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Zeke Hausfather

@hausfath

7 Jun

@FT

Hi Roger, while I agree that the new, more realistic scenarios adopted by the ECB are laudable, I do have some small qualms with your @FT op-ed.

1/4

https://twitter.com/RogerPielkeJr/status/1401940374470291458

@Nature

First, you suggest that our @Nature paper says "fossil fuel emissions would be about 25 Gt by 2100, under assumed 2019 policies and technologies." We argue that current policies (as reflected by the 2019 @IEA WEO) implied around 3C warming (similar to SSP2-4.5 or SSP4-6.0). 2/4

We did not, however, imply that the particular emission pathways in SSP2-4.5 or SSP4-6.0, which are characterized by near-term emission increases or late-century emissions declines are implied by current policies. Flat emissions are arguably more consistent, but who knows! 3/4

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Zeke Hausfather

@hausfath

7 Jun

@CopernicusECMWF

May global temps are out for the @CopernicusECMWF ERA5 dataset. It was the 5th warmest May on record, after 2020, 2016, 2017, and 2019.

May temperatures have risen around 0.7C in the past 40 years, and was 1.2C above the temperatures of the late 1800s. climate.copernicus.eu/surface-air-te…

With five months of the year under our belt, I estimate that 2021 will likely be somewhere between the 4th and 7th warmest since records began, and will be well in-line with the long-term warming trend:

Here is how my forecasts of 2021 temperatures from ERA5 have evolved as each month of the year has come in (and the ENSO forecast has been updated):

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Zeke Hausfather

@hausfath

25 May

@BerkeleyEarth

We often look at monthly or annual climate datasets, but daily data matters a lot for studying extremes. Using @BerkeleyEarth daily homogenized gridded data, I took a look at how the number of daily maximum and minimum records has changed over time:

To calculate how the number of records have changed over time, I looked at when the record low and high daily temperature over the 1880-2019 period was recorded in each grid cell for each day of the year, resulting in 365 days * 5498 gridcell max and min records.

If we look specifically at the contiguous US (e.g. excluding Alaska and Hawaii), we see a more pronounced set of 1930s daily maximum records corresponding to the dust bowl, but also see that the past decade (2010-2019) has set more daily maximum records.

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Zeke Hausfather

@hausfath

25 May

I often get asked about the role of behavior change vs technology in mitigating climate change.

But I find it hard to separate the two; we often forget that there is a virtuous cycle where technology enables behavior change, and behavior change accelerates technological change.

For example, dietary changes (reducing red meat consumption) are a hugely important behavioral change in an otherwise hard-to-decarbonize sector. But switching from beef hamburgers to black bean patties or tofu steaks is a hard sell for many folks.

@ImpossibleFoods

Now that we have meat alternatives like @ImpossibleFoods that taste nearly the same and can be used in the same recipes, the "costs" of behavioral change are much smaller. The same will happen as we transition from traditional beef steaks to lab-grown meats.

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Zeke Hausfather

@hausfath

21 May

@PopSci

Good post-mortem in @PopSci about the controversy over @ClimateEnvoy's remarks last week. He meant to say largely what the new IEA report says: that we will ultimately need to help bring technologies that are not mature today to market to reach net-zero.
popsci.com/environment/ne…

I suggested that a lot of the controversy stemmed from the fact that "People are sort of using this as a proxy for their own larger debates, be it futuristic techno fixes versus technologies that are available today, or large scale reforms of capitalism versus green growth."

@JesseJenkins

@JesseJenkins noted that “the challenge is less about invention and more about taking techs like CCS, air capture, biomass gasification, electrolysis – which are invented today and have been demonstrated at pilot or commercial scale – and making them cheap, mature, and scalable.”

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Zeke Hausfather

@hausfath

21 May

2021 is off to a cooler start, with the seventh warmest Jan-April period since records began in the mid-1800s.

That said, it is still warmer than 164 of the 171 years on record, showing just how much human activity has changed what seems normal. carbonbrief.org/state-of-the-c…

@CarbonBrief

Based on the first four months temperatures and the El Nino/La Nina forecast, @CarbonBrief estimates that annual 2021 temperatures also gave the best chance of ending up as the 7th warmest year on record – and its very likely to be somewhere between the fourth and ninth warmest.

We do not expect every year to set a new record in a warming world, as a lot of year-to-year variability is influenced by El Nino and La Nina cycles. The moderate La Nina event in late 2020 and early 2021 is contributing to cooler temperatures, though its is quickly fading:

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