Climate Change - General Discussion : Read the Mod Note in post #1 before posting

Akrasia wrote: »

MT, you say that global average temperatures have flatlined, but 16 of the last 17 hottest recorded years happened this century, and the last 4 years have been dramatically warmer still
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On an increasing long-term background trend it's no surprise that recent years have been warmer than earlier ones. I think MT was referring to the flat line from the start of this century.

Akrasia

MT, you say that global average temperatures have flatlined, but 16 of the last 17 hottest recorded years happened this century, and the last 4 years have been dramatically warmer still

It's fine to point at individual global record events, and question why they haven't been broken recently, but the bigger picture is that every place in the world has it's own climate, and the hottest ever temperature recorded in Death Valley isn't any more significant than a hottest ever temperature recorded at Belmullet apart from the human instinct to play top trumps. When the data is analysed, there are more than twice as many record highs as record lows recorded

https://www.skepticalscience.com/Record-high-temperatures-versus-record-lows.html

It's true that we don't fully understand every element of how heat is redistributed, but we have measured a cooling stratosphere, warming atmosphere, melting ice and warming oceans. All of this points to significant build up of thermal energy in the biosphere and there is no plausible explanation other than the greenhouse effect, of which human emissions are the dominant drivers of change in the radiative forcing.

M.T. Cranium

By the way, if you want to say that evidence of climate change is irrefutable, then why are all of the following things true?

-- the worst hurricane season on record in the North Atlantic was 1780.

-- the most severe outbreak of tornadoes in the U.S. (by numbers of F-4 or F-5, not by death toll, although that was the highest) was in 1925.

-- the most severe heat waves were in 1934 and 1936. 1911 ranks third.

-- in Britain, over 360 years, the warmest January was 1916 and the warmest February was 1779. The warmest winter was 1868-69. It is only the December warmth in 2015 that comes from the modern winter period.

None of these fairly significant indicators can be used to support the most frequently heard argument for climate change, namely, that "we" are causing severe or unusual weather events. It doesn't stand up to analysis. Apparently, our unsuspecting grandparents or further back generations were doing this, or perhaps it's just natural variability.

As to 97% of climate scientists agreeing with the notion of climate change, first of all we need to break that down by what kind of climate change. I might not qualify as part of the sample, or maybe I do, but I would agree that there is climate change simply on the basis that there is always climate change. Our climates have long-term variability. They always have had, and sometimes much larger variations than we've seen. This isn't even the warmest time since the last glacial, that came about five thousand years ago. So I would like to know, is that 97% like 90% who are concerned about human caused variation and 7% only natural, or is it 40-47 or what is it? And who are these 3% that don't believe in climate change, they must believe in a steady-state climate, but I suspect the 3% is like what the Russians used to report as opposition to the party in state elections, it sounded worse if you said 0%.

Now if it's maybe 60% who are concerned about human modification and 37% only natural (I don't think there are any other horses in this race) then okay, how many of those 60% feel no peer or workplace pressure and have no reservations?

The reason I doubt these numbers apply to human-induced change is simple, on weather forums where meteorologists participate, the discussion quite often seems more balanced than 97-3, more like 50-50. I know for a fact that a lot of AMS members whose jobs are in local forecasting are skeptics. One reason why a local forecaster is more likely to be a skeptic is that today's record highs (and lows) flash before your eyes once a day, and it's sobering to notice after five minutes of the news guy waffling on about "extreme weather" that today's warmish high fell five degrees short of 1890 or even 1942.

I hope there will be a more flexible poll taken with more than two options, to some extent the question asked now is a "do you beat your wife?" question, especially if your boss at the institute happens to be listening in.

M.T. Cranium

Interesting discussion.

I tend to accept that instrumental records from 1659 (start of CET records) to mid-19th century come with some uncertainty but the averages are probably reliable, for one thing, the more severe winters can be cross-checked against more robust indicators like freezing of certain rivers or snow cover duration reported by reliable observers.

So I accept in general terms the concept that the Little Ice Age was a long interval of colder weather, that it had a last hurrah in the 19th century, and that the 20th century was generally warmer.

Beyond that, I don't entirely trust the narrative about ever-increasing warmth because it seems at variance with specific locations. I think what's going on generally is a complex mixture of expanding urban heat islands, regional changes in the subarctic, and a certain amount of fiddling with the data to improve the look.

At some point that reaches a point of no return and that's exactly what the most recent trends indicate -- even using their own questionable numbers, the gatekeepers have to admit that the temperature trends have flat-lined. There's no more give in the system. This may mean one of three things.

(1) We have reached an equilibrium where the forces at work on temperature trends have exhausted their ability to provide further warming, combined with a lack of easily manipulated new data opportunities, in other words, the IPCC are stuck with this steady-state situation which reminds one of the transition from a warming climate around the 1930s to a more variable one in the 1940s.

(2) All of these observed trends, while reliable and un-manipulated, have been due more to natural than anthropogenic causes, and the cycle there is swinging towards a cooling trend, largely because of lower solar activity, where a lag time of 10-20 years is expected from past analogues.

(3) There really is an AGW problem and we just happened to hit a natural downturn that is keeping it in check. Later on, if we don't abandon fossil fuels, we will see a fast increase in temperatures.

I don't know which of these three is the most likely option. However, I do suspect that our atmosphere has many undiagnosed or unsuspected ways of redistributing the warmth we might be generating, in complex feedback mechanisms. The climate change people are beginning to lean this way too, they want to have all bases covered so there is more emphasis on the warmth in the subarctic causing displacement of arctic air (the polar vortex scenario). While I think much of this is hype, it should be noted that glacial periods usually begin with open seas in the far north.

By the time we work out what's really going on (and it is bound to be more complicated, all things global-climate are complicated) we will probably have exhausted fossil fuels and perfected cleaner technologies. If we get over the widespread fears of nuclear technology, that might be the way forward. There is no shortage of hydrogen.

As to the climate of Ireland changing very much, can that be bad? Or should I say, must that be bad? There is always this assumption behind the climate change argument that all change is bad. But the climate has always been changing, that part we can't dispute, even skeptics of the AGW theory don't dispute that climate is changing, it always is, and always will be unless we perfect weather modification.

Then I wonder, how much will the Boards snow fanatics have to raise to bribe the weather modification people to make it snow?

sdanseo

Gaoth Laidir wrote: »

Ah, to pay the salaries of the 1-9 employees. There's the problem. True charities should be run voluntarily.

Almost all charities have a base of volunteers but some level of paid management that are often villified for being paid - but the truth is no one has the level of time required to manage anything but the smallest charity on a full time basis. There would either be constant changes at management level or no one willing to do it at all, both of which would doom any organisation to failure.

I agree with posters who have stated climate change is beyond denial at this point. The extent to which we humans are causing it will probably never be measurable. However the initiatives to attempt to halt any damage we are doing can only be a good thing.

Gaoth Laidir wrote: »

That's a dead link. But here's a chart for you (albeit missing the last few years), showing that observations are not even keeping up with RPC4.5, which would suggest that this particular forecast (the second lowest of the four) may not be reflective of reality. Of course the highest RPC (8.5) is the one that invariably gets quoted on here and elsewhere when speaking of the likely future climate. That's what I mean by exaggeration and hyperbole.

I never said 2018, but 2020 was a widely-stated estimation some 10 years or so back. Of course that's now been moved out and out, but I still hear people speak of ice-free in the next decade or so, yet there is no scientific evidence of it.

I'm not angry about climate change, so I don't know where you got that. I don't like tabloid exaggeration, whatever the topic. The facts you speak of have become inflated and hijacked as a one-size-fits-all scapegoat for everything and anything. I heard talk that Ophelia was due to global warming, yet a week after it passed a paper was published stating it was not. Didn't matter, there are still some who are telling us to expect more of the same, more severe and more often. Scientific evidence actually shows that the number of high-end tropical systems has been DEcreasing, contrary to previously thought.

We need to get off fossil fuels. We need to use renewable energy. Everyone should have a solar panel on their roof. Aircraft wings should have them on the upper surface. We should have more wind farms. But not because the Maldives is going under, or Florida gets hurricanes, but because the energy is there, and whatever small contribution we are to warming will be mitigated.

I added the link incorrectly, https://www.nasa.gov/press-release/nasa-noaa-data-show-2016-warmest-year-on-record-globally , 16 of the last 17 years have been the warmest on record that can't be disputed. I don't recall it being mainstream opinion that Arctic sea ice would have disappeared by 2020. And some people said Ophelia was because of climate change? So what. Where they qualified on the subject? Climate change means there will be an increase in extreme weather events, a particular weather event does not necessarily mean its because of climate change but the frequency of these events will increase. I think that's where you're getting mixed up.

Akrasia

Gaoth Laidir wrote: »

That's a dead link. But here's a chart for you (albeit missing the last few years), showing that observations are not even keeping up with RPC4.5, which would suggest that this particular forecast (the second lowest of the four) may not be reflective of reality. Of course the highest RPC (8.5) is the one that invariably gets quoted on here and elsewhere when speaking of the likely future climate. That's what I mean by exaggeration and hyperbole.

At this point in the RCP scenarios, they don't really diverge, so RCP 8.5 and RCP 4.5 show that temperatures should be about the same for the period up to 2017. The RCP curves relate to emissions, and we are closer to the RCP 8.5 emissions graph than we are to the RCP 4.5 path, and the RCP 3.0 is fantasy, we'll never ever be able to achieve that.

Regarding the temperatures, it's good that you acknowledged that the graph is out of date. What do you think it would show if the previous 4 years of data were included? The last 4 years have shown a staggering surge in temperatures so that unless there is a dramatic cooling in the next few years, we may have already arrived at the 1 degrees above pre-industrial levels that weren't projected to be reached until around 2030 under the RCP 4.5 scenario, and we're well ahead of even the RCP 8.5 scenario, which would indicate that climate sensitivity is higher than we have modelled to.

The above would become moot if the next few years are substantially cooler than 2014 - 2017, but is anyone willing to bet that 2018 wont be a top 5 warmest year on record?

I never said 2018, but 2020 was a widely-stated estimation some 10 years or so back. Of course that's now been moved out and out, but I still hear people speak of ice-free in the next decade or so, yet there is no scientific evidence of it.

There isn't any way of knowing for certain because sea ice formation in the arctic is chaotic, but the trend is absolutely downwards with sea ice on both poles at record low extents for the 2nd year in a row
[https://www.theweathernetwork.com/news/articles/global-sea-ice-hits-record-low-second-year-straight/93263

and would anyone really be surprised if 2020 did have an ice free arctic summer? Even if it still has nominal sea ice up to 2025, in the grand scheme of things, Arctic sea ice is on a death spiral

Shedbebreezy wrote: »

What observations? Sixteen of the 17 warmest years in the 136-year record all have occurred since 2001. Www.climate.nasa.gov/vital-signs/global-temperature/

That's a dead link. But here's a chart for you (albeit missing the last few years), showing that observations are not even keeping up with RPC4.5, which would suggest that this particular forecast (the second lowest of the four) may not be reflective of reality. Of course the highest RPC (8.5) is the one that invariably gets quoted on here and elsewhere when speaking of the likely future climate. That's what I mean by exaggeration and hyperbole.

You're being hyperbolic now, it was never mainstream opinion that the Arctic would be ice free by 2018. Please supply all this new evidence that is coming to light. You seem angry about climate change, stating facts is ramming it down our throats apparently.

I never said 2018, but 2020 was a widely-stated estimation some 10 years or so back. Of course that's now been moved out and out, but I still hear people speak of ice-free in the next decade or so, yet there is no scientific evidence of it.

I'm not angry about climate change, so I don't know where you got that. I don't like tabloid exaggeration, whatever the topic. The facts you speak of have become inflated and hijacked as a one-size-fits-all scapegoat for everything and anything. I heard talk that Ophelia was due to global warming, yet a week after it passed a paper was published stating it was not. Didn't matter, there are still some who are telling us to expect more of the same, more severe and more often. Scientific evidence actually shows that the number of high-end tropical systems has been DEcreasing, contrary to previously thought.

We need to get off fossil fuels. We need to use renewable energy. Everyone should have a solar panel on their roof. Aircraft wings should have them on the upper surface. We should have more wind farms. But not because the Maldives is going under, or Florida gets hurricanes, but because the energy is there, and whatever small contribution we are to warming will be mitigated.

Wanderer78

I find it upsetting that some people still question the existence of climate change and our involvement in its development, we have to change our ways now, or this could exterminate our species and others. We can be a truly ignorant and selfish species at times

Akrasia

ABC101 wrote: »

Well the points I raised are not my own, in fact it was explained by a scientist that with regards climate change, this is what they have been doing, going back through every and any records. So for example if something of interest was written by a Irish Monk, they would look for that evidence elsewhere as well, to see if the observation was also seen across Europe for example, is it replicated in tree trunk rings etc.

It’s a bit like forensics, they can work backwards etc

Stone carvings and human cultural shifts are at the very best, supporting evidence of pre-modern climate and on their own, they are absolutely not sufficient to conclude anything about global climate before scientific measurements began

There are however many other proxy records for global climate and atmospheric co2 which can be collated to create a scientific record of past global temperatures. These are natural proxies of temperature and climate, like tree rings, corals, ice cores, frozen pollen, ocean sediments etc...

Note that the uncertainty bar definitely widens the further back we go, but also, that observed temperature increases are well above even the uncertainty bar

https://earthobservatory.nasa.gov/Features/GlobalWarming/page3.php

So in order to think that current temperatures are within the range of normal within the past 2000 years, you would have to choose to believe that the extreme hottest estimates on the extreme north of the error bar of past temperature reconstructions are all true, and none of the extreme cold estimates are true.

If you believe this, then you need to challenge yourself on what basis you could possibly have for believing that the most unlikely interpretation of the data must be true.

The last 10 years has seen a very worrying leap forward in global average temperatures by about a half a degree C. This is extremely worrying and it is not explained by anything other than the greenhouse effect. No 'skeptics' have put forward any hypothesis to explain the warming that has any adequate supporting data, and of the small percent of skeptical scientists in the field, they can't even agree on why they think the science is wrong, there is no unified alternative theory to climate change, just a hodge podge of poorly evidenced pet theories that have not gained any traction even within the 'skeptical' scientific community.

When one side is in broad agreement for a scientific principle, and the other 'side' can't even agree amongst themselves why the establishment is wrong, then it's a clear indication that the establishment theory is very robust and until a clear body of evidence challenges it, it would be a serious mistake to disregard it, especially on a matter so gravely detrimental and urgent as global climate change.

Gaoth Laidir wrote: »

I'm well aware of the "impacts" that are alleged to be already happening. It's hard not to when every weather event is being attributed to mmcc. It's being rammed down our throats and we're not meant to question it. Most of it is hyperbole that hasn't come to pass yet. Ice-free Arctic, inundated countries, etc. No sign of many of the impacts that a while back were being warned in the most dramatic of terms.

Increased CO2 does affect global temperature, but just not to the extent that was once believed by the 97%. Observations and new research are showing that to be the case. Science moves on as new evidence comes to light. Move with it.

What observations? Sixteen of the 17 warmest years in the 136-year record all have occurred since 2001. Www.climate.nasa.gov/vital-signs/global-temperature/

You're being hyperbolic now, it was never mainstream opinion that the Arctic would be ice free by 2018. Please supply all this new evidence that is coming to light. You seem angry about climate change, stating facts is ramming it down our throats apparently.

MJohnston wrote: »

If you think that, try not to just make glib put downs of the whole thing - explain what exactly you think is exaggerated and dramatised. Otherwise you're essentially just "vaguebooking"

I already have.

If you actually read the blurb about this 2050 thing, it's talking about issues regarding "transport, waste & energy" - if you don't think that'll look very different in 32 years time, you're very wrong.

I don't think these things will be very different to today. Certainly not to the dramatic extent they make out.

Well it's a charity running it, so you can easily find out for yourself: https://charitiesregister.ie/org/b8b8d0a2-76f6-47ab-8002-b6f4fea5ca74/centre-for-climate-change

That says it's purely focused in this visitor centre in Powerscourt and nothing else. So what are the corporate sponsors doing? I assume they're putting money into it, so why charge into it? Ah, to pay the salaries of the 1-9 employees. There's the problem. True charities should be run voluntarily.

Shedbebreezy wrote: »

I didn't mention your name don't be paranoid. I'm quoting Scientists who conducted studies in to it Gaoth. People who know more about the subject than you or me. Imagine that. And I think you should brush up on your knowledge on the impacts of climate change, especially for developing countries instead of downplaying it as a bit of nothing. Tell them it's hyperbole. I'm sure it'll be comforting to them.

I'm well aware of the "impacts" that are alleged to be already happening. It's hard not to when every weather event is being attributed to mmcc. It's being rammed down our throats and we're not meant to question it. Most of it is hyperbole that hasn't come to pass yet. Ice-free Arctic, inundated countries, etc. No sign of many of the impacts that a while back were being warned in the most dramatic of terms.

Increased CO2 does affect global temperature, but just not to the extent that was once believed by the 97%. Observations and new research are showing that to be the case. Science moves on as new evidence comes to light. Move with it.

Roger_007

I am no expert on climate but I often worry about the claims that 97% of climate scientists are of one mind on the subject. Some of these people have made silly predictions in the past which have proved very wide of the mark.
Example: article published in 2007, which made big headlines at the time, predicting that the Arctic would be ice-free in summer by 2013.

http://news.bbc.co.uk/2/hi/science/nature/7139797.stm

There was also the prime minister of the Maldives who made a speech to the UN in 2012 that he had been advised by his climate experts that the Maldives would be under water in 5 years, i.e. 2017.

None of the above predictions came to pass but I assume those scaremongers responsible for those predictions are part of the 97%. This is what worries me.

Gaoth Laidir wrote: »

I'm also all for promoting science to children, but the "science" that appears to be on display (from reading the website) seems to be exaggerated and dramatised.

If you think that, try not to just make glib put downs of the whole thing - explain what exactly you think is exaggerated and dramatised. Otherwise you're essentially just "vaguebooking"

Yes, make it engaging, but the idea that you transport them to their town only 30 years from now and it's "very different to the town they know today" is laughable and just inaccurate.

If you actually read the blurb about this 2050 thing, it's talking about issues regarding "transport, waste & energy" - if you don't think that'll look very different in 32 years time, you're very wrong.

I don't think it's irrelevant to ask where the entrance money is going when there is a long list of corporate sponsors.

Well it's a charity running it, so you can easily find out for yourself: https://charitiesregister.ie/org/b8b8d0a2-76f6-47ab-8002-b6f4fea5ca74/centre-for-climate-change

Gaoth Laidir wrote: »

Since when did anyone deny mmcc? I certainly didn't. I do have a problem with hyperbole and exaggeration, though, and with the attribution of every weather event to mmcc. Observations are not following the most pessimistic scenarios of the IPCC, yet these are invariably the only ones that are quoted and if you point that out you're a "denier".

I reckon you need to familiarise yourself a bit deeper with the actual facts and figures and how the observation curve is fitting the projections curves and less on pasting paragraph after paragraph of the basic theory.

I didn't mention your name don't be paranoid. I'm quoting Scientists who conducted studies in to it Gaoth. People who know more about the subject than you or me. Imagine that. And I think you should brush up on your knowledge on the impacts of climate change, especially for developing countries instead of downplaying it as a bit of nothing. Tell them it's hyperbole. I'm sure it'll be comforting to them.

Shedbebreezy wrote: »

I can't actually believe we have so many man made climate change deniers on here. Over 97% of climate scientists agree its real.

......

IMO its just pure ignorance and stupidly to deny it.

Since when did anyone deny mmcc? I certainly didn't. I do have a problem with hyperbole and exaggeration, though, and with the attribution of every weather event to mmcc. Observations are not following the most pessimistic scenarios of the IPCC, yet these are invariably the only ones that are quoted and if you point that out you're a "denier".

I reckon you need to familiarise yourself a bit deeper with the actual facts and figures and how the observation curve is fitting the projections curves and less on pasting paragraph after paragraph of the basic theory.

MJohnston wrote: »

Not being in any way a part of the company running it, I'm not sure why you would expect me to be privy to the financial ins and outs of the it, but I think it's rather irrelevant. I also have no idea what the Ploughing Championships have to do with anything, but anyway.

My thinking is that it's great to see a science-positive resource that is clearly targeted at school-age children and school groups.

I'm also all for promoting science to children, but the "science" that appears to be on display (from reading the website) seems to be exaggerated and dramatised. Yes, make it engaging, but the idea that you transport them to their town only 30 years from now and it's "very different to the town they know today" is laughable and just inaccurate.

I don't think it's irrelevant to ask where the entrance money is going when there is a long list of corporate sponsors. The Ploughing Championships is really nothing to do with Ploughing Championships and also to do with corporate advertising. Much the same way as this event appears to be, to me anyway.

Say my name wrote: »

No point just the article.
Carbon dioxide (carbon) came from the earth or molten lava and it will return to the earth again.
Whether the earth will return to a lava ball again or even a frozen ball is anybody's guess.
It's interesting that there was 5 times more carbon dioxide in the atmosphere during the time of the dinasours that is all.
No argument.

These tectonic movements made the oceans close up and the tectonic plates sink into the Earth. This process, called subduction,led to volcanism at the surface, with rocks constantly melting and emitting CO2 into the atmosphere. Huge amounts of this greenhouse gas made the climate during the Jurassic Period extremely humid and warm.

Didn't sound like a great time to be alive.

Say my name

Shedbebreezy wrote: »

And what's your point?

No point just the article.
Carbon dioxide (carbon) came from the earth or molten lava and it will return to the earth again.
Whether the earth will return to a lava ball again or even a frozen ball is anybody's guess.
It's interesting that there was 5 times more carbon dioxide in the atmosphere during the time of the dinasours that is all.
No argument.

JCX BXC wrote: »

While I won't give my opinion either way on this debate, I will state that there's clearly an interest by some organisations to create a profit from this issue. Some of this is fine, eg Companies becoming greener in order to gain a better brand image, which is dare I say a good thing. However that's the nice way in which this issue is being exploited.

It would seem to me that this would pale in significance compared to the money profited by those who have...lets call it climate change indifference - to be extremely kind.

Say my name wrote: »

I will take your 800,000 years ago and raise you 250m years ago.

https://www.google.ie/amp/s/amp.livescience.com/44330-jurassic-dinosaur-carbon-dioxide.html

And what's your point?

George Sunsnow wrote: »

I agree
But jeepers until Trump came along they’ve been doing a terrible job at it!!
It’s probably unlikely his direction will forever have legs though

Trump doesn't need to enact anything permanent to cause major 'damage', he just needs to hold up progress for a while.

JCX BXC

While I won't give my opinion either way on this debate, I will state that there's clearly an interest by some organisations to create a profit from this issue. Some of this is fine, eg Companies becoming greener in order to gain a better brand image, which is dare I say a good thing. However that's the nice way in which this issue is being exploited.

George Sunsnow

nacho libre wrote: »

I have no iron in the fire so to speak, but
you could just as easily point out it's also in the interest of big corporations to play down the link between climate change and man, so they can carry on some activities in environmentally sensitive regions.

I agree
But jeepers until Trump came along they’ve been doing a terrible job at it!!
It’s probably unlikely his direction will forever have legs though

Say my name

Shedbebreezy wrote: »

I can't actually believe we have so many man made climate change deniers on here. Over 97% of climate scientists agree its real.

Q: What causes global warming?
A: Global warming occurs when carbon dioxide (CO2) and other air pollutants and greenhouse gases collect in the atmosphere and absorb sunlight and solar radiation that have bounced off the earth’s surface. Normally, this radiation would escape into space—but these pollutants, which can last for years to centuries in the atmosphere, trap the heat and cause the planet to get hotter. That's what's known as the greenhouse effect.

There are those who say the climate has always changed, and that carbon dioxide levels have always fluctuated. That’s true. But it’s also true that since the industrial revolution, CO₂ levels in the atmosphere have climbed to levels that are unprecedented over hundreds of millennia.

So here’s a short video we made, to put recent climate change and carbon dioxide emissions into the context of the past 800,000 years.

The temperature-CO₂ connection
Earth has a natural greenhouse effect, and it is really important. Without it, the average temperature on the surface of the planet would be about -18℃ and human life would not exist. Carbon dioxide (CO₂) is one of the gases in our atmosphere that traps heat and makes the planet habitable.

We have known about the greenhouse effect for well over a century. About 150 years ago, a physicist called John Tyndall used laboratory experiments to demonstrate the greenhouse properties of CO₂ gas. Then, in the late 1800s, the Swedish chemist Svante Arrhenius first calculated the greenhouse effect of CO₂ in our atmosphere and linked it to past ice ages on our planet.

Modern scientists and engineers have explored these links in intricate detail in recent decades, by drilling into the ice sheets that cover Antarctica and Greenland. Thousands of years of snow have compressed into thick slabs of ice. The resulting ice cores can be more than 3km long and extend back a staggering 800,000 years.

Scientists use the chemistry of the water molecules in the ice layers to see how the temperature has varied through the millennia. These ice layers also trap tiny bubbles from the ancient atmosphere, allowing us to measure prehistoric CO₂ levels directly.

Temperature and CO₂
The ice cores reveal an incredibly tight connection between temperature and greenhouse gas levels through the ice age cycles, thus proving the concepts put forward by Arrhenius more than a century ago.

In previous warm periods, it was not a CO₂ spike that kickstarted the warming, but small and predictable wobbles in Earth’s rotation and orbit around the Sun. CO₂ played a big role as a natural amplifier of the small climate shifts initiated by these wobbles. As the planet began to cool, more CO₂ dissolved into the oceans, reducing the greenhouse effect and causing more cooling. Similarly, CO₂ was released from the oceans to the atmosphere when the planet warmed, driving further warming.

But things are very different this time around. Humans are responsible for adding huge quantities of extra CO₂ to the atmosphere – and fast.

The speed at which CO₂ is rising has no comparison in the recorded past. The fastest natural shifts out of ice ages saw CO₂ levels increase by around 35 parts per million (ppm) in 1,000 years. It might be hard to believe, but humans have emitted the equivalent amount in just the last 17 years.

Before the industrial revolution, the natural level of atmospheric CO₂ during warm interglacials was around 280 ppm. The frigid ice ages, which caused kilometre-thick ice sheets to build up over much of North America and Eurasia, had CO₂ levels of around 180 ppm.

Burning fossil fuels, such as coal, oil and gas, takes ancient carbon that was locked within the Earth and puts it into the atmosphere as CO₂. Since the industrial revolution humans have burned an enormous amount of fossil fuel, causing atmospheric CO₂ and other greenhouse gases to skyrocket.

In mid-2017, atmospheric CO₂ now stands at 409 ppm. This is completely unprecedented in the past 800,000 years.

The massive blast of CO₂ is causing the climate to warm rapidly. The last IPCC report concluded that by the end of this century we will get to more than 4℃ above pre-industrial levels (1850-99) if we continue on a high-emissions pathway.

If we work towards the goals of the Paris Agreement, by rapidly curbing our CO₂ emissions and developing new technologies to remove excess CO₂ from the atmosphere, then we stand a chance of limiting warming to around 2℃.

The fundamental science is very well understood. The evidence that climate change is happening is abundant and clear.

Full article and video http://theconversation.com/the-three-minute-story-of-800-000-years-of-climate-change-with-a-sting-in-the-tail-73368

IMO its just pure ignorance and stupidly to deny it.

I will take your 800,000 years ago and raise you 25m years ago.
https://www.livescience.com/44330-jurassic-dinosaur-carbon-dioxide.html