Category Archives: Uncategorized

Why herd immunity to COVID-19 is reached much earlier than thought – update

By Nic Lewis

I showed in my May 10th article Why herd immunity to COVID-19 is reached much earlier than thought that inhomogeneity within a population in the susceptibility and in the social-connectivity related infectivity of individuals would reduce, in my view probably very substantially, the herd immunity threshold (HIT), beyond which an epidemic goes into retreat. I opined, based on my modelling, that the HIT probably lay somewhere between 7% and 24%, and that evidence from Stockholm County suggested it was around 17% there, and had been reached. Mounting evidence supports my reasoning.[1]

I particularly want to highlight an important paper published on July 24th “Herd immunity thresholds estimated from unfolding epidemics” (Aguas et al.).[2] The author team is much the same as that of the earlier theoretical paper (Gomes et al.[3]) that prompted my May 10th article. Continue reading

The progress of the COVID-19 epidemic in Sweden: an analysis

By Nic Lewis

The course of the COVID-19 pandemic in Sweden is of great interest, as it is one of very few advanced nations where no lockdown order that heavily restricted people’s movements and other basic freedoms was imposed. As there has been much comment, some of it ill-informed, on how the COVID-19 epidemic has developed in Sweden, but relatively little detailed analysis published in English, it is worth exploring what their excellent publicly-available data reveal. Continue reading

Did lockdowns really save 3 million COVID-19 deaths, as Flaxman et al. claim?

By Nic Lewis

Key points about the recent Nature paper by Flaxman and other Imperial College modellers

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Mass spectrometry and climate science. Part I: Determining past climates

by Roland Hirsch

Mass spectrometry is essential for research in climate science.

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Covid discussion thread: Part VIII

by Judith Curry

Interesting papers that I’ve recently spotted

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When does government intervention make sense for COVID-19?

By Nic Lewis

Introduction

I showed in my last article that inhomogeneity within a population in the susceptibility and infectivity of individuals would reduce the herd immunity threshold, in my view probably very substantially, and that evidence from Stockholm County appeared to support that view. In this article I will first provide other evidence pointing to such population inhomogeneity being very considerable. I will then go on to consider how the overshoot of infections beyond the herd immunity threshold could be reduced. Continue reading

Why herd immunity to COVID-19 is reached much earlier than thought

By Nic Lewis

Introduction

A study published in March by the COVID-19 Response Team from Imperial College (Ferguson20[1]) appears to have been largely responsible for driving government actions in the UK and, to a fair extent, in the US and some other countries. Until that report came out, the strategy of the UK government, at least, seems to have been to rely on the build up of ‘herd immunity’ to slow the growth of the epidemic and eventually cause it to peter out. Continue reading

A sensible COVID-19 exit strategy for the UK

By Nic Lewis

The current approach

A study by the COVID-19 Response Team from Imperial College (Ferguson et al. 2020[i]) appears to be largely responsible for driving UK government policy actions. The lockdown imposed in the UK appears, unsurprisingly, to have slowed the growth of COVID-19 infections, and may well soon lead to total active cases declining. However, it comes at huge economic and social costs, and substantial COVID-19-unrelated health costs.

Worse, the lockdown is merely a holding strategy, which offers no long term solution to the COVID-19 problem. The eventual total number of deaths for COVID-19 are not reduced relative to any less restrictive policy that likewise avoided the health system being overwhelmed. Deaths are merely spread over a longer period, assuming that eventually restrictions are lifted and people’s lives return to normal. Continue reading

CoV Discussion Thread III

By Judith Curry

My latest selection of interesting articles.

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Imperial College UK COVID-19 numbers don’t seem to add up

By Nic Lewis

Introduction and summary

A study published two weeks ago by the COVID-19 Response Team from Imperial College (Ferguson20[1]) appears to be largely responsible for driving UK government policy actions. The study is not peer reviewed; indeed, it seems not to have been externally reviewed at all. Moreover, the computer code used to produce the estimates in the study – which on Ferguson’s own admission is old, unverified and documented inadequately, if at all – has still not been published. That, in my view, shows a worrying approach to a matter of vital public concern.

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CoV discussion thread II

by Judith Curry

Time for a new thread.

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COVID-19: Updated data implies that UK modelling hugely overestimates the expected death rates from infection

By Nic Lewis

Introduction

There has been much media coverage about the danger to life posed by the COVID-19 coronavirus pandemic. While it is clearly a serious threat, one should consider whether the best evidence supports the current degree of panic and hence government policy. Much of the concern in the UK resulted from a non-peer reviewed study published by the COVID-19 Response Team from Imperial College (Ferguson et al 2020[1]). In this article, I examine whether data from the Diamond Princess cruise ship – arguably the most useful data set available – support the fatality rate assumptions underlying the Imperial study. I find that it does not do so. The likely fatality rates for age groups from 60 upwards, which account for the vast bulk of projected deaths, appear to be much lower than those in the Ferguson et al. study. Continue reading

Coronavirus technical thread

by Judith Curry

A thread devoted to technical topics, e.g. epidemiology, immunology, treatments.  A more general thread will be coming shortly.

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Coronavirus discussion thread

by Judith Curry

Discuss.

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Climate sensitivity in light of the latest energy imbalance evidence

by Frank Bosse

Equilibrium climate sensitivity computed from the latest energy imbalance data.

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Comment by Cowtan & Jacobs on Lewis & Curry 2018 and Reply: Part 2

By Nic Lewis

In an earlier article here I discussed a Comment on Lewis and Curry 2018 (LC18) by Kevin Cowtan and Peter Jacobs (CJ20), and a Reply from myself and Judith Curry recently published by Journal of Climate (copy available here). I wrote that I would defer dealing with the differences between observed and CMIP5 model-simulated historical warming, which formed the basis of CJ20’s numerical analysis, until a subsequent article. I now do so. Continue reading

Gregory et al 2019: Unsound claims about bias in climate feedback and climate sensitivity estimation

By Nic Lewis

The recently published open-access paper “How accurately can the climate sensitivity to CO2 be estimated from historical climate change?” by Gregory et al.[i] makes a number of assertions, many uncontentious but others in my view unjustified, misleading or definitely incorrect.

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Week in review – science edition

by Judith Curry

A few things that caught my eye this past week.

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Beto’s climate action plan

by Judith Curry

Beto O’Rourke’s Climate Change Plan deserves a close look.

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What’s the worst case? A possibilistic approach

by Judith Curry

Are all of the ‘worst-case’ climate scenarios and outcomes described in assessment reports, journal publications and the media plausible? Are some of these outcomes impossible? On the other hand, are there unexplored worst-case scenarios that we have missed, that could turn out to be real outcomes? Are there too many unknowns for us to have confidence that we have credibly identified the worst case? What threshold of plausibility or credibility should be used when assessing these extreme scenarios for policy making and risk management?

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Hurricanes and Climate Change: Attribution

by Judith Curry

Part II:  what causes variations and changes in hurricane activity?

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The most amazing greening on Earth

by Patrick J. Michaels

We’ve long been fond of showing the satellite evidence for planetary greening caused by increasing carbon dioxide, particularly the work of Zhu et al.(2016):

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The debate. Part II

by Judith Curry

Countdown to the ‘conversation’ between Mann, Titley, Moore, Curry.  Looks like you can now register for the live broadcast, for a fee of $10 [link].

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Why Dessler et al.’s critique of energy-budget climate sensitivity estimation is mistaken

By Nic Lewis

Plain language summary

  • A new paper by Andrew Dessler et al. claims, based on 100 simulations of the historical period (1850 to date) by the MPI‑ESM1.1 climate model, that estimates of climate sensitivity using the energy-budget method can vary widely due to internal climate system variability.
  • I calculated what effect the uncertainty implied by the internal variability affecting the MPI‑ESM1.1 simulations had on the distribution of the primary climate sensitivity estimate in the recent Lewis & Curry energy-budget paper.
  • The result was a marginal narrowing of the Lewis & Curry sensitivity estimate. This is because the allowance for internal variability by Lewis & Curry is larger than internal variability in MPI‑ESM1.1.
  • Since historical period energy-budget sensitivity estimates are much more  imprecise for other reasons, internal variability contributes little to their total uncertainty; it is an unimportant factor.
  • Nothing in the new Dessler et al. paper indicates that the Lewis & Curry energy-budget climate sensitivity estimates are likely to be biased low.

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Impact of recent forcing and ocean heat uptake data on estimates of climate sensitivity

by Nic Lewis

We have now updated the LC15 paper with a new paper that has been published in the Journal of Climate “The impact of recent forcing and ocean heat uptake data on estimates of climate sensitivity“.  The paper also addresses critiques of LC15.

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