Zeke Hausfather Profile picture
Climate scientist working on temp records, climate and energy system models. Director of Climate and Energy @TheBTI. Also: @CarbonBrief, @BerkeleyEarth. He/him.
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25 Feb
One of the best parts about writing for @CarbonBrief is the ability to do in-depth explainers about complex climate and energy issues. Here are a few of my favorites that I worked on over the years.

First up, explaining the shared socioeconomic pathways: carbonbrief.org/explainer-how-…
CMIP6, the next generation of climate models: carbonbrief.org/cmip6-the-next…
Understanding climate sensitivity: carbonbrief.org/explainer-how-…
Read 25 tweets
22 Feb
In recent months three different deep decarbonization scenarios have been produced from high-resolution grid integration models. In a new analysis at @TheBTI, my colleague @erikolsonn and I look at lessons they provide about what is needed: thebreakthrough.org/issues/energy/…

A thread: 1/19
The three models we examine are Princeton's Net Zero America (NZA) project (by @JesseJenkins et al), the @VibrantCE Zero By Fifty scenario, and results by a team of researchers led by Jim Williams at USF. 2/
All three take a deep-dive into how US could reach net-zero emissions by 2050, down to level of where each new generating facility might be located, where transmission lines would be built, and how electricity sources can meet hourly demand in different regions of the country 3/
Read 21 tweets
20 Feb
There is some truth in Gates's suggestion that making new clean energy tech cheap for can be more important than deploying existing clean tech.

But it neglects the fact that a big part of making clean tech cheap is deployment: driving economies of scale and learning-by-doing.
We should recognize the need to do both: accelerate the deployment of existing clean tech to further drive down costs (particularly for more nascent clean tech like EVs that are on the cusp of cost-competitiveness with fossil alternatives) AND dramatically scale up RD&D.
The quote in the original post is from @yayitsrob's excellent interview in the @TheAtlantic this week: theatlantic.com/science/archiv…
Read 5 tweets
18 Feb
Geoengineering is not a solution to climate change, and at best might be a "break the glass in case of emergency"-type bandaid to buy us time.

That said, I disagree with Bill here that small-scale research projects will "take the heat off" of the push for decarbonization. 1/5
Here is where I could see geoengineering playing a role: say, at some point in the future we have gotten our emissions under control, but climate sensitivity was high and we've locked in 2.5-3C warming even though we thought we would limit warming to 2C. 2/5
We discover some previously unknown planetary-scale climate feedback mechanism with hysteresis that will lead to substantial additional warming if temperatures remain >2.5C. We need to actively suck lots of CO2 from the atmosphere to get temperatures down to safe levels. 3/5
Read 5 tweets
17 Feb
There has been a lot of confusion over the drivers of the Texas blackouts. While more will become clear in the coming days, neither renewables nor insufficient gas capacity were the culprits. Rather, it was the lack of resiliency of to extreme cold conditions.

A thread: 1/9
Texas has seen an explosion of cheap wind power in recent years. Wind now produces around 20% of Texas' electricity. However, at the same time Texas has also been building a lot of gas capacity; gas generally works well with wind, able to quickly ramp up to fill in gaps. 2/
Because it is intermittent, the grid manager @ERCOT_ISO does not rely much on wind to meet extreme demand events such as the one we are experiencing right now. Rather, they have enough gas (and nuclear/coal) capacity on standby just in case high demand coincides with low wind. 3/
Read 9 tweets
15 Feb
Much of the US is experiencing extreme cold temperatures. But we should not read too much into this when it comes to climate change; its both not an unusual day for global temperatures, and there is not much evidence that climate change is making cold extremes more common.
We can see that while the US and part of Russia are exceptionally cold at the moment, other parts of the world have much warmer than average temperatures. A warming world is still one with regional weather variability!
At the same time, there has been a strong decrease in the number of extreme cold events in many parts of the world. Today's event feels so extreme in part because its become much rarer in recent decades. (@RARohde has a good graph of this, but I can't seem to dig it up)
Read 8 tweets
11 Feb
There has been a lot of discussion about negative emissions technologies (NETs) lately. While we need to be skeptical of assumed planetary-scale engineering and wary of moral hazard, we also need much greater RD&D funding to keep our options open. A quick thread: 1/10
Energy system models love NETs, particularly for very rapid mitigation scenarios like 1.5C (where the alternative is zero global emissions by 2040)! More problematically, they also like tons of NETs in 2C scenarios where NETs are less essential. 2/10
In model world the math is simple: very rapid mitigation is expensive today, particularly once you get outside the power sector, and technological advancement may make later NETs cheaper than near-term mitigation after a point. 3/10
Read 10 tweets
9 Feb
Quite the tour-de-force from @Sammy_Roth on what would actually be needed to get California to 100% clean energy by 2045 and the somewhat-telling unwillingness to build fast and big enough today: latimes.com/business/story…

A few highlights: 1/9
In response to rolling blackouts this summer, CA is extending the life of its natural gas plants. At the same time, however, it is failing to invest in clean firm generation to ultimately replace the role that gas plays on the grid, "sowing the seeds for the next crisis” 2/9
The CPUC is planning to would make a relatively weak 2030 of 25% emission reductions as the basis for approving or rejecting new transmission lines, likely leading to a substantial underinvestment in the magnitude of transmission needed for deep decarbonization. 3/9
Read 10 tweets
2 Feb
The National Academy of Sciences has a great new report on accelerating decarbonization of the US energy system, taking a deep look at what is needed to put us on track for net-zero by 2050. A few major takeaways: nap.edu/resource/25932… 1/5
1) Clean energy needs to scale up dramatically by 2030. This will require record-setting deployment of solar and wind technologies, get rid of all coal and some gas-fired power plants, and preserving operating nuclear plants and hydroelectric facilities where possible. 2/5
2) Zero-emission vehicles as 50% of new sales by 2030, prioritize heat pumps in homes and buildings (mandatory for most new construction) while increasing efficiency, start decarbonizing industrial processes/heat with low-carbon alternatives (hydrogen, CCS, adv nuclear) 3/5
Read 5 tweets
1 Feb
Ten years ago I made a bet with @BigJoeBastardi; he thought that the world would cool, while I projected it would warm. We settled on a paid dinner for me each year 0.1C above the prior decade avg (2001-2010) and for him each year 0.1C below, using UAH.

He now owes me 5 dinners
I had originally suggested a $10k bet, based on the past warming trend continuing, as I outlined here: rankexploits.com/musings/2011/b…
Joe countered in the comments that he was not willing to wager $10k, but was happy to make a bet around dinners. He suggested using UAH satellite troposphere data instead of surface temperature data, and making it relative to the prior decade's average:
Read 6 tweets
29 Jan
Meeting Paris Agreement climate targets will involve building a lot of big clean energy projects extremely quickly. We need to streamline permitting, remove barriers, and take the power away from NIMBYies to gum up the works if we want any hope of a rapid energy transition
We are talking about some large-scale land use changes happening in a 30-year timeframe; here is what the region around St. Louis might look like in 2050, for example:
Similarly, we will require a huge amount of new transmission to help balance out generation and demand in a high renewable future:
Read 5 tweets
28 Jan
A lot of time is wasted in oft-superficial debased about whether renewables or nuclear will be the key to decarbonization.

The reality is that both will play a key role in reaching our ambitious climate goals. Some new results by @VibrantCE show how.

A thread 1/10
Some of the most cutting edge research on how to integrate clean energy into the grid is done by @DrChrisClack and his team at @VibrantCE. They have done perhaps more than any other group in analyzing the important role that variable renewables can play.
They find – as do most others who build similar models – that wind and solar will be biggest driver of near-term power sector decarbonization. However, they do so using the huge amount of gas capacity we have to fill in the gaps. Heres capacity in their new zero-by-2050 scenario:
Read 11 tweets
28 Jan
Theres lots to be excited about with the new Biden climate EOs. But at the same time meaningful, durable climate policy will also require legislation.

In a new @TheBTI report we take a deep dive into policies that are both impactful and could become law: s3.us-east-2.amazonaws.com/uploads.thebre…
On the energy side some big ones are supercharging DOE loan authorizations to support early-stage clean energy companies, more funding for geothermal/carbon removal/small modular nuclear, grid modernization through a nationwide "supergrid", and extending support for renewables.
On the transport side, we argue for investing in expanded EV charging infrastructure and investments in ports and airports to reduce emissions, deal with maintenance backlogs and adapt to future climate changes:
Read 6 tweets
28 Jan
There was quite the epic energy twitter thread yesterday involving dozens of different folks. Unfortunately Twitter makes it rather difficult to read the whole thing, so I wanted to highlight one set of discussions for potential follow-up:
Based on a discussion of differences between @JesseJenkins's GenX model and @DrChrisClack's WIS:dom model, I brought up the idea of a CMIP-like process to compare outputs given a common set of inputs/scenarios, similar to whats done in EMF for IAMs today:
Jesse suggested that he is working with EDM to fundraise for something like this:
Read 9 tweets
27 Jan
Current commitments by Paris Agreement signatories are far from sufficient to get us to well-below 2C. But @ClimateEnvoy's statement today that Paris alone would lead to "3.7 to 4.5 degrees" C warming appears to be inaccurate. state.gov/special-guest-…

A thread: 1/4
When the Paris Agreement was first passed, a detailed analysis by @JoeriRogelj and colleagues in Nature found a best-estimate (50th percentile) warming of 2.9C (2.2C-3.5C) for unconditional NDCs and 2.7C (2.1C-3.2C) when including conditional NDCs: nature.com/articles/natur… 2/4
Similarly, the folks at @climateactiontr at the time estimated that that Paris commitments would result in around 2.7C (2.2C to 3.4C) if pledges and targets were met. At the time current policies led to ~3.6C warming, but today they only lead to ~2.9C reflecting progress made 3/4
Read 4 tweets
14 Jan
Remember the 15-year "hiatus" in global warming?

Turns out the last 15 years (2006-2020) were twice as far above the long term trend as the hiatus (1998-2012) was below it.

Lets not over-interpret short-term variability, but perhaps its time to start talking about acceleration Image
It is important to emphasize that some of the discussion of the "hiatus" was driven by observational data artifacts (lack of arctic coverage, biases due to the transition from ships to buoys for ocean measurements) that have now been corrected.
That said, there is growing evidence that the rate of warming has accelerated in recent years.

1970-2020: 0.19C per decade
1998-2012: 0.13C per decade
2006-2020: 0.31C per decade

The next few years will be quite important to watch.
Read 4 tweets
14 Jan
Our State of the Climate 2020 is live! carbonbrief.org/state-of-the-c…

⬆ Surface temps tied w/ 2016 as warmest
⬆ Record high land temps
⬆ Record ocean heat content
⬆ 1st or 2nd highest troposphere temps
⬆ Record high GHGs
⬆ Sea level
⬇ Glaciers
⬇ Sea ice
⬇ Likely 2021 temps
Global surface temps were between 1.2C and 1.3C above preindustrial levels across the various groups for 2020. NASA had it as the warmest, others have it as 2nd warmest, but in all cases the difference with 2016 (< 0.03C) is smaller than the measurement uncertainty (~0.05C): (2)
We also include a raw temp record based on GHCNv4 land data and ICOADS (HadSST3 raw) ocean data (black dashed line). It shows similar warming to preindustrial, and that warming since preindustrial does not depend on adjustments to the data. (3) carbonbrief.org/explainer-how-…
Read 22 tweets
12 Jan
Michael Mann has new book out – The New Climate War. I've coauthored papers in the past with Mike and respect his scientific and communications work. However, in his book he claims that my organization @TheBTI was "initially linked to the fossil fuel industry". This is false. (1)
Prior to the release of his book we reached out and sent the following letter to Mike, giving him the opportunity to correct the record. Unfortunately, as we never heard back we have decided to make it public: thebreakthrough.org/articles/lette… (2)
The @TheBTI has never accepted any money from the fossil fuel industry or industry employees. Mike suggests otherwise based on the fact that BTI once received some funding from the George and Cynthia Mitchell Foundation. thebreakthrough.org/about/who-we-a… (3)
Read 12 tweets
11 Jan
One of the under-appreciated aspects of the Chinese 2060 net-zero target is the massive spillover effects it would have on the rest of the world. An economy as large as China's mobilizing to decarbonize the entire economy would substantially drive down clean energy costs. 1/6
The recent IEA WEO 2020 predicts that global CO2 emissions will plateau around 2019 levels, but does not include recent net-zero targets. Including China's (via the Tsinghua University analysis) would lead to global emissions declining in coming years: 2/6
If China were to decarbonize while the rest of the world did nothing, it alone would drive global solar prices down by 65% and wind prices down by 17% assuming historical learning rates continue. These effects will be even more pronounced for nascent tech outside power sector 3/6
Read 6 tweets
7 Jan
If we can get emissions down to zero (or net-zero), the planet will likely stop warming. Good @guardian piece covering this issue – which is well understood by the scientific community but often missed in public discussions. theguardian.com/environment/20… 1/6
This is good news, because it means that warming that occurs this century is almost entirely under our control. We can decided how much CO2 and other greenhouse gases we emit, and the climate will respond accordingly. 2/6
However, the downside of this finding is that even if we get emissions all the way down to zero, temperatures will not fall, at least for the next few centuries. Without net-negative emissions climate change is largely irreversible. 3/6
Read 6 tweets
5 Jan
Lets clarify something about "committed warming". A world where concentrations of CO2 and other GHGs remain constant in the atmosphere is not the same as a world where emissions go to zero. The former has ~0.5C or more warming "in the pipeline", while the latter is closer to 0C.
If concentrations stay constant (e.g. atmospheric CO2 remains at 412 ppm indefinitely), the oceans continue to heat up for the next few millennia. The vast heat capacity of the deep oceans currently buffers warming, as some of the heat diffuses down to the deep ocean.
If emissions actually fall all the way to zero (or net-zero), atmospheric CO2 concentrations start declining. This mostly counteracts the warming in the pipeline as the oceans continue to warm to reach equilibrium. agupubs.onlinelibrary.wiley.com/doi/full/10.10… Image
Read 7 tweets