stop so it continues today. The insanity grows more and more so that all weather, and anomalies are basically now affected by this minor trace gas through a feedback mechanism. But this narrative is working...the politicians are listening and this could fundamentally change the western world into a socialist hell. Cheap energy is good for the environment. Again, look at Haiti where there is barely a tree standing because they use charcoal and wood for cooking and heat. Life expectancies are very low. Poverty means destruction of the environment. In Venezuela, they are poached wild animals, birds and even eating their own pets to survive. Again, extreme poverty because of socialism is decimating their environment. People live shorter brutal lives. We don't want that in America. Going to renewables by 2035 would destroy our economy. And if you like the fact that countries like Haiti have minimal carbon emission why don't you move there? In fact, why do you folks even drive cars? You shouldn't use electricity either, or heat your home. I bet you can find a cave to live in and go back to the stone age. That would help and make you guys FEEL better.  

There’s no empirical evidence that rapid adoption of renewable energy, for which costs of production have been falling rapidly relative to fossil fuels—cost developments that have already rendered coal economically nonviable—would mean economic destruction. If anything, insistence on the status quo is far more likely to ensure that sustainable competitive advantages in energy will emerge outside the United States. The opportunity costs of such an outcome would only add to the already high and growing costs related to fossil fuel externalities that are currently borne by society rather than the industries responsible for that pollution. In fact, compelling society as a whole to bear those costs leads to severe underpricing of fossil fuels, both in absolute and relative terms.

Had FDR had such limited confidence in American science, the U.S. would never have developed the atomic bomb ahead of Germany. Had JFK had such low confidence in the nation’s capacity to innovate, the U.S. would have resigned itself to Soviet domination in space. Had Reagan lacked confidence in the nation’s ability to replace CFC’s, Antarctica’s ozone hole would have continued to grow. All three cases were successful, because the nation’s leaders believed that its people, scientists, and industries could meet big challenges. 

Setting big challenges is not socialism. Socialism is defined by who owns the means of production. Instead,  big challenges framed more appropriately are big opportunities for those who dare to pursue them. 

A “can’t do” perspective stifles the dynamism that is the soul of creative destruction. Creative destruction in which innovation, which often leverages scientific advances, supplants earlier technologies and entrepreneurs displace established firms, are major reasons why living standards have advanced. 

Locking in the status quo would constrain progress. A world in which innovation ceases would produce stagnation. One in which energy innovation is discouraged by protecting the politically-favored industries responsible for the anthropogenic emissions driving climate change will face increased heat, more expansive wildfires, more intense storms, rising sea levels as Greenland’s and Antarctica’s ice continue to melt, shifts in agriculture, shifts in the zones in which tropical diseases spread, among other adverse developments.