Robert McLachlan
@robertmclachlan.bsky.social
New Zealand mathematician, writing on climate & the environment at http://planetaryecology.org
Reposting this perennial favourite, "Coal Consumption Affecting Climate" from the Rodney & Otamatea Times (New Zealand) of 1912. Andrew Revkin (New York Times) brought it to wide attention in 2016. 🧵
December 29, 2025 at 8:18 PM
Reposting this perennial favourite, "Coal Consumption Affecting Climate" from the Rodney & Otamatea Times (New Zealand) of 1912. Andrew Revkin (New York Times) brought it to wide attention in 2016. 🧵
Reposted by Robert McLachlan
The strategic road network is managed by a charity and relies on the goodwill of land owners for access. Some motorways will be muddy and flooded each winter.
Also
The strategic road network stops randomly at council boundaries and investment is where councils are willing.
(UK edition).
Also
The strategic road network stops randomly at council boundaries and investment is where councils are willing.
(UK edition).
If car infrastructure was designed like bike infrastructure:
— motorists would have to end trip because “lane ends”
— they would have to give priority to airplanes
— they would have to drive longer because curvy road is more esthetic
— every time they drove, someone would say “you drove here”??
— motorists would have to end trip because “lane ends”
— they would have to give priority to airplanes
— they would have to drive longer because curvy road is more esthetic
— every time they drove, someone would say “you drove here”??
December 29, 2025 at 11:24 AM
The strategic road network is managed by a charity and relies on the goodwill of land owners for access. Some motorways will be muddy and flooded each winter.
Also
The strategic road network stops randomly at council boundaries and investment is where councils are willing.
(UK edition).
Also
The strategic road network stops randomly at council boundaries and investment is where councils are willing.
(UK edition).
Reposted by Robert McLachlan
New Zealand has just over 2 million households which makes a theoretical average rooftop capacity of 6.6GW which would generate ~8.5 TWh / year
Assumptions: 55% home roofs suitable for solar, assume 6kW solar system, 3.547 system performance per kW factor
Assumptions: 55% home roofs suitable for solar, assume 6kW solar system, 3.547 system performance per kW factor
December 29, 2025 at 1:15 AM
New Zealand has just over 2 million households which makes a theoretical average rooftop capacity of 6.6GW which would generate ~8.5 TWh / year
Assumptions: 55% home roofs suitable for solar, assume 6kW solar system, 3.547 system performance per kW factor
Assumptions: 55% home roofs suitable for solar, assume 6kW solar system, 3.547 system performance per kW factor
NZ solar power generation up 31% in 2023, 52% in 2024, 61% in 2025. Long may it continue. Still only 1.9% of total power generation to there is plenty of remaining scope.
The 4th quarter of 2025 is likely to come in at the lowest emissions and highest renewable proportion on record.
The 4th quarter of 2025 is likely to come in at the lowest emissions and highest renewable proportion on record.
December 27, 2025 at 10:33 PM
NZ solar power generation up 31% in 2023, 52% in 2024, 61% in 2025. Long may it continue. Still only 1.9% of total power generation to there is plenty of remaining scope.
The 4th quarter of 2025 is likely to come in at the lowest emissions and highest renewable proportion on record.
The 4th quarter of 2025 is likely to come in at the lowest emissions and highest renewable proportion on record.
"Backer LanzaTech, founded in Auckland in 2005, relocated to Skokie in 2014... [Trump so] LanzaJet shifted to ethanol from U.S. corn. “Maybe it’s a 10 or 20% improvement rather than a 50 or 60 or 70% improvement,” he says of initial CO2 reductions using corn ethanol."
Skokie, that rings a bell.
Skokie, that rings a bell.
MAGA-to-jet will not end well.
www.inc.com/fast-company...
www.inc.com/fast-company...
How This Sustainable Jet Fuel Company Is Charting a New Route in the Trump Era
LanzaJet aims to power planes without petroleum. Its first plant got caught up in politics—forcing a sudden retooling before it can begin producing sustainable aviation fuel.
www.inc.com
December 26, 2025 at 9:39 PM
"Backer LanzaTech, founded in Auckland in 2005, relocated to Skokie in 2014... [Trump so] LanzaJet shifted to ethanol from U.S. corn. “Maybe it’s a 10 or 20% improvement rather than a 50 or 60 or 70% improvement,” he says of initial CO2 reductions using corn ethanol."
Skokie, that rings a bell.
Skokie, that rings a bell.
In a few days' time NZ's first ever emissions budget period (2022-25), set up by the 2019 "Zero Carbon Act", ends. It will be a year before we get the full reckoning including methane & forests. But here are the fossil CO2 emissions for 2-year periods ending in September: [1/3]
December 26, 2025 at 8:37 PM
In a few days' time NZ's first ever emissions budget period (2022-25), set up by the 2019 "Zero Carbon Act", ends. It will be a year before we get the full reckoning including methane & forests. But here are the fossil CO2 emissions for 2-year periods ending in September: [1/3]
New Zealand just recorded its first-ever day of zero coal- or gas-fired electricity. In fact two days, 20 & 21 December. (Still some co-gen, about 1.8%.)
December 21, 2025 at 9:36 PM
New Zealand just recorded its first-ever day of zero coal- or gas-fired electricity. In fact two days, 20 & 21 December. (Still some co-gen, about 1.8%.)
Reposted by Robert McLachlan
That makes me feel very good. As it happens I’m on my way from Cambridge to the France/Spain border (stopping off in Paris) and will soon have completed a second flight-free year. Oslo to Rome sounds pretty cool.
December 20, 2025 at 10:52 PM
That makes me feel very good. As it happens I’m on my way from Cambridge to the France/Spain border (stopping off in Paris) and will soon have completed a second flight-free year. Oslo to Rome sounds pretty cool.
My 20-min talk on "Technological optimism", the absurd claim that tech change will solve all environmental problems. With "The Paradise Within Reach of All Men, Without Labour, By Powers of Nature & Machinery", Thoreau's reply, and the amazing Aerial Steam Carriage. www.youtube.com/watch
PLAN Seminar with Robert McLachlan (October 30, 2025)
YouTube video by Ahmed Afzaal
www.youtube.com
December 20, 2025 at 9:36 PM
My 20-min talk on "Technological optimism", the absurd claim that tech change will solve all environmental problems. With "The Paradise Within Reach of All Men, Without Labour, By Powers of Nature & Machinery", Thoreau's reply, and the amazing Aerial Steam Carriage. www.youtube.com/watch
Reposted by Robert McLachlan
We need subsidies to support people to get batteries. And mandatory solar on new home builds
December 20, 2025 at 5:26 AM
We need subsidies to support people to get batteries. And mandatory solar on new home builds
Although the winter months are not great for solar, the third quarter saw a terrific boost, especially in utility solar (farms)
Utility solar 41.2 GWh in Q2, 62.9 in Q3 (+53%)
Distributed 128 in Q2, 148.5 in Q3 (+16%)
Total up 25% for the quarter, 64% yoy.
Next two quarters will be sensational!
Utility solar 41.2 GWh in Q2, 62.9 in Q3 (+53%)
Distributed 128 in Q2, 148.5 in Q3 (+16%)
Total up 25% for the quarter, 64% yoy.
Next two quarters will be sensational!
December 20, 2025 at 2:11 AM
Although the winter months are not great for solar, the third quarter saw a terrific boost, especially in utility solar (farms)
Utility solar 41.2 GWh in Q2, 62.9 in Q3 (+53%)
Distributed 128 in Q2, 148.5 in Q3 (+16%)
Total up 25% for the quarter, 64% yoy.
Next two quarters will be sensational!
Utility solar 41.2 GWh in Q2, 62.9 in Q3 (+53%)
Distributed 128 in Q2, 148.5 in Q3 (+16%)
Total up 25% for the quarter, 64% yoy.
Next two quarters will be sensational!
Reposted by Robert McLachlan
Always nice to get a scientific poll to remind us that TalkBack radio and the Facebook comment section are not actually representative of public opinion
www.phcc.org.nz/briefing/pub...
www.phcc.org.nz/briefing/pub...
Public support for investing in urban cycleways outweighs opposition – National Survey | PHCC
While more New Zealanders support increasing investment in urban cycleways than oppose it, there remains a substantial proportion of people who are unsure or unengaged on this issue.
www.phcc.org.nz
December 19, 2025 at 1:05 PM
Always nice to get a scientific poll to remind us that TalkBack radio and the Facebook comment section are not actually representative of public opinion
www.phcc.org.nz/briefing/pub...
www.phcc.org.nz/briefing/pub...
What RNZ says: "Stats NZ data showed GDP rose 1.1 percent in the three months ended September, to be 1.4 percent higher than a year ago." www.rnz.co.nz/news/busines...
What StatsNZ say:
??? @musicalchairs.bsky.social?
What StatsNZ say:
??? @musicalchairs.bsky.social?
December 17, 2025 at 10:31 PM
What RNZ says: "Stats NZ data showed GDP rose 1.1 percent in the three months ended September, to be 1.4 percent higher than a year ago." www.rnz.co.nz/news/busines...
What StatsNZ say:
??? @musicalchairs.bsky.social?
What StatsNZ say:
??? @musicalchairs.bsky.social?
Like Simon Upton I am still hopping mad about the destruction of the Clean Car Standard. Thanks to Liz Kivi at Carbon News for opening up this article. www.carbonnews.co.nz/news/36339/n...
Transport
www.carbonnews.co.nz
December 15, 2025 at 11:13 PM
Like Simon Upton I am still hopping mad about the destruction of the Clean Car Standard. Thanks to Liz Kivi at Carbon News for opening up this article. www.carbonnews.co.nz/news/36339/n...
RNZ's report on the new glacier-loss study prompted me to check out the current state of Lake Tasman. Dramatic, especially from 2010-2012! Ironically RNZ use a file photo of tourists walking up the valley floor which is no longer possible.
www.rnz.co.nz/news/environ...
www.rnz.co.nz/news/environ...
December 15, 2025 at 8:12 PM
RNZ's report on the new glacier-loss study prompted me to check out the current state of Lake Tasman. Dramatic, especially from 2010-2012! Ironically RNZ use a file photo of tourists walking up the valley floor which is no longer possible.
www.rnz.co.nz/news/environ...
www.rnz.co.nz/news/environ...
Love to see NZ solar set record after record as we approach the summer solstice. 2114 MWh of utility solar on Sunday 14 December (enough for 63 million cups of tea, or 40 km of e-bike propulsion for everyone in the country), 99.6% renewable overall.
December 14, 2025 at 10:31 PM
Love to see NZ solar set record after record as we approach the summer solstice. 2114 MWh of utility solar on Sunday 14 December (enough for 63 million cups of tea, or 40 km of e-bike propulsion for everyone in the country), 99.6% renewable overall.
NZ emissions from fossil fuel burning, Q3 2025:
Electricity emissions are down (it rained!) but oil, gas, and coal are up, leaving total emissions down 0.7% for the quarter.
Annual emissions are down 6% for the year, but just 1.4% over two years.
Electricity emissions are down (it rained!) but oil, gas, and coal are up, leaving total emissions down 0.7% for the quarter.
Annual emissions are down 6% for the year, but just 1.4% over two years.
December 13, 2025 at 8:35 PM
NZ emissions from fossil fuel burning, Q3 2025:
Electricity emissions are down (it rained!) but oil, gas, and coal are up, leaving total emissions down 0.7% for the quarter.
Annual emissions are down 6% for the year, but just 1.4% over two years.
Electricity emissions are down (it rained!) but oil, gas, and coal are up, leaving total emissions down 0.7% for the quarter.
Annual emissions are down 6% for the year, but just 1.4% over two years.
Reposted by Robert McLachlan
This appears to be an equity issue, but it actually opens up speakers of marginalised languages to extractive practices that seek to siphon their culture and then sell it back to those users to benefit AI shareholders.
What if artificial intelligence looks at your language — and sees nothing? For millions of people, this is the daily reality of interacting with AI systems that simply do not understand the language they use to participate in public life, Sofia Olofsson writes.
When AI Can’t Understand Your Language, Democracy Breaks Down | TechPolicy.Press
Language equity in AI is not a niche fairness issue but rather a growing democratic fault line, Sofia Olofsson writes.
www.techpolicy.press
December 11, 2025 at 8:01 PM
This appears to be an equity issue, but it actually opens up speakers of marginalised languages to extractive practices that seek to siphon their culture and then sell it back to those users to benefit AI shareholders.
The NZ Ministry of Foreign Affairs and Trade is undertaking its triennial Strategic Foreign Policy Assessment.
Read Heidi O’Callahan’s submission at blog.planetaryecology.org/2025/12/11/n....
Submit at www.surveymonkey.com/r/J7J8P9V until 5pm 24/12/25.
Post yours in the comments.
Read Heidi O’Callahan’s submission at blog.planetaryecology.org/2025/12/11/n....
Submit at www.surveymonkey.com/r/J7J8P9V until 5pm 24/12/25.
Post yours in the comments.
December 11, 2025 at 2:34 AM
The NZ Ministry of Foreign Affairs and Trade is undertaking its triennial Strategic Foreign Policy Assessment.
Read Heidi O’Callahan’s submission at blog.planetaryecology.org/2025/12/11/n....
Submit at www.surveymonkey.com/r/J7J8P9V until 5pm 24/12/25.
Post yours in the comments.
Read Heidi O’Callahan’s submission at blog.planetaryecology.org/2025/12/11/n....
Submit at www.surveymonkey.com/r/J7J8P9V until 5pm 24/12/25.
Post yours in the comments.
Here is New Zealand's warming compared to the global average. We have more fluctuations (because smaller area) & possibly slightly faster warming recently. The estimate for 2025 does not include December which has already broken numerous records. See also: blog.planetaryecology.org/2024/08/28/g...
December 10, 2025 at 3:45 AM
Here is New Zealand's warming compared to the global average. We have more fluctuations (because smaller area) & possibly slightly faster warming recently. The estimate for 2025 does not include December which has already broken numerous records. See also: blog.planetaryecology.org/2024/08/28/g...
Reposted by Robert McLachlan
Wellington is a cycling city
December 9, 2025 at 6:33 PM
Wellington is a cycling city
Reposted by Robert McLachlan
Does weakening domestic action on climate change risk NZ being found in breach of international law? YES
Could other states take legal action against NZ for failing to comply with its international obligations? YES
By law scholar Karen Scott theconversation.com/nzs-rejectio...
Could other states take legal action against NZ for failing to comply with its international obligations? YES
By law scholar Karen Scott theconversation.com/nzs-rejectio...
NZ’s rejection of emission targets fuels risk of international law breach
The International Court has set out clear rules for addressing climate change – and the rights of states to take legal action against others for breaching them.
theconversation.com
December 6, 2025 at 8:06 AM
Does weakening domestic action on climate change risk NZ being found in breach of international law? YES
Could other states take legal action against NZ for failing to comply with its international obligations? YES
By law scholar Karen Scott theconversation.com/nzs-rejectio...
Could other states take legal action against NZ for failing to comply with its international obligations? YES
By law scholar Karen Scott theconversation.com/nzs-rejectio...
Based on data from January to October, I estimate that 2025 will be New Zealand's 3= warmest year, similar to what is expected globally (2nd or 3rd). The 2020s are proving to be extremely hot here even relative to the rest of the 21st century.
December 5, 2025 at 1:15 AM
Based on data from January to October, I estimate that 2025 will be New Zealand's 3= warmest year, similar to what is expected globally (2nd or 3rd). The 2020s are proving to be extremely hot here even relative to the rest of the 21st century.
Reposted by Robert McLachlan
Paywall lifted: A trove of briefings and Cabinet documents reveals the Govt was advised its new methane target is only consistent with warming of 2-2.7C (and possibly up to 4.5C).
Climate scientists have said 2.7C would represent 'unprecedented peril'.
newsroom.co.nz/2025/12/04/g...
Climate scientists have said 2.7C would represent 'unprecedented peril'.
newsroom.co.nz/2025/12/04/g...
Govt warned new methane target aligned with 'catastrophic' warming
Newly released documents reveal the Govt's new methane target is associated with 2.7C of warming – a level labelled 'catastrophic' by the UN.
newsroom.co.nz
December 4, 2025 at 9:42 PM
Paywall lifted: A trove of briefings and Cabinet documents reveals the Govt was advised its new methane target is only consistent with warming of 2-2.7C (and possibly up to 4.5C).
Climate scientists have said 2.7C would represent 'unprecedented peril'.
newsroom.co.nz/2025/12/04/g...
Climate scientists have said 2.7C would represent 'unprecedented peril'.
newsroom.co.nz/2025/12/04/g...
Reposted by Robert McLachlan
I. Just. Can't.
"It is our view that a detailed framework for post-2050 reductions and removals is best developed closer to 2050." - wrong. We need action now to avoid disaster in 2050.
www.rnz.co.nz/news/politic...
www.rnz.co.nz/news/politic...
Government rejects all of Climate Change Commission's emissions target recommendations
It comes despite a Climate Change Commission warning that New Zealand is being hit sooner and more severely than expected.
www.rnz.co.nz
December 3, 2025 at 10:02 PM
I. Just. Can't.