Currently just 2 billion tons of CO2 are being removed by CDR per year, mostly through conventional methods like tree planting.

Let’s just pause to emphasise this point: no amount of R&D, innovation or technology will allow us to remove CO2 from the atmosphere without spending at least 191 kWh per tonne of CO2.

Most future climate scenarios envisage large-scale deployment of so-called “negative emissions,” where we suck CO2 out of the atmosphere in order to keep warming below 2°C. One proposed method for achieving that is “enhanced weathering”—accelerated silicate weathering done by grinding up silicate rock and spreading it on agricultural fields to react with CO2 from the air and fertilize plants at the same time. Brantley’s work shows that for such efforts to be successful, those fields would need a good supply of water and—crucially—would probably need to be plowed regularly to expose fresh minerals to the air. “If you're not going to be turning it over, you'll start to precipitate secondary minerals, and… most of the surface area could be occluded from reaction,” said Brantley.

first i think it's important to remember that net zero is a new phrase it's it's nothing we haven't had newton this language of net zero this framing of net zero is is something just appeared just in 00:11:54 the last few years if you look at the sr 1.5 report 2018 in the summary for policy makers then um it's mentioned 16 times if you look at the ar-5 the previous report from the ipcc and their synthesis report 00:12:06 for the summary for policy makers it's not mentioned once you look in the the committee on climate uk committee on climate change's sixth budget report and it's it's a long report 427 pages 00:12:18 it's on numerous times on every page it's somewhere between it's referred to somewhere between three thousand and five thousand times they use the expression net zero look at the previous fifth budget report from the committee on 00:12:31 climate change in 2015 it's not mentioned once now it is true to say that the language of net cumulative missions in various ways has been referred to if you like within the science but the appealing translation and the 00:12:44 ubiquitous use of net zero by everyone is a very new phenomena and one i think that we've taken on board unproblematically because it allows us to to basically um avoid near-term action on climate 00:12:57 change and we can hide all sorts behind it so it's important to recognize that net zero net zero 2050 net zero 20 20 45 for sweden firstly this is not based on the concept of a total carbon budget 00:13:10 and it's interesting note that the uk previously had legislation that was based on the total carbon budget for the uk as i mean i think the budget was too large but it was deemed to be an appropriate contribution to staying below 2 degrees centigrade but now 00:13:24 that's gone now we simply have this net zero 2050 framing so this whole language it moves the debate from what we need to do today which is what carbon budgets force us to 00:13:36 face it moves it off to some far-off point 2045 or 2050 which we have to think about that in which which policymakers in sweden and the uk will still be policymakers in 2045 and 50 they'll either be dead 00:13:49 or retired as indeed with the scientists that are behind a lot of this net zero language so it's in that sense it's we are passing that net zero is a is a generational passing of the challenge of the buck um to our children and our children's 00:14:02 children it's also worth bearing in mind that net zero typically assumes some sort of multi-layered form of substitution between different greenhouse gases so carbon dioxide for me thing between different sources 00:14:15 carbon dioxide from a car can be compared with agricultural fertilizer and nitrous oxide emissions but these these are very different things but across decades a flight carbon dioxide 00:14:27 from a flight we take today can be considered in relation to carbon capture in a tree that's planted in 2050 that's growing in 2070. this assumption within net zero that a ton is a ton is a ton regardless of different 00:14:40 chemistries different atmospheric lifetimes of the gases in the atmosphere and and different levels of certainty and indeed levels of risk and hugely different things this is this is incredibly dangerous and again it's another 00:14:52 it's another thing that makes net zero attractive and appealing in a machiavellian way because it allows us to hide all sorts of things behind this language of net zero the other thing about net zero is that 00:15:07 perhaps with no exceptions but typically anyway it relies on huge planetary scale carbon dioxide removal cdrs often well that's the latest acronym i'm sure there'll be another one out in the next year or two 00:15:20 um carbon dioxide removal captures two important elements first negative emission technologies nets as they're often referred to and second nature-based solutions um nbs so these two approaches one is sort of 00:15:32 using technology to remove carbon dioxide from the atmosphere and the other one is using various nature-based approaches like planting trees or peat bog restoration and things like this that are claimed to absorb carbon dioxide 00:15:45 and just to get a sense of the scale of negative emissions that's assumed in almost every single 1.5 and 2 degree scenario at the global level but indeed at national levels as well we're typically assuming hundreds of 00:15:57 billions of tons of carbon dioxide being absorbed from the atmosphere most of it is post 2050 and quite a lot of it is beyond 2100 again look at those dates who in the scientific community that's 00:16:09 promoting these who in the policy realm that's promoting these is going to be still at work working in 2015 and 2100 some of the early career researchers possibly some of the younger policymakers but most of us will 00:16:21 will say be dead or um or retired by them and just have another flavor if those numbers don't mean a lot to you what we're assuming here is that technologies that are today at best small pilot schemes will be 00:16:34 ramped up in virtually every single scenario to something that's that's akin to the current um global oil and gas industry that sort of size now that would be fine if it's one in ten scenarios or you know five and a 00:16:47 hundred scenarios but when virtually every scenario is doing that it demonstrates the deep level of systemic bias that we've got now that we've all bought into this language of net zero so it's not to outline my position on 00:16:59 carbon dioxide removal because it's often said that i'm opposed to it and that's simply wrong um i i would like just to see a well-funded research and development programs into negative emission technologies nature-based solutions and so forth 00:17:12 and potentially deploy them if they meet stringent sustainability criteria and i'll just reiterate that stringent sustainability criteria but we should mitigate we should cut our emissions today assuming that these carbon dioxide removal techniques of one 00:17:25 sort or another do not work at scale and another important factor to bear in mind here and there's a lot of double counting that gotham goes on here as far as i can tell anyway is that we're going to require some level of carbon 00:17:36 dioxide removal because there's going to be a lot of residual greenhouse gas emissions not you know not co2 principally methane and n2o nitroxites and fertilizer use um we're going to come from agriculture anyway if you're going to feed 9 billion 00:17:49 people now quite what those numbers are there's a lot of uncertainty but somewhere probably around 6 to 10 billion tons of carbon dioxide equivalent every single year so we'll have to find some way of compensating for the warming from feeding the world's population and certainly there are plenty of things we 00:18:01 can do with our food eating habits and with our agricultural practices but nonetheless it still looks like there will be a lot of emissions from the agricultural sector and therefore we need to have real zero emissions 00:18:14 from energy we cannot be using all of these other techniques nets mbs and so forth to allow us to carry on with our high energy use net zero has become if you like a policy 00:18:28 framework for all and some argue and there's been some question discussion in some of the um journalist papers around climate change recently saying well actually that's what it's one of its real strengths is it brings everyone together 00:18:40 but in my view it it's so vague that it seriously undermines the need for immediate and deep cuts and emissions so i can see some merit in a in an approach that does bring people together but if it sells everything out in that process then i think it's actually more 00:18:53 dangerous than it is of benefit and i think net zero very much falls into that category i just like to use the uk now as an example of why i come to that conclusion