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Comment by mrfusion | Hacker News Reader

(Disclaimer I believe in climate change with all my heart)

If methane levels are higher than we thought wouldn’t that make our climate models wrong? Ie less of a heating effect from co2?

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That would be true if methane had been higher than we thought all along. That's not the case, since it's not hard to measure the methane level.

What's happening is that the methane level is increasing faster than people expected. It could be from permafrost melting, or leaks from natural gas infrastructure, or various other things.

Which in turn means our models are probably underestimating heating going forward, since the total GHG will be higher in the future than predicted.

It would mean that a lower fraction of the heating effect we're observing is from CO2. However, if we've correctly estimated the impact of CO2, then that just means that there will be more absolute heating than we had otherwise predicted.

We’re both on the same side and I don’t want to seem like arguing within the team. But those two sentences seem to be contradictory?

I appreciate your civility, but it’s mildly disturbing hearing climate change advocacy being referred to as a team. I understand what you mean, but there shouldn’t be teams so much as many independent inquirers who come to the same conclusions

They aren't contradictory sentences. Methane is increasing faster than we expected it to. So, going forward, a higher % of warming will be due to methane than we expected before our recent methane measurements. This likely means more warming, as methane (CH4) is a much more potent warmer than CO2.

This is a confusing comment and not particularly responsive.

My statement is intended to be an isomorph of https://news.ycombinator.com/item?id=21026594 with a different emphasis. I'm sorry you found it confusing, but it is absolutely responsive, and I resent your accusation that it isn't. If you want to be helpful in the future, you could explain what about it you find confusing, and maybe the person you're responding to could clarify whatever point was previously unclear.

Methane is increasing now precipitously compared to the last couple of decades. We hit an inflection point apparently in the last couple of years.

Any model is going to have some things that are exogenous and some that are endogenous. Climate models usually don't try to predict how much carbon people are going to emit but simply say what the response of the climate is to our emissions under various scenarios. So if this methane is man-made they shouldn't be expected to predict it.

But also climate modeling is very hard. Nate Silver had a whole chapter on what climate scientists are up against in his book, The Signal and the Noise. They have to make due with very long feedback cycles and noisy data. We've known since Svante Arrhenius's work in 1895 that more carbon in the atmosphere will tend to lead to warmer temperatures. Since then we've developed complicated models trying to relate air temperature to sea temperature to water vapor in the atmosphere to plant growth and so on. But this is a very hard task. We know that complicated interactions are going on beyond the simple CO2->temperature model because of things like the weird warming pause in the 2000s before temperature roared back up to trend-lines. But so far we haven't been particularly successful at predicting deviations from the simple model.

This is scary because while we lucked into some climate buffering in the 2000s there's also the possibility of positive feedback loops that might get set off. Scientists have several in mind that might exist, they're trying to predict how much warming might set them off, but they really can't be sure when and/or if they might trigger.

One known possible positive feedback loop is methane release from the arctic. This is something of a known unknown, in that we know its possible but know that we don't have very good estimates of when it'll release and how much. Hence the people in the arctic. Hence people like the scientists in the article going up there trying to lessen the scope of the unknown. Given that methane levels are increasing we know something bad is happening. It might just be a burp before things settle again with most arctic methane staying locked away until global temperatures hit 4C over baseline or something. Or it might be about to get Very Bad right now. More research is required.

Thankfully methane only has a half life in the atmosphere before turning into CO2 and water of something like a dozen years so there might be hope of riding out a methane release, and slow releases can be managed. It's not CO2 which also has an a half-life in the air and oceans dues to rock weathering, but that half life is so long it's beyond any planning horizon we might have unless we start geoengineering to speed it up.

It’s a runaway reaction with a positive feedback loop feeding into itself. Current scientific opinion is that within a certain range, increases in temperature caused by CO2 emissions can trigger a negative feedback loop but beyond a certain horizon (which we passed long ago) and up to the point of a doomsday scenario, the warmer it gets the more it causes secondary results that directly contribute to accelerating CO2 and methane emissions. Melting of permafrost being a chief source of the latter, in this case.

there's a climate lag. also, methane isn't higher than we thought, it's just higher than we'd expect given what we know about energy production, so there's some hidden source somewhere.

>Disclaimer I believe in climate change with all my heart

Ridiculous that the subject has become so dogmatic that one must prostrate oneself before stating anything even potentially critical

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