As Climate Worsens, a Cascade of Tipping Points Looms

Perfectly meaningless. The current Global warming started in the 1800’s.

 

And the globe cooled in the lia at constant CO2.

 

Did it?

Proof?

 

Did it?

Proof?

 

One has to consider all factors affecting global mean temperature changes but the rate of global mean surface temperature change has been around 0.17 degrees C. per decade since 1970. The changes in ocean heat content which is part of the
climate system and accounts for more than 90% of the energy absorbed due to the earth's planetary energy imbalance must also be considered.

 

So? That proves nothing.

 

Yes it did.

 

Yes it did.

 

You claim that the corrupt temperature data sets can be used to accurately resolve a global average temperature change of 0.17 degrees Centigrade per decade in the last 50 years ??? What are the +/- error bands on that 0.17 degrees Centigrade difference ???

 

https://www.bbc.com/news/science-environment-16797075 From BBC.com "Volcanic Origin of the Little ice Age"

The Little Ice Age was caused by the cooling effect of massive volcanic eruptions, and sustained by changes in Arctic ice cover, scientists conclude.

An international research team studied ancient plants from Iceland and Canada, and sediments carried by glaciers.

They say a series of eruptions just before 1300 lowered Arctic temperatures enough for ice sheets to expand.

Writing in Geophysical Research Letters, they say this would have kept the Earth cool for centuries.

What caused it has been uncertain. The new study, led by Gifford Miller at the University of Colorado at Boulder, US, links back to a series of four explosive volcanic eruptions between about 1250 and 1300 in the tropics, which would have blasted huge clouds of sulphate particles into the upper atmosphere.


Putting these records together showed that cooling began fairly abruptly at some point between 1250 and 1300. Temperatures fell another notch between 1430 and 1455.

The first of these periods saw four large volcanic eruptions beginning in 1256, probably from the tropics sources, although the exact locations have not been determined.

The later period incorporated the major Kuwae eruption in Vanuatu.

Aerosols from volcanic eruptions usually cool the climate for just a few years.

When the researchers plugged in the sequence of eruptions into a computer model of climate, they found that the short but intense burst of cooling was enough to initiate growth of summer ice sheets around the Arctic Ocean, as well as glaciers.

The extra ice in turn reflected more solar radiation back into space, and weakened the Atlantic ocean circulation commonly known as the Gulf Stream.

"It's easy to calculate how much colder you could get with volcanoes; but that has no permanence, the skies soon clear," Dr Miller told BBC News.

"And it was climate modelling that showed how sea ice exports into the North Atlantic set up this self-sustaining feedback process, and that's how a perturbation of decades can result in a climate shift of centuries."

Analysis of the later phase of the Little Ice Age also suggests that changes in the Sun's output, particularly in the ultraviolet part of the spectrum, would also have contributed cooling.

 

You claim that volcanic activity cooled the earth for centuries ??? Amazing.

 

Volcanos have a very short term effect.

 

Exactly.

 

Proof?

 

Mike is not making the claim the scientists who published that research he quoted are making that supported claim but not as you assert it

Now how about you critique the paper and tell us where they are wrong but then since your response was not in keeping with the paper cited it appears you did not read that paper

 

I am done responding to you.

Ditto. And you know why.

 

you claim the temperature datasets are corrupt How many are “corrupt” What percentage of the total? Which datasets in what country? Is this an ongoing issue or has an anomaly been resolved?

 

That is true most of the time but not all of the time. This article describes how volcanic eruptions increased the growth of Arctic sea ice which prolonged the initial cooling effect of several

very large volcanic eruptions.

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2011GL050168

Geophysical Research Letters
Abrupt onset of the Little Ice Age triggered by volcanism and sustained by sea‐ice/ocean feedbacks

Abstract
[1] Northern Hemisphere summer temperatures over the past 8000 years have been paced by the slow decrease in summer insolation resulting from the precession of the equinoxes. However, the causes of superposed century‐scale cold summer anomalies, of which the Little Ice Age (LIA) is the most extreme, remain debated, largely because the natural forcings are either weak or, in the case of volcanism, short lived. Here we present precisely dated records of ice‐cap growth from Arctic Canada and Iceland showing that LIA summer cold and ice growth began abruptly between 1275 and 1300 AD, followed by a substantial intensification 1430–1455 AD. Intervals of sudden ice growth coincide with two of the most volcanically perturbed half centuries of the past millennium. A transient climate model simulation shows that explosive volcanism produces abrupt summer cooling at these times, and that cold summers can be maintained by sea‐ice/ocean feedbacks long after volcanic aerosols are removed. Our results suggest that the onset of the LIA can be linked to an unusual 50‐year‐long episode with four large sulfur‐rich explosive eruptions, each with global sulfate loading >60 Tg. The persistence of cold summers is best explained by consequent sea‐ice/ocean feedbacks during a hemispheric summer insolation minimum; large changes in solar irradiance are not required.


a) Total solar irradiance (VSK [Schmidt et al., 2011]). (b) Global stratospheric sulfate aerosol loadings [Gao et al., 2008]. (c) Ice cap expansion dates based on a composite of 94 Arctic Canada calibrated 14C PDFs. (d) 30‐year running mean varve thickness in Hvítárvatn sediment core HVT03‐2 [Larsen et al., 2011]. (e) Arctic Ocean sea ice recorded in a sediment core on the north Iceland shelf [Massé et al., 2008]; heavy sea ice years correlate with anomalously cold summers across Iceland. (f) Temperature anomalies over southern Greenland (wrt 1881–1980 AD mean) from the borehole temperature inversion at DYE‐3 [Dahl‐Jensen et al., 1998].

 

The past changes every iteration. Should give you a clue.

 

Iceland has 4 major eruptions every century. That’s been the pattern for centuries. And yet there were no glaciers in Iceland in the Medieval Warm Period when volcanic activity was normal for Iceland.

 

Correction. Iceland has a volcanic eruption every ~ 4 years.

 

Proof?

 

Proof?

At some time mate you have to link to something valid

 

Again - where are you getting this information?

This book that you keep alluding to must be very very comprehensive to have such a diverse range of information

 

I don't have any evidence that Iceland's eruptions during the Medieval Warm Period were significant enough to affect the climate like the eruptions that occurred during the Little Ice Age. I don't
see any major volcanic eruptions during the MWP shown in the graph below from https://www.nap.edu/read/11676/chapter/13#103, Temperature Reconstruction for the Last 2000 Years ,Ch. 10.
The text below is from the same source.


FIGURE 10-3 Ice core estimates of global stratospheric sulfate loading from volcanoes (A.D. 1–2005). SOURCE: T. Crowley, Duke University, 2006, unpublished material. Reprinted with permission; copyright 2006.

The radiative effect of a volcanic eruption depends on its magnitude and location, the time of year, the vertical orientation of the eruption, and the types and sizes of the ejecta (Robock 2000). Explosive volcanic eruptions add large amounts of ash and sulfur gases to the atmosphere, which diminish the amount of solar radiation reaching the surface, thereby cooling the Earth. Larger ash particles settle rapidly to the surface and generally only cool the surface temperature over a small region for several days to a few weeks. The sulfur gases combine with water vapor to form sulfate aerosols. In large explosive eruptions, the smaller sulfate aerosols are injected high into the atmosphere where they remain for up to several years. Sulfate aerosols from tropical eruptions are transported globally by high-altitude winds, whereas sulfate aerosols from high-latitude eruptions are more spatially restricted and have less effect on global temperature. Although large eruptions can lead to significant cooling immediately after the eruption, such as “the year without a summer” after the 1815 eruption of Mount Tambora in Indonesia, the effect is isolated to a few years. Accumulation of sulfate aerosols from several volcanoes closely spaced in time can lead to more extended global cooling.

Reconstructions of volcanic activity over the last two millennia all distinguish the large eruptions of 1258 or 1259, 1453, and 1815, along with periods of more active volcanism in the late 13th century, the 17th century, and the early 19th century, although the various reconstructions differ with respect to some of the details