4 ms·

Does anyone here knows what is the temperature value that we are comparing to? I cannot find that anywhere.

by luis_cho 3y ago

explaininjs 3y ago
[flagged]
- deleted 3y ago
  [deleted]
- dymk 3y ago
  > The 1.5 ºC number was chosen in an attempt to limit the severity of the impacts of warming, taking into account factors such as food security and extreme weather events.
  - explaininjs 3y ago
    [flagged]
- BobbyJo 3y ago
  If by made up you mean a chosen measured timeframe[1], sure. [1]https://climatepositions.com/global-warming-pre-industrial-temperature-baselines-measurements-and-the-2c-limit/ https://climatepositions.com/global-warming-pre-industrial-t...
  - explaininjs 3y ago
    Arbitrarily selected with little to no scientific basis. Check the siblings, it was some random “scientist” that pulled a number out of who knows where, under the consideration “politicians like limits and people tend to go over speed limits, so I said 1.5”. There’s no science to it, just fear mongering and grant seeking. When this happens in any other “scientific” field HN is quick to jump on it, but when it comes to climate change we love to toe the party line.
    - BobbyJo 3y ago
      1.5° was a good guess as to what we could achieve and what would avoid a good deal of harm. Was there a dictum from objective reality to stay below that threshold? No. It was mostly a cost benefit decision on the part of politicians and scientists. The baseline was chosen because it had good data and was prior to the vast majority of greenhouse gas emissions. Pretty much all baselines and goals are chosen to some extent based on circumstances and possibility. That doesn't make them arbitrary. using 1970 as a baseline would ruin the pre-industrial comparison. Aiming to say under 5° would be ridiculously dangerous.
      - explaininjs 3y ago
        > The baseline was chosen because it had good data and was prior to the vast majority of greenhouse gas emissions. We have data going back literal hundreds of thousands of years via ice cores. Of course if we picked that data the numbers would look incredibly dumb: depending on what 57 year chunk you took as “baseline” at we’d be a delta of anywhere from -2 to 8 degrees, and where exactly on that range we’d fall would vary more or less randomly with the time of the chunk’s start. We’re looking at the most minuscule (~100yr) chunk of 500,000 year time series and getting worried about its slope. It’s laughable. > Aiming to say under 5° would be ridiculously dangerous. Dangerous how? Because that’s the exact temperature range we were at ~0.4mya, and look how well we’re doing now! Civilization and everything. http://www.climatedata.info/proxies/ice-cores/ http://www.climatedata.info/proxies/ice-cores/
        BobbyJo 3y ago
        > We have data going back literal hundreds of thousands of years via ice cores. Of course if we picked that data the numbers would look incredibly dumb: depending on what 57 year chunk you took as “baseline” at we’d be a delta of anywhere from -2 to 8 degrees, and where exactly on that range we’d fall would vary more or less randomly with the time of the chunk’s start. You're ignoring that the thing we are trying to track/correct is man made warming. If that's the goal, what's a good anchor? How about the period where we have the most data prior to us causing warming? That'd be the late 19th century. Furthermore, that data going back hundreds of thousands of years is exactly the reason we know 5° Celsius would be dangerous: we are changing the planet faster than any of those records would indicate has happened previously, outside of massive extinction events. The speed of the change is as important as the degree, so reversing 400k years of cooling in a few hundred seems like an incredibly dangerous thing to do.
c0nfused 3y ago
It is 1850-1900 average per the article
- luis_cho 3y ago
  Ok but what is the value? Is there hard value like "15.4 degree celcius"?
  - jeffbee 3y ago
    Nobody ever expresses it that way because various sources of that baseline temperature have absolute offset errors and uncertainties, but with consistent methods you can ignore the absolute offset and work with the delta over historical average instead.
  - Lutger 3y ago
    Somewhere between 13 and 14.
sho_hn 3y ago
> Reflecting the long-term warming trend since pre-industrial times, observed global mean surface temperature (GMST) for the decade 2006–2015 was 0.87°C (likely between 0.75°C and 0.99°C) higher than the average over the 1850–1900 period (very high confidence). Estimated anthropogenic global warming matches the level of observed warming to within ±20% (likely range). Estimated anthropogenic global warming is currently increasing at 0.2°C (likely between 0.1°C and 0.3°C) per decade due to past and ongoing emissions (high confidence). https://www.ipcc.ch/sr15/chapter/spm/ https://www.ipcc.ch/sr15/chapter/spm/
revelio 3y ago
There are two ways to interpret your question: 1. If you mean what 1.5 degrees is above, it's an anomaly, which is defined as the difference from an average computed over a somewhat arbitrary time window. I think this one is defined as 1850-1900, which is defined as "pre industrial" times. Britain and America might disagree about that classification, but this is how it's done. 2. If you mean what 1.5 degrees is below, the answer is nothing. A 1.5 degree limit is a goal designed to motivate politicians. It's not justified by any particular research. It is discussed in this interview in Der Spiegel with an IPCC climatologist [1]: SPIEGEL: Why then have you, as one of the creators of the two-degree target, imposed such a magical limit to which all countries must slavishly adhere? Schellnhuber: Politicians like to have clear targets, and a simple number is easier to handle than a complex temperature range. Besides, it was important to introduce a quantitative orientation in the first place, which the 1992 Framework Convention on Climate Change managed to elegantly wangle its way out of. And let's be honest: Even if we aim for the two-degree target, we'll end up somewhat higher. Whenever there's a speed limit, most drivers tend to go a little faster. [...] And of course the world won't end if temperatures go up by 2.01 degrees, let alone end suddenly. From today's scientific perspective, we could possibly live with a warming of two to three degrees [1] https://www.spiegel.de/international/world/german-climatologist-on-criticism-of-ipcc-we-received-a-kick-in-the-pants-a-712113.html https://www.spiegel.de/international/world/german-climatolog...
- luis_cho 3y ago
  It's not the goal but the value itself (1). It's strange that we don't a value but a definition of a value. I totally understand that we need a target to motivate politicians (sad but true).
  - revelio 3y ago
    The problem is that for every politician you motivate by making things up, you also motivate another politician to stop listening to scientists in general. Maybe those other politicians are out of power at the moment, or not even in politics yet at all, but that can change. It's a recipe for deepening the divisions in society. And if / when those other politicians do gain power, they may lash out at the people who were manipulating them.
mensetmanusman 3y ago
"The year 2022 was the sixth warmest year since global records began in 1880 at 0.86°C (1.55°F) above the 20th century average of 13.9°C (57.0°F)." https://www.ncei.noaa.gov/access/monitoring/monthly-report/global/202213#:~:text=Updated%20NOAAGlobalTemp%20dataset-,Global%20Temperatures,C%20(57.0°F) https://www.ncei.noaa.gov/access/monitoring/monthly-report/g....
- luis_cho 3y ago
  Thanks, raising 1,5 degrees on a average of 13,9 it's really a lot. In my opinion the only way to slow down involves changing this growth oriented economy. I hope the EU conference "Beyond growth" is a start of a new movement.
  - bobbylarrybobby 3y ago
    You can't look at temperatures like that. 1.5° is a lot but as a ratio it's meaningless (what if the average temperature were 0?). You'd have to convert to Kelvin. But I'm not even sure ratios matter here. The earth is a sensitive system and the amount of change it takes to knock it out of wack is peculiar to it. I don't think you can just look at ratios of (absolute) temperatures.
    - revelio 3y ago
      > The earth is a sensitive system How sensitive exactly is called equilibrium climate sensitivity (ECS). Climatologists compute it using global climate models and different climatology groups have different models, so they produce different numbers. Unfortunately the span is wide and has been getting wider with time as the simulations become more detailed, so confidence in this value has been falling. This isn't meant to happen and we're rarely directly told it is, actually we're told the opposite (that there is consensus on everything). IPCC 2013 AR5: "No best estimate for equilibrium climate sensitivity can now be given because of a lack of agreement on values across assessed lines of evidence". The most recent IPCC reports try to solve this by de-weighting the models that compute a high ECS i.e. a highly sensitive climate. They do this because they know the models must be wrong, as they conflict with observational data. The climate can't actually be all that sensitive to CO2 relative to what some climatologists try to claim. Unfortunately most climatological research does not do this and assumes all models are equally valid, so justs averages all of them. It's clearly not valid when error bars are so wide. Also, this situation leads to the obvious question of why not simply compute ECS from observed data to begin with? Unfortunate answer: because if you do, you get a very low value indeed (see the work of Lewis). With ECS values that low CO2 stops being a significant environmental problem and is probably less important than other environmental problems like e.g. clean rivers, biodiversity. Climatologists don't like to do this and prefer to continue deriving values from models, even though they know that at least some of them cannot be correct. tl;dr - what you state as fact is actually one of the most bitterly argued and controversial aspects of climate science. They have a way to express it numerically but nobody can agree what the right number is.

Does anyone here knows what is the temperature value that we are comparing to? I cannot find that anywhere.

explaininjs 3y ago

[flagged]

deleted 3y ago
[deleted]
dymk 3y ago
> The 1.5 ºC number was chosen in an attempt to limit the severity of the impacts of warming, taking into account factors such as food security and extreme weather events.
- explaininjs 3y ago
  [flagged]
BobbyJo 3y ago
If by made up you mean a chosen measured timeframe[1], sure. [1]https://climatepositions.com/global-warming-pre-industrial-temperature-baselines-measurements-and-the-2c-limit/ https://climatepositions.com/global-warming-pre-industrial-t...
- explaininjs 3y ago
  Arbitrarily selected with little to no scientific basis. Check the siblings, it was some random “scientist” that pulled a number out of who knows where, under the consideration “politicians like limits and people tend to go over speed limits, so I said 1.5”. There’s no science to it, just fear mongering and grant seeking. When this happens in any other “scientific” field HN is quick to jump on it, but when it comes to climate change we love to toe the party line.
  - BobbyJo 3y ago
    1.5° was a good guess as to what we could achieve and what would avoid a good deal of harm. Was there a dictum from objective reality to stay below that threshold? No. It was mostly a cost benefit decision on the part of politicians and scientists. The baseline was chosen because it had good data and was prior to the vast majority of greenhouse gas emissions. Pretty much all baselines and goals are chosen to some extent based on circumstances and possibility. That doesn't make them arbitrary. using 1970 as a baseline would ruin the pre-industrial comparison. Aiming to say under 5° would be ridiculously dangerous.
    - explaininjs 3y ago
      > The baseline was chosen because it had good data and was prior to the vast majority of greenhouse gas emissions. We have data going back literal hundreds of thousands of years via ice cores. Of course if we picked that data the numbers would look incredibly dumb: depending on what 57 year chunk you took as “baseline” at we’d be a delta of anywhere from -2 to 8 degrees, and where exactly on that range we’d fall would vary more or less randomly with the time of the chunk’s start. We’re looking at the most minuscule (~100yr) chunk of 500,000 year time series and getting worried about its slope. It’s laughable. > Aiming to say under 5° would be ridiculously dangerous. Dangerous how? Because that’s the exact temperature range we were at ~0.4mya, and look how well we’re doing now! Civilization and everything. http://www.climatedata.info/proxies/ice-cores/ http://www.climatedata.info/proxies/ice-cores/
      - BobbyJo 3y ago
        > We have data going back literal hundreds of thousands of years via ice cores. Of course if we picked that data the numbers would look incredibly dumb: depending on what 57 year chunk you took as “baseline” at we’d be a delta of anywhere from -2 to 8 degrees, and where exactly on that range we’d fall would vary more or less randomly with the time of the chunk’s start. You're ignoring that the thing we are trying to track/correct is man made warming. If that's the goal, what's a good anchor? How about the period where we have the most data prior to us causing warming? That'd be the late 19th century. Furthermore, that data going back hundreds of thousands of years is exactly the reason we know 5° Celsius would be dangerous: we are changing the planet faster than any of those records would indicate has happened previously, outside of massive extinction events. The speed of the change is as important as the degree, so reversing 400k years of cooling in a few hundred seems like an incredibly dangerous thing to do.

c0nfused 3y ago

It is 1850-1900 average per the article

luis_cho 3y ago
Ok but what is the value? Is there hard value like "15.4 degree celcius"?
- jeffbee 3y ago
  Nobody ever expresses it that way because various sources of that baseline temperature have absolute offset errors and uncertainties, but with consistent methods you can ignore the absolute offset and work with the delta over historical average instead.
- Lutger 3y ago
  Somewhere between 13 and 14.

sho_hn 3y ago

> Reflecting the long-term warming trend since pre-industrial times, observed global mean surface temperature (GMST) for the decade 2006–2015 was 0.87°C (likely between 0.75°C and 0.99°C) higher than the average over the 1850–1900 period (very high confidence). Estimated anthropogenic global warming matches the level of observed warming to within ±20% (likely range). Estimated anthropogenic global warming is currently increasing at 0.2°C (likely between 0.1°C and 0.3°C) per decade due to past and ongoing emissions (high confidence). https://www.ipcc.ch/sr15/chapter/spm/ https://www.ipcc.ch/sr15/chapter/spm/

revelio 3y ago

There are two ways to interpret your question: 1. If you mean what 1.5 degrees is above, it's an anomaly, which is defined as the difference from an average computed over a somewhat arbitrary time window. I think this one is defined as 1850-1900, which is defined as "pre industrial" times. Britain and America might disagree about that classification, but this is how it's done. 2. If you mean what 1.5 degrees is below, the answer is nothing. A 1.5 degree limit is a goal designed to motivate politicians. It's not justified by any particular research. It is discussed in this interview in Der Spiegel with an IPCC climatologist [1]: SPIEGEL: Why then have you, as one of the creators of the two-degree target, imposed such a magical limit to which all countries must slavishly adhere? Schellnhuber: Politicians like to have clear targets, and a simple number is easier to handle than a complex temperature range. Besides, it was important to introduce a quantitative orientation in the first place, which the 1992 Framework Convention on Climate Change managed to elegantly wangle its way out of. And let's be honest: Even if we aim for the two-degree target, we'll end up somewhat higher. Whenever there's a speed limit, most drivers tend to go a little faster. [...] And of course the world won't end if temperatures go up by 2.01 degrees, let alone end suddenly. From today's scientific perspective, we could possibly live with a warming of two to three degrees [1] https://www.spiegel.de/international/world/german-climatologist-on-criticism-of-ipcc-we-received-a-kick-in-the-pants-a-712113.html https://www.spiegel.de/international/world/german-climatolog...

luis_cho 3y ago
It's not the goal but the value itself (1). It's strange that we don't a value but a definition of a value. I totally understand that we need a target to motivate politicians (sad but true).
- revelio 3y ago
  The problem is that for every politician you motivate by making things up, you also motivate another politician to stop listening to scientists in general. Maybe those other politicians are out of power at the moment, or not even in politics yet at all, but that can change. It's a recipe for deepening the divisions in society. And if / when those other politicians do gain power, they may lash out at the people who were manipulating them.

mensetmanusman 3y ago

"The year 2022 was the sixth warmest year since global records began in 1880 at 0.86°C (1.55°F) above the 20th century average of 13.9°C (57.0°F)." https://www.ncei.noaa.gov/access/monitoring/monthly-report/global/202213#:~:text=Updated%20NOAAGlobalTemp%20dataset-,Global%20Temperatures,C%20(57.0°F) https://www.ncei.noaa.gov/access/monitoring/monthly-report/g....

luis_cho 3y ago
Thanks, raising 1,5 degrees on a average of 13,9 it's really a lot. In my opinion the only way to slow down involves changing this growth oriented economy. I hope the EU conference "Beyond growth" is a start of a new movement.
- bobbylarrybobby 3y ago
  You can't look at temperatures like that. 1.5° is a lot but as a ratio it's meaningless (what if the average temperature were 0?). You'd have to convert to Kelvin. But I'm not even sure ratios matter here. The earth is a sensitive system and the amount of change it takes to knock it out of wack is peculiar to it. I don't think you can just look at ratios of (absolute) temperatures.
  - revelio 3y ago
    > The earth is a sensitive system How sensitive exactly is called equilibrium climate sensitivity (ECS). Climatologists compute it using global climate models and different climatology groups have different models, so they produce different numbers. Unfortunately the span is wide and has been getting wider with time as the simulations become more detailed, so confidence in this value has been falling. This isn't meant to happen and we're rarely directly told it is, actually we're told the opposite (that there is consensus on everything). IPCC 2013 AR5: "No best estimate for equilibrium climate sensitivity can now be given because of a lack of agreement on values across assessed lines of evidence". The most recent IPCC reports try to solve this by de-weighting the models that compute a high ECS i.e. a highly sensitive climate. They do this because they know the models must be wrong, as they conflict with observational data. The climate can't actually be all that sensitive to CO2 relative to what some climatologists try to claim. Unfortunately most climatological research does not do this and assumes all models are equally valid, so justs averages all of them. It's clearly not valid when error bars are so wide. Also, this situation leads to the obvious question of why not simply compute ECS from observed data to begin with? Unfortunate answer: because if you do, you get a very low value indeed (see the work of Lewis). With ECS values that low CO2 stops being a significant environmental problem and is probably less important than other environmental problems like e.g. clean rivers, biodiversity. Climatologists don't like to do this and prefer to continue deriving values from models, even though they know that at least some of them cannot be correct. tl;dr - what you state as fact is actually one of the most bitterly argued and controversial aspects of climate science. They have a way to express it numerically but nobody can agree what the right number is.