Global Warming/Climate Change/Global Weirding?

[Conan71]

Um, no. Climate Science is hundreds of years old. The first prediction of global warming due to human caused CO2 dates to the late 19th century, almost 125 years ago, not 25 years ago.

https://skepticalscience.com/history-climate-science.html
https://history.aip.org/climate/timeline.htm

You are being lied to by the energy industry

Remember when oil drilling didn't cause earthquakes and smoking didn't cause cancer?

Again: Putting it into perspective, the current belief in global warming, climate change, or whatever we want to call it, is only about 25 or so years old.

[TheArtist]

Again: Putting it into perspective, the current belief in global warming, climate change, or whatever we want to call it, is only about 25 or so years old.

I think 25 years is quite a long time actually.  A lot of "hypothesis" get shot down in months to only a couple of years these days. 

For quite a while I kept expecting that you would see more "Well we hadn't thought of this and it really changes our views that perhaps global whatever may not happen/be as bad etc.  Then you would see some ideas and discoveries shift back, then to the other direction and so fourth.

After the 70s and early 80s when scientists were indeed throwing out big ideas and new notions (I mean, there were not many before this time that really believed that we puny humans could have an appreciable effect on the climate of the entire earth?! Surely you jest!) and there was broader arguments going on as new ideas shifted the possibilities back and fourth. 

But after that in an amazingly short time actually, what I have instead seen is the occasional "this actually may have a cooling effect" but then that is followed by ever more and stronger "oh we have also learned that this will make things warmer" things. 

Instead of the idea becoming weaker or more questionable as time has gone on, the idea just keeps getting on ever firmer and ever more detailed footing.  I keep waiting for that big "Oh no why didn't we think of that?" notion to pop up.  But it hasn't and what we have instead seen is a growing avalanche in the opposite direction.  Every year that goes by adds more data points, more studies are finished, more "this should knock it down" disproven, ever more detailed and powerful models STILL pointing in the same direction and more often than not, we find that we have UNDERESTIMATED the warming potential.

The "arrow" keeps MORE firmly pointing in one direction. 


For me though, my main concern has become about health.  Cars spewing out pollutants.

Again, here more and more studies keep showing bad health effects from auto exhaust.   And of course as fate would have it... I live right near a highway.  It was my choice, should have thought of that before moving here. But there you are.  Do I move and let some other family move in and it harm their health?  What if they have children? That would bother me.  So I am becoming more and more a fan of renewable energy and clean/electric vehicles.  My and others health is a more immediate concern than climate warming/change.  But as luck would have it, working to make the world safer and cleaner for ourselves and our families would also go a long way to allaying whatever climate concerns there are.

[cannon_fodder]

Again: Putting it into perspective, the current belief in global warming, climate change, or whatever we want to call it, is only about 25 or so years old.

That isn't accurate.

As previously stated, the original hypothesis is more than 125 years old.  The tools to begin measuring it started in earnest in the 1930s.  But the 1960s satellite data, core samples, and historic measurements were being confirmed by climate models.  By 1977 scientists for Exxon concluded that global warming caused by man made C02 emissions was a scientific consensus.   by the mid 1980s nearly every scientific organization had issued statements confirming the consensus.  BY the end of the 1980s there had been multiple worldwide conferences on limited C02 emissions (consistently veto'd, refused, or withdrawn from by only one advanced nation).

This isn't a "current" belief any more than the current "belief" in any other scientific endeavor.  The list of scientific discoveries or achievements that are newer than this is long and distinguished, and nearly all of them go unquestioned.    From seedless watermelons to smart phones.  From GPS to stealth technology.  From  the 401k to Al Gore inventing the internet (OK, I grant the 401k isnt a science, but I was trying to think of something opposite of Al Gore inventing the internet).  Scientists have discovered an un-observable sub-atomic universe consisting of stringy things that pop in and out of existence at random but somehow comprises the static world we know, and everyone went "wow, that's weird, but OK."  Scientists tell us for a couple of generations that there is observable evidence that man made C02 emissions are warming the planet and there's push back...

This might sound like a wild conspiracy, but in the midst of a scientific consensus on global warming and the oil bust of the 1980s - an industry group was formed to try to lobby America into thinking that there wasn't a consensus, that the science was too new, and that the course of action was unclear.  It even had a name straight out of a scary conspiracy handbook:  "The Global Climate Coalition," and included some of the same companies whose internal scientists were telling them to start planning for climate change. Unlike the conspiracies though, this wasn't some covert or hidden operation.  Setting up a paradigm to deny global warming and to stop efforts to fight it that would hinder their industries was the state purpose.

Denial of the scientific consensus became a part of the GOP platform and persists, even as the industry group folded and scientific evidence continues to mount. But it remains a fact that there is as much or more scientific consensus on global warming as there is on just about anything else, and there has been for a long time.  It isn't new.  it isn't a "belief" any more than any scientific consensus is.  And the "current" belief has only changed in that it has become more accurate with new data (a pesky rule in science).  You can only argue that the scientific consensus is too new for so many decades...

https://history.aip.org/climate/timeline.htm
https://history.aip.org/climate/public.htm#L_M032
https://en.wikipedia.org/wiki/Guy_Stewart_Callendar
https://en.wikipedia.org/wiki/Mauna_Loa_Observatory
http://what-when-how.com/global-warming/villach-conference-global-warming/
https://www.scientificamerican.com/article/exxon-knew-about-climate-change-almost-40-years-ago/

[patric]

I love today's global cooling... I mean weather.

Someone please explain why being supportive of our energy industry means you have to become a science denier?

It doesnt seem that far off from the deeply religious who deny scientific explanations for the world around them because it might contradict long-held beliefs that are based on profound misunderstandings of physics, biology, etc.

Last night Mr. Trump rallied he "ended the war on beautiful, clean coal" to West Virginia billionaire coal baron Gov. Jim Justice and his slogan-swallowing peons.  He really said that.  Maybe he was "just joking" like last week's rally promoting brutality in front of a police department who recently had to replace their chief for beating up a man who stole his bag of dildos?

[Townsend]

this is long and distinguished

[Red Arrow]

Another example of the science being settled:

http://www.jyi.org/issue/delayed-gratification-why-it-took-everybody-so-long-to-acknowledge-that-bacteria-cause-ulcers/

[heironymouspasparagus]

Another example of the science being settled:

http://www.jyi.org/issue/delayed-gratification-why-it-took-everybody-so-long-to-acknowledge-that-bacteria-cause-ulcers/

Been there, done that, got the t-shirt.  Years of denial by the ulcer deniers who only wanted to maintain their kickbacks from the Nexium crowd.  Two hospital visits over 6 years with serious internal bleeding, with a strong recommendation by the gastropod for "exploratory surgery".  The surgeon chosen came in and talked to me.  Looked thoroughly disgusted, put me on the twin antibiotics intravenously.  Continued with pills for 3 weeks after getting out of hospital.  No more ulcers/acid reflux/gastritis for over 10 years.


Much the same way the climate change deniers are digging in, dragging us down solely to maintain their revenue stream.

[Conan71]

Great research! Follow your timeline.  The period I speak of starts with:

"1990 First IPCC report says world has been warming and future warming seems likely. =>International"

So I was off by two years.  This is my recollection: that the momentum started around 1990 or 1991 on the current and more solidified belief that man-made global warming was a thing.  In the 1970's it was smog, acid rain, and the potential of cooling.  In the 1980's it was the hole in the ozone layer.  IIRC, global warming was identified somewhat as an environmental issue in the 1992 POTUS election.

As recent as this year, there have been dust ups amongst noted climatologists about how data is collected and interpreted.  (Google "Karl Study" on the 1998-2013 warming "hiatus" which was essentially disproven by the Karl report but the methodology rankled some NOAA scientists).  No one is trying to say this makes the theory of global warming climate change bunk, but it does seem to indicate some dissension in the ranks of climatologists in the way data is collated and interpreted.  Hence: this is still a rather new era of climate science and there is still some protocol which appears to be in dispute or disagreement.

Many of the devices (satellites, sea buoys, etc.) used to collect the data scientists are using in their predictions have been deployed in the last 20-25 years.  So this is a relatively new field of study with so many scientists and apparatus now dedicated to tracking and interpreting the data.

It is certainly believable that we might be able to change the course of climate change as smog and emissions regulations employed in the 1970's mitigated acid rain and many smog issues. As an interesting aside and somewhat off-topic, there are writings from Spanish explorers of the smog or haze in the L.A. basin dating back hundreds of years before the internal combustion engine due to temperature inversion.

Ostensibly restricting CFC's is helping to mitigate the hole in the ozone layer which was discovered in 1985.  Oh wait, that continues to grow, but scientists say it grows later in the season and forms at a slower rate, so that's a win even though the goal posts moved somewhat.  Even with restrictions on CFC's it continued to grow.  So much for human intervention there, right?  http://www.latimes.com/projects/la-sci-sn-ozone-hole-healing/  Perhaps limiting CFC's helps or perhaps this hole is cyclical like other climate issues.

I'm all for cleaner air, and there's little doubt that increased emissions and BTU's sent into the atmosphere do help contribute to climate change.  I simply see a certain amount of hubris when mankind seems to think it has all the keys to changing something as huge as our atmosphere.

YMMV

That isn't accurate.

As previously stated, the original hypothesis is more than 125 years old.  The tools to begin measuring it started in earnest in the 1930s.  But the 1960s satellite data, core samples, and historic measurements were being confirmed by climate models.  By 1977 scientists for Exxon concluded that global warming caused by man made C02 emissions was a scientific consensus.   by the mid 1980s nearly every scientific organization had issued statements confirming the consensus.  BY the end of the 1980s there had been multiple worldwide conferences on limited C02 emissions (consistently veto'd, refused, or withdrawn from by only one advanced nation).

This isn't a "current" belief any more than the current "belief" in any other scientific endeavor.  The list of scientific discoveries or achievements that are newer than this is long and distinguished, and nearly all of them go unquestioned.    From seedless watermelons to smart phones.  From GPS to stealth technology.  From  the 401k to Al Gore inventing the internet (OK, I grant the 401k isnt a science, but I was trying to think of something opposite of Al Gore inventing the internet).  Scientists have discovered an un-observable sub-atomic universe consisting of stringy things that pop in and out of existence at random but somehow comprises the static world we know, and everyone went "wow, that's weird, but OK."  Scientists tell us for a couple of generations that there is observable evidence that man made C02 emissions are warming the planet and there's push back...

This might sound like a wild conspiracy, but in the midst of a scientific consensus on global warming and the oil bust of the 1980s - an industry group was formed to try to lobby America into thinking that there wasn't a consensus, that the science was too new, and that the course of action was unclear.  It even had a name straight out of a scary conspiracy handbook:  "The Global Climate Coalition," and included some of the same companies whose internal scientists were telling them to start planning for climate change. Unlike the conspiracies though, this wasn't some covert or hidden operation.  Setting up a paradigm to deny global warming and to stop efforts to fight it that would hinder their industries was the state purpose.

Denial of the scientific consensus became a part of the GOP platform and persists, even as the industry group folded and scientific evidence continues to mount. But it remains a fact that there is as much or more scientific consensus on global warming as there is on just about anything else, and there has been for a long time.  It isn't new.  it isn't a "belief" any more than any scientific consensus is.  And the "current" belief has only changed in that it has become more accurate with new data (a pesky rule in science).  You can only argue that the scientific consensus is too new for so many decades...

https://history.aip.org/climate/timeline.htm
https://history.aip.org/climate/public.htm#L_M032
https://en.wikipedia.org/wiki/Guy_Stewart_Callendar
https://en.wikipedia.org/wiki/Mauna_Loa_Observatory
http://what-when-how.com/global-warming/villach-conference-global-warming/
https://www.scientificamerican.com/article/exxon-knew-about-climate-change-almost-40-years-ago/

[Red Arrow]

there are writings from Spanish explorers of the smog or haze in the L.A. basin dating back hundreds of years before the internal combustion engine due to temperature inversion.

Burning wood for cooking etc probably contributed to the smog part.  Haze due to water vapor is what it is.

[guido911]

Lat night's unusual August tornado obviously a result of climate change. Or manbearpig was secretly rummaging through the Promenade area.

[dbacksfan 2.0]

Lat night's unusual August tornado obviously a result of climate change. Or manbearpig was secretly rummaging through the Promenade area.

Tornado's in August unusual and rare? Don't think so. December 1975 was rare. I would say they are more common in the northern US in August but they are far from rare or unusual in Oklahoma.

http://www.ustornadoes.com/2015/08/17/heres-where-tornadoes-typically-form-in-august-across-the-united-states/

[cannon_fodder]

Great research! Follow your timeline.  The period I speak of starts with:

"1990 First IPCC report says world has been warming and future warming seems likely. =>International"

So I was off by two years.  This is my recollection: that the momentum started around 1990 or 1991 on the current and more solidified belief that man-made global warming was a thing.  In the 1970's it was smog, acid rain, and the potential of cooling.  In the 1980's it was the hole in the ozone layer.  IIRC, global warming was identified somewhat as an environmental issue in the 1992 POTUS election

. . .

I'm all for cleaner air, and there's little doubt that increased emissions and BTU's sent into the atmosphere do help contribute to climate change.  I simply see a certain amount of hubris when mankind seems to think it has all the keys to changing something as huge as our atmosphere.

Let me try to be more clear on the timeline:

Global warming from man emitted CO2 was identified as an issue in the late 1800s.  It was studied throughout the 1900s.  IN 1977 Exxon scientist felt it was a scientific consensus.  The conclusions had been drawn much earlier than that even - this is when Exxon scientists internally came to accept it.  1977.  The National Academy of Science, known for being a conservative body (scientifically, not politically), declared global warming "highly credible" in 1979.

By the mid 1980s almost all  bodies had declared a consensus.  The IPPC was formed in the late 1980s after a near universal consensus was reached to try to clarify the damage and what can be done.  That's why their first report wasn't issued until the early 1990s - they didn't exist much before that.

If political discord is an important signal in science, Ronald Reagan discussed climate change when he first ran for the White House.  More than a decade before the first IPPC report.  Climate change and funding for research has been a conservative issue since the early 1980s.  International conferences for action on climate change took place before the end of the 1980s.  Industry groups joined forces for a lobbying and PR effort against the science before the 1980s ended. 

There has been 80 years of research on the issue and broad scientific consensus for more than 30 years.  The general principal that man made co2 emission are causing Earth to warm is about as solid a scientific consensus as ever exists. There is a broader consensus on global warming than there is on the link between smoking and cancer.  There is very little that can be done to make the scientific fact of global warming more robust.

That doesn't mean it is set in stone (no science ever should be), but it does mean that there is as little basis to deny global warming as about any other scientific fact.  If we had to wait longer than 30 or 40 years to act on a scientific fact, we'd be living in the 1970s still.

(see all the previous citations, no need to repeat)

- - -


Also, BTUs into the air have little effect.  All the BTUs man has ever produced pale in comparison to the energy adsorbed from the sun in a few days (fun fact: the energy from the sub hitting the earth in an hour and a half has more energy in it than all energy used by humans in a year.  The sunlight hitting earth is 89,300 TeraWatts of energy).

Finally, the atmosphere isn't nearly as vast as you may believe and changes to it are easy to measure.  When put into scale of the earth, there is a tiny sliver of atmosphere.  The total volume of C02 is a known quantity:

- 3200 gigatons of C02, that's not much for the entire atmosphere - about .041% of the atmosphere.

- At the start of the industrial revolution, the CO2 concentration was 280ppm, ice core samples and other isolated pockets (such as lava) show that it was stable for ~10,000 years before that.

- Current concentrations are 403 PPM, and rising an average of 2ppm per year (that's a lot compared to how much there is).

- The best evidence suggests 400 ppm is the highest the earth has seen in more than 10 million years.

- Man made emissions of CO2 are about 10 gigatons per year

- Measurements of CO2 concentrations are accurate enough to see the effects of the growing season in the different hemispheres - as plants absorb C02.

- Water is able to absorb some CO2 (making it more acidic), but not nearly all of it.

There is no scientific doubt about the levels of CO2 or that they are rising.  There is no doubt about the greenhouse effect of CO2.  The questions that remain is what is the buffering ability of the oceans, how dependent are the currents on stable temperatures, and what the effects will be at different intervals of CO2 concentration and temperature (and other variables can come into play - changes to the sun, volcanic eruptions, snow coverage and other weather patters, etc.).  The facts don't care about human hubris, they don't care if most people think it is impossible.  They simply are.

http://calgary.rasc.ca/images/Earth_Atmosphere1.gif

http://www.sandia.gov/~jytsao/Solar%20FAQs.pdf

CO2 Summary: https://en.wikipedia.org/wiki/Carbon_dioxide_in_Earth%27s_atmosphere

[heironymouspasparagus]

- At the start of the industrial revolution, the CO2 concentration was 280ppm, ice core samples and other isolated pockets (such as lava) show that it was stable for ~10,000 years before that.

- Current concentrations are 403 PPM, and rising an average of 2ppm per year (that's a lot compared to how much there is).

The Vostok cores show CO2 ranging from about 200 to about 300 ppm, repeatedly, over more than 400,000 years.  (I have posted links to those here, also repeatedly over the last 400,000 years!)

Not sure any direct evidence has been found yet like the actual CO2 found in the cores, but I am betting it would be hundreds of million or quite likely billions of years ago since it was this high.  Back when oceans were forming and we had little to no oxygen in the atmosphere.



Oh, yeah...almost forgot...the earth is only 6,000 years old, too...!!  And climate change is a Chinese plot...

[Conan71]

Let me try to be more clear on the timeline:

Global warming from man emitted CO2 was identified as an issue in the late 1800s.  It was studied throughout the 1900s.  IN 1977 Exxon scientist felt it was a scientific consensus.  The conclusions had been drawn much earlier than that even - this is when Exxon scientists internally came to accept it.  1977.  The National Academy of Science, known for being a conservative body (scientifically, not politically), declared global warming "highly credible" in 1979.

By the mid 1980s almost all  bodies had declared a consensus.  The IPPC was formed in the late 1980s after a near universal consensus was reached to try to clarify the damage and what can be done.  That's why their first report wasn't issued until the early 1990s - they didn't exist much before that.

If political discord is an important signal in science, Ronald Reagan discussed climate change when he first ran for the White House.  More than a decade before the first IPPC report.  Climate change and funding for research has been a conservative issue since the early 1980s.  International conferences for action on climate change took place before the end of the 1980s.  Industry groups joined forces for a lobbying and PR effort against the science before the 1980s ended. 

There has been 80 years of research on the issue and broad scientific consensus for more than 30 years.  The general principal that man made co2 emission are causing Earth to warm is about as solid a scientific consensus as ever exists. There is a broader consensus on global warming than there is on the link between smoking and cancer.  There is very little that can be done to make the scientific fact of global warming more robust.

That doesn't mean it is set in stone (no science ever should be), but it does mean that there is as little basis to deny global warming as about any other scientific fact.  If we had to wait longer than 30 or 40 years to act on a scientific fact, we'd be living in the 1970s still.

(see all the previous citations, no need to repeat)

- - -


Also, BTUs into the air have little effect.  All the BTUs man has ever produced pale in comparison to the energy adsorbed from the sun in a few days (fun fact: the energy from the sub hitting the earth in an hour and a half has more energy in it than all energy used by humans in a year.  The sunlight hitting earth is 89,300 TeraWatts of energy).

Finally, the atmosphere isn't nearly as vast as you may believe and changes to it are easy to measure.  When put into scale of the earth, there is a tiny sliver of atmosphere.  The total volume of C02 is a known quantity:

- 3200 gigatons of C02, that's not much for the entire atmosphere - about .041% of the atmosphere.

- At the start of the industrial revolution, the CO2 concentration was 280ppm, ice core samples and other isolated pockets (such as lava) show that it was stable for ~10,000 years before that.

- Current concentrations are 403 PPM, and rising an average of 2ppm per year (that's a lot compared to how much there is).

- The best evidence suggests 400 ppm is the highest the earth has seen in more than 10 million years.

- Man made emissions of CO2 are about 10 gigatons per year

- Measurements of CO2 concentrations are accurate enough to see the effects of the growing season in the different hemispheres - as plants absorb C02.

- Water is able to absorb some CO2 (making it more acidic), but not nearly all of it.

There is no scientific doubt about the levels of CO2 or that they are rising.  There is no doubt about the greenhouse effect of CO2.  The questions that remain is what is the buffering ability of the oceans, how dependent are the currents on stable temperatures, and what the effects will be at different intervals of CO2 concentration and temperature (and other variables can come into play - changes to the sun, volcanic eruptions, snow coverage and other weather patters, etc.).  The facts don't care about human hubris, they don't care if most people think it is impossible.  They simply are.

http://calgary.rasc.ca/images/Earth_Atmosphere1.gif

http://www.sandia.gov/~jytsao/Solar%20FAQs.pdf

CO2 Summary: https://en.wikipedia.org/wiki/Carbon_dioxide_in_Earth%27s_atmosphere

Look Sonny, I know what I know and that's all that matters.  Don't try to school me on my personal recollections, whippersnapper. 

I'm not denying the thought and hypothesis of global warming didn't exist before 1990.  I believe I first heard of the theory late in elementary or early middle school in the late 1970's or early 1980's. You keep missing the simple point I've made that the GW community didn't really start gaining a lot of momentum until the 1990's with more funding and grooming a whole generation of climatologists dedicated specifically to that field of study nor was it at the forefront of the public conscience as it is today.  It didn't get much coverage outside of scientific journals or publications for general consumption like Popular Science or Popular Mechanics prior to the early 1990's. 

If greenhouse gasses trap heat in the atmosphere, that necessarily would have to include human-generated BTU's as some part of it.  As an immutable truth of physics, heat rises, correct?  I would also think that helps contribute to the heat island effect of large urban areas in addition to all the concrete and metal which reflect solar-generated heat.

If science has taught us anything it is that it is constantly evolving.  Old theories are disproven by new discoveries all the time.  The use of satellite data for climatological purposes is still very much, if not in its infancy, then it's in its teen years.  We did not have that kind of reliable global observation of temperatures 150, 100, or even 50 years ago nor did we have the sort of coordination of data between scientists globally like we do today.  We also are putting a lot of faith in scientists who interpret ice core data to be 100% accurate.  Again, science evolves.

[cannon_fodder]

Argh!  You're killing me  smalls.  Really, I think you actually want the info.  So I will keep supplying it...here is another knowledge dump!

- - -

BTUs do contribute.  I did the math, human produced BTUs contribute less than 0.02% of the heat energy on planet earth each year (also please recall that nearly all of the heat energy the planet has in a year is lost to space...that's why it cools down overnight.  The concern is the retention rate, which is why a "greenhouse effect" is a thing).  Happy to stand corrected, so I showed my work.

The sun's energy reaching the earth is 8.93x10^16 Watts per hour.  24 hours a day, 365 days a year.  That's 7.82268 X 10^20 Watts of power per year of energy from the sun reaching the earth.

Humans produce and used  1.575 x 10^17 watts of energy in an entire year.

So...   1.575x10^17 / 7.82268x10^20 = .000201338.  Subtract from that energy generated from the sun (solar etc.) or energy generated from geothermal.  Subtract from that the heat radiance of the earth itself.  Even if we adjust more for reflection of energy (likely offset by core energy), it seems safe to say less than 2 one hundredths of 1% of the heat is from made generated BTUs.  

Also worth noting, heat islands are not so much caused by the heat we generate, as they are by creating surfaces that more efficiently absorb and radiate solar radiation.

- - -

On the larger issue - my entire point is this:  global warming is as robust of a scientific consensus as anything else.  You can choose to believe "hey, it might change," but that same lack of logic could be applied to any scientific consensus.  It isn't an honest intellectual debate (it appears the theory is flawed because...), its an expression of cognitive dissonance.  People don't want to accept the conclusion, so they choose not to.  

More specifically to your points - yes, we have been coordinating global scientific efforts for centuries.  Recall Ben Franklin's kite experiment made him a household name in Europe.  National Academies of science have been publishing papers since before Isaac Newton "discovered" gravity.  Things got done before the internet.  

Also, we have been observing the earths weather for as long as there has been written records.  Tide, rain, and temperature most commonly.  The first weather satellite went up in 1960.  The standard thermometer was developed in 1709, the mercury thermometer in 1714 (well before the industrial revolution).  Of course before that we have records of the weather that are less accurate or reliable (it snowed today... or crop was killed by frost).  Many scientific fields use many methods to analyze temperatures way further back in time.  NASA has an entire webpage discussing the topic, but they use pollen, the presence of tropical fossils, or what animals lived there to get a general idea of climate (gee, Alaska used to be tropical).  To be more accurate you can look at the ice cores - chemistry tells us the precise temperature at which calcium carbonate is formed (the ratio of oxygen isotopes varies depending on temperature at formation, you can recreate the results i a lab).  So we can go back 1.5 million years with great accuracy (probably more accurate than John Q. reading it off a thermometer).

If we want to go back further than ice cores allow (as stated about 1.5 million years),  you need to find layers of sediment (or rock at this point) that were formed under water.  There are several species of tiny sea creatures (think chalk) that use calcium carbonate to form their shells. This isn't a "hey look, a snail lived here so it was 85 degrees!"  Remember, there is a known ratio in chemistry of different oxygen isotopes depending on the temperature when it bonded with the Calcium and Carbon.  The difficulty is getting rid of externalities in the data (most notably the O18 concentrations in the water during formation) when you go back further than 1.5 million years.

Many scientific fields contribute to the knowledge base.  Chemistry, physics, geology, even biology and archaeology.    This isn't some "guess" or "theory" that just sounds good.  The components that go into proving it are testable, repeatable, and explanatory.  Again, it is as sound of a scientific fact as you are likely to ever find.