Sunday, June 04, 2017

US's Progress Towards Meeting Its Paris Commitment (= On Target)

So, most of the US's recent reductions in CO2 emissions are due to fracking, which has produced enough natural gas at a low enough price to outperform coal, leading utility managers to shutter coal plants.

I don't see why this won't continue, Paris Agreement or not -- it's pure economics. I estimated here that 70% of recent US CO2 reductions are due to fracking -- that is, not down to a deliberate shift to renewable energy sources or increases in energy efficiency, but simply due to getting the same amount X of energy from natural gas instead of coal.

This shift can't go on forever. I estimated here that at best this can lead to a US per capita CO2 emissions about 15 metric tons (t) CO2/yr. That's still huge, relative to the world, whose per capita emissions are about 5 t CO2/yr.

Obama got lucky with fracking. It grew during the end of the GW Bush administration, and progressed strongly throughout Obama's two terms. The US committed to a 26-28% reduction in 2005 CO2 emissions by 2025. Fracking has actually put us on that trendline:

Trump can try to affect the 30% of US CO2 reductions that come from nonfracking sources -- better gas mileage, more electric cars, some utilities' shifts towards wind and solar, and what else? -- but I don't really see how he will delay the transition of utility power sources from coal to natural gas. That will remain as long as natural gas is the cheaper source.

And is Trump really going to expect car manufacturers to build cars that get less gas mileage? No -- they're not just designing and building for the US, but for Europe too, and Asia. And to consumers who can afford new cars, who are more smart and level-headed.

It seems to me that at best Trump can delay some CO2 reductions -- though only a fraction of what the US emits. The other reductions are happening because it's finally economical for them to happen.

And because major US states want them to happen, because they see and understand the future in a way that completely eludes Trump.

So I think Trump's decision on the Paris Agreement -- probably based more on his psychological weaknesses, of needing to always play the victim, to think that everyone, everywhere is against him, which he clearly projects onto America -- might not be as bad as is currently feared. But in no way because of him.


JoeT said...

Great post David! Do you have any further plans to write this up for an article?

A couple of other questions if you don't mind. Does the CO2 emission include non-energy sources such as land use or the chemical process to create concrete? Are there reliable data as to CO2 emissions for China up to 2016 or so?

David in Cal said...

Nice post, David. I watched the President's press conference announcing this decision. He had a good, logical, detailed presentation. (I wonder who wrote it.) Anyhow, he presented several reasons for his decision, including:
1. The Paris agreement would have only a tiny impact on warming.
2. It puts significant economic costs on the US.
3. It treats the US more harshly than other countries.

David Appell said...

Thanks Joe. I tuned this up some and am trying to submit it for publication somewhere. So far no response from the Huffington Post -- perhaps they are too anti-Trump for this.

No, the CO2 emissions I quoted do not include land use changes, or concrete manufacturing.

The global data I posted go up thru 2012 -- from the World Resource Institute's CAIT database:

Am always looking for more up-to-date numbers; if you find any, please let me know. Thanks.

David Appell said...

Thanks, David in Cal, for your comments.

I agree with your #1.

But I don't agree with #2 and #3. The US emits huge amounts of CO2 per capita. We've already contributed to AGW at least twice as much as any other country. So we have a moral obligation, I believe, to take the lead in addressing this problem.

JoeT said...

David, I'll keep an eye out for more up-to-date emission data.

If you haven't seen it, I wanted to point you to Zeke Hausfather's article at CarbonBrief that came out today.

He shows a range of estimates of how much decrease in warming there would be with the Paris Accords compared to BAU. Most of the estimates are around 1C; Lomborg's is the sole estimate around 0.2 C because he assumes emissions after 2030 would go back to where they were before the agreement.

There is a link in Zeke's article that I think would interest you especially.

climate data analysis said...

Hey, JoeT --

I have heavily revised and expanded the discussion here of the elegantly simple temperature-vs-log-CO2 analyses:

CO2 vs temperature: background

CO2 versus temperature: examples

CO2 versus temperature: troposphere examples

I "discovered" an interesting coincidence involving this CO2/temperature relationship. Recall that the graph (or regression model) relates the base-2 log of CO2 to global mean temperature; the slope of the trend line is the change in temperature per doubling of CO2. That of course sounds a lot like climate sensitivity, but there are two caveats:

(1) CO2 is not the only forcing, so ascribing all the observed temperature change to it would be wrong.

(2) The method here is really showing a transient climate response (TCR) rather than equilibrium climate sensitivity (ECS); ECS should be larger than TCR because of lagged warming "in the pipeline".

Now here is the ultra-cool thing:

If you ignore stratospheric aerosol forcings (mostly intermittent short-term spikes from volcanoes), CO2 represents an average of 0.57 of the total forcing, over the period from 1950-present. This fraction varies a bit, but is surprisingly consistent.

According to Isaac Held (per a discussion from 2011), the median estimate of the ratio of TCR to ECS is ... 0.56.

0.56 is almost identical to 0.57 ... so those two "problems" basically cancel out. As a result, the graphical estimate of climate sensitivity from the CO2/temperature relationship really should be a pretty reasonable estimate of ECS, without the need for a lot of additional manipulation. Just divide the temperature change by the change in the base-2 log of CO2, and voila.

Anyway, it seems cool to me!

JoeT said...


I agree, very cool. I especially liked the graph by Held since I've seen different ratios of TCR to ECS and wondered why they weren't all the same. At least he gives us some idea what the spread is. I think you've made an extremely strong case that this method gives a very simple and reasonably accurate model of estimating future warming due to increased CO2 emissions. You have also given a very compelling argument that the slope is closer to ECS than to TCR. Very well written as well.

I'll give you my opinion of one particular strength of this approach. We pretty much know that there are people who won't buy any science argument at all --- a view put forth by Katherine Hayhoe among others. But there may be some who are still willing to be open to a clearly presented argument. There are those over at Spencer's site or WUWT who claim that there are no feedbacks --- or if there are feedbacks, they are negative! These are the people who think the climate sensitivity ranges from 0 to one at most. What you have shown is that even if you take the one outlier in the data sets beloved by deniers, UAH LT v6, you get a slope of 1.8 which is higher than the 1.2 one gets from CO2 only. Often times I challenge people to make such a plot themselves and convince themselves that there have to be net positive feedbacks in the system. Hello water vapor feedback.

A few other points I would make. You took the mean of the 4 RCP scenarios to project future warming ---- I guess I would have preferred just keeping them the way they are to convey a sense of how future CO2 emission might affect the global mean temperature by the end of the century. In fact, this could be a blog post --- compare your results to the IPCC model results. Another possible post could be on how the Paris accords affects future warming (as discussed in this thread). Does the simple model give results like Zeke Hausfather showed --- roughly 1 C decrease compared to BAU?

At one point you made a comment that CO2 represents 0.57 of the forcing then it would be 0.57 of the temperature change. I might suggest that this may not be immediately obvious for 2 reasons: 1) One might want to explain that taking the differential of the SB equation allows you to linearize the temperature/forcing relation 2) As shown in Marvel (2015) the temperature response to a forcing depends on what the forcing is, ie, aerosol and CO2 lead to different temperature responses even if the forcing is exactly the same.

Finally, I know one person in particular (besides David) who would write such a clear explanation with data files and references. We've posted on the same 'Forum' before, yes? If so, it's great that you're still active! I look forward to more of your posts.