Is Global Warming becoming unstoppable?

[basilio]

Just how unstable is the massive Thwaites glacier? Scientists are about to find out.
PRI's The World

May 01, 2018 · 7:45 AM EDT

By Carolyn Beeler
US and British scientific agencies announced their biggest joint Antarctic research effort in more than a generation on Monday.

The focus is Thwaites Glacier, which is roughly the size of Florida and sits on the western edge of Antarctica.

Ice melting on Thwaites accounts for 4 percent of global sea level rise, an amount that’s nearly doubled since the 1990s. Scientists in the new five-year research collaboration hope to determine how much more, and how fast, the glacier will melt as the world continues to warm.

...“Really the whole program is about understanding that extra uncertainty attached to sea level rise and doing what we can to remove it, allowing people to protect their coastal environments and to prepare property to protect their populations,” said David Vaughan, director of Science at British Antarctic Survey, at a press conference announcing the research in Cambridge, England on Monday.

https://www.pri.org/stories/2018-05...hwaites-glacier-scientists-are-about-find-out

 

[basilio]

This story is almost 3 years old. It examines the range of research that glaciologists had done on the causes and rate of melting around the Thwaites glacier.

Two Antarctic ice shelves on the verge of collapsing—the Pine Island Glacier (shown) and the Thwaites Glacier—will cause the ultimate collapse of the entire West Antarctic Ice Sheet, a new study shows.

NASA/Maria-José Viñas
Just a nudge could collapse West Antarctic Ice Sheet, raise sea levels 3 meters
By Carolyn GramlingNov. 2, 2015 , 3:00 PM

It won’t take much to cause the entire West Antarctic Ice Sheet to collapse—and once it starts, it won’t stop. In the last year, a slew of papers has highlighted the vulnerability of the ice sheet covering the western half of the continent, suggesting that its downfall is inevitable—and probably already underway. Now, a new model shows just how this juggernaut could unfold. A relatively small amount of melting over a few decades, the authors say, will inexorably lead to the destabilization of the entire ice sheet and the rise of global sea levels by as much as 3 meters.

Previous models have examined the onset of the collapse in detail. In 2014, two papers, one in Science and one in Geophysical Review Letters, noted that the Thwaites Glacier, which some scientists call the “weak underbelly” of the West Antarctic Ice Sheet, has retreated dramatically over the past 2 decades. Most Antarctic researchers chalk this up to warm seawater melting the floating ice shelves at their bases; seawater temperatures there have risen since the 1970s, in part because of global temperature increases. Right now, an underwater ledge is helping anchor the glacier in place. But when the glacier retreats past that bulwark, it will collapse into the ocean; then seawater will intrude and melt channels into the ice sheet, setting the juggernaut in motion.

http://www.sciencemag.org/news/2015...antarctic-ice-sheet-raise-sea-levels-3-meters

 

[cynic]

This story is almost 3 years old. It examines the range of research that glaciologists had done on the causes and rate of melting around the Thwaites glacier.

Two Antarctic ice shelves on the verge of collapsing—the Pine Island Glacier (shown) and the Thwaites Glacier—will cause the ultimate collapse of the entire West Antarctic Ice Sheet, a new study shows.

NASA/Maria-José Viñas
Just a nudge could collapse West Antarctic Ice Sheet, raise sea levels 3 meters
By Carolyn GramlingNov. 2, 2015 , 3:00 PM

It won’t take much to cause the entire West Antarctic Ice Sheet to collapse—and once it starts, it won’t stop. In the last year, a slew of papers has highlighted the vulnerability of the ice sheet covering the western half of the continent, suggesting that its downfall is inevitable—and probably already underway. Now, a new model shows just how this juggernaut could unfold. A relatively small amount of melting over a few decades, the authors say, will inexorably lead to the destabilization of the entire ice sheet and the rise of global sea levels by as much as 3 meters.

Previous models have examined the onset of the collapse in detail. In 2014, two papers, one in Science and one in Geophysical Review Letters, noted that the Thwaites Glacier, which some scientists call the “weak underbelly” of the West Antarctic Ice Sheet, has retreated dramatically over the past 2 decades. Most Antarctic researchers chalk this up to warm seawater melting the floating ice shelves at their bases; seawater temperatures there have risen since the 1970s, in part because of global temperature increases. Right now, an underwater ledge is helping anchor the glacier in place. But when the glacier retreats past that bulwark, it will collapse into the ocean; then seawater will intrude and melt channels into the ice sheet, setting the juggernaut in motion.

http://www.sciencemag.org/news/2015...antarctic-ice-sheet-raise-sea-levels-3-meters

Basilio, when conducting their research, are these scientists disrupting the structure of these ice formations in any way?
( I.e drilling into them or cutting out pieces of them etc.)

If they care so much, then maybe they should desist from meddling.
Consecutive armies of researchers, taking core sample after core sample, cannot be a good thing (even a behemoth may be totally consumed by a sufficiently large quantity of small bites).

Climate catastrophists could easily be to blame for at least some of the perceived diminution of the antarctic.

 

[cynic]

What the.... ?

How duplicitous can you people get? The reasearch shows that those such as yourself are doing nothing at all, quite the opposite, soothing your grotesque hypocrisy with consicious consumption, large centrally heated and air conditioned homes, and holiday apartments on the other side of the world.

All the while lecturing us who are either doubtful or moderate beliefs to do something... WHEN WE ARE DOING MORE FOR THE ENVIRONMENT THAN YOU!!!

Then you further console yourselves as being "messengers" making you exempt.

How ****ing obscene!

There is however, one notable exception to be found amidst the catastrophe credulists participating in this thread. Unlike so many others, he has actually put his religion into practice and truly walks the walk. If only the others would follow his example and spend more of their talking time walking instead.
Perhaps then, their vocal message/s wouldn't get so thoroughly undermined by the betrayals of their actions.

 

[wayneL]

There is however, one notable exception to be found amidst the catastrophe credulists participating in this thread. Unlike so many others, he has actually put his religion into practice and truly walks the walk. If only the others would follow his example and spend more of their talking time walking instead.
Perhaps then, their vocal message/s wouldn't get so thoroughly undermined by the betrayals of their actions.

Yes agreed, he has integrity and I give him kudos for that.

 

[wayneL]

There is however, one notable exception to be found amidst the catastrophe credulists participating in this thread. Unlike so many others, he has actually put his religion into practice and truly walks the walk. If only the others would follow his example and spend more of their talking time walking instead.
Perhaps then, their vocal message/s wouldn't get so thoroughly undermined by the betrayals of their actions.

Yes agreed, he has integrity and I give him kudos for that.

 

[basilio]

Basilio, when conducting their research, are these scientists disrupting the structure of these ice formations in any way?
( I.e drilling into them or cutting out pieces of them etc.)

If they care so much, then maybe they should desist from meddling.
Consecutive armies of researchers, taking core sample after core sample, cannot be a good thing (even a behemoth may be totally consumed by a sufficiently large quantity of small bites).

Climate catastrophists could easily be to blame for at least some of the perceived diminution of the antarctic.

Cynic could you please try and find some sense of proportion when you respond to these questions. This is just rubbish and only diminishes anything else you care to say on the subject.

What ever 8 inch ice drills are made to ascertain what has happened in the ice caps will have absolutely no impact versus the oceans of warm water melting out the underside of the glacier.

At the last point of examination an area the size of Greater London had melted as a result of the ingress of warmer waters.

 

[basilio]

Yes agreed, he has integrity and I give him kudos for that.

Thanks for that wayne. Much appreciated...

I didn't realise you were so aware of my wideranging environmental good works and modest ecological footprint.

Now have you had an opportunity to consider the integrity of the glaciologists who are all over the Thwaites glacier situation and their concerns?

 

[cynic]

Cynic could you please try and find some sense of proportion when you respond to these questions. This is just rubbish and only diminishes anything else you care to say on the subject.

What ever 8 inch ice drills are made to ascertain what has happened in the ice caps will have absolutely no impact versus the oceans of warm water melting out the underside of the glacier.

At the last point of examination an area the size of Greater London had melted as a result of the ingress of warmer waters.

Sense of proportion! What qualifies you to accuse others of lacking a sense of proportion!!
Oh I know! You clearly subscribe to the "it takes one to know one!" philosophy.

 

[Sdajii]

You are referring to the ice age.
This is quite a different scenario.

I'm not referring to 'the' ice age (there have been many, they happen all the time, for various reasons). I'm referring to more events than can be counted over billions of years including not just the cold periods but also hotter periods than we're currently experiencing. Even in very recent (just a few thousand years, and more than a small few climate scientists believe a few hundred years - the debate among climate scientists is whether the last time was about 500 or 5,000 years, but effectively none say longer than that) times, the climate was warmer than it is now. 5,000 years is like a couple of minutes ago in terms of the global climate fluctuations. Over the last 100,000 years we've seen quite a number of dramatic fluctations. A bit over 100,000 years ago (before anyone saying humans were having any impact at all, around the time people say humans were first becoming human, there was a really severely hot period in which there was mass extinction across Australia, species became extinct and new species began to evolve. My honours year at university involved studying a couple of these species and looking at how climate interacted with their creation and spread, and how future climate change would affect them and other species.

Looking further back than 100,000 years there are many tremendous fluctuations both high and low, although it becomes very difficult for us to identify the severe short term fluctuations (no doubt at all they were occurring but we weren't there to take detailed measurements) and we can only see the overall trends, and even they fluctuate wildly, and outside the current range including hotter, and during those periods where the world was hotter for long periods of time there couldn't possibly have been an absence of brief fluctuations in both directions. The brief hot periods during those large hot periods would have been completely brutal, and then, the world cooled, and heated, and so on. Looking at the range of climate states the world has been in over the last billion years, or few hundred million years, or few million years (take your pick), the current climate is actually extremely favourable for us, and choosing between getting a bit hotter or going to the average level we see, a bit hotter and wetter is more favourable (you get more living things overall when it's warm, you can grow more crops more quickly, etc).

I like the old vegetable farms in Europe where people were actually growing stuff, you can still see the vegie garden beds if you go there today, people were farming stuff, it's less than a thousand years old, and today it's far too cold to grow the stuff they were growing there. But, apparently, according to social media and sometimes mainstream media, it's now the hottest it has ever been!

I am not talking about one ice age.

 

[luutzu]

Basilio, when conducting their research, are these scientists disrupting the structure of these ice formations in any way?
( I.e drilling into them or cutting out pieces of them etc.)

If they care so much, then maybe they should desist from meddling.
Consecutive armies of researchers, taking core sample after core sample, cannot be a good thing (even a behemoth may be totally consumed by a sufficiently large quantity of small bites).

Climate catastrophists could easily be to blame for at least some of the perceived diminution of the antarctic.

I thought human cannot possibly have any impact on the environment.

 

[Knobby22]

I'm not referring to 'the' ice age (there have been many, they happen all the time, for various reasons). I'm referring to more events than can be counted over billions of years including not just the cold periods but also hotter periods than we're currently experiencing. Even in very recent (just a few thousand years, and more than a small few climate scientists believe a few hundred years - the debate among climate scientists is whether the last time was about 500 or 5,000 years, but effectively none say longer than that) times, the climate was warmer than it is now. 5,000 years is like a couple of minutes ago in terms of the global climate fluctuations. Over the last 100,000 years we've seen quite a number of dramatic fluctations. A bit over 100,000 years ago (before anyone saying humans were having any impact at all, around the time people say humans were first becoming human, there was a really severely hot period in which there was mass extinction across Australia, species became extinct and new species began to evolve. My honours year at university involved studying a couple of these species and looking at how climate interacted with their creation and spread, and how future climate change would affect them and other species.

Looking further back than 100,000 years there are many tremendous fluctuations both high and low, although it becomes very difficult for us to identify the severe short term fluctuations (no doubt at all they were occurring but we weren't there to take detailed measurements) and we can only see the overall trends, and even they fluctuate wildly, and outside the current range including hotter, and during those periods where the world was hotter for long periods of time there couldn't possibly have been an absence of brief fluctuations in both directions. The brief hot periods during those large hot periods would have been completely brutal, and then, the world cooled, and heated, and so on. Looking at the range of climate states the world has been in over the last billion years, or few hundred million years, or few million years (take your pick), the current climate is actually extremely favourable for us, and choosing between getting a bit hotter or going to the average level we see, a bit hotter and wetter is more favourable (you get more living things overall when it's warm, you can grow more crops more quickly, etc).

I like the old vegetable farms in Europe where people were actually growing stuff, you can still see the vegie garden beds if you go there today, people were farming stuff, it's less than a thousand years old, and today it's far too cold to grow the stuff they were growing there. But, apparently, according to social media and sometimes mainstream media, it's now the hottest it has ever been!

I am not talking about one ice age.

I am sure you are aware that the latest research shows it was the effects of humans that wiped out the large animals in Australia (as occurred in Europe and Asia). The giant kangaroo, diprotodon, giant wombat, etc. all existed 40,000 years ago though gradual climate change of Australia moving towards India exacerbated this.

I agree the current climate is favourable for us but getting hotter will have adverse effects, especially with the effects of carbon dioxide acidifying the oceans. Of course there have been periods where life on earth has been severely disrupted over previous billions of years including the iceball earth period and the big die offs for various reasons. We have only really been around 150,000 years.

Of course we could create our own big die off, it could be argued we are succeeding at this without global warming but it is obvious that global warming is happening quite rapidly and if we don't modify our behaviour it will continue increasing for hundreds of years. The effect will be to cause a massive die off and make some areas such as the tropics unliveable. Of course you are right, some regions might be better off such as Canada and Siberia but other areas will suffer greatly and our many coastal cities will be in great danger due to rising sea levels.

So what is the argument for doing nothing and letting it happen, does it effect the profits of the Koch brothers too much?

 

[Sdajii]

I am sure you are aware that the latest research shows it was the effects of humans that wiped out the large animals in Australia (as occurred in Europe and Asia). The giant kangaroo, diprotodon, giant wombat, etc. all existed 40,000 years ago though gradual climate change of Australia moving towards India exacerbated this.

I agree the current climate is favourable for us but getting hotter will have adverse effects, especially with the effects of carbon dioxide acidifying the oceans. Of course there have been periods where life on earth has been severely disrupted over previous billions of years including the iceball earth period and the big die offs for various reasons. We have only really been around 150,000 years.

Of course we could create our own big die off, it could be argued we are succeeding at this without global warming but it is obvious that global warming is happening quite rapidly and if we don't modify our behaviour it will continue increasing for hundreds of years. The effect will be to cause a massive die off and make some areas such as the tropics unliveable. Of course you are right, some regions might be better off such as Canada and Siberia but other areas will suffer greatly and our many coastal cities will be in great danger due to rising sea levels.

So what is the argument for doing nothing and letting it happen, does it effect the profits of the Koch brothers too much?

I am indeed well aware of the huge extinction event which wiped out the Australian megafauna tens of thousands of years ago, though it's laughable to suggest climate change did it. It existed in Australia for many millions of years through all sorts of climatic fluctuations, then died out when the climate wasn't doing anything out of the ordinary relative to what it had experienced and lived through for that massive amount of time, but suddenly the aboriginals (which weren't aboriginal at the time I suppose) arrived and wiped them all out, partly by burning down forests, but mostly by hunting them to extinction, and partly by introducing dingos which outcompeted them (and directly wiped out some of the smaller species too). At no stage during hominid occupation of Australia did the climate come anywhere near making it outside natural extremes. It is still yet to do so. Those extinct species already survived greater climatic extremes with no trouble. Regularly. For millions of years.

Indeed, climate change does change the places which are better and worse off. This has always been the case.

I never said environmentalism is a worthless pursuit. I am simply addressing the question of this thread (check the title). The answer is a very big, clear 'no'. Most of what people say about climate change is garbage which any person with intelligence not too dramatically below average can easily see to be garbage if they are capable of looking with unbiased eyes and not being a slave to herd thinking. These second two are very difficult for most people. And I'm talking both about the alarmists and the 'climate deniers' (sic).

If we are to put an effort into environmentalism, which we currently are not other than token publicity stunts amounting to little more than nothing, we should do it rationally, in a way which would be effective. Even if we were to try to take the action the alarmists want we'd we wasting our efforts (as opposed to not bothering with efforts). Even if we do end up putting significant efforts into environmentalism, which is doubtful, I doubt it will be done in an effective way.

As a young fella I was very interested in helping the world. I became a scientist, I studied climate and biology, I worked as an ecologist. I realised any effort I put in would be wasted and threw it in, put my attention into the stock market and made a pile of money, and started full time travel. I'm still interested in analysing stuff, I still enjoy looking at the planet and seeing what is happening, predicting what will happen, laughing at how stupid the mainstream thinking is, and it doesn't take much analysis to see that there's nothing I can do to change anything, so I might as well just have fun

 

[cynic]

I thought human cannot possibly have any impact on the environment.

At last, you make a post consistent with your actions! Let's hope that this becomes a lasting and fashionable trend!

 

[wayneL]

Thanks for that wayne. Much appreciated...

I didn't realise you were so aware of my wideranging environmental good works and modest ecological footprint.

It is my belief we were referring to Plod

 

[cynic]

It is my belief we were referring to Plod

That was my belief also.

Could it be that a certain somebody else, mistook the meaning of the phrase "noteable exception" to be somehow synonymous with "notable example"?

 

[luutzu]

I am indeed well aware of the huge extinction event which wiped out the Australian megafauna tens of thousands of years ago, though it's laughable to suggest climate change did it. It existed in Australia for many millions of years through all sorts of climatic fluctuations, then died out when the climate wasn't doing anything out of the ordinary relative to what it had experienced and lived through for that massive amount of time, but suddenly the aboriginals (which weren't aboriginal at the time I suppose) arrived and wiped them all out, partly by burning down forests, but mostly by hunting them to extinction, and partly by introducing dingos which outcompeted them (and directly wiped out some of the smaller species too). At no stage during hominid occupation of Australia did the climate come anywhere near making it outside natural extremes. It is still yet to do so. Those extinct species already survived greater climatic extremes with no trouble. Regularly. For millions of years.

Indeed, climate change does change the places which are better and worse off. This has always been the case.

I never said environmentalism is a worthless pursuit. I am simply addressing the question of this thread (check the title). The answer is a very big, clear 'no'. Most of what people say about climate change is garbage which any person with intelligence not too dramatically below average can easily see to be garbage if they are capable of looking with unbiased eyes and not being a slave to herd thinking. These second two are very difficult for most people. And I'm talking both about the alarmists and the 'climate deniers' (sic).

If we are to put an effort into environmentalism, which we currently are not other than token publicity stunts amounting to little more than nothing, we should do it rationally, in a way which would be effective. Even if we were to try to take the action the alarmists want we'd we wasting our efforts (as opposed to not bothering with efforts). Even if we do end up putting significant efforts into environmentalism, which is doubtful, I doubt it will be done in an effective way.

As a young fella I was very interested in helping the world. I became a scientist, I studied climate and biology, I worked as an ecologist. I realised any effort I put in would be wasted and threw it in, put my attention into the stock market and made a pile of money, and started full time travel. I'm still interested in analysing stuff, I still enjoy looking at the planet and seeing what is happening, predicting what will happen, laughing at how stupid the mainstream thinking is, and it doesn't take much analysis to see that there's nothing I can do to change anything, so I might as well just have fun

The last three paragraphs can be summed up as "Meh, fark it. Make money and enjoy life."

And people accused me of being long winded.

The first paragraph... did you mean to say that with or without CC human would wipe out other species anyway?

Yea... I think we're currently extinct-ing about 1 specie per year for the past 100 years. Haven't seen rate of extinction since the dino goes bye bye.

But to the point, CC is not just about other species going extinct... possibly organised civil society as we know it.

I know, that sounds alarmist. But being alarmist does not make it untrue.

For example, what would happen if sea level rises and the Indonesians, a hundred million of them, need to get away from the shore line?

Nauru wouldn't fit them. And nuking or building a wall is probably out of the question.

 

[Sdajii]

The last three paragraphs can be summed up as "Meh, fark it. Make money and enjoy life."

And people accused me of being long winded.

The first paragraph... did you mean to say that with or without CC human would wipe out other species anyway?

Yea... I think we're currently extinct-ing about 1 specie per year for the past 100 years. Haven't seen rate of extinction since the dino goes bye bye.

But to the point, CC is not just about other species going extinct... possibly organised civil society as we know it.

I know, that sounds alarmist. But being alarmist does not make it untrue.

For example, what would happen if sea level rises and the Indonesians, a hundred million of them, need to get away from the shore line?

Nauru wouldn't fit them. And nuking or building a wall is probably out of the question.

Yes, climate change was irrelevant in the mass extinction caused by aboriginal Australians tens of thousands of years ago. People like to spread this nonsense myth that the aboriginals lived in harmony with the land, but their arrival saw a swift extinction of many species, at a time when the climate wasn't doing anything more interesting than it usually does, or had been doing for millions of years previously.

I think it's highly likely that 'organised civil society as we know it' ceases to exist. I think it probably will before 2045, and it will have nothing to do with climate change. I hope some of us survive beyond that and rebuild.

Sea levels naturally fluctuate as you describe. If humans had been exterminated 200,000 years ago, it still would have happened. It was happening before then, it has been happening over the last 200,000 years, and with or without humans, it will happen in the future (unless we get really really good at manipulating the climate and stopping it for the first time since sea levels existed). Yes, if it happens now for whatever reason, it will cause chaos. I think we have bigger problems coming much sooner anyway.

 

[luutzu]

Yes, climate change was irrelevant in the mass extinction caused by aboriginal Australians tens of thousands of years ago. People like to spread this nonsense myth that the aboriginals lived in harmony with the land, but their arrival saw a swift extinction of many species, at a time when the climate wasn't doing anything more interesting than it usually does, or had been doing for millions of years previously.

I think it's highly likely that 'organised civil society as we know it' ceases to exist. I think it probably will before 2045, and it will have nothing to do with climate change. I hope some of us survive beyond that and rebuild.

Sea levels naturally fluctuate as you describe. If humans had been exterminated 200,000 years ago, it still would have happened. It was happening before then, it has been happening over the last 200,000 years, and with or without humans, it will happen in the future (unless we get really really good at manipulating the climate and stopping it for the first time since sea levels existed). Yes, if it happens now for whatever reason, it will cause chaos. I think we have bigger problems coming much sooner anyway.

In That TEDx talk, the admiral was saying something like sea level rises over the last 200,000 years being an inch. In the last 200 years, it's a foot. Don't quote me on the exact figures but it's definitely not stable "like before".

I heard somewhere that the average, i.e. "normal", extinction rate is about 1 specie per 100 years. Natural selection and maybe aboriginal abuses.

AUstralian Aborigines have been on this continent for how long now? 50,000 years? So if we take that 1 specie going extinct per 100 years as being "normal" cycle of evolution... that's 500 species since the arrival and it'd still be normal.

 

[Sdajii]

In That TEDx talk, the admiral was saying something like sea level rises over the last 200,000 years being an inch. In the last 200 years, it's a foot. Don't quote me on the exact figures but it's definitely not stable "like before".

I heard somewhere that the average, i.e. "normal", extinction rate is about 1 specie per 100 years. Natural selection and maybe aboriginal abuses.

AUstralian Aborigines have been on this continent for how long now? 50,000 years? So if we take that 1 specie going extinct per 100 years as being "normal" cycle of evolution... that's 500 species since the arrival and it'd still be normal.

It's really amazing how much misinformation is out there on the alarmist side. More amazing is how blatantly wrong it is, and more amazing still is that people believe it.

Okay, on the sea level fluctuations, consider that many times, as a semi regular cycle with a period of a few thousand years (that is to say it happens every few thousand years, not tens of thousands or hundreds of thousands), the sea level fluctuates enough so that it forms land bridges between mainland Australia and PNG. Now, without looking it up, I'm willing to say Torres Strait is more than an inch deep. Your information is completely and utterly wrong. I've already pointed this out earlier in the thread. I'm not sure how you can say you think an inch over 200,000 years makes any sense when it literally fluctuates enough to create dry land between Australia and PNG. It happened many times over the last 200,000 years. It happened several times over the last few tens of thousands of years.

People argue about how long ago hominids invaded Australia, but I won't split hairs, let's say 50,000 years. As an ecologist by training, it's a little annoying when people talk about species extinctions as though they are all equivalent, and even ignoring that, they caused far more extinctions than have been counted. It's a lot easier to see some obscure little marsupial going extinct today than to observe that happening 50,000 years before anyone was cataloguing anything. But, even ignoring that, at the time hominids first stepped on to Australia (which was almost certainly a case of walking there rather than arriving by boat), there were giant lizards which made Komodo Dragons look small, snakes far, far larger than anything alive today, wombats the size of cars, marsupial wolves, giant kangaroos far larger than anything alive today, the world's only terrestrial crocodiles (crocodiles that didn't live in or near water), and many others. We know about these because they were big and obvious and if we find remains they're clearly different from anything else. These things went extinct in the blink of an eye right after aboriginals arrived, and shortly after, extinctions largely stopped until they brought in dingos and there was then another wave of extinctions. These days biologists constantly relabel every little population of species as separate species, so when one population goes extinct they say an entire species has gone extinct. If we were to apply the same rules and had the same observational abilities over the last 100,000 years the extinction rate would have been much higher. What exactly constitutes as a 'species' is very vague, and one species going extinct is not the same as another. It doesn't really relate to climate change and I'm not sure why you want to focus on this point, but aboriginals caused a massive extinction event when they arrived, and this happened at a time when no unusual climate activity was occurring. The background/base level extinction rate you're talking about is meaningless in this context, but even so, if we were able to measure things (or if we just look at what happened and take best estimates) it goes against what you are saying.