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NASA has one up to 2017. It does not look pretty. https://climate.nasa.gov/vital-signs/global-temperature/ https://climate.nasa.gov/vital-signs/global-temperat

NASA has one up to 2017. It does not look pretty. https://climate.nasa.gov/vital-signs/global-temperature/ https://climate.nasa.gov/vital-signs/global-temperature/

sgt101 9y ago
Thank you - perfect.
IncRnd 9y ago
My first question, looking at that graph, is "how does that graph calculate a global temperature for an entire year?" Do you know the actual source of the global temperature readings going back to 1880? Sure, the webpage says the dataset came from https://climate.nasa.gov/system/internal_resources/details/original/647_Global_Temperature_Data_File.txt https://climate.nasa.gov/system/internal_resources/details/o..., but where did they come from? These are the first 10 lines of the linked dataset, showing land and sea temperatures for the entire earth from 1880 to 1889. 1880 -0.19 -0.11 1881 -0.1 -0.14 1882 -0.1 -0.17 1883 -0.19 -0.21 1884 -0.28 -0.24 1885 -0.31 -0.26 1886 -0.32 -0.27 1887 -0.35 -0.27 1888 -0.18 -0.27 1889 -0.11 -0.26 I'm curious where this data originated - and that curiosity has nothing to do with belief in or disbelief of climate change.
- sgt101 9y ago
  I believe in climate change, but I am very much with you on the curiosity. Is this a long running carefully curated experiment or is this a case of data science - many experiments carefully integrated with confounding and conflating factors managed out of the picture?
  - SiempreViernes 9y ago
    The latter, its simply weather station data carefully examined, see my other comment. I guess you could do an actual global measurement if you put a satellite fairly far out with capable of measuring the IR and optical. Then you could define a black body effective temperature, but I'm not sure that straightforwardly tells us about surface temperatures.
    - sgt101 9y ago
      Thank you - this is a very nice case study.
- SiempreViernes 9y ago
  To be precise, these are global averages, so from this alone it is clear the numbers aren't measurements but rather the output of some analysis. The linked file is simply the analysis output, the source is the Goddard Institute for Space Studies, presumably their GISTEMP dataset (since that's the one about global average surface temperature). The original GISTEMP analysis is documented here: https://pubs.giss.nasa.gov/abs/ha00700d.html https://pubs.giss.nasa.gov/abs/ha00700d.html with later refinements found elsewhere on the GISS site. In brief they simply use weather station data, and build their global average from that. They also talk about change in the average rather than the absolute value, which makes sense since you are then much less sensitive to the absolute calibration error of each station. Then they do a lot of statistics on it to compensate for lack of coverage etc etc, read it yourself if 30 year old statistics papers are interesting to you.
  - IncRnd 9y ago
    Thank you for that, but if you look once more, you will see that you didn't answer my question.
    - Certhas 9y ago
      They did. As they said, they use (weather) station data + statistics to compensate for missing data. We have temperature records from weather stations going back to the 18th century. Just quickly googling I found this paper that works to make historical records usable for today: https://rmets.onlinelibrary.wiley.com/doi/full/10.1002/gdj3.11 https://rmets.onlinelibrary.wiley.com/doi/full/10.1002/gdj3.... "Daily observations of weather and climate for the province of Québec, Canada, start in the 18th century and continue to the present day. Daily temperature observations from 12 observers ranging from 1742 to 1873 are described here." That's why the 1880 forward data is different from other reconstructions going further back. These are measurement instruments by scientists recording temperature.
- Certhas 9y ago
  We have measurement stations that go back that far, and where we use the same instruments and methods today as back in the 19th century for the express purpose to have a data series that can be interpreted that far back. A concrete data set: https://crudata.uea.ac.uk/cru/data/temperature/ https://crudata.uea.ac.uk/cru/data/temperature/ This includes the following list of original source data: https://crudata.uea.ac.uk/cru/data/temperature/crutem4/station-data.htm https://crudata.uea.ac.uk/cru/data/temperature/crutem4/stati... So you see, a lot of things go into making that one number for 1880, and there are many stations going back much further than that. Updating these data sets is a massive, careful, effort.
- conistonwater 9y ago
  Nitpick: it's not a graph of "global temperature", it's a graph of temperature anomaly. The anomaly for a single site is the difference between the current temperature and the average for a fixed period in the past for that same site. Temperature would instead be the actual value of temperature. Calculating the average global temperature is rather more difficult (https://www.ncdc.noaa.gov/monitoring-references/faq/anomalies.php https://www.ncdc.noaa.gov/monitoring-references/faq/anomalie...). See https://earthobservatory.nasa.gov/Features/WorldOfChange/decadaltemp.php https://earthobservatory.nasa.gov/Features/WorldOfChange/dec... which I think also addresses your other questions.
  - IncRnd 9y ago
    Thank you.

NASA has one up to 2017. It does not look pretty. https://climate.nasa.gov/vital-signs/global-temperature/ https://climate.nasa.gov/vital-signs/global-temperature/

sgt101 9y ago

Thank you - perfect.

IncRnd 9y ago

My first question, looking at that graph, is "how does that graph calculate a global temperature for an entire year?" Do you know the actual source of the global temperature readings going back to 1880? Sure, the webpage says the dataset came from https://climate.nasa.gov/system/internal_resources/details/original/647_Global_Temperature_Data_File.txt https://climate.nasa.gov/system/internal_resources/details/o..., but where did they come from? These are the first 10 lines of the linked dataset, showing land and sea temperatures for the entire earth from 1880 to 1889. 1880 -0.19 -0.11 1881 -0.1 -0.14 1882 -0.1 -0.17 1883 -0.19 -0.21 1884 -0.28 -0.24 1885 -0.31 -0.26 1886 -0.32 -0.27 1887 -0.35 -0.27 1888 -0.18 -0.27 1889 -0.11 -0.26 I'm curious where this data originated - and that curiosity has nothing to do with belief in or disbelief of climate change.

sgt101 9y ago
I believe in climate change, but I am very much with you on the curiosity. Is this a long running carefully curated experiment or is this a case of data science - many experiments carefully integrated with confounding and conflating factors managed out of the picture?
- SiempreViernes 9y ago
  The latter, its simply weather station data carefully examined, see my other comment. I guess you could do an actual global measurement if you put a satellite fairly far out with capable of measuring the IR and optical. Then you could define a black body effective temperature, but I'm not sure that straightforwardly tells us about surface temperatures.
  - sgt101 9y ago
    Thank you - this is a very nice case study.
SiempreViernes 9y ago
To be precise, these are global averages, so from this alone it is clear the numbers aren't measurements but rather the output of some analysis. The linked file is simply the analysis output, the source is the Goddard Institute for Space Studies, presumably their GISTEMP dataset (since that's the one about global average surface temperature). The original GISTEMP analysis is documented here: https://pubs.giss.nasa.gov/abs/ha00700d.html https://pubs.giss.nasa.gov/abs/ha00700d.html with later refinements found elsewhere on the GISS site. In brief they simply use weather station data, and build their global average from that. They also talk about change in the average rather than the absolute value, which makes sense since you are then much less sensitive to the absolute calibration error of each station. Then they do a lot of statistics on it to compensate for lack of coverage etc etc, read it yourself if 30 year old statistics papers are interesting to you.
- IncRnd 9y ago
  Thank you for that, but if you look once more, you will see that you didn't answer my question.
  - Certhas 9y ago
    They did. As they said, they use (weather) station data + statistics to compensate for missing data. We have temperature records from weather stations going back to the 18th century. Just quickly googling I found this paper that works to make historical records usable for today: https://rmets.onlinelibrary.wiley.com/doi/full/10.1002/gdj3.11 https://rmets.onlinelibrary.wiley.com/doi/full/10.1002/gdj3.... "Daily observations of weather and climate for the province of Québec, Canada, start in the 18th century and continue to the present day. Daily temperature observations from 12 observers ranging from 1742 to 1873 are described here." That's why the 1880 forward data is different from other reconstructions going further back. These are measurement instruments by scientists recording temperature.
Certhas 9y ago
We have measurement stations that go back that far, and where we use the same instruments and methods today as back in the 19th century for the express purpose to have a data series that can be interpreted that far back. A concrete data set: https://crudata.uea.ac.uk/cru/data/temperature/ https://crudata.uea.ac.uk/cru/data/temperature/ This includes the following list of original source data: https://crudata.uea.ac.uk/cru/data/temperature/crutem4/station-data.htm https://crudata.uea.ac.uk/cru/data/temperature/crutem4/stati... So you see, a lot of things go into making that one number for 1880, and there are many stations going back much further than that. Updating these data sets is a massive, careful, effort.
conistonwater 9y ago
Nitpick: it's not a graph of "global temperature", it's a graph of temperature anomaly. The anomaly for a single site is the difference between the current temperature and the average for a fixed period in the past for that same site. Temperature would instead be the actual value of temperature. Calculating the average global temperature is rather more difficult (https://www.ncdc.noaa.gov/monitoring-references/faq/anomalies.php https://www.ncdc.noaa.gov/monitoring-references/faq/anomalie...). See https://earthobservatory.nasa.gov/Features/WorldOfChange/decadaltemp.php https://earthobservatory.nasa.gov/Features/WorldOfChange/dec... which I think also addresses your other questions.
- IncRnd 9y ago
  Thank you.