We often hear from Greens, including very senior ones, that #HS2 is a climate disaster because it won’t be CO2-neutral for a long time. “120 years!” is quoted, “HS2’s own figures!”. One big problem with this: it isn’t true. Let’s take a look at HS2 and CO2... /1

HS2’s official position is that after 60 years #HS2 will either be slightly CO2-negative (if construction doesn’t improve its CO2 efficiency) or slightly CO2-positive (if it does). (The Oakervee review covers this: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/870092/oakervee-review.pdf - sections 5.30 to 5.37) /2

The modelling is covered in more detail in this document: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/568547/D25_WEB_C331_Sustainability_Statement_Including_Post_Consultation_Update_Volume_1_Main_Report_WEB_VERSION.pdf. We’ve extracted the numbers below from that. They consider 2 future scenarios - Scenario A in which electric cars and grid decarbonisation happen slowly, and a more optimistic B. /3

These charts summarise it. In red are things that emit GHG (mostly construction and operations) and in green things that save them (mostly journeys shifting from other modes, plus more rail freight). The final column shows the net position after 60 years. /4

We’ve shown the numbers for “Scenario B” - faster decarbonisation of the electricity grid and introduction of electric cars. The 2 charts show the without- and with-improvement of construction cases. Results: without improvement: net production 1.2 mTCO2e; with, net gain 4 mT. /5

(From work already done on HS2, we know that the actual construction emissions will probably be nearer the with-improvement case. @safemyth’s report - good read, recommended! - describes this: https://www.rail-leaders.com/wp-content/uploads/HSRIL-HS2-Towards-a-Zero-Carbon-Future-Report-Nov-19.pdf, p9) /6

So over 60 years #HS2 will be pretty much CO2 neutral, on their calculations. Just to give a sense of scale, even the no-improvement case is equivalent to less than 4 days’ worth of current UK road transport emissions! It’s a drop in the ocean. But there’s more... /7

Let’s have another look at where the CO2 savings come from. The main win comes from trips that would have been done by air shifting to HS2; next is getting lorries off the road through more rail freight on freed-up lines. There are 2 really important things to note about this. /8

Firstly, HS2’s forecasts of where #HS2 passengers come from show just 1% of them switching from air and 4% from car - see the chart (data: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/365065/S_A_1_Economic_case_0.pdf#page=85). These are ridiculously low compared to actual high speed rail elsewhere. Why is this? /9

The forecast method is known to be weak. It specifically excludes any factors that would favour rail over car or air ( we’ll do a thread on this). Even so, those few air passengers make a huge difference. (remember this from our earlier thread on why? https://twitter.com/Greens4HS2/status/1261082337342824449?s=20) /10

Imagine if we could double the share coming from air - that would be a massive CO2 win! Easily doable with Green transport policies: air taxes, frequent flyer levy, slot recapture, additional rail fare subsidies. Mainland Europe HS rail has much higher from-air percentage. /11

Secondly - all those passengers coming from existing rail are freeing up vital space on the network for new LOCAL train services. With Green policy support these trains can get thousands of people every day off the roads - that’s another CO2 win, not included in the figures! /12

(The plans for what to do with all that freed-up space are still being developed, but Midlands Connect have ambitious ones https://www.midlandsconnect.uk/media/1692/final-midlands-engine-rail-report.pdf - as do Transport for the North https://transportforthenorth.com/wp-content/uploads/TFTN_-_NPR_At_a_Glance.pdf). Green policy would maximise benefits to local people and CO2 saving. /13

It’s hard to work out exactly what the CO2 impact of Green policies could be on modal shift both on and off #HS2, but in a future thread we’ll do some simple modelling to see. It’s fair to say, though, that dismissing #HS2 as a CO2 disaster is wrong: it’s a huge opportunity. /14

And what about that 120 years thing? Well, the #HS2 figures actually show that in years 61-120 an additional 8.2 million tonnes of CO2 could be saved. So the overall picture looks like this chart - a CO2 gain of over 12 million tonnes over the life of HS2! /15

That so many Greens parrot the fake 120-years line without question shows how poorly thought-through our stance is. For a start, as we’ve shown, it’s not based on fact - it’s spin by the Stop HS2 campaign, copied by lazy commentators (and politicians) who don’t check. /16

Secondly, where’s the critical thought? Why are we not questioning so bald a statement? We should be asking what do we mean by “CO2 neutral”, what are the assumptions behind that number, how has it been calculated, what are the sources and can we trust them? /17

Thirdly, where’s the holistic thinking? Greens are supposed to be all about understanding the linkages and connectedness of all things. How can we just accept that something as fundamental as the CO2 impact of a transport scheme isn’t affected by a whole range of influences? /18

And finally, just stating it as fixed in stone betrays a complete failure to grasp how our own policies can impact #HS2’s CO2 and how we can turn it to our advantage - a shocking lack of political ambition. /19

So, a sorry tale of ignorance and naivety completely at odds with Green principles. To tackle transport CO2 we need radical change. Tinkering isn’t going to cut it at all. We’re bold and radical in other policy areas - why not be equally bold and use HS2 to further our own goals?

(Quite a lot of new readers of our threads - welcome to you! If you like this one, maybe take a look at some of the other #HS2 topics we've covered - the need for more rail capacity / ancient woodland / power consumption / aquifers. Start here: https://twitter.com/Greens4HS2/status/1269044170037039107?s=20)

And if you're a @TheGreenParty member and think we need a change in party policy on #HS2, read this bit, ask us questions and contact us directly if you wish - DMs are open. https://twitter.com/Greens4HS2/status/1257329232847519751?s=20

Addendum: what's included in HS2's CO2 modelling? We keep hearing that some source or other of CO2 is left out so the figures are suspect. Here, taken from the document that describes the modelling ( https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/259613/Volume5_Climate_Summary_carbon_calculation_outputs_CL-002-000.pdf), is a list of what's included:
Earthworks

Embankments and cuttings
Disposal of waste material
Change of land use (= clearing of trees and other vegetation)
Bridges and viaducts
Access and haul roads
Retaining walls
Tunnels
Tunnel boring machine operation
Stations and depots
Trains

For each of these categories, the calculation includes materials, transport of materials and people, and equipment.
Operational CO2 comes from:
Train electricity
Station electricity
Tunnel fans electricity
Maintenance of trains.
Most things seem to be covered!