Archives par mot-clé : Holocene

@UCSUSA “Union of Concerned Scientists” doesn’t understand what “unprecedented” means when used with the word “warming”

by Anthony Watts, August 30, 2018 in WUWT


Earth’s surface has undergone unprecedented warming over the last century, and especially in this century.

Every single year since 1977 has been warmer than the 20th century average, with 16 of the 17 warmest years on record occurring since 2001, and 2016 being the warmest year on recorded history. A study from 2016 found that without the emissions from burning coal and oil, there is very little likelihood that 13 out of the 15 warmest years on record would all have happened.

Source: https://www.ucsusa.org/global-warming/science-and-impacts/science/human-contribution-to-gw-faq.html


First a definition of the word “unprecedented”:

Note that “in this century” isn’t part of the definition. it says “never done or known before”

So in that spirit, here’s some other “unprecedented” warming in Earth’s history, via the Vostok Ice Core dataset:

Holocene Sea Level Trends

by P. Homewood, August 22, 2018 in NotaLotofPeopleKnowThat


There seems to be a general acceptance about overall sea level trends during the Holocene.

There was naturally a very rapid rise in sea levels at the end of the ice age, until 6000 years ago, since when the rise has been much more gradual. Some research puts the rate of rise in the last 2000 years at 0.07mm/yr, and this reflects the fact that ice caps left over from the ice age are still melting, rather than that the world is warmer than before.

However, the impression is often given that, until the 20thC, this rate of rise has been pretty steady. This is despite the fact some of the authors of the above studies have warned of the existence of significant short-term fluctuations in sea level such that the sea level curve might oscillate up and down about this ~1 kyr mean state. [The above graph is based around 1000 year averages].

 

HH Lamb looked carefully at many expert studies in his day, and wrote about the very significant fluctuations they found. The following excerpts come from “Climate, History and the Modern World”:

1) The most rapid phases [of sea level rise] were between 8000 and 5000 BC, and that the rise of general water level was effectively over by about 2000 BC, when it may have stood a metre or two higher than today.

2) …

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https://commons.wikimedia.org/wiki/File:Holocene_Sea_Level.png

 

The Holocene Climate Optimum

by P. Homewood, August 19, 2018 in NotaLotofPeopleKnowThat


Booker commented the other day how one scientist claimed last week that we now have “the highest temperatures on Earth since the last ice age”. The BBC failed to even challenge this statement.

This certainly is not the first time I have heard claims (presented as fact) to this effect.

We have already seen concerted attempts to disappear the MWP, so it is time to reclaim the Holocene Optimum (so named for good reason), which is generally accepted to have run from about 9000 to 5000 years ago

Obviously we had no thermometers around in those days, so nobody knows what the average temperature of the Earth was then. There again, nobody really knows now either.

But there is plentiful evidence that many places were significantly warmer than now. I present some of this evidence below, though this is probably only skimming the surface: …

See also here

Evidence for the impact of the 8.2-kyBP climate event on Near Eastern early farmers

by M. Roffet-Salque et al., August 13, 2018


This study reveals that animal fats preserved in pottery vessels from the United Nations Educational, Scientific and Cultural Organization (UNESCO) World Heritage site of Çatalhöyük recorded the abrupt 8.2-thousand years B.P. climatic event in their hydrogen isotopic compositions. In addition, significant changes are observed in the archaeology and faunal assemblage of the site, showing how the early farming community at Çatalhöyük had to adapt to climate change. Significantly, this contribution shows that individual biomolecules preserved in ancient animal fats can be used to reconstruct paleoclimate records and thus, provides a powerful tool for the detection of climatic events at well-dated onsite terrestrial locations (i.e., at the very settlements where human populations lived).

How the Little Ice Age affected South American climate

by Fundação de Amparo à Pesquisa do Estado de São Paulo, July 24, 2018 in ScienceDaily


A new study published in Geophysical Research Journal shows that the so-called Little Ice Age — a period stretching from 1500 to 1850 in which mean temperatures in the northern hemisphere were considerably lower than at present — exerted effects on the climate of South America.

Based on an analysis of speleothems (cave formations) in the Brazilian states of Mato Grosso do Sul and Goiás, the study revealed that in the seventeenth and eighteenth centuries, the climate of southwestern Brazil was wetter than it is now, for example, while that of the country’s Northeast region was drier.

The same Brazilian cave records showed that the climate was drier in Brazil between 900 and 1100, during a period known as the Medieval Climate Anomaly (MCA), when the northern hemisphere’s climate was warmer than it is now.

 

Study: abrupt shifts occurred in the ancient European climate

by A. Watts, July 23, 2018 in WUWT and NatureCommunications


From the University of Helsinki and the “no SUV’s needed” department comes this study which suggests big cold snaps occurred right in the middle of the warm Eemian period. My only concern is perhaps they over-rely on climate models. For reference (and not part of the study) here’s the Eemian graph in context. Data sources listed int he graph.

New Science Affirms Arctic Region Was 6°C Warmer Than Now 9000 Years Ago, When CO2 Levels Were ‘Safe’

by K. Richard, July 12, 2018 in NoTricksZone


Unearthed new evidence (Mangerud and Svendsen, 2018) reveals that during the Early Holocene, when CO2 concentrations hovered around 260 ppm, “warmth-demanding species” were living in locations 1,000 km farther north of where they exist today in Arctic Svalbard, indicating that summer temperatures must have been about “6°C warmer than at present”.

Proxy evidence from two other new papers suggests Svalbard’s Hinlopen Strait  may have reached about 5 – 9°C warmer than 1955-2012 during the Early Holocene (Bartels et al., 2018), and Greenland may have been “4.0 to 7.0 °C warmer than modern [1952-2014]” between 10,000 and 8,000 years ago according to evidence found in rock formations at the bottom of ancient lakes (McFarlin et al., 2018).

In these 3 new papers, none of the scientists connect the “pronounced” and “exceptional” Early Holocene warmth to CO2 concentrations.

New Holocene geological subdivisions. The Anthropocene nowhere to be found.

by Javier, July 9, 2018 in WUWT


The International Commission on Stratigraphy (ICS) has announced that the proposal by the International Subcommission on Quaternary Stratigraphy (ISQS) for the subdivision of the Holocene Series/Epoch has been ratified unanimously by the International Union of Geological Sciences (IUGS).

(…)

 

nb:  ‘No Christiana, the geologists do not think the Anthropocene is a concept worthy of consideration, and you should be better informed.’

Friday Funny- Welcome to the Anthropocene Narcisscene

by Mark Sagoff, June 29, 2018 in WUWT


In view of the glacial pace of geologic events and the time it takes for things to turn into rock or become encased in it, you might think there would be no hurry to name a new geologic epoch, especially because the current one, the Holocene, started only about 11,500 years ago. You would be wrong. In 2002, Crutzen published an article in Nature magazine, “Geology of Mankind,” which called on geologists “to assign the term ‘Anthropocene’ to the present, in many ways human-dominated, geological epoch, supplementing the Holocene — the warm period of the past 10–12 millennia” and the beginning of which roughly coincided with the advent of human agriculture.The idea of the Anthropocene, which Earth system scientists initiated and advocated, landed like a meteor, setting off a stampede among academics. Nature followed with an editorial that urged that the Anthropocene be added to the geologic timescale. “The first step is to recognize,” Nature editorialized, “that we are in the driver’s seat.”

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Scientists Find Sun-Driven Temperature Changes Led CO2 Changes By 1300-6500 Years In The Ancient Past

by Kenneth Richard, June 7, 2018 in NoTricksZone


It has long been established in the scientific literature (and affirmed by the IPCC) that CO2 concentration changes followed Antarctic temperature changes by about 600 to 1000 years during glacial-interglacial transitions throughout the last ~800,000 years (Fischer et al., 1999Monnin et al., 2001Caillon et al., 2003Stott et al., 2007Kawamura et al., 2007).
In contrast, two new papers cite evidence that the timing of the lagged CO2 response to temperature changes may have ranged between 1300 and 6500 years in some cases.  It would appear that a millennial-scale lagged response to temperature undermines the claim that CO2 concentration changes were a driver of climate in the ancient past.

New Scientific Evidence Robustly Affirms Scandinavian Temperatures Were 3-4°C Warmer 9000 Years Ago

by K. Richard, May 31, 2018 in NoTricksZone

Because trees may only grow within narrowly-defined temperature ranges and elevations above sea level, perhaps the most reliable means of assessing the air temperatures of past climates is to collect ancient treeline evidence.  In a new paper, Kullman (2018) found tree remnants at mountain sites 600 to 700 meters north of where the modern treeline ends, strongly implying Early Holocene air temperatures in northern Sweden were 3-4°C warmer than recent decades.

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Changes in the Rate of Sea Level Rise

by Willis Eschenbach, May 22, 2018 in WUWT


There’s been some discussion of the rate of sea level rise lately, so I thought I’d take a look at some underlying data.

I started with a 2016 paper by the modern master of failed serial doomcasting, James Hansen. It has the frightening title of Ice melt, sea level rise and superstorms: evidence from paleoclimate data, climate modeling, and modern observations that 2°C global warming could be dangerous… yikes! Be very afraid!

In Figure 29 of that paper, Hansen claims to show that sea level rise has been accelerating, from 0.6 mm/year from 1900 to 1930, to 1.4 mm/year from 1930 to 1992, and 2.6 mm/year from 1993 to 2015.

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Solar activity over nine millennia: A consistent multi-proxy reconstruction

by C.J. Wu et al., April 5, 2018 in Astronomy&Astrophysics


.pdf (13 pages)

The solar activity in the past millennia can only be reconstructed from cosmogenic radionuclide proxy records in terrestrial archives. However, because of the diversity of the proxy archives, it is difficult to build a homogeneous reconstruction. All previous studies were based on individual, sometimes statistically averaged, proxy datasets. Here we aim to provide a new consistent multi- proxy reconstruction of the solar activity over the last 9000 years, using all available long-span datasets of 10Be and 14C in terrestrial archives.

Another New Paper Shows Arctic Sea Ice Has Been INCREASING Overall Since The 1930s

by K.  Richard, March 1, 2018 in NoTricksZone


In his seminal 1982 book Climate, History, and the Modern World, the renown climatologist Dr. H.H. Lamb revealed that sea ice in the subarctic and Arctic regions was much less extensive during the Medieval Warm Period (9th-13th centuries) compared to today.

For example, records indicate that there were decadal and centennial-scale periods without any sea ice invading any of Iceland’s coasts.  These no-ice periods coincided with atmospheric CO2 concentrations of 275 ppm, which is about 130 ppm less than today’s calculated CO2 values.

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