Inconvenient stumps

Reblogged from Watts Up With That:

Climate alarmists tell us that the Earth has never been warmer, and that we can tell by looking at tree rings, treelines, and other proxy indicators of climate.

Climate scientists claim the warmth is unprecedented.

We’ve been told it is warming so fast, we have only 12 years left!

Yet nature seems to not be paying attention to such pronouncements, as this discovery shows.

This photo shows a tree stump of White Spruce that was radiocarbon dated at 5000 years old. It was located 100 km north of the current tree line in extreme Northwest Canada.

The area is now frozen tundra, but it was once warm enough to support significant tree growth like this.

If climate was this warm in the past, how did that happen before we started using the fossil fuels that supposedly made our current climate unprecedentedly warm?

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Experts reveal that clouds have moderated warming triggered by climate change

Reblogged from Watts Up With That:

A new study has revealed how clouds are modifying the warming created by human-caused climate change in some parts of the world

Swansea University

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Trees are removed from cold lake beds in Scandinavia. Credit: Professor Mary Gagen, Swansea University

A new study has revealed how clouds are modifying the warming created by human-caused climate change in some parts of the world.

Led by Swansea University’s Tree Ring Research Group, researchers from Sweden, Finland and Norway analysed information contained in the rings of ancient pine trees from northern Scandinavia to reveal how clouds have reduced the impact of natural phases of warmth in the past and are doing so again now to moderate the warming caused by anthropogenic climate change.

Even though northern Scandinavia should be strongly affected by global warming, the area has experienced little summer warming over recent decades – in stark contrast to the hemispheric trend of warming temperatures, which is strongly linked to rising greenhouse gas emissions. According to the study, temperature changes have been accompanied by an increase in cloudiness over northern Scandinavia, which in turn has reduced the impact of warming.

Mary Gagen, Professor of Geography at Swansea University, said: “The surface warming caused by rising greenhouse gases is modified by many complicated feedbacks – one thing changing in response to another – meaning that there are large geographical variations in the temperature of a particular place at a particular time, as the global average temperature rises. One of the most important, and most poorly understood, climate feedbacks is the relationship between temperature and clouds. We might think that, simply, when it is cool it is cloudy, and when it is warm it is sunny, but that is not always the case.”

The research team analysed tree ring records to find out what summer temperatures were like in the past, and how cloudy it was. Using their collected data, the team produced a new reconstruction of summer cloud cover for northern Scandinavia and compared it to existing temperature reconstructions to establish the relationship between temperature and cloud cover.

Professor Mary Gagen said: “Most people know that the width of a tree ring can tell us what the temperature was like in the summer that ring grew, but we can also measure other things in tree rings such as the isotopes of carbon and water that the wood is made from. Isotopes are just different types of an element, the amount of the different isotopes of carbon in the wood tells us how cloudy it was in the summer the tree ring grew. By combining the tree ring width and tree ring carbon measurements we built a record of both past summer temperatures and past summer cloud cover. Summer temperatures in Scandinavia have increased by less than the global average in recent decades because it also got cloudier at the same time, and that modified and reduced the warming. That turns out to also be the case back through time.”

Author Professor Danny McCarroll explained: “We found that over short timescales, increased cloud cover lead to cooler temperatures and vice versa in the past. However, over longer timescales -decades to centuries-we found that in warmer times, such as the medieval, there was increased cloud cover in this part of the world, which reduced local temperatures. The opposite being true in cool periods, such as the Little Ice Age.

“These finding are important as they help to explain the feedback relationship between cloud cover and temperature, which is one of the major uncertainties in modelling future climate. Understanding the past relationship between temperature and cloud cover in this part of the world means we can now predict that, as the global temperature continues to rise, that warming will be moderated in northern Scandinavia by increasing cloud cover. The next step is to find out whether the same is true for other parts of the world.”

Professor Mary Gagen added: “One of the main sources of uncertainty about future climate change is the way that clouds are going to respond to warming, cloud cover has a really big influence on temperature at the surface of the Earth.

“Clouds are going to be critical in modify warming of the climate. In some places, like Scandinavia, it turns out that the summer climate gets cloudier as the planet warms, in other places though it is likely that warming will be enhanced by a reduction in cloudiness which will make the surface of the Earth even warmer. What is really worrying is that climate models have shown that, if greenhouse gas emissions are allowed to continue until there is double or even triple the pre industrial amount of carbon dioxide in the atmosphere, then some of the most important clouds for cooling our planet, the big banks of oceanic clouds that reflect a lot of sunlight back to space, could stop forming altogether and this would really accelerate warming.”

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The study, Cloud Cover Feedback Moderates Fennoscandian Summer Temperature Changes Over the Past 1,000 Years, is published in Geophysical Research Letters.

From EurekAlert!

Public Release: 25-Mar-2019

Tree-ring analysis explains physiology behind drought intolerance

Reblogged from Watts Up With That:

Public Release: 26-Dec-2018

Oregon State University

CORVALLIS, Ore. – Tree rings tell the story of what’s happening physiologically as fire suppression makes forests more dense and less tolerant of drought, pests and wildfires, new research shows.

Scientists at Oregon State University and Utah State University studied 2,800 hectares of mixed-conifer forest in central Oregon, with many of the ponderosa pines in the study area dating back hundreds of years prior to 1910, when putting out wildfires became federal policy.

Other trees in the area, where fire history has been studied extensively, were younger, comparatively fire- and drought-intolerant grand firs.

The findings, published in Global Change Biology, indicate that as stands of trees became thicker over the past century, trees were forced to use progressively more of the heavier stable isotope of carbon for photosynthesis, indicative of increasing drought stress as they restricted the passage of gases into their leaves.

The research also suggests that rising carbon dioxide levels – atmospheric CO2 has increased 40 percent since the dawn of the industrial age – can’t help trees overcome the effects of forests having become more dense without fires.

“We wanted to document the trajectory of sensitivity to drought stress in response to progressively increasing fire deficits, and the threshold level of stand occupancy where decreasing resistance and resilience to drought stress, bark beetles and wildfire set in,” said study co-author Christopher Still of the OSU College of Forestry. “This was an intersection of fire ecology and physiological ecology – two areas that don’t meet up as often as they should.”

Before 1910, frequent low-severity surface fires played a key role in maintaining the forests of the dry mountain regions of the western United States. In the decades since, the fire deficits that resulted from federal policy – in concert with grazing, logging and land-use changes – have caused major structural shifts in older forests as shade-tolerant and fire-intolerant species have moved in.

Over the same period of time, concentrations of carbon dioxide in the atmosphere have not only been rising but doing so at an increasing rate; the higher CO2 concentrations have an effect on leaf gas exchange – the processes through which trees obtain oxygen for respiration and carbon dioxide for photosynthesis.

“We’ve known for a long time that fire suppression has led to crowded forests, which means more competition for resources,” said College of Forestry graduate student Andrew Merschel, another study co-author. “We’ve known that because of that, trees are more prone to drought, which makes sense – there’s less water reaching deep below ground and more trees pumping it out. Our research shows in a physiological way what’s happening. We thought there would be signals in the annual tree rings, and there are.”

A tree adds a ring for each year of growth, and in a conifer the ring consists of a lighter-colored “early wood” portion and a darker-colored “late wood” component.

Ring-size variation reflects temperature and precipitation at the time the growth occurred. And the chemistry of each ring tells a tale too, including whether a tree can use more of the lighter carbon-12 isotope it prefers, or had to resort to using relatively more of the heavier carbon-13 isotope for photosynthesis as well.

Tree-ring carbon isotope records also have shown that trees respond to drought by becoming more efficient with their water use.

What hadn’t been known, though, was whether increases in water-use efficiency, bolstered by rising CO2 concentrations, were enough to overcome increased drought stress resulting from a recent in-growth pulse of younger, fire-intolerant trees.

“Increased tree density seems to outweigh the benefits of carbon dioxide ‘fertilization,’” Merschel said. “It’s not necessarily bad if younger, drought-sensitive trees that established since fire exclusion die because that’s consistent with way these forests used to look – more open, allowing ponderosa pine to live to be 600 years old. Fewer trees and reduced competition allow the old, fire-resistant trees that have survived centuries of drought, insects, and fire to persist as the structural backbone of dry forests.”

Lead author Steven Voelker of Utah State University notes that drought sensitivity of forests in the dry mountain regions of the Pacific Northwest may be compounded as climate change increases the length of the snow-free season.

“Recent research from OSU and other institutions also shows that denser forests reduce snowpack across the Northwest,” Voelker said. “We cannot predict exactly how all of these factors affecting forests will interact in the future, but it is certain that lower-density forests will have more snow and less drought stress.”

And without “major changes to policy and management aimed at reducing stand densities,” many forests in central Oregon will cross a threshold that makes them less resistant to drought and less resilient to wildfires and bark beetle outbreaks, he said.

Future work by this research group will expand tree-ring isotope analyses into different areas of Oregon and other parts of the western United States to assess the effect of increased competition across conifer forests where it might be dryer and hotter – and thereby provide a more comprehensive view of how forest resilience has changed because of fire suppression.

Concord and discord among Northern Hemisphere paleotemperature reconstructions from tree rings

From Science Direct

Scott St. George Jan Esper
Department of Geography, Environment and Society, University of Minnesota, Minneapolis, USA
Department of Geography, Johannes Gutenberg University, Mainz, Germany

Received 3 September 2018, Revised 8 November 2018, Accepted 9 November 2018, Available online 15 November 2018.

https://doi.org/10.1016/j.quascirev.2018.11.013 Get rights and content

Highlights

  • Tree rings are the backbone of most last millennium temperature reconstructions.
  • Maximum density is a superior temperature proxy than ring-width but is less available.
  • The newest tree-ring reconstructions agree better with instrumental temperatures.
  • They also fit the memory structure of instrumental temperatures more closely.
  • It is imperative to develop new, long and up-to-date maximum density chronologies.

Abstract

We review the current generation of large-scale, millennial-length temperature reconstructions derived from tree rings and highlight areas of agreement and disagreement among these state-of-the-art paleotemperature estimates. Although thousands of tree ring-width chronologies are now available from temperate and boreal forest sites across the Northern Hemisphere, only a small fraction of those records are suited as proxies for surface temperature. Maximum latewood density is clearly a superior temperature proxy but is less available, with few densitometric records that are both long and up-to-date. Compared to previous efforts, the newest generation of tree-ring reconstructions correlate more strongly against hemispheric summer temperatures and show better performance in tracking decadal/multi-decadal variability and year-to-year fluctuations. They also fit the observed memory structure of instrumental temperatures more closely than their predecessors. These new estimates still show signs of the so-called ‘divergence problem’ (the apparent loss of temperature sensitivity under recent warming), but do not extend after 2004 and cannot be used to evaluate the impact of the past decade’s warming on northern temperature-limited forests. We caution against averaging together the latest hemispheric-scale reconstructions because they have each been constructed to suit different purposes and share much of the same underlying tree-ring data, especially prior to CE 1500. Past temperatures are recorded more clearly in maximum latewood density than total ring-width, so we recommend the Northern Hemisphere densitometry network be modernized through a new round of field collections and observations.

Full paper here

HT/Caligula Jones

Scottish Sunspots

From Watts Up With That:

In a recent post, Anthony published Leif Svalgaard’s new paper showing 9,000 years of reconstructed solar activity.

In the discussion, someone pointed out that the “Maunder Minimum”, a time of very low solar activity, corresponds with the coldest decade in a long-term reconstruction of summer temperatures in Scotland. Their temperature reconstruction is based on a group of pine tree-ring records spanning 800 years. Their graph is shown below:

As you can see, the period around 1690 is extremely cold. This was put forward as support for the idea that sunspot cycles affect the temperature. The idea is that when sunspots are low, temperatures are low as well. And the year 1690 is during the Maunder Minimum, a time of low sunspots.

However, as you may know if you follow my work, I like to take the largest look at the longest data that I can find. So rather than build a theory based on one decade of cold temperatures lining up with one sunspot minimum, I decided to compare the two graphs shown above. I first “standardized” both datasets, meaning that I set each of their averages to zero and each of their standard deviations to one. That allows us to compare them directly. Here is that result:

Now, the commenter was indeed correct that the low temperature in 1690 was during the Maunder Minimum.

However, the other minima do not line up with much of anything. The Wolf Minimum occurred during not just a warm period, but during the warmest period in the record. Similarly, the Sporer Minimum occurred during the warm period just before the drop to the “Little Ice Age” of the 1600s.

Then we have the Maunder Minimum. Temperatures started dropping about 150 years before the start of the Maunder Minimum, and during the first hundred years of dropping temperatures the sunspots were increasing. So obviously, the sun was not the cause of the drop in temperature.

Next, although the Dalton minimum occurred during a cold period. temperatures started dropping some seventy years or so before the start of the Dalton minimum … and temperatures warmed from the start to the end of the Dalton Minimum.

Finally, in recent times, you can see that sunspots started decreasing about 1980, while temperatures have risen during that time.

I leave the reader to draw the obvious conclusions regarding sunspots and Scottish temperatures …

w.

PS—When you comment, please quote the exact words that you are referring to, so that we can all understand what you are discussing.


–Hifast Note:  Excellent comment thread at WUWT: Click here, then scroll

You can always tell a Mann, but you can’t tell him much – why tree ring data (and climatic conclusions from it) sucks

From Watts Up With That:

From the “we only select wood for hockey stick construction” department.

Yamalometer_scr.jpg

Steve McIntyre comes back into the fray with a scathing review of just how crappy the tree ring proxies used by Michael Mann were (and still are), and shows without the questionable stripbark portion of the data, why no “hockey stick” appears. But even worse, McIntyre illustrates that Mann, the hockey team, and the paleoclimate community haven’t learned one damn thing with the release of the latest set of tree ring data.

From Climate Audit:


The PAGES (2017) North American network consists entirely of tree rings. Climate Audit readers will recall the unique role of North American stripbark bristlecone chronologies in Mann et al 1998 and Mann et al 2008 (and in the majority of IPCC multiproxy reconstructions).  In today’s post, I’ll parse the PAGES2K North American tree ring networks in both PAGES (2013) and PAGES (2017) from two aspects:

  • even though PAGES (2013) was held out as the product of superb quality control, more than 80% of the North American tree ring proxies of PAGES (2013) were rejected in 2017, replaced by an almost exactly equal number of tree ring series, the majority of which date back to the early 1990s and which would have been available not just to PAGES (2013), but Mann et al 2008 and even Mann et al 1998;
  • the one constant in these large networks are the stripbark bristlecone/foxtail chronologies criticized at Climate Audit since its inception. All 20(!) stripbark chronologies isolated by Mann’s CENSORED directory re-appear not only in Mann et al (2008), but in PAGES (2013). In effect, the paleoclimate community, in apparent solidarity with Mann, ostentatiously flouted the 2006 NAS Panel recommendation to “avoid” stripbark chronologies in temperature reconstructions. In both PAGES (2013) and PAGES (2017), despite ferocious data mining, just as in Mann et al 1998, there is no Hockey Stick shape without the series in Mann’s CENSORED directory.

PAGES2K references: PAGES (2013) 2013 article and PAGES (2017) url; (Supplementary Information).

Background: Stripbark Bristlecones and Mann’s CENSORED Directory

In our 2005 articles, Ross and I pointed out that the Mann’s hockey stick is merely an alter ego for Graybill’s stripbark bristlecone chronologies and that the contribution from all other proxies was nothing more than whitish noise. We noted that Graybill himself had attributed the marked increase in late 19th and 20th century bristlecone growth to CO2 fertilization, not temperature – a theory which was arguably a harbinger of the massive and widespread world greening, especially in dry areas, over the 30 years since Graybill et al (1985).

In a CA blogpost here, I further illustrated the unique contribution of bristlecones by segregating the additive contribution to the MBH98 reconstruction of bristlecones (red) and other proxy classes (e.g. ice cores, non-bristlecone North American tree rings, South American proxies, etc. in blue, green, yellow ). This clearly showed that (1) the distinctive MBH98 Hockey Stick shape arose entirely from bristlecones and that (2) all other proxy classes contributed nothing more than whitish noise – with their combined contribution diminishing in accordance with the Central Limit Theorem of statistics.

Mann had, of course, done a principal components analysis of his North American tree ring network without stripbark bristlecones – an analysis not reported in his articles, but which could be established through reverse engineering of his now notorious CENSORED directory – see CA post here. ) These non-descript PCs further illustrate the non-HSness of the Mann et al 1998 North American tree ring network without strip bark bristlecones.

Figure 2. Plot of five principal components in MBH98 CENSORED directory i.e. without Graybill stripbark chronologies, mainly from bristlecones, but a couple of limber pines. 

The 2006 NAS panel stated that stripbark chronologies (i.e. the Graybill bristlecone chronologies) should be “avoided” in temperature reconstructions. Although Mann et al 2008 stated that it was compliant with NAS recommendations, Mann flouted this most essential recommendation by including all 20 stripbark series isolated from the CENSORED analysis.

Because of persistent criticism over the impact of these flawed proxies, Mann et al (2008) made the grandiose assertion that he could get a hockey stick without tree rings (and thus, a fortiori, without stripbark bristlecones) – a claim credulously promoted by Gavin Schmidt at Real Climate. However, it was almost immediately pointed out at Climate Audit (here) that Mann’s non-bristlecone hockey stick critically depended on a Finnish lake sediment “proxy”, the modern portion of which (its blade) had been contaminated by modern agriculture and road construction and which had been used upside-down to its interpretation as a temperature proxy in pre-modern times. Mann was aware of the contamination of lake sediments, but argued that his use of contaminated (and upside down) data was legitimate because he could get a HS without them  – in a calculation which used stripbark bristlecones. When challenged to show results without either stripbark bristlecones or upside-down mud, Mann (and Gavin Schmidt) stuck their fingers in their ears, with the larger climate community obtusely refusing to understand a criticism that was obvious to any analyst not subservient to the cause.

In the weeks prior to Climategate, I used increasingly harsher terms for the addiction of the paleoclimate community to the data-snooped stripbark chronologies, describing them as “heroin for paleoclimatologists”, with Briffa’s spurious Yamal chronology as “cocaine” (e.g. herehere), occasioning much pearl-clutching within the hockey stick “community”.

Conclusions

  • ex post screening based on recent proxy trends necessarily biases the resulting data towards a Hockey Stick shape – a criticism made over and over here and at other “ske;ptic” blogs, but not understood by Michael (“I am not a statistician”) Mann and the IPCC paleoclimate “community”;
  • the PAGES 2017 North American tree ring network has been severely screened ex post from a much larger candidate population: over the years, approximately 983 different North American tree ring chronologies have been used in MBH98, Mann et al 2008, PAGES 2013 or PAGES 2017. I.e. only ~15% of the underlying population was selected ex post – a procedure which, even with random data, would impart Hockey Stick-ness to any resulting composite
  • despite this severe ex post screening (in both PAGES 2013 and PAGES 2017), the composite of all data other than stripbark bristlecones had no noticeable Hockey Stick-ness and does not resemble a temperature proxy.
  • PAGES 2013 and PAGES 2017 perpetuate the use of Graybill stripbark chronologies – despite the recommendation of the 2006 NAS Panel that these problematic series be “avoided” in future reconstructions. PAGES 2013 (like Mann et al 2008) used all 20(!) stripbark chronologies, the effect of which had been analysed in Mann’s CENSORED directory. PAGES 2017 continued the use of the most HS stripbark chronologies (Sheep Mt etc) both in the original Graybill version and in a more recent composite (Salzer et al 2014), while adding two stripbark chronologies used in Esper et al 2002 and other IPCC multiproxy studies.

In the past, I charged Mannian paleoclimatologists as being addicted to Graybill stripbark bristlecone chronologies – which I labeled as “heroin for paleoclimatologists” (also describing Briffa’s former Yamal chronology as “cocaine for paleoclimatologists”. Unfortunately, rather than confronting their addiction, Gavin Schmidt and others responded with haughty pearl-clutching indignation, while, behind the scenes, the PAGES consortium doubled down by perpetuating use of these problematic proxies into PAGES 2013 and PAGES 2017.

On this day in 2009, (Oct24) a few weeks before Climategate, I suggested appropriate theme music by Eric Clapton and Velvet Underground. Still apt nine years later.


READ THE ENTIRE ESSAY HERE

In the first comment at Climate Audit, Willis sums up the Mannian mendaciousness very well:

Well, it seems to me that you could have saved yourself lots of work by just reposting your objections to the original Mann HS paper, which are the same objections to every succeeding Mann-alike since then … it’s deja vu all over again.

I gotta say, I am totally gobsmacked. Near as I can tell, they’ve got a perfect record—every error, every wrong process, every data-mining method, every after-the-fact proxy selection, every piece of bad data, every bogus stripbark pine record, they have have all simply been moved from one study, to the next, to the next, without the slightest sign that they have learned from, or even noticed, their egregious errors …

Can’t say enough for your patience in all of this, wading endlessly through the murky waters only to find the same bovine waste material as you found last time.

Gotta say, if I were doing it, I certainly wouldn’t have been as … well … Canadian … in my description of these double-dealing lying malfeasant pseudo-scientists.

Grrrr …

As always, the world owes you immense thanks for your tireless work in revealing this unending deception time after time.

Well done, that man!

w.

Don’t forget, there’s always this book:

a-disgrace-to-the-profession

Review here, and available on Amazon here.

Receding Swiss Glaciers Reveal 4000 Year Old Forests – Warmists Try To Suppress Findings

NOT A LOT OF PEOPLE KNOW THAT

By Paul Homewood

I ran this story in 2014, but it is worth re-posting:

As many sources, including HH Lamb, have pointed out, back in the Bronze Age around 2000BC, the climate in the Alps was much warmer than now.

It is therefore no surprise to find direct evidence of this from geologist Dr. Christian Schlüchter, Professor emeritus at the University of Bern in Switzerland.

Larry Bell at Newsmax has the story:

Dr. Christian Schlüchter’s discovery of 4,000-year-old chunks of wood at the leading edge of a Swiss glacier was clearly not cheered by many members of the global warming doom-and-gloom science orthodoxy.

This finding indicated that the Alps were pretty nearly glacier-free at that time, disproving accepted theories that they only began retreating after the end of the little ice age in the mid-19th century. As he concluded, the region had once been much warmer than today, with…

View original post 804 more words

Study – Global Tree cover on the rise – possibly due to CO2/global warming

Global tree canopy cover increased by 2.24 million square kilometers (865,000 square miles) between 1982 and 2016, reports a new study in Nature. These new findings contradict earlier studies that reported a continuing net loss of forest cover.

Researchers using satellite data tracked the changes in various land covers to find that gains in forest area in the temperate, subtropical, and boreal climatic zones are offsetting declines in the tropics. In addition, forest area is expanding even as areas of bare ground and short vegetation are shrinking. Furthermore, forests in montane regions are expanding as climate warming enables trees to grow higher up on mountains.

Tree canopy in Europe, including European Russia, has increased by 35 percent—the greatest gain among all continents. The researchers attribute much of that increase to the “natural afforestation on abandoned agricultural land,” which has been “a common process in Eastern Europe after the collapse of the Soviet Union.”

Full story at Reason Online


 

The study: https://www.nature.com/articles/s41586-018-0411-9

Global land change from 1982 to 2016

Abstract

Land change is a cause and consequence of global environmental change. Changes in land use and land cover considerably alter the Earth’s energy balance and biogeochemical cycles, which contributes to climate change and—in turn—affects land surface properties and the provision of ecosystem services. However, quantification of global land change is lacking. Here we analyse 35 years’ worth of satellite data and provide a comprehensive record of global land-change dynamics during the period 1982–2016. We show that—contrary to the prevailing view that forest area has declined globally—tree cover has increased by 2.24 million km2 (+7.1% relative to the 1982 level). This overall net gain is the result of a net loss in the tropics being outweighed by a net gain in the extratropics. Global bare ground cover has decreased by 1.16 million km2 (−3.1%), most notably in agricultural regions in Asia. Of all land changes, 60% are associated with direct human activities and 40% with indirect drivers such as climate change. Land-use change exhibits regional dominance, including tropical deforestation and agricultural expansion, temperate reforestation or afforestation, cropland intensification and urbanization. Consistently across all climate domains, montane systems have gained tree cover and many arid and semi-arid ecosystems have lost vegetation cover. The mapped land changes and the driver attributions reflect a human-dominated Earth system. The dataset we developed may be used to improve the modelling of land-use changes, biogeochemical cycles and vegetation–climate interactions to advance our understanding of global environmental change.