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Comment by misja111 | Hacker News Reader

So 14 of the 15 hottest years ever have taken place since 2000. I'm wondering, if this is the result of global heating due to emissions, why do we see so many new record highs only now? The industrial revolution has been going on already for over 150 years. Why were there so few records broken in, say, 1980 - 1996, and so many in 2000 - 2016?

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I think you're misunderstanding the arithmetic. Take a look at https://en.wikipedia.org/wiki/Instrumental_temperature_recor...

The Nth "hottest years" are relative to the present day. So in the graph, it looks like 1981 would have been a record hot year - but now it's only the 30th (or whatever) hottest year.

If the graph were a completely smooth upward-sloping line, then you'd expect that 15 of the 15 hottest years would have been since 2000.

I find interesting, in that graph you are linking, that there is a spike in the years of the second world war.

It would be interesting to know if there is causality between human activity in those years and that spike.

Thanks for the chart. To me it still seems like we are missing something. If you look at the period of 1940 - 1980, then there was not really an upward or downward trend. But in the 36 years after 1980, the global temperature has been going up like crazy. Should all of that be attributed to statistical noise? To me it looks like some new factor has started to influence the climate in the recent years, whatever that factor may be.

The standard explanation is that aerosol emissions (soot and SO2) masked the warming during 1940-1980. Once environmental protections in the West kicked in, the warming due to CO2 has taken up.

When you put a kettle on a stove, it doesn't start boiling immediately. Double so if there is some ice floating in the kettle.

Similarly if you turn off the stove, the water will continue boiling for some time.

If you compare the rate of fossil fuel use over time, you'll find that that has also been accelerating tremendously. There are other factors involved, including particulate emissions (mostly from coal) which tended to repress warming trends.

From 1945 - 1975, fuel consumption was roughly doubling every decade. The rate of increase moderated slightly during the 1970s oil crises, but picked up afterward, with China's growth since 2000 being particularly troubling.

http://macaulay.cuny.edu/eportfolios/alternativeenergyinnewy...

Rather than eyeballing it, why not do a proper regression?

To me, it looks like a line going up from 1900 with a bump in 1940. But you don't have to take my word for it, there's piles and piles of data out there.

I'm not denying that the world has been heating up since 1900. I'm saying that during the last ca. 36 years it is suddenly going very much faster than it did before.

World CO2 emissions in 2014 were about 9.8 gigatonnes. The current concentration of atmospheric CO2 is about 400 parts per million. In 1980, the relevant figures were about 5.3 gigatonnes and 340ppm.

We've got the accelerator to the floor. It's no wonder that we're getting all the speeding tickets now.

Essentially, think compound interest, except carbon in the atmosphere. More carbon in the atmosphere causes and uses more carbon to combat this. Everyone using A/C is a good example. Also China and India are industrializing right now, at a scale we can't comprehend.

The problem is the accumulation of these emissions over decades. CO2 lingers in the atmosphere for roughly a century. Also, the recent industrialisation of countries like China means we are emitting more today than ever before.

> Why were there so few records broken in, say, 1980 - 1996 ?

Were there ? In 1980, it was the hottest year ever. But in 1996, that was the hottest year ever. And that trend continues.

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