<p>I would estimate 0%, as long as we are considering the same types of models. See, climate models and in the regard that you may think of observations. Climate models aren't really initialized on observations of the system, but rather on inputs/forcings and mean state.</p>
<p>Observations of today's climate may validate the accuracy/tuneness of a climate model, but the types of observations used to run climate models may be different from what you expect. <a href="https://en.wikipedia.org/wiki/Thermometer#History" rel="nofollow noreferrer">For example, the thermometer was invented either near 10 AD or in the 17th century</a>, so it was obviously not a widespread invention then. Usually, those temperature measurements are taken as proxies, <a href="https://en.wikipedia.org/wiki/Proxy_(climate)" rel="nofollow noreferrer">such as the amount of oxygen isotope or atmospheric composition in ice cores</a>. So the answer to the climate skeptic is that it isn't just the temperature itself, but the modern day observations of temperature proxies that show past warming.</p>

CC BY-SA 4.0
2020-10-31T20:32:36.560Z
2020-10-31T20:32:36.560Z
BarocliniCplusplus
<p>&quot;In short, the question is basically from a climate change sceptic that goes like - &quot;Thermometers have gotten better and we are just measuring the true temperature and it's not that the world is warming up. So how can we accept climate change/global warming?&quot;</p>
<p>You could point them to the satellite datasets, which show that there has been significant warming since the late 1970s.</p>
<p><a href="https://i.sstatic.net/iTi8n.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/iTi8n.png" alt="enter image description here" /></a>(<a href="https://www.woodfortrees.org/plot/rss/plot/uah5/plot/uah6/plot/none" rel="nofollow noreferrer">source</a>)</p>
<p>You could point out that instrumental record has error bars that are published with the data that reflect the decrease in uncertainty over time, e.g.</p>
<p><a href="https://i.sstatic.net/QPB1K.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/QPB1K.png" alt="enter image description here" /></a></p>
<p>which makes it clear that the warming we have observed cannot be explained by the uncertainty.  The best group provide code and papers allowing any skeptic to check their methodology (although I can't find the link just at the moment).</p>
<p>Similarly, the uncertainties of paleoclimate proxy reconstructions are not able to explain the current warming either (especially the rate at which it is happening).</p>
<p><a href="https://i.sstatic.net/QEDfP.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/QEDfP.png" alt="enter image description here" /></a></p>
<p>Often the diagrams shown in the media do not include the uncertainty, but generally the uncertainties are stated in the original data sources.</p>

CC BY-SA 4.0
2020-11-02T14:45:04.170Z
2020-11-02T14:45:04.170Z
Dikran Marsupial
<p>The graphs you mention, with temperatures extending for centuries or even millennia, are actually not measurements from thermometers. They are based on <a href="https://en.wikipedia.org/wiki/Proxy_(climate)" rel="nofollow noreferrer">proxies</a> such as tree rings or ice cores, from which temperature is <em>estimated</em>, not <em>measured</em>. Of course this estimate is based on some measurable variable (tree ring width, for example), which itself has an uncertainty, but this uncertainty does not vary with time. If you analyse tree rings from a 1000 years old tree, measurements of width (or wood density) will be as accurate on the oldest rings than on the more recent ones, as all will be accomplished with the same, modern method.</p>

CC BY-SA 4.0
2020-11-02T10:10:09.733Z
2020-11-02T10:10:09.733Z
Jean-Marie Prival
<p>Often the graphs depicting the earth's historical temperature, the time axis extends well over couple of centuries. Also there are few that extends over thousands of years.</p>
<p>I wonder to what degree the measurement inaccuracies are taken into account while using these charts to communicate the ongoing climate change. Its a valid question that older temperature measurement suffer a higher error compared to modern day's methods.</p>
<p>Even the feared 2.5°C temperature rise over the industrial revolution time is a minute variation over centuries. To what degree has the climate models taken into account these measurement errors into account? (In short, the question is basically from a climate change sceptic that goes like - &quot;Thermometers have gotten better and we are just measuring the true temperature and it's not that the world is warming up. So how can we accept climate change/global warming?&quot;)</p>

CC BY-SA 4.0
2020-11-02T14:46:41.223Z
Hi, the title (which mention climate change models) is inconsistent with the body of the question (which is more about uncertainty in charts of observations)
Dikran Marsupial
CC BY-SA 4.0
2020-11-02T15:31:09.963Z
I felt the climate models tag made sense as I wanted to also discuss whether the uncertainties were taken into the climate forecast modelling and it's impact
karthikeyan
CC BY-SA 4.0
2020-11-02T16:32:59.600Z
Hi, the uncertainty in the observations has no impact on the climate forecasts using models.  The modellers often use 20th C climate for comparing models, but the observational uncertainty in the 20th century is pretty small (as shown in the second diagram in my answer).  It would probably be better to have two focused questions than one ambiguous one?
Dikran Marsupial
<climate-change><temperature><measurements><climate-models>
To what degree does historical measurement inaccuracies contribute to climate change models?
karthikeyan
# To what degree does historical measurement inaccuracies contribute to climate change models?

(Asked by: username_0 on 2020-10-31)

Often the graphs depicting the earth's historical temperature, the time axis extends well over couple of centuries. Also there are few that extends over thousands of years.

I wonder to what degree the measurement inaccuracies are taken into account while using these charts to communicate the ongoing climate change. Its a valid question that older temperature measurement suffer a higher error compared to modern day's methods.

Even the feared 2.5°C temperature rise over the industrial revolution time is a minute variation over centuries. To what degree has the climate models taken into account these measurement errors into account? (In short, the question is basically from a climate change sceptic that goes like - "Thermometers have gotten better and we are just measuring the true temperature and it's not that the world is warming up. So how can we accept climate change/global warming?")

**Tags:** climate-change, temperature, measurements, climate-models

> **Comments:**
> **username_1**: Hi, the title (which mention climate change models) is inconsistent with the body of the question (which is more about uncertainty in charts of observations)  
> **username_0**: I felt the climate models tag made sense as I wanted to also discuss whether the uncertainties were taken into the climate forecast modelling and it's impact  
> **username_1**: Hi, the uncertainty in the observations has no impact on the climate forecasts using models.  The modellers often use 20th C climate for comparing models, but the observational uncertainty in the 20th century is pretty small (as shown in the second diagram in my answer).  It would probably be better to have two focused questions than one ambiguous one?  

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## 3 answers

### Answer by username_2 on 2020-10-31. Score: 4

I would estimate 0%, as long as we are considering the same types of models. See, climate models and in the regard that you may think of observations. Climate models aren't really initialized on observations of the system, but rather on inputs/forcings and mean state.

Observations of today's climate may validate the accuracy/tuneness of a climate model, but the types of observations used to run climate models may be different from what you expect. [For example, the thermometer was invented either near 10 AD or in the 17th century](https://en.wikipedia.org/wiki/Thermometer#History), so it was obviously not a widespread invention then. Usually, those temperature measurements are taken as proxies, [such as the amount of oxygen isotope or atmospheric composition in ice cores](https://en.wikipedia.org/wiki/Proxy_(climate)). So the answer to the climate skeptic is that it isn't just the temperature itself, but the modern day observations of temperature proxies that show past warming.


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### Answer by username_1 on 2020-11-02. Score: 2

"In short, the question is basically from a climate change sceptic that goes like - "Thermometers have gotten better and we are just measuring the true temperature and it's not that the world is warming up. So how can we accept climate change/global warming?"

You could point them to the satellite datasets, which show that there has been significant warming since the late 1970s.

[![enter image description here](https://i.sstatic.net/iTi8n.png)](https://i.sstatic.net/iTi8n.png)([source](https://www.woodfortrees.org/plot/rss/plot/uah5/plot/uah6/plot/none))

You could point out that instrumental record has error bars that are published with the data that reflect the decrease in uncertainty over time, e.g.

[![enter image description here](https://i.sstatic.net/QPB1K.png)](https://i.sstatic.net/QPB1K.png)

which makes it clear that the warming we have observed cannot be explained by the uncertainty. The best group provide code and papers allowing any skeptic to check their methodology (although I can't find the link just at the moment).

Similarly, the uncertainties of paleoclimate proxy reconstructions are not able to explain the current warming either (especially the rate at which it is happening).

[![enter image description here](https://i.sstatic.net/QEDfP.png)](https://i.sstatic.net/QEDfP.png)

Often the diagrams shown in the media do not include the uncertainty, but generally the uncertainties are stated in the original data sources.


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### Answer by username_3 on 2020-11-02. Score: 0

The graphs you mention, with temperatures extending for centuries or even millennia, are actually not measurements from thermometers. They are based on [proxies](https://en.wikipedia.org/wiki/Proxy_(climate)) such as tree rings or ice cores, from which temperature is *estimated*, not *measured*. Of course this estimate is based on some measurable variable (tree ring width, for example), which itself has an uncertainty, but this uncertainty does not vary with time. If you analyse tree rings from a 1000 years old tree, measurements of width (or wood density) will be as accurate on the oldest rings than on the more recent ones, as all will be accomplished with the same, modern method.


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