Human-induced climate change will affect humans on the timescales of tens, to hundreds, to thousands of years. It will affect us and our children and their children, as it is already affecting us (deadly heatwaves in India, more powerful storms, etc).

What the planet does in three million years time is not a problem that any of us has to think about- we as a species are not anywhere near that old.

Saying there is no point keeping the Earth's climate stable today because 3 million years ago it was warm is like claiming there's no point in bothering shovelling the snow off your drive in December because you know in four months it might thaw out on its own. You might well be right, but in the meantime you're going to go very hungry for four months, and you won't be able to get to work.. Isn't it better to take action to change the things you can control rather than irrationally find excuses not to do anything about it?

This study does absolutely no such thing. Its topic wasn't even related to showing climate cycles- the subject of the paper is looking at the effect on CO2 of ice sheets scraping soil and weathered rock off the Earth's surface over ice ages.

CO2 rise and warming that is happening now is entirely something that we have caused (see here for some helpful pointers: https://skepticalscience.com/empirical-evidence-for-co2-enhanced-greenhouse-effect-basic.htm). We can control our CO2 release, and so we can control our current rate of warming. What the background conditions do over millions of years is not the point, and is only used in this article as a distraction.

This is not anti-science. It is the position of almost every scientist in this field. It is rather rich for an article such as this to call anything else anti-science, given their refusal to engage with scientific papers or facts in any way.

The 12-year figure quoted comes from the 2018 UN “Special Report on Global warming of 1.5ºC,” released last October. In this report, the year 2030 — 12 years from now — is given as the 'point of no return', if we keep releasing CO2 at our current rate. What this means is that after this point, it is almost impossible to imagine how CO2 in the atmosphere could ever be brought back down to levels needed to keep global temperatures less than 1.5 ˚C warmer. This figure comes from the IPCC report scientists- hundreds of scientists from different fields working all around the world.

The article has taken this figure out of context, and is comparing it to something very different. What ThinkProgress says is related to the timescales it takes for the maximum effects of the CO2 released now to take hold. This is not in conflict with the IPCC figure of 12 years cited by AOC- this report talks about the year we must stop releasing CO2 by in order for the long term knock on effects of this CO2 release to not be so detrimental to humankind.

This study does no such thing. This is factually incorrect.

Again, this is possible because at various times in the Earth's history, sources and sinks of CO2 into the atmosphere have had varying strengths. These are natural changes in CO2 levels that have slowly happened for 100s of millions of years. However, modern CO2 rise is faster than any rise ever seen in the last 66 million years (https://www.nature.com/articles/ngeo2681) and quite possibly ever before in the geological record.

It is possible because CO2 sources (e.g. volcanic degassing) and CO2 sinks (e.g. from chemical weathering of the Earth's surface) were differently balanced back then. It is not a mystery, it is well understood science that has countless papers about it, and a serious journalist (if they profess to be one) would have made some effort to educate themselves before writing such an article.

What this study tells us is that the last time CO2 was as high as 410ppm (back then through natural causes), there was no ice on Greenland or West Antarctica. What this means is that we can potentially expect (once the climate has equilibrated to its new CO2 levels) that these ice bodies will melt in the future from anthropogenic CO2 release. If this happens, the sea level will rise by metres, and many coastal and lowland cities will be affected.

In a way I have to profess my admiration- how a news outlet could take a paper presenting evidence that we should be very worried about CO2 being 410ppm, and turns it into a paper that 'debunks climate change', is beyond me. It really is a feat that must have taken a lot of imagination and creative thinking.

This wasn't a period of global warming, as we might know today. It was the steady level of climate and CO2 at this time.

We are well aware that there are climatic fluctuations through geological time. Huge numbers of scientists study how the Earth's climate has fluctuated before, and we know what caused those changes. Current warming is not related to any natural climate cycle, or process, or astronomic phenomenon.

Again, there being a time in the past where CO2 was steadily higher than today is not related to human CO2 input today. It's like saying because much of the Netherlands was above sea level before, then that somehow disproves the fact that the Netherlands is reclaiming land from the sea today. This is irrational and illogical.

The author writes this as if this is something that is a surprise. We all know that the Earth's CO2 levels were higher at various times in the past. In the Eocene, 50 million years ago, they may have even been four times as high. This is not an issue. In the past, rates of volcanic CO2 emissions globally were higher as continental spreading rates changed, for example. Saying that CO2 isn't rising now due to humans just because it used to be high in the past is like saying "I didn't chop the cherry tree down because 40 years ago there was never a cherry tree there". It is totally unrelated.

This is factually incorrect.

not probably- definitely

This assumes a very high climate sensitivity compared to most IPCC-class models. Can the authors give a source for where they got this estimate? It appears to be a quote from the previous link, which itself has no reference either. Most estimates tend to fall around 3 ˚C/doubling, and 550 is ~1 doubling of CO2 vs. pre-industrial of 280ppm. So that would suggest ~3˚C total, of which maybe 1 ˚C has already happened. Maybe one saving grace here is that 550 ppm is perhaps one of the more conservative estimates for the end of the century.

It's probably fair to say that there remain a few disagreements, but the community is largely moving toward acceptance that the Pliocene was likely around this high (see e.g. www.p-co2.org). Nothing really strictly wrong with this passage, although I think most would agree the Pliocene is more likely than the Miocene.

This is perhaps over-stated here. The study that the writer is citing studied behaviour in an office environment at 600, 1000, and 2,500 ppm. The prospect of 2,500 ppm CO2 in the atmosphere is, I would hope, quite some way off (it is beyond the vast majority of projections for 2100 for example).. so this seems a little excessive here. If CO2 gets to 2,500ppm, I'm pretty certain it's not going to be the reduced performance in decision-making performance that kills us!

Or use other temperature proxies to compare with the oxygen isotope data to see if they are consistent- which is what has been done for years.

It doesn't just change over time anyway.. Firstly, we are talking about the isotope ratio of oxygen, not the amount. Secondly, the authors show evidence that in some depositional settings this sort of 'resetting' of temperatures could occur. By over-simplifying here the author of the article loses and obscures the original study.

Again, this is incorrect.

This is a huge overstatement. It in fact means that some paleotemperature estimates made up to now may be incorrect. An interesting finding, but being over-stated in the extreme.

There is not enough information here.. This research specifically only showed that they could change when heated to 300˚C. By not saying what the circumstances are under which the temperature estimates can be altered, the article throws undue doubt on what is in most settings (despite what the authors of the study seem to be suggesting) pretty robust.

Again, it's nothing to do with the amount of Oxygen. It's CaCO3, so oxygen content is pretty much fixed- it's the isotopic ratio of the oxygen that is incorporated.

It is not the 'oxygen content' (which means more or less oxygen) but the isotope ratio of the oxygen.

This is only one way that scientists have calculated the temperature of the ocean, and they will continue to do so.

This title and subtitle are totally misleading. The question of whether or not some (and I stress some because this only affects one proxy, not the others that suggest warm temperatures) temperature estimates were wrong has no bearing at all on the rate of current climate change.

It seems the authors of this paper are not au fait with the decades of work that has been done with other proxies that also show warmth at these times, since they take their observed changes in oxygen isotopes in deeply buried and heated sediments, and extend their results outrageously, discounting hundreds of papers on either shallow, well-preserved samples, or organic temperature proxies, or pollen assemblages, or leaf margin analysis, or clumped isotopes- all of which show that the poles were indeed warmer at this time.

"Relatively" being the operative word here. And in any case- there is evidence of warmer poles from other proxies besides oxygen isotopes. Organic biomolecule-based proxies (like TEX86) for example. Quite aside from that, there were lush forests where today there is only ice. The fact that the poles were warmer is not something to be called into question by this one study on one proxy, on one type of foraminifera subjected to very high temperatures in the lab. I don't suggest that this can't be operating on oxygen isotopes at some level, but given the wealth of other evidence, I suggest the authors of this study, and subsequently the author of this piece, have gone well overboard with their assessment.

I again dispute this. Over-egging the pudding.

The study suggests some periods of time may (according to one proxy) be cooler than originally thought, but this doesn't change the 'rate' of warming seen today.. i.e. the rate of temperature change.. This isn't anything to do with the study. There are confused messages coming out here about rate of change vs. absolute values. Certainly we are not reaching temperatures today that are warmer than over the last 100 million years, either- with or without the results of this study.

I don't think there's a link between alteration of deeply buried sediments in this study (i.e. oxygen isotope measurements from millions of years ago) and current rates of temperature increase (directly measured from satellites and weather stations). It may challenge the way we work out sea temperatures (although as I will note later the paper seriously overstates its case), but this doesn't change the observed rates of change in the post-industrial era. This is inaccurately presented.

Note that the interpretation of the DMI's data cited here is not the DMI's own interpretation.

Worth noting that the author of the Telegraph's article has a position on the UK's Climate Change Act that has been debunked thoroughly by scientists, economists, business groups and politicians from both sides of the aisle. See here for just one analysis.. https://www.carbonbrief.org/uk-climate-change-act-costs-benefits

This appears to be a misunderstanding of what trends are. Just because 1998 was warmer than any of the years before it, and 2016 was warmer still, making it warmer than all of the years before it (including 1998), this doesn't mean that there has been no warming between 1998 and 2017. This is simply wrong.

1998 was the hottest year on record. It has since been surpassed, as global temperatures get higher still. Nothing about this is notable.

There is no clear reason why the author of the original, or indeed this piece, should pick 2008, other than cherry picking to suit their requirements. In fact the statistical trend over 30 years is of an average of 42,000 km2 of sea ice loss per year.

This is a known natural phenomenon called Winter. In fact Arctic temperatures on average for this period should be considerably lower than the -20˚C mentioned here. this shows a basic misunderstanding of what winter in the Arctic circle looks like.

There is no evidence at all for the global temperature having stayed the same for 19 years. This is counter to all observations of global temperature.

The claim that the Climate Change act is economically damaging is based on flawed and subjective judgements, and wilful disregard for economic benefits. This claim is thoroughly debunked here: https://www.carbonbrief.org/uk-climate-change-act-costs-benefits See also this research report: http://www.lse.ac.uk/GranthamInstitute/wp-content/uploads/2016/05/Bassi-and-Duffy-policy-brief-May-2016.pdf

I would question why the author has chosen 2008 here? Picking one particular year that may have been thin to compare to, rather than the statistical long term trend, is cherry picking to suit the author's preconceptions.

The very graph that he refers to suggests that the Arctic is losing on average 42,000 km2 a year of sea ice. The author is very subjectively taking a 13 year period from a noisy climate dataset and ignoring the statistically significant trend within it.

Actually some of the more recent estimates have suggested that we may have crossed over the 400 ppm threshold briefly as recently as 2.4 Million years age.. And again at 2.9 Mya. (see Martinez-Boti et al., Nature, 2015: http://www.nature.com/nature/journal/v518/n7537/fig_tab/nature14145_ft.html). I think climate scientists typically think of the Pliocene as being the last time period where CO2 may have been more or less permanently above the 400 ppm threshold though, so perhaps this is what they are referring to here. It might be advisable to tidy up the terminology a little here nonetheless.

The layman's summary of the Permo-Triassic mass extinction here seems factually sound.

I echo Andreas's caution here: if the work has not yet been peer reviewed, it could be damaging to present such an alarmist argument before the work in question has been properly scrutinized. There is a group at the University of Southampton who are actually directly monitoring Atlantic circulation. Their recent paper in Nature, suggests that recent changes in the strength of Atlantic circulation are due to natural variability- the North Atlantic Oscillation.

While perhaps probable, I urge a note of caution that the link between jet stream patterns and anthropogenic reduction in sea ice is still not 100% certain. See this article

Even planting vast numbers of trees will only store carbon temporarily in biomass while the trees are alive. When these trees decay the carbon will (mostly) re-enter the atmosphere- therefore it's not really correct to say that planting trees can remediate CO2 release. If the trees were burnt and the resultant CO2 pumped into carbon storage reservoirs (such as expended gas fields), this could constitute remediation.