Werbeanzeigen

Claim: Climate Change is Helping Herbivorous Crabs To Wreck Salt Marshes

Claim: Climate Change is Helping Herbivorous Crabs To Wreck Salt Marshes

According to a study, higher sea levels / more inundation of salt marshes has softened the soil, allowing burrowing crabs to munch their way through cord grass which holds salt marshes together. But a 2012 study by the same group blamed overfishing of predators for the rise in the crab population, and dismissed climate change as a factor.

via Watts Up With That?

Sesarma-reticulatum
Sesarma-reticulatum / purple marsh crab. By Eric A. Lazo-Wasem – Gall L (2019). Invertebrate Zoology Division, Yale Peabody Museum. Yale University Peabody Museum. Occurrence dataset https://doi.org/10.15468/0lkr3w accessed via GBIF.org on 2019-06-22. https://www.gbif.org/occurrence/1270752499CC0Link

According to a study, higher sea levels / more inundation of salt marshes has softened the soil, allowing burrowing crabs to munch their way through cord grass which holds salt marshes together.

But a 2012 study by the same group blamed overfishing of predators for the rise in the crab population, and dismissed climate change as a factor.

Burrowing crabs reshaping salt marshes, with climate change to blame

Given higher sea levels and softer soil in the wake of a shifting climate, Sesarma crabs, which have already decimated salt marshes in the Northeast, are now rising to prominence in southeastern marshes, a new study finds.

PROVIDENCE, R.I. [Brown University] – A new study reveals how climate change has enabled a voracious crab species to dramatically alter salt marsh ecosystems across the southeastern U.S.

The study, published in Proceedings of the National Academy of Sciences, shows that soils beneath salt marshes from South Carolina to Florida have been softened by higher sea levels and increased tidal inundation. That softening has allowed the burrowing crab species Sesarma reticulatum to thrive, feeding on the cordgrass that holds the marshes together.

“What we’ve found is an example of how sea level rise can activate a keystone species that’s now dramatically remodeling these salt marshes,” said Mark Bertness, a professor emeritus of ecology and evolutionary biology at Brown University and a coauthor of the research. “That’s a big deal because sea level rise is a pervasive global phenomenon, and this is a largely unexpected consequence. We need to start thinking about how global climate change could activate new keystone species in other ecosystems.”

Research on Sesarma crabs and their impact on salt marshes has a long history in Bertness’s lab at Brown. In 2011, Bertness and his students discovered that Sesarma, voracious grazers of cordgrass roots and leaves, were behind sudden die-offs of marshes on Cape Cod. In that case, overfishing had suddenly pulled predator species like striped bass out of the water, giving the crabs free reign to decimate the marshes. One of the undergraduate co-authors on that earlier research was Christini Angelini, now an associate professor at the University of Florida and a senior author on this new paper.

Read more: https://www.miragenews.com/burrowing-crabs-reshaping-salt-marshes-with-climate-change-to-blame/

The abstract of the study 2020 Bertness Labs study;

Sea-level rise and the emergence of a keystone grazer alter the geomorphic evolution and ecology of southeast US salt marshes

Sinéad M. Crotty, Collin Ortals, Thomas M. Pettengill, Luming Shi, Maitane Olabarrieta, Matthew A. Joyce, Andrew H. Altieri, Elise Morrison, Thomas S. Bianchi, Christopher Craft, Mark D. Bertness, and Christine Angelini

Keystone species have large ecological effects relative to their abundance and have been identified in many ecosystems. However, global change is pervasively altering environmental conditions, potentially elevating new species to keystone roles. Here, we reveal that a historically innocuous grazer—the marsh crab Sesarma reticulatum—is rapidly reshaping the geomorphic evolution and ecological organization of southeastern US salt marshes now burdened by rising sea levels. Our analyses indicate that sea-level rise in recent decades has widely outpaced marsh vertical accretion, increasing tidal submergence of marsh surfaces, particularly where creeks exhibit morphologies that are unable to efficiently drain adjacent marsh platforms. In these increasingly submerged areas, cordgrass decreases belowground root:rhizome ratios, causing substrate hardness to decrease to within the optimal range for Sesarma burrowing. Together, these bio-physical changes provoke Sesarma to aggregate in high-density grazing and burrowing fronts at the heads of tidal creeks (hereafter, creekheads). Aerial-image analyses reveal that resulting “Sesarma-grazed” creekheads increased in prevalence from 10 ± 2% to 29 ± 5% over the past <25 y and, by tripling creek-incision rates relative to nongrazed creekheads, have increased marsh-landscape drainage density by 8 to 35% across the region. Field experiments further demonstrate that Sesarma-grazed creekheads, through their removal of vegetation that otherwise obstructs predator access, enhance the vulnerability of macrobenthic invertebrates to predation and strongly reduce secondary production across adjacent marsh platforms. Thus, sea-level rise is creating conditions within which Sesarma functions as a keystone species that is driving dynamic, landscape-scale changes in salt-marsh geomorphic evolution, spatial organization, and species interactions.

Read more: https://www.pnas.org/content/early/2020/07/09/1917869117

The following is the abstract of a 2012 study by the same lead author, which blames overfishing;

A trophic cascade triggers collapse of a salt-marsh ecosystem with intensive recreational fishing

Article (PDF Available)inEcology 93(6):1402-10 · June 2012 with 894 Reads DOI: 10.2307/23213769 · Source:  PubMedCite this publication

Andrew H AltieriMark D BertnessTyler CoverdaleNicholas Carl Herrmann

Overexploitation of predators has been linked to the collapse of a growing number of shallow-water marine ecosystems. However, salt-marsh ecosystems are often viewed and managed as systems controlled by physical processes, despite recent evidence for herbivore-driven die-off of marsh vegetation. Here we use field observations, experiments, and historical records at 14 sites to examine whether the recently reported die-off of northwestern Atlantic salt marshes is associated with the cascading effects of predator dynamics and intensive recreational fishing activity. We found that the localized depletion of top predators at sites accessible to recreational anglers has triggered the proliferation of herbivorous crabs, which in turn results in runaway consumption of marsh vegetation. This suggests that overfishing may be a general mechanism underlying the consumer-driven die-off of salt marshes spreading throughout the western Atlantic. Our findings support the emerging realization that consumers play a dominant role in regulating marine plant communities and can lead to ecosystem collapse when their impacts are amplified by human activities, including recreational fishing.

Read more: https://www.researchgate.net/publication/230571469_A_trophic_cascade_triggers_collapse_of_a_salt-marsh_ecosystem_with_intensive_recreational_fishing

The body of the 2012 study appears to dismiss climate change as a factor;

… the discontinuous distribution of marshes with die-off interspersed with healthy, vegetated marshes suggests that local interactions within fished marshes, rather than regional-scale physical forcing by a factor such as sediment starvation or climate effects, is driving salt- marsh die-off. …

I guess everyone has a right to change their mind. The mirage news article discusses the process by which the group came to appreciate the dramatic impact of a few mm / year of sea level rise.

https://ift.tt/3j1x3S3

July 14, 2020 at 10:40AM

Werbeanzeigen

UK Flooding and Rainfall

UK Flooding and Rainfall

In response to this winter’s severe floods there have been some alarming claims about climate change and the impact it may be having on flooding throughout Britain. 

But what does the evidence actually show? 

Recent intense rainfall

Source: Met Office

Rainfall in February 2020 was the heaviest February rainfall on record for the UK as a whole, but also notably in both England and Wales, which suffered severe floods as a result. 

This kind of event is very unusual. However, before drawing broader lessons, it is important to review the historical data, so we can place it in the context of longer-term trends. 

Long-term precipitation trends 

According to Met Office data, England, Wales and Northern Ireland have not seen any significant increases in annual rainfall since 1910. In Scotland however, precipitation levels have risen slightly since the 1970s. There also have been seasonal variations in rainfall trends, with winters becoming wetter in recent decades and summers becoming slightly drier. 

Source: Met Office

Going back further, to 1766, the England and Wales precipitation series shows that annual rainfall has been remarkably consistent since that time.

Source: England and Wales Precipitation Series, Met Office

Looking specifically at the prevalence of sustained heavy rainfall, of the kind that can lead to flooding, a small positive trend of 0–3 mm/decade in maximum annual consecutive five-day precipitation has been identified over recent decades. 

However, the trend was only statistically significant in parts of Scotland and during the winter. The period covered was 1960–2018. 

Source: Commonwealth Scientific and Industrial Research Organisation (CSIRO)

It has been suggested that these modest changes are related to anthropogenic climate change, because of increased moisture in the air owing to warmer temperatures (the Clausius–Clapeyron relation). However, trend attribution is complicated by interference from cyclical drivers of natural variability. The North Atlantic Oscillation (NAO) and El Niño Southern Oscillation (ENSO), which are recognised drivers of natural climate variability, have been found to influence extreme rainfall in the UK.

Impact on flooding 

Changes in precipitation levels do not necessarily equate to increases in the intensity, extent, or harmfulness of flooding. This depends on many factors, such as land management, investment in flood defences, population dynamics, as well as other physical processes. 

recent study showed that the percentage of the population in Europe exposed to river flooding has been falling since 1960, and that the UK specifically has seen a decline in the percentage of people at risk of flood over the period 1870–2016. 

Source: Trends in flood losses in Europe over the past 150 years. Nat Commun 9, 1985 (2018)

The study also looked at financial losses caused by flooding and found that between 1870 and 2016, after adjusting for demographic and economic growth, there were no significant trends in flood losses, both on European scale, and for individual countries. However, the biggest shift in financial losses occurs for the period between 1950 and 2016 where the negative trend (−2.6% per year) is statistically significant. 

Source: Trends in flood losses in Europe over the past 150 years. Nat Commun 9, 1985 (2018)

Conclusion 

There appears to have been a modest increase in the frequency of sustained heavy rainfall, but this is only apparent in the winter, and it is largely centred on Scotland. Over most of the UK’s land area there appear to be no significant trends. 

The share of the UK population exposed to flooding is not increasing, and if anything, economic losses from flooding are becoming less severe rather than more so. With appropriate land management and flood defences, there is every reason to expect and demand that flood risk can be contained and managed effectively.

by Paul Homewood and Harry Wilkinson

We will update our factsheets as new evidence emerges. Feel free to contact us with any new data or information.

Published by: The Global Warming Policy Forum

http://www.thegwpf.com

Printable Version (PDF)

The post UK Flooding and Rainfall appeared first on The Global Warming Policy Forum (GWPF).

via The Global Warming Policy Forum (GWPF)

https://ift.tt/2AYZZJl

July 14, 2020 at 11:54AM

Claim: Climate Change is Helping Herbivorous Crabs To Wreck Salt Marshes

Sesarma-reticulatum / purple marsh crab. By Eric A. Lazo-Wasem – Gall L (2019). Invertebrate Zoology Division, Yale Peabody Museum. Yale University Peabody Museum. Occurrence dataset https://doi.org/10.15468/0lkr3w accessed via GBIF.org on 2019-06-22. https://www.gbif.org/occurrence/1270752499CC0Link

Guest essay by Eric Worrall

According to a study, higher sea levels / more inundation of salt marshes has softened the soil, allowing burrowing crabs to munch their way through cord grass which holds salt marshes together.

But a 2012 study by the same group blamed overfishing of predators for the rise in the crab population, and dismissed climate change as a factor.

Burrowing crabs reshaping salt marshes, with climate change to blame

Given higher sea levels and softer soil in the wake of a shifting climate, Sesarma crabs, which have already decimated salt marshes in the Northeast, are now rising to prominence in southeastern marshes, a new study finds.

PROVIDENCE, R.I. [Brown University] – A new study reveals how climate change has enabled a voracious crab species to dramatically alter salt marsh ecosystems across the southeastern U.S.

The study, published in Proceedings of the National Academy of Sciences, shows that soils beneath salt marshes from South Carolina to Florida have been softened by higher sea levels and increased tidal inundation. That softening has allowed the burrowing crab species Sesarma reticulatum to thrive, feeding on the cordgrass that holds the marshes together.

“What we’ve found is an example of how sea level rise can activate a keystone species that’s now dramatically remodeling these salt marshes,” said Mark Bertness, a professor emeritus of ecology and evolutionary biology at Brown University and a coauthor of the research. “That’s a big deal because sea level rise is a pervasive global phenomenon, and this is a largely unexpected consequence. We need to start thinking about how global climate change could activate new keystone species in other ecosystems.”

Research on Sesarma crabs and their impact on salt marshes has a long history in Bertness’s lab at Brown. In 2011, Bertness and his students discovered that Sesarma, voracious grazers of cordgrass roots and leaves, were behind sudden die-offs of marshes on Cape Cod. In that case, overfishing had suddenly pulled predator species like striped bass out of the water, giving the crabs free reign to decimate the marshes. One of the undergraduate co-authors on that earlier research was Christini Angelini, now an associate professor at the University of Florida and a senior author on this new paper.

Read more: https://www.miragenews.com/burrowing-crabs-reshaping-salt-marshes-with-climate-change-to-blame/

The abstract of the study 2020 Bertness Labs study;

Sea-level rise and the emergence of a keystone grazer alter the geomorphic evolution and ecology of southeast US salt marshes

Sinéad M. Crotty, Collin Ortals, Thomas M. Pettengill, Luming Shi, Maitane Olabarrieta, Matthew A. Joyce, Andrew H. Altieri, Elise Morrison, Thomas S. Bianchi, Christopher Craft, Mark D. Bertness, and Christine Angelini

Keystone species have large ecological effects relative to their abundance and have been identified in many ecosystems. However, global change is pervasively altering environmental conditions, potentially elevating new species to keystone roles. Here, we reveal that a historically innocuous grazer—the marsh crab Sesarma reticulatum—is rapidly reshaping the geomorphic evolution and ecological organization of southeastern US salt marshes now burdened by rising sea levels. Our analyses indicate that sea-level rise in recent decades has widely outpaced marsh vertical accretion, increasing tidal submergence of marsh surfaces, particularly where creeks exhibit morphologies that are unable to efficiently drain adjacent marsh platforms. In these increasingly submerged areas, cordgrass decreases belowground root:rhizome ratios, causing substrate hardness to decrease to within the optimal range for Sesarma burrowing. Together, these bio-physical changes provoke Sesarma to aggregate in high-density grazing and burrowing fronts at the heads of tidal creeks (hereafter, creekheads). Aerial-image analyses reveal that resulting “Sesarma-grazed” creekheads increased in prevalence from 10 ± 2% to 29 ± 5% over the past <25 y and, by tripling creek-incision rates relative to nongrazed creekheads, have increased marsh-landscape drainage density by 8 to 35% across the region. Field experiments further demonstrate that Sesarma-grazed creekheads, through their removal of vegetation that otherwise obstructs predator access, enhance the vulnerability of macrobenthic invertebrates to predation and strongly reduce secondary production across adjacent marsh platforms. Thus, sea-level rise is creating conditions within which Sesarma functions as a keystone species that is driving dynamic, landscape-scale changes in salt-marsh geomorphic evolution, spatial organization, and species interactions.

Read more: https://www.pnas.org/content/early/2020/07/09/1917869117

The following is the abstract of a 2012 study by the same lead author, which blames overfishing;

A trophic cascade triggers collapse of a salt-marsh ecosystem with intensive recreational fishing

Article (PDF Available)inEcology 93(6):1402-10 · June 2012 with 894 Reads DOI: 10.2307/23213769 · Source:  PubMedCite this publication

Andrew H AltieriMark D BertnessTyler CoverdaleNicholas Carl Herrmann

Overexploitation of predators has been linked to the collapse of a growing number of shallow-water marine ecosystems. However, salt-marsh ecosystems are often viewed and managed as systems controlled by physical processes, despite recent evidence for herbivore-driven die-off of marsh vegetation. Here we use field observations, experiments, and historical records at 14 sites to examine whether the recently reported die-off of northwestern Atlantic salt marshes is associated with the cascading effects of predator dynamics and intensive recreational fishing activity. We found that the localized depletion of top predators at sites accessible to recreational anglers has triggered the proliferation of herbivorous crabs, which in turn results in runaway consumption of marsh vegetation. This suggests that overfishing may be a general mechanism underlying the consumer-driven die-off of salt marshes spreading throughout the western Atlantic. Our findings support the emerging realization that consumers play a dominant role in regulating marine plant communities and can lead to ecosystem collapse when their impacts are amplified by human activities, including recreational fishing.

Read more: https://www.researchgate.net/publication/230571469_A_trophic_cascade_triggers_collapse_of_a_salt-marsh_ecosystem_with_intensive_recreational_fishing

The body of the 2012 study appears to dismiss climate change as a factor;

… the discontinuous distribution of marshes with die-off interspersed with healthy, vegetated marshes suggests that local interactions within fished marshes, rather than regional-scale physical forcing by a factor such as sediment starvation or climate effects, is driving salt- marsh die-off. …

I guess everyone has a right to change their mind. The mirage news article discusses the process by which the group came to appreciate the dramatic impact of a few mm / year of sea level rise.

Eric Worrall / 34 mins ago July 14, 2020

Watts Up With That?

The world’s most viewed site on global warming and climate change

„Fridays-for-future“-Aktivisten geben zu: Klimarettung soll Kapitalismus abschaffen

„Fridays-for-future“-Aktivisten geben zu: Klimarettung soll Kapitalismus abschaffen

Unsere Kollegen von Große Freiheit TV aus Hamburg berichteten schon letztes Jahr, daß die eigentlich monothematische Bewegung Fridays for future FFF gemeinsame Sache mit der extremistischen und gefährlichen Antifa macht. In Anbetracht der Zerstörungen anläßlich der G20-Proteste 2017 und in Anbetracht des Übergewichtes junger Gymnasialschülerinnen bei FFF seltsam. Man sieht, wie über ein scheinbar neutrales und soziales Thema Bürgerkinder radikalisiert werden sollen.

Ein krasses Beispiel dafür ist ein Video der taz, auf das uns ein findiger Leser aufmerksam machte. (Sie wissen ja, EIKE-Leser sind exzellente Rechercheure und damit viel, viel besser als die Redakteure der Relotius- und Hengameh-Presse.) Darin sieht man, wie drei Frauen unterschiedlichen Alters Salon-sozialistische Verschwörungstheorien spinnen. Eine davon, Lilith Rein von FFF Berlin, meinte schon im Juni,

Wir beobachten seit Jahren eine systematische Verlangsamung der Energiewende und die Verstrickung der fossil-kapitalistischen Kohlekonzerne mit der Regierung! Daß im neuen Gesetzestext verankert ist, daß die Bundesregierung ohne den Bundestag mit Braunkohlebetreibern Verträge abschließen darf, ist respektlos und zeigt die offensichtlichen undemokratischen Verbindungen auf. Das Kohleausstiegsgesetz ist ein Skandal und darf in dieser Form keinesfalls verabschiedet werden- andernfalls droht die Beschleunigung der Klimakrise und damit die Zerstörung unserer Zukunft!

Die Schülerin (?), wie Luisa Neubauer und Carla Reemtsma erkennbar Sproß der Oberschicht, ist vermutlich noch nicht einmal 20, benutzt aber ein Vokabular, das den Normalbürger erschauern läßt. „Fossil-kapitalistische Kohlekonzerne“, das klingt wie „antifaschistischer Schutzwall“, „nichtsozialistisches Ausland“ oder ein anderer Ausdruck aus dem Wortschatz der Genickschuß-Marxisten. Die gelernten DDR-Bürger unter den Lesern werden sich erinnern. Die gelernten Westdeutschen mögen einen Anklang an RAF-Texte aus den 70ern erkennen.

Die Äußerungen der beiden anderen Frauen im Video sind nicht weniger verstörend, aber auch erstaunlich ehrlich. Die Ältere gibt unumwunden zu, daß wir alle „Kinder des Kapitalismus“ seien, da der Wohlstand in Europa durch das Wachstum der Marktwirtschaft entstanden sei. Genau deswegen sei das Wirtschaftssystem aber auch für die Klimazerstörung verantwortlich, da viel mehr verbrannt und verbraucht werde. Pustekuchen: Die schlecht geplante Planwirtschaft mit ihren zerfallenden Industrien, die kein Geld für Naturschutz hatte, war wesentlich schmutziger als die Konkurrenz im Westen. Die Region Halle/Saale mit den Standorten Buna, Leuna und Wolfen-Bitterfeld zum Beispiel sah 1989 schlimmer aus als das Ruhrgebiet in den 1960ern. Und die verklappten Nuklear-Schrott-Uboote im russischen Nordmeer haben ebenfalls keine Entsprechung im Westen (oder sonst irgendwo in der Welt).

Da unsere Marktwirtschaft auf Wachstum und Konsum ausgelegt sei, müssen daher Wachstum und Konsum und damit der Wohlstand heruntergefahren werden. Und dann? Soll DAS menschenfreundlich sein? Man merkt, die drei Frauen im Video leben in einer Welt der reichen Akademiker, die immer schon von den Steuergeldern der Unter- und Mittelschicht leben, daher nie wertschöpfend arbeiten mußten und somit Zeit und Muße hatten, verquere Ideologien zu entwickeln, deren Umsetzung sie nun fordern.

Aber warum eigentlich? In einer knappen sozialistischen Energie-Armutsgesellschaft wird es kein Internet, keine modernen Rechner, keine Netzkameras und vieles andere nicht mehr geben, mit denen die Genickschuß-Marxistinnen ihre Ansichten verbreiten könnten. Selbst Toilettenpapier würde wie zu Beginn der Volksquarantäne knapp. Wieso wollen die das? Bewußt ist es ihnen höchstwahrscheinlich nicht, aber verarmte Gesellschaften ohne dezentrale wirtschaftliche Machtverteilung sind das Paradies für ideologisch-politische Eliten. Deswegen neigen beispielsweise südamerikanische oder afrikanische Diktatoren dazu, jegliche Entwicklung im Land zu torpedieren. Die Wirtschaft bewegt sich wie heuer in Venezuela auf Subsistenz-Niveau, aber die kleine Elite hat viel mehr Macht als in einer Demokratie und kann sich nach Belieben am Volksvermögen bedienen. Daher ist die Diktatur ohne Marktwirtschaft für diese Gruppe deutlich attraktiver als die Demokratie, weil

Quelle: — EIKE – Europäisches Institut für Klima & Energie

Climate Models: No Warming For 30 Years – Possibly

Climate Models: No Warming For 30 Years – Possibly

A new study demonstrates how a prolonged warming pause or even global cooling may happen in coming years despite increasing greenhouse gases — caused by natural climatic variability.

Natural climatic variability has always been a topic that contains a lot of unknowns, but it has been rare that how little we know about it has been explicitly stated. Such variability has been habitually underplayed as it was “obvious” that the major driver of global temperature was the accumulation of greenhouse gasses with natural variability a weaker effect.

But the global temperature data of this century demonstrate that natural variability has dominated in the form of El Ninos. ‘Doesn’t matter’, came the reply, ‘just wait and the signal of greenhouse warming will emerge out of the noise of natural climatic variability.’ How long will we have to wait for that signal? Quite a long time, according to some researchers as more papers acknowledge that natural climatic variability has a major, if not a dominant, influence on global temperatures.

With the usual proviso concerning climatic predictions there does seem to be a growing number of research papers suggesting that the global annual average temperature of at least the next five years will remain unchanged, and the reason, natural climatic variability.

Only last week the UK Met Office produced figures suggesting that there is only a 1 in 34 chance that the 1.5°C threshold will be exceeded for the next five years. Now a new paper by climate modellers extends such predictions, suggesting that because of natural climatic variability the average global temperature up to 2049 could remain relatively unchanged – even with the largest increase in greenhouse gas emissions.

Using two types of computer models in a first of its kind study, Nicola Maher of the Max Planck Institute for Meteorology, Hamburg, Germany, and colleagues writing in Environmental Research Letters looked at the 2019-2034 period concluding that,

We first confirm that on short-term time-scales (15-years) temperature trends are dominated by internal variability. This result is shown to be remarkably robust.”

Looking even further they say that natural variability is still important,

… even out to thirty years large parts of the globe could still experience no-warming due to internal variability,” they add.

The researchers demonstrate internal variability and its importance in driving the climate that we observe, with a series of maps to visualise both the maximum and minimum global and future trends that could occur on short and mid-term timescales. They demonstrate clearly the cooling that could occur under increasing greenhouse gases, caused by internal variability.

In percentages, the role of internal climatic variability. Source: Maher et al., 2020

The researchers say,

In the short-term all points on the globe could individually experience cooling or no warming, although in a probabilistic sense they are much more likely to warm.”

Looking beyond the short-term they add,

We find that even on the mid-term time-scale a large proportion of the globe could by chance still not experience a warming trend due to internal variability, although this result is somewhat model dependent.”

In the past climate extremists have grasped natural El Ninos and enlisted them as examples of rapid greenhouse global warming. It’s a disingenuous approach that may become harder and harder to do if research like this is any indication.

Feedback: David.Whitehouse@thegwpf.com

The post Climate Models: No Warming For 30 Years – Possibly appeared first on The Global Warming Policy Forum (GWPF).

via The Global Warming Policy Forum (GWPF)

https://ift.tt/3ftICzi

July 14, 2020 at 09:18AM

Ocean Temps Dropping June 2020

Ocean Temps Dropping June 2020

The best context for understanding decadal temperature changes comes from the world’s sea surface temperatures (SST), for several reasons:

  • The ocean covers 71% of the globe and drives average temperatures;
  • SSTs have a constant water content, (unlike air temperatures), so give a better reading of heat content variations;
  • A major El Nino was the dominant climate feature in recent years.

HadSST is generally regarded as the best of the global SST data sets, and so the temperature story here comes from that source, the latest version being HadSST3.  More on what distinguishes HadSST3 from other SST products at the end.

The Current Context

The cool 2020 Spring was not just your local experience, it’s the result of Earth’s ocean cooling off after last summer’s warming in the Northern Hemisphere.  The chart below shows SST monthly anomalies as reported in HadSST3 starting in 2015 through June 2020.
A global cooling pattern is seen clearly in the Tropics since its peak in 2016, joined by NH and SH cycling downward since 2016.  In 2019 all regions had been converging to reach nearly the same value in April.

Then  NH rose exceptionally by almost 0.5C over the four summer months, in August exceeding previous summer peaks in NH since 2015.  In the 4 succeeding months, that warm NH pulse reversed sharply.  Now NH temps are warming to a lower 2020 summer peak, while the SH and Tropics are cooling sharply.  Thus the Global anomaly has steadily decreased since March, presently matching last Autumn

Note that higher temps in 2015 and 2016 were first of all due to a sharp rise in Tropical SST, beginning in March 2015, peaking in January 2016, and steadily declining back below its beginning level. Secondly, the Northern Hemisphere added three bumps on the shoulders of Tropical warming, with peaks in August of each year.  A fourth NH bump was lower and peaked in September 2018.  As noted above, a fifth peak in August 2019 exceeded the four previous upward bumps in NH.

And as before, note that the global release of heat was not dramatic, due to the Southern Hemisphere offsetting the Northern one.  The major difference between now and 2015-2016 is the absence of Tropical warming driving the SSTs, along with SH anomalies nearly the lowest in this period.

A longer view of SSTs

The graph below  is noisy, but the density is needed to see the seasonal patterns in the oceanic fluctuations.  Previous posts focused on the rise and fall of the last El Nino starting in 2015.  This post adds a longer view, encompassing the significant 1998 El Nino and since.  The color schemes are retained for Global, Tropics, NH and SH anomalies.  Despite the longer time frame, I have kept the monthly data (rather than yearly averages) because of interesting shifts between January and July.

To enlarge, open image in new tab,

1995 is a reasonable (ENSO neutral) starting point prior to the first El Nino.  The sharp Tropical rise peaking in 1998 is dominant in the record, starting Jan. ’97 to pull up SSTs uniformly before returning to the same level Jan. ’99.  For the next 2 years, the Tropics stayed down, and the world’s oceans held steady around 0.2C above 1961 to 1990 average.

Then comes a steady rise over two years to a lesser peak Jan. 2003, but again uniformly pulling all oceans up around 0.4C.  Something changes at this point, with more hemispheric divergence than before. Over the 4 years until Jan 2007, the Tropics go through ups and downs, NH a series of ups and SH mostly downs.  As a result the Global average fluctuates around that same 0.4C, which also turns out to be the average for the entire record since 1995.

2007 stands out with a sharp drop in temperatures so that Jan.08 matches the low in Jan. ’99, but starting from a lower high. The oceans all decline as well, until temps build peaking in 2010.

Now again a different pattern appears.  The Tropics cool sharply to Jan 11, then rise steadily for 4 years to Jan 15, at which point the most recent major El Nino takes off.  But this time in contrast to ’97-’99, the Northern Hemisphere produces peaks every summer pulling up the Global average.  In fact, these NH peaks appear every July starting in 2003, growing stronger to produce 3 massive highs in 2014, 15 and 16.  NH July 2017 was only slightly lower, and a fifth NH peak still lower in Sept. 2018.

The highest summer NH peak came in 2019, only this time the Tropics and SH are offsetting rather adding to the warming. Since 2014 SH has played a moderating role, offsetting the NH warming pulses. Now in January 2020 last summer’s unusually high NH SSTs have been erased. (Note: these are high anomalies on top of the highest absolute temps in the NH.)

What to make of all this? The patterns suggest that in addition to El Ninos in the Pacific driving the Tropic SSTs, something else is going on in the NH.  The obvious culprit is the North Atlantic, since I have seen this sort of pulsing before.  After reading some papers by David Dilley, I confirmed his observation of Atlantic pulses into the Arctic every 8 to 10 years.

But the peaks coming nearly every summer in HadSST require a different picture.  Let’s look at August, the hottest month in the North Atlantic from the Kaplan dataset.
The AMO Index is from from Kaplan SST v2, the unaltered and not detrended dataset. By definition, the data are monthly average SSTs interpolated to a 5×5 grid over the North Atlantic basically 0 to 70N. The graph shows warming began after 1992 up to 1998, with a series of matching years since. Because the N. Atlantic has partnered with the Pacific ENSO recently, let’s take a closer look at some AMO years in the last 2 decades.
This graph shows monthly AMO temps for some important years. The Peak years were 1998, 2010 and 2016, with the latter emphasized as the most recent. The other years show lesser warming, with 2007 emphasized as the coolest in the last 20 years. Note the red 2018 line is at the bottom of all these tracks. The black line shows that 2020 began slightly warm, then set records for 3 months before dropping below 2016 and 2017.

Summary

The oceans are driving the warming this century.  SSTs took a step up with the 1998 El Nino and have stayed there with help from the North Atlantic, and more recently the Pacific northern “Blob.”  The ocean surfaces are releasing a lot of energy, warming the air, but eventually will have a cooling effect.  The decline after 1937 was rapid by comparison, so one wonders: How long can the oceans keep this up? If the pattern of recent years continues, NH SST anomalies may rise slightly in coming months, but once again, ENSO which has weakened will probably determine the outcome.

Footnote: Why Rely on HadSST3

HadSST3 is distinguished from other SST products because HadCRU (Hadley Climatic Research Unit) does not engage in SST interpolation, i.e. infilling estimated anomalies into grid cells lacking sufficient sampling in a given month. From reading the documentation and from queries to Met Office, this is their procedure.

HadSST3 imports data from gridcells containing ocean, excluding land cells. From past records, they have calculated daily and monthly average readings for each grid cell for the period 1961 to 1990. Those temperatures form the baseline from which anomalies are calculated.

In a given month, each gridcell with sufficient sampling is averaged for the month and then the baseline value for that cell and that month is subtracted, resulting in the monthly anomaly for that cell. All cells with monthly anomalies are averaged to produce global, hemispheric and tropical anomalies for the month, based on the cells in those locations. For example, Tropics averages include ocean grid cells lying between latitudes 20N and 20S.

Gridcells lacking sufficient sampling that month are left out of the averaging, and the uncertainty from such missing data is estimated. IMO that is more reasonable than inventing data to infill. And it seems that the Global Drifter Array displayed in the top image is providing more uniform coverage of the oceans than in the past.

uss-pearl-harbor-deploys-global-drifter-buoys-in-pacific-ocean
USS Pearl Harbor deploys Global Drifter Buoys in Pacific Ocean

via Science Matters

https://ift.tt/2CBPID3

July 14, 2020 at 09:06AM

Acid Oceans? & Oyster Shells

Acid Oceans? & Oyster Shells

What’s Natural?

Guest post by Jim Steele

Published July 14, 2020 in the Pacifica Tribune

(I wrote a white paper for the CO Coalition, providing more details and references to peer reviewed science regards how marine life counteracts ocean acidification. That paper can be downloaded here )

Search the internet for “acid oceans” and you’ll find millions of articles suggesting the oceans are becoming more corrosive due the burning of fossil fuels, and “acid oceans” are threatening marine life. Although climate modelers constantly claim the oceans’ surface pH has dropped since the 1800s, that change was never measured, as the concept of pH was not created until the early 1900s by beer-makers.

In 2003 Stanford’s Dr. Ken Caldeira coined the term “ocean acidification” to generate public concern about increasing CO . As New Yorker journalist Elizabeth Kolbert reported, “Caldeira told me that he had chosen the term ‘ocean acidification’ quite deliberately for its shock value. Seawater is naturally alkaline, with a pH ranging from 7.8 to 8.5—a pH of 7 is neutral—which means that, for now, at least, the oceans are still a long way from actually turning acidic.” Nonetheless Caldeira’s term “ocean acidification” evoked such undue fears and misunderstandings, we are constantly bombarded with catastrophic media hype and misdiagnosed causes of natural change.

For example, for nearly a decade the media has hyped the 2006-2008 die-off of larval oysters in hatcheries along Washington and Oregon. They called it a crisis caused by rising atmospheric CO and the only solution was to stop burning fossil fuels. But it was an understanding of natural pH changes that provided the correct solutions. Subsurface waters at a few hundred meters depth naturally contain greater concentrations CO and nutrients and a lower pH than surface waters. Changes in the winds and currents periodically bring those waters to the surface in a process called upwelling. Upwelling promotes a burst of life but also lowers the surface water pH.  Not fully aware of all the CO dynamics, the hatcheries had made 3 mistakes.

First, they failed to recognize not all oyster species are well adapted to the low pH of upwelled water. The larvae of native Olympia oysters naturally survive intense upwelling events along the Washington coast because that species “broods” its larvae. The larvae initiate their shells protected inside their parents’ shells where pH is more controlled. However, the Olympia oysters were over-harvested into near extinction in the 1800’s.

So, fishermen imported the Japanese oyster, which is now the mainstay of the Washington and Oregon fisheries. Japanese oysters did not evolve within an intense upwelling environment similar to Washington’s coast. Each Japanese oyster simply releases over 50 million eggs into the water expecting their larvae to survive any mild changes in pH during initial shell formation. Hatcheries didn’t realize the Japanese oyster’s larvae had a 6-hour window during which the larvae’s initial shell development and survival was vulnerable to low pH.

Second, because cooler waters inhibit premature spawning, hatcheries pumped cool water from the estuary in the early morning. As measured in coral reefs, photosynthesis raises pH during the day, but nighttime respiration drops pH significantly. By pumping early morning water into their tanks, they imported estuary water at its lowest daily pH. Finally, they failed to recognize natural upwelling events transport deeper waters with naturally low pH into the estuary, further lowering the pH of water pumped into their tanks.

Now, hatcheries simply pump water from the estuary later in the day after photosynthesis has raised pH. Scientists also developed a metering device that detects intrusions of low pH waters, so hatcheries avoid pumping water during upwelling events. As for most shellfish, once the shell is initiated, a protective layer prevents any shell corrosion from low pH conditions. Problem easily solved and crisis averted!

The simplistic idea that burning fossil fuels is causing the surface ocean to become more acidic is based on the fact that when CO interacts with water a series of chemical changes results in the production of more hydrogen ions which lowers pH. Unfortunately, all catastrophic analyses stop there. But living organisms then reverse those reactions. Whether CO enters the surface waters via the atmosphere or from upwelling, it is quickly utilized by photosynthesizing plankton which counteracts any “acidification”. A percentage of the organic matter created in the sunlit waters sinks or is actively transported to depths, further counteracting any surface “acidification’. Some organic matter sinks so rapidly, CO is trapped at depths for hundreds and thousands of years. The dynamics that carry carbon to ocean depths largely explains why the oceans hold 50 times more CO than the atmosphere.

To maintain marine food webs, it is essential that upwelling bring sunken nutrients back into the sunlight to enable photosynthesis. Upwelling also brings stored CO and low pH water to the surface. Wherever upwelling recycles nutrients and lowers surface pH, the greatest abundance and diversity of marine life is generated.

Jim Steele is director emeritus of the Sierra Nevada Field Campus, SFSU and authored Landscapes and Cycles: An Environmentalist’s Journey to Climate Skepticism.

Like this:

Like Loading…

Related

via Watts Up With That?

https://ift.tt/3enVsxv

July 14, 2020 at 08:40AM

%d Bloggern gefällt das:
Zur Werkzeugleiste springen