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« Salt for the Earth | Main | Mann at the Cabot »

Getting lower

Nic Lewis and Judith Curry have a new paper out in Climate Dynamics and report that climate sensitivity is even lower than previously thought. There is a long but somewhat technical writeup at WUWT, so this is my attempt to explain it all in layman's terms.

There seem to be two main strands of innovation in the paper. Firstly Nic and Judy have used the estimates of ocean heat uptake and radiative forcings reported in the Fifth Assessment itself. Secondly, they have made their energy budget approach somewhat more sophisticated in order to deal with the twin problems of volcanos and natural cycles.

The energy budget method involves calculating how much heat the Earth should have absorbed between a starting period (typically back in the 19th century) and a more recent closing period. Then by analysing temperature changes and ocean heat uptake, you should be able to get a feel for how much the surface should be warming per doubling of carbon dioxide. The complication comes if one or both of the two periods is affected by natural cycles or volcanos, which will bias the results one way or another. The new approach seeks to minimise this effect by finding opening and closing periods that are well-matched in terms of volcanic activity and positions in the natural cycles (such as the AMO).

Anyway the result of all this work is that ECS and TCR seem to be slightly lower than Lewis and Crok reported in their GWPF report on the subject.

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Reader Comments (38)

To return to my own hypothesis, the more likely climate sensitivity will be zero. While gasses might be able to display greenhouse effects in the laboratory, in the field, the effect is likely to be completely swamped by other factors. The heating of the atmosphere is more probably to be by conduction from the surface to the air, and then by convection as the heated air rises; “capturing” of radiated heat by “greenhouse gasses” is probably of minimal effect upon the temperatures – any capturing of radiated heat is more likely to be by the solid particles (and, perhaps, liquid water) that wander about the atmosphere by the bucket-load, as well as by the undersides of the many other solid items above the surface (leaves, rocks, buildings, etc.).

Now, where can I get the grant to pursue the idea?

Sep 24, 2014 at 9:08 PM | Registered CommenterRadical Rodent

Bishop, there are two other important features of this new paper worth calling attention to. First, it also used (and carefully explained how) the AR5's own uncertainties around its T, Q, and F estimates. So the probability density functions, not just the 'best' mode estimates truly reflect current IPCC. Second, because this so, the observational TCR of 1.33 and ECS of 1.64 falsify the CMIP5 models (TCR 1.2, ECS 3.2) in a way independent of the pause. All this truly brings the ' science is settled' house of cards down.

Sep 24, 2014 at 9:20 PM | Unregistered CommenterRud Istvan

This paper along with the Koonin WSJ opinion piece (now elaborated on in Physics Today) are a bit of a one-two punch at the consensus. Lewis and Curry have found a way to estimate the ECS and TCR using climate observations and while Koonin pours cold water on the state of the art climate models that predict most likely ECS and TCR values that are twice as high as observations. The attack from within and outside of the climate establishment and the scientific establishment is going to be hard for many in the media to ignore for much longer and attempts to discredit the messengers will likely backfire.

Sep 24, 2014 at 9:34 PM | Unregistered CommenterSean

" you should be able to get a feel for how much the surface should be warming per doubling of carbon dioxide"

Feel is good enough for me. Let's destroy the economy and freeze as many old Malthusian deniers as we can this winter. During the Medieval Warm Period, no one over the age of 24 was allowed to burn wood. That's what saved the planet back then.

Sep 24, 2014 at 9:41 PM | Unregistered Commenteresmiff

Pardon me for asking, but is the GHG space wards enhanced radiation following the enhanced convection due to GHG absorption taken into account?

Sep 24, 2014 at 10:13 PM | Unregistered CommenterSchrodinger's Cat

Time to unplug some supercomputers or put them to a better use than generating pretty colour plots of nonsense.

Sep 24, 2014 at 10:57 PM | Unregistered Commenternot banned yet

Climate Sensitivity and Antarctic Sea Ice.

Two ships passing in the night, one tacking south into an anthropogenic head wind (downgraded from gale force), the other coming home with a wet sail.

Sep 24, 2014 at 11:22 PM | Registered CommenterGreen Sand

Shall I say it, or you, Martin?

Sep 24, 2014 at 11:22 PM | Unregistered Commentermichael hart


Supercomputers crunching away at even inaccurate simulations will generate useful heat in the coming cold snap

Sep 24, 2014 at 11:31 PM | Unregistered Commentermrsean2k

After you, mh.

Sep 24, 2014 at 11:34 PM | Registered CommenterMartin A

O/T but I draw your attention to the picture of Climate Activists in which will brighten a few people's day.

Sep 24, 2014 at 11:38 PM | Unregistered CommenterGraeme No.3

There is no such thing as climate sensitivity, at least as far as something that can actually be measured in the real world. It is an abstraction from the models. The climate is not, and never will be at equilibrium. Transient climate response is the less unforgivable term in that it amounts to saying "this is what I, or my model, predicts what might [not what will] happen".

If we all live to the year 2100 there'll be at least one saying "look my sensitivity was right." Another will say "No, you were doubly wrong because you also got the aerosol contribution wrong but they cancelled each other out."

And just how do you discuss the thermodynamics of "climate sensitivity" in a non linear system that might change states in sudden jerks? [There. I said that without mentioning tipping points.]

Sep 25, 2014 at 12:00 AM | Unregistered Commentermichael hart

As shown in an updated paper at, thermalization makes CO2 change have no significant effect on average global temperature .

Sep 25, 2014 at 12:30 AM | Unregistered Commenterdan pangburn

Esmiff, you really do have to get a grip on reality. I could suggest several places. But not until knowing that your meds were working, rather futile.
Are you perchance an avitar for the English Patient?

Sep 25, 2014 at 3:38 AM | Unregistered CommenterRud Istvan

mh, Is it crazy to doubt the possibility of tipping points? Belief in their existence seems all the rage. But not for me.

Sep 25, 2014 at 4:07 AM | Registered Commenterjferguson

Rud Istvan

My psychiatrist told me never to reveal my extremely finely balanced mixture of psychiatric medications to a Malthusian. He also told me never to buy a semi automatic weapon.

Sep 25, 2014 at 4:12 AM | Unregistered CommenterE. Smiff

It's nice to see someone beat the theory with its own stick. But a dose of reality is needed. For instance, the underlying data used in climate science has massive uncertainties much more than justifies the amount of heat generated when anomalies change or TCR is calculated. We really don't know much and not to the accuracy needed. Anyone else who thinks otherwise needs to go check their assumptions.

But as the Chinese proverb says: the wise man points at the moon, the fool looks at the finger. Let's not get caught up in this game of fools.

Sep 25, 2014 at 7:04 AM | Unregistered CommenterMicky H Corbett

It is evident that ECS and TCR are gradually converging to the true values of zero (plus or minus a bit of uncertainty too small to detect).

Sep 25, 2014 at 7:20 AM | Registered CommenterPhillip Bratby

As others have alluded this appears to be playing with pretty made up numbers to start with and with assumptions in place. Where is the physics in all of this. How does heat get into the deep ocean in any quantity? I can see the sun is good at getting it some depth into the ocean, but some atmosphere that might be a fraction of a degree warmer above the sea..... doesn't the sun totally dominate heat entering the ocean. Perhaps the reduced cloudiness in the late 20th century might have had a significant affect.

Sep 25, 2014 at 7:31 AM | Unregistered CommenterRob Burton

Could homeopathic principles be involved, here? I only ask because this is something HRH Prince Charles might have an informed view on.

Sep 25, 2014 at 7:34 AM | Unregistered CommenterAlex Cull

Unfortunately HRH Prince Charles has revealed himself over time to be an idiot advised by fools.

Sep 25, 2014 at 8:38 AM | Unregistered Commenterroger

The abstract for this paper ends with "Uncertainty in aerosol forcing is the dominant contribution to the ECS and TCR uncertainty ranges."

Note that the estimated aerosol negative forcing for the 1859-1885 period is considerably lower than for 1995-2011.

Has this been properly accounted for? Could this be why they get a TCR around 1.3C when everyone else is getting TCR around 1.8C?

Excuse me, the voices in my head are telling me to go polish my guns. :-)

Sep 25, 2014 at 10:53 AM | Unregistered CommenterEntropic man

jferguson, I try to keep an open mind on the subject. But if 'tipping points' exist (defined how?), how would one know when the system was approaching one, and what the new state would look like?

None of this is new, but it's another area where the consensus seems to prefer the view that, if publicly discussed at all, ignorance is a valid support for the worst case scenarios, having first carefully pre-selected which doom-laden scenarios are to be considered.

Sep 25, 2014 at 11:00 AM | Unregistered Commentermichael hart

Andrew, I seem to recall that Steven McIntyre did a post some years ago in which he ran figures to assess the ECS arising from Guy Callendar's celebrated 1938 Paper on the Greenhouse effect. I may be faulty in my recollection, but I believe he came up with a figure of about 1.67 ECS. If my memory is right that figure is not dissimilar to the best estimate of Lewis and Curry 2014.
I note Wikipedia puts Callendar's figure for ECS at 2.0, " at the lower end of the IPCC assessment."

Sep 25, 2014 at 11:11 AM | Unregistered CommenterHerbert

All lies, funded by "Big Oil" and the Koch brothers.

Sep 25, 2014 at 11:23 AM | Unregistered CommenterDon Keiller

Regarding my earlier comment , the Steve McIntyre post is "Guy Callendar vs. the GCM's," on Climate Audit, July 26, 2013. The Callendar ECS was 1.67, according to Steve.

Sep 25, 2014 at 11:39 AM | Unregistered CommenterHerbert

Entropic man:
"Note that the estimated aerosol negative forcing for the 1859-1885 period is considerably lower than for 1995-2011. Has this been properly accounted for?"

You might try asking this at Judith Curry's blog Climate Etc. Curry & Lewis used -0.90 Wm-2 as the central estimate for 1750-to-2011 change in aerosol forcing, based on AR5. They mention that one could also justify using -0.78 Wm-2 which derives from "six satellite-based studies that were used in AR5". The effect of such a change is described: "sensitivity to setting ERF_LUC to zero is shown; shifting the 2011 ERF_Aerosol distribution by +0.12 Wm−2 has almost the same effect."

Sep 25, 2014 at 12:12 PM | Registered CommenterHaroldW

Statement / 25. SEP, 2014

At the end of the Climate Summit in New York, UN Secretary General Ban Ki-moon summarised the outcome. He told the assembled leaders:

This was a great day!

His full summary of the outcomes of the summit follows:

The purpose of the 2014 Climate Summit was to raise political momentum for a meaningful universal climate agreement in Paris in 2015 and to galvanize transformative action in all countries to reduce emissions and build resilience to the adverse impacts of climate change.

I asked leaders from government, business, finance and civil society to crystallize a global vision for low-carbon economic growth and to advance climate action on five fronts: cutting emissions; mobilizing money and markets; pricing carbon; strengthening resilience; and mobilizing new coalitions.

An unprecedented number of world leaders attended the Summit, including 100 Heads of State and Government. They were joined by more than 800 leaders from business, finance and civil society. This Summary details their most significant announcements.

Convergence on a Long-Term Vision

A comprehensive global vision on climate change emerged from the statements of leaders at the Summit:
•World leaders agreed that climate change is a defining issue of our time and that bold action is needed today to reduce emissions and build resilience and that they would lead this effort.
•Leaders acknowledged that climate action should be undertaken within the context of efforts to eradicate extreme poverty and promote sustainable development.
•Leaders committed to limit global temperature rise to less than 2 degrees Celsius from pre-industrial levels.
•Many leaders called for all countries to take national actions consistent with a less than 2 degree pathway and a number of countries committed to doing so.
•Leaders committed to finalise a meaningful, universal new agreement under the United Nations Framework Convention on Climate Change (UNFCCC) at COP-21, in Paris in 2015, and to arrive at the first draft of such an agreement at COP-20 in Lima, in December 2014.
•Leaders concurred that the new agreement should be effective, durable and comprehensive and that it should balance support for mitigation and adaptation.
•Many underlined the importance of addressing loss and damage.
•Many leaders affirmed their commitment to submit their Intended Nationally Determined Contributions (INDCs) for the new agreement in the first quarter of 2015.
•Many leaders reaffirmed the objectives and principles of the UNFCCC, including the principles of equity and common but differentiated responsibilities. In addition, others highlighted that the global effort to meet the climate challenge should reflect evolving realities and circumstances.

Cutting Emissions

Without significant cuts in emissions by all countries, and in key sectors, the window of opportunity to stay within less than 2 degrees will soon close forever:
•Many leaders, from all regions and all levels of economic development advocated for a peak in greenhouse gas emissions before 2020, dramatically reduced emissions thereafter, and climate neutrality in the second half of the century.
•European Union countries committed to a target of reducing emissions to 40 per cent below 1990 levels by 2030.
•Leaders from more than 40 countries, 30 cities and dozens of corporations launched large-scale commitment to double the rate of global energy efficiency by 2030 through vehicle fuel efficiency, lighting, appliances, buildings and district energy.
•The New York Declaration on Forests, launched and supported by more than 150 partners, including 28 government, 8 subnational governments, 35 companies, 16 indigenous peoples groups, and 45 NGO and civil society groups, aims to halve the loss of natural forests globally by 2030.
•Twenty-four leading global producers of palm oil as well as commodities traders committed to contribute to the goal of zero net deforestation by 2020 and to work with Governments, private sector partners and indigenous peoples to ensure a sustainable supply chain.
•The transport sector brought substantial emissions reduction commitments linked to trains, public transportation, freight, aviation and electric cars.
•Some of the world’s largest retailers of meat and agricultural products committed to adapt their supply chains to reduce emissions and build resilience to climate change. They will assist 500 million farmers in the process.

Moving markets and mobilizing money

Moving markets across a wide range of sectors is essential for transforming economies at scale. Mobilizing sufficient public and private funds for low carbon, climate resilient growth is essential to keep within a less than 2 degree Celsius pathway:
•A new coalition of governments, business, finance, multilateral development banks and civil society leaders announced their intent to mobilise over $200 billion for financing low-carbon and climate-resilient development.
•Countries strongly reaffirmed their support for mobilising public and private finance to meet the $100 billion dollar goal per annum by 2020.
•Leaders expressed strong support for the Green Climate Fund and many called for the Fund's initial capitalization at an amount no less than $10 billion. There was a total of $2.3 billion in pledges to the Fund's initial capitalization from six countries. Six others committed to allocate contributions by November 2014.
•The European Union committed $3 billion for mitigation efforts in developing countries between 2014 and 2020.
•The International Development Finance Club (IDFC) announced that it is on track to increase direct green/climate financing to $100 billion a year for new climate finance activities by the end of 2015.
•Significant new announcements were made on support for South-South cooperation on climate change.
•Leaders from private finance called for the creation of an enabling environment to undertake the required investments in low-carbon climate resilient growth. They announced the following commitments:
•Leading commercial banks announced their plans to issue $30 billion of Green Bonds by 2015, and announced their intention to increase the amount placed in climate-smart development to 10 times the current amount by 2020.
•A coalition of institutional investors, committed to decarbonizing $100 billion by December 2015 and to measure and disclose the carbon footprint of at least $500 billion in investments.
•The insurance industry committed to double its green investments to $84 billion by the end of 2015.
•Three major pension funds from North America and Europe announced plans to accelerate their investments in low-carbon investments across asset classes up to more than $31 billion by 2020.

Pricing carbon

Putting a price on carbon will provide markets with the policy signals needed to invest in climate solutions.
•Seventy-three national Governments, 11 regional governments and more than 1,000 businesses and investors signalled their support for pricing carbon. Together these leaders represent 52 per cent of global GDP, 54 per cent of global greenhouse gas emissions and almost half of the world’s population.
•Some leaders agreed to join a new Carbon Pricing Leadership Coalition to drive action aimed at strengthening carbon pricing policies and redirecting investment
•More than 30 leading companies announced their alignment with the Caring for Climate Business Leadership Criteria on Carbon Pricing.

Strengthening resilience

Strengthening both climate and financial resilience is a smart investment in a safer, more prosperous future.
•A variety of innovative resilience initiatives were announced at the Summit, including many that will strengthen countries and communities on the climate front lines. These include an initiative to provide user-friendly “news you can use” climate information for countries around the world.
•Leaders agreed to strengthen and scale up the risk financing mechanisms for Africa and the Caribbean.
•The African Risk Capacity announced an expansion of its services and coverage, including the introduction of Catastrophe Bonds.
•An initiative to integrate climate risk into the financial system by 2020 was launched by a coalition of investors, credit ratings agencies, insurers and financial regulators in response to the growing number of extreme weather events.
•Leaders from the insurance industry, representing $30 trillion in assets and investments committed to creating a Climate Risk Investment Framework by Paris in 2015.

Mobilizing New Coalitions

Governments, business and civil society are creating the coalitions needed to meet the full scope of climate challenge.
•Leaders welcomed multilateral and multi-stakeholder actions between Governments, finance, the private sector, and civil society to address emissions in critical sectors and support adaptation and resilience, especially in Small Island Developing States, Africa and the Least Developed Countries.
•Leaders from 19 countries and 32 partners from Government, regional organisations, development institutions and private investors committed to creating an 8,000 kilometre-long African Clean Energy Corridor.
•The Global Alliance for Climate-Smart Agriculture, comprised of 16 countries and 37 organisations, was launched to enable 500 million farmers worldwide to practice climate-smart agriculture by 2030.
•Leaders of the oil and gas industry, along with national Governments and civil society organisations, made an historic commitment to identify and reduce methane emissions by 2020. A second industry-led initiative was launched by leading producers of petroleum who committed to address methane as well as other key climate challenges, followed by regular reporting on ongoing efforts. Industry leaders and Governments also committed to reduce HFCs in refrigeration and food storage
•A new Global Mayors Compact, representing well over 2,000 cities pledged new commitments on climate action supported by new funding from public and private sources -- 228 cities have voluntary targets and strategies for greenhouse gas reductions, that could avoid up to 2.1 gigatonnes of greenhouse gas emissions per year.
•A new coalition of more than 160 institutions and local Governments and more than 500 individuals committed to divesting $50 billion from fossil fuel investments within the next three-five years and reinvest in new energy sources.
•Panels comprised of eminent global leaders, policy experts and citizen activists discussed the need for, and multiple benefits of, accelerated climate action. Panellists focussed on the need for science-based decision making; strengthening economic performance while cutting emissions, generating jobs and enhancing resilience; pricing and reducing pollution for improved health; mobilizing new coalitions to help move markets; and ensuring that the most affected are at the centre of the global response to climate change.

The Way Forward to Lima, Paris and beyond

I thank all the leaders from Government, business, finance and civil society who came to New York with ambition and commitment.
•If we want the vision laid out by leaders from Government, finance, business, and civil society throughout the day, we must fulfil and expand on all the pledges and initiatives announced today.
•We must maintain the spirit of commitment and action that characterized the Summit.
•As we look forward to Lima, later this year, and Paris in December 2015, let us look back on today as the day when we decided – as a human family – to put our house in order to make it sustainable, safe and prosperous for future generations.
•Today’s Summit has shown that we can rise to the climate challenge.

Sep 25, 2014 at 12:58 PM | Unregistered Commenternot banned yet

"they get a TCR around 1.3C when everyone else is getting TCR around 1.8C?"

Not true. At my request Nic has put up table at CA, showing that the Lewis & Curry value for TCR fits very well with Otto et al (2013) and Skeie et al (2014).

Sep 25, 2014 at 1:33 PM | Registered CommenterPaul Matthews


Thanks. I'll think on that.

jferguson, michael hart

Tipping points are unstable transition points at which a complex or chaotic system switches between stable states. An apparantly small change produces a large effect.

In climate systems the classic case is the effect of small high latitude insolation changes switching between glacial and interglacial conditions.

In past data they show up as stable periods punctuated by rapid change. Near-tipping point conditions tend to be characterised by instability, large and rapid changes in conditions with a tendency to temporary extremes.

Sep 25, 2014 at 1:38 PM | Unregistered CommenterEntropic man

You're nearly getting there, EM.
A 'tipping point' may be characterised by rapid changes, but rapid changes do not a tipping point make.

Sep 26, 2014 at 12:36 AM | Unregistered Commentermichael hart

Are people missing the point here? Tbis paper uses AR5 data and shows the likely results. These results are way lower than the alarmists claim in terms that the alarmists will find it hard to refute. It does not matter whether you believe that sensitivity is a nmeaningful nmeasure, it is is a major debunking exercise. Done on the terms specified by the IPCC.

Sep 26, 2014 at 1:15 AM | Unregistered Commenterdiogenes


The mistake you make is assuming the consenoratti have to refute the paper. They won't. What they will do is ignore the paper and continue to refer to themselves on matters of science.


Sep 26, 2014 at 9:12 AM | Unregistered Commentermailman

Is this game over?

If sensitivity is 1.3 using IPCC figures and assumptions, then... err... that's it, surely?

Either they have to come up with a serious rebuttal or alarmism is toast.

Seems to me I should be hearing champagne corks.

Sep 26, 2014 at 8:32 PM | Unregistered CommenterJames Evans

@ NBY - thanks for the heads up on this madness - he stated -

" I asked leaders from government, business, finance and civil society to crystallize a global vision for low-carbon economic growth and to advance climate action on five fronts: cutting emissions; mobilizing money and markets; pricing carbon; strengthening resilience; and mobilizing new coalitions"

Wonder who the "leaders from ...civil society" are ? and what it even means ? what % of society do they claim to speak for ?
NGO's are my bet & I think they have never had to work for a living.

how this inept guy is still in this position speaks volumes.

Sep 26, 2014 at 11:38 PM | Unregistered Commenterdougieh

the commitment shown by folks such as Steve Bloom and co to bebunking this paper are highly amusing....

they need to show a disaster in place, which is a weird kind of psychosis

Sep 28, 2014 at 1:03 AM | Unregistered Commenterdiogenes

"Are people missing the point here?"

I don't think so and I can see some reason to try and refocus on AR5 measures. I just don't see much use in applying 'good' stats to iffy data with plenty of assumptions made in the process.

Sep 28, 2014 at 2:36 PM | Unregistered CommenterRob Burton

... and from my earlier point, can we knock this heat 'lost' in the ocean bit until we can at least come up with a plausable mechanism to get it there in the required quantities. It just seems a very weak hypothesis to me.

Sep 28, 2014 at 2:38 PM | Unregistered CommenterRob Burton

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