Hacker News Reader

Comment by jhoechtl | Hacker News Reader

> During the Little Ice Age, which spanned roughly 1250 to 1860, average global temperatures dropped by as much as 3.6 degrees Fahrenheit.

Serious question: When we say mean annual temperature rose because of man-induced climate change, what is the time span we use for comparison?

View on HN

https://www.nature.com/articles/d41586-024-00281-8

> The Intergovernmental Panel on Climate Change (IPCC) uses a baseline for pre-industrial global mean temperatures that reference the earliest global instrumental temperature records. This period is around 1850–1900, when the first ship-based records of sea-surface temperatures became available.

I think you'll find the graph in the "Little Ice Age" Wikipedia page telling:

https://en.wikipedia.org/wiki/Little_Ice_Age

Hah, that graph perfectly answers his question. Thanks. :)

And that’s only to y2k, we’re another 0.5 degrees C above the graph now, in 20 years. Wheeee.

That focuses on global temperatures where the little ice age only really impacted Europe. Is there a graph like that for just the areas impacted by the little ice age?

I'm confused. The Smithsonian article says mean global temperature dropped as low as 3.6 F (2 C). The Wikipedia image shows mean global temperature dropped at most 0.5 C. What's the cause for this large discrepancy?

I'm always wary about weasel words like "As Much As", especially with no direct reference to see how the original data was presented. I always just assume that means "By the most optimistic possible reading of the data that furthers the goal of this article" - so it may be that the value from the most extreme single data point of minimum->maximum is 3.6f.

The wikipedia graph even states in the description that "Little Ice Age was not a distinct planet-wide period but a regional phenomenon" - though that again in turn doesn't seem to be directly stated in the referenced citation and editorialization too....

It might be confusing global temperatures with European temperatures. The article it references doesn't say global for the 2C figure and probably means regional temps. The European 2C makes sense, and the global 0.5C matches other sources.

Personally i like xkcd's take: https://xkcd.com/1732/ - it really puts the scale in perspective.

That is one of the most interesting and frightening graphs I've ever seen. Way more impactful than the hockeystick graph, all of our efforts over dozens if not hundreds of civilisations leading to this, quick end.

There are many layers of questions. At what percentage climate change is man made? What timeframe should we consider for the basis of measuring temprature changes? And so on.

Many countries changed from Julian to Gregorian calendar between 16th and 19th century.

When they did the switch - they skipped about 13 days (depends on when exactly they did it, for some it was 12 days).

And yes - the recorded monthly/quarterly/annual and hence min/max/avg temperature that we can find online [1] for the year particlar country switched is 0, NaN, YOLO, or maybe even negative ...

Hence combination of "average earth temperature" intially being set by just handfull of countries/records/rows would make you think that there was a small ice age, when it was just Christians (re)doing date math to catch up with actually natural seasons

PS [1] wife did some data analysis training during Covid lockdowns, students were given links to github "reference" annual temperature data and some outliers caught our attention

Why, of all the people who have researched this, is this the only time I’ve seen this theory and can’t find it anywhere online when I Google it.

Because it makes no sense. An event that took place over hundreds of years obviously can't be a math error due to a change in calendar on one specific year.

Reply on news.ycombinator.com