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Comment by ergothus | Hacker News Reader

Okay - help someone that doesn't truly understand this.

Earth's surface can gain heat through 4 ways I can think of (and this is just what I can think of and is likely wrong):

1) Geothermal brings more heat from core/mantle up. I don't think this is currently any larger than normal, nor do I imagine this varies much.

2) Oceans can give up heat they are storing and provide it on the surface. I don't know if El Nino is this, or if that just means "surface" ocean temperatures are up from whatever source.

3) Solar radiation (including infrared) can be higher than normal. I honestly have no idea if there's any significant variation in this, ever.

4) Earth can retain more heat that it was previously (global warming, be it man-made or not)

When they say the annual variation is usually hundredths of a degree, that sounds to me like 1-3 are generally non-factors, but that's all gut interpretation. Can someone with actual knowledge validate this?

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The Earth can only "gain" heat through #3, solar radiation. The other 3 items you list can store and release heat at a later time, but they can not generate more heat than they already possess now. (This is not strictly true, conversion of mass to energy, e=mc^2, means that nuclear and fusion energy could create new heat at the expense of matter, but we generally assume that on planets, this is negligible.)

So if people talk about "El Nino" increasing the temperature for the year, this is only possible because previous "La Nina" cycles decreased the temperature by an equivalent amount in previous years, and the oceans are returning the heat to the atmosphere.

Geothermal energy was stored back during the formation of the planet and there is generally just enough to keep the planet a few degrees above absolute zero. The energy released is highly variable though, volcanoes can release lots on one particular day, but then diminished activity for years follows.

>Geothermal energy was stored back during the formation of the planet

"Nuclear Fission Confirmed as Source of More than Half of Earth's Heat"

http://blogs.scientificamerican.com/observations/nuclear-fis...

That's talking about radioactive decay, not fission. The article doesn't do a great job distinguishing between the two, but it's _not_ talking about the process of splitting atoms.

>The new measurements suggest radioactive decay provides more than half of Earth's total heat, estimated at roughly 44 terawatts based on temperatures found at the bottom of deep boreholes into the planet's crust.

AFAIK nuclear fission also includes radioactive decay, which does split atoms, or at least part of atoms.

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

Not only is this pedantic in the context of whether Earth's geothermal energy is "stored" or "generated", it's also wrong. Fission is when an atom breaks into smaller pieces. What is it that you think happens in radioactive decay?

From Wikipedia, first line in the article: "...nuclear fission is either a nuclear reaction or a radioactive decay process in which the nucleus of an atom splits into smaller parts (lighter nuclei)."

Why would you assume that Scientific American got such an elementary thing wrong, then post it as an argument without even checking?

Fission is effectively catalyzed radioactive decay from neutrons at the right energy levels. There could be some differences in decay products, but simply waiting will eventually release that energy. http://www.mpoweruk.com/nuclear_theory.htm

Earth can only gain energy through stuff coming from space (solar radiation), but it can gain heat by converting energy stored in other forms.

The Earth's heat budget over geological time is 50% radiogenic..

That's why I specified "surface".

[not an expert] What you say is mostly correct. Two things though I think are critical and under-appreciated in understanding climate change:

1) rate of change & sixth mass extinction - many natural systems can adapt to gradual change over the course of many millennia but cannot to the incredibly rapid change our planet is now undergoing. this leads to loss of ecosystems & biomass which help to regulate our climate/CO2 levels

2) positive feedback loops - many systems are also at risk of destabilizing feedback loops, e.g melting ice increasing solar radiation absorption, ice sheets whose disintegration will accelerate with rising and warming oceans warming them from frontally and from below and moulins turning them into swiss cheese, potential permafrost melting w/ massive methane outgassing, etc.

The combination of these effects mean this is not a simple "calories in/out" type calculation, but a complex system geared towards maintaining equilibrium, which as we rapidly push further and further out of that equilibrium will face rising risks of a highly nonlinear, rapid shift to a dramatically new equilibrium climate the likes of which our planet has not seen since well before the dawn of our species.

Solar radiation is variable but it's pretty predictable. There's an 11-year sunspot cycle that accounts for most of that variation. https://en.wikipedia.org/wiki/Solar_cycle

Oceans so far have been storing heat, and keeping the average temperature increase down. No one knows how long that will continue. They also store a fair bit of CO2 which has lead to acidification. https://en.wikipedia.org/wiki/Ocean_acidification

I think this Ars Technica article does a better job of showing how short-term weather patterns like El Niño and La Niña cause variations from the overall trend https://arstechnica.com/science/2016/01/2015-was-official-th...

4) is the biggest, yes. 3) does vary a bit ("Maunder minimum"). 2) is the other way round - the oceans are a big stabiliser of temperature.

A subtlety of (4) is the feedback loops, especially involving water. Water vapor increases heat retention and is increased by heat, but this is where weather interacts with climate and it gets non-linear.

The actual quote was: “A lot of times, you actually look at these numbers, when you break a record, you break it by a few hundredths of a degree,"

So it's not clear if only record-setting years have small variation, or whether year-to-year is also very small variation.

Interesting analysis of the effects of various factors :http://www.bloomberg.com/graphics/2015-whats-warming-the-wor...

I second that. Any real climatologists on HN?

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