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A potential rule of thumb for hourly rainfall?

Future global warming will be accompanied by more intense rainfall and flash floods due to increased evaporation, as a consequence of higher surface temperatures which also lead to a higher turn-around rate for the global hydrological cycle. In other words, we will see changing rainfall patterns. And if the global area of rainfall also shrinks, then a higher regional concentration of the rainfall is bound to lead to more intense downpours (the global rainfall indicator is discussed here). 

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Regional information for society (RifS) and unresolved issues

It’s encouraging to note the growing interest for regional climate information for society and climate adaptation, such as recent advances in the World Climate Research Programme (WCRP), the climate adaptation summit CAS2021, and the new Digital Europe. These efforts are likely to boost the Global Framework for Climate Services (GFCS) needed as a guide to decision-makers on matters influenced by weather and climate. 

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Climate Adaptation Summit 2021

Filed under: — rasmus @ 31 January 2021

The first ever Climate Adaptation Summit (#adaptationsummit) that I have heard about took place last week, on January 25-26. I think such a summit was a step in the right direction. It was adapted to the Covid-19 situation and therefore an online virtual summit streamed on YouTube

I watched a few of the streamed sessions, and it struck me that climate change adaptation seems to be a fairly new concept to many leaders. It were sometimes mix-ups with mitigation during the high-level talks. Mitigation and adaptation are both important and sometimes they overlap, so mix-ups are understandable. 

One important point addressed during the summit was of course financing climate change adaptation, which is promising. Financing is clearly needed for climate change adaptation. To ensure progress and avoid lofty visions without results on the ground, there may also be a need for tangible results and to show examples and demonstrations. One specific type discussed at the summit was “Early warning systems” which play an important role.

But it was not crystal clear what was meant by the concept “early warning systems”. My interpretation is that it involves something on par with weather forecasts which would imply that they are more about weather than climate. This is of course important too. Probably the first priority in many places. 

But early warning systems, the way I understand them, don’t provide information about climate risks on longer timescales. Weather and climate – short and long timescales – are of course connected but nevertheless different (“climate” can be viewed as weather statistics). Other examples of climate adaptation can be found in a recent Eos article on food security in Africa. I think it is important to mention maladaptation and avoid long-term problems connected to short-term fixes. Resilience is a keyword. 

As with many other summits, I felt that the scientists’ voice was largely missing. There seems to be a gap between high-level politics and science. I think we need a better dialogue between the leaders and climate scientists partly to help distinguish between different and difficult concepts. But the main reason is that we need to know what we must adapt to. We need to know the situation: the state of the climate and how it is changing. This knowledge is not readily downloadable from the Internet.

There are key questions that should involve scientists: What is needed for proper climate change adaptation? And what are the challenges in terms of meeting our objectives? What do we know about future risks? In addition, biodiversity, nature conservation, cultural, social and economic aspects are important. 

Data is crucial, but is often unavailable because of lack of sharing and lack of openness. Often due to lacking finance. Information about the regional climate change must be distilled from large volumes of data, and we need to ask what information is useful and how it can be used in the best possible way.

The required analysis is often carried out in climate services and often includes downscaling. It involves tools, methods and understanding that are still evolving with regards to these topics. This fact wasn’t explained clearly during the summit in the sessions I watched. I think it would be useful with a presentation of the state of climate science relevant for climate change adaptation at a high level in the summit. Perhaps science should get an equal amount of attention as the NGOs and the businesses. 

Much of the latest research relevant to the climate adaptation summit is coordinated within the World Climate Research Programme (WRCP) which also is setting a new focus on regional information for society (“RifS”). Furthermore, there is considerable scientific experience on adaptation from the Arctic with the fastest climate change on Earth, such as the Adaptive Actions in a Changing Arctic (AACA) report for the Arctic Council. 

Climate adaptation involves many communities and disciplines (e.g. weather forecasting, climate services, regional climate modelling, “distillation“, disaster risk reduction) which I think aren’t well coordinated at the moment. One message from the summit was “Let’s work together” which I think implies a better coordination of the different disciplines and communities.

2020 vision

A meeting of smoke and storms (NASA Earth Observatory)

No-one needs another litany of all the terrible things that happened this year, but there are three areas relevant to climate science that are worth thinking about:

  • What actually happened in climate/weather (and how they can be teased apart). There is a good summary on the BBC radio Discover program covering wildfires, heat waves, Arctic sea ice, the hurricane season, etc. featuring Mike Mann, Nerlie Abram, Sarah Perkins-Kilpatrick, Steve Vavrus and others. In particular, there were also some new analyses of hurricanes (their rapid intensification, slowing, greater precipitation levels etc.), as well as the expanding season for tropical storms that may have climate change components. Yale Climate Connections also has a good summary.
  • The accumulation of CMIP6 results. We discussed some aspects of these results extensively – notably the increased spread in Equilibrium Climate Sensitivity, but there is a lot more work to be done on analyzing the still-growing database that will dominate the discussion of climate projections for the next few years. Of particular note will be the need for more sophisticated analyses of these model simulations that take into account observational constraints on ECS and a wider range of future scenarios (beyond just the SSP marker scenarios that were used in CMIP). These issues will be key for the upcoming IPCC 6th Assessment Report and the next National Climate Assessment.
  • The intersection of climate and Covid-19.
    • The direct connections are clear – massive changes in emissions of aerosols, short-lived polluting gases (like NOx) and CO2 – mainly from reductions in transportation. Initial results demonstrated a clear connection between cleaner air and the pandemic-related restrictions and behavioural changes, but so far the impacts on temperature or other climate variables appear to be too small to detect (Freidlingstein et al, 2020). The impact on global CO2 emissions (LeQuere et al, 2020) has been large (about 10% globally) – but not enough to stop CO2 concentrations from continuing to rise (that would need a reduction of more like 70-80%). Since the impact from CO2 is cumulative this won’t make a big difference in future temperatures unless it is sustained through post-pandemic changes.
    • The metaphorical connections are also clear. The instant rise of corona virus-denialism, the propagation of fringe viewpoints from once notable scientists, petitions to undermine mainstream epidemiology, politicized science communications, and the difficulty in matching policy to science (even for politicians who want to just ‘follow the science’), all seem instantly recognizable from a climate change perspective. The notion that climate change was a uniquely wicked problem (because of it’s long term and global nature) has evaporated as quickly as John Ioannidis’ credibility.

I need to take time to note that there has been human toll of Covid-19 on climate science, ranging from the famous (John Houghton) to the families of people you never hear about in the press but whose work underpins the data collection, analysis and understanding we all rely on. This was/is a singular tragedy.

With the La Niña now peaking in the tropical Pacific, we can expect a slightly cooler year in 2021 and perhaps a different character of weather events, though the long-term trends will persist. My hope is that the cracks in the system that 2020 has revealed (across a swathe of issues) can serve as an motivation to improve resilience, equity and planning, across the board. That might well be the most important climate impact of all.

A happier new year to you all.


  1. P.M. Forster, H.I. Forster, M.J. Evans, M.J. Gidden, C.D. Jones, C.A. Keller, R.D. Lamboll, C.L. Quéré, J. Rogelj, D. Rosen, C. Schleussner, T.B. Richardson, C.J. Smith, and S.T. Turnock, "Current and future global climate impacts resulting from COVID-19", Nature Climate Change, vol. 10, pp. 913-919, 2020.
  2. C. Le Quéré, R.B. Jackson, M.W. Jones, A.J.P. Smith, S. Abernethy, R.M. Andrew, A.J. De-Gol, D.R. Willis, Y. Shan, J.G. Canadell, P. Friedlingstein, F. Creutzig, and G.P. Peters, "Temporary reduction in daily global CO2 emissions during the COVID-19 forced confinement", Nature Climate Change, vol. 10, pp. 647-653, 2020.

An ever more perfect dataset?

Filed under: — gavin @ 15 December 2020

Do you remember when global warming was small enough for people to care about the details of how climate scientists put together records of global temperature history? Seems like a long time ago…

Nonetheless, it’s worth a quick post to discuss the latest updates in HadCRUT (the data product put together by the UK’s Hadley Centre and the Climatic Research Unit at the University of East Anglia). They have recently released HadCRUT5 (Morice et al., 2020), which marks a big increase in the amount of source data used (similarly now to the upgrades from GHCN3 to GHCN4 used by NASA GISS and NOAA NCEI, and comparable to the data sources used by Berkeley Earth). Additionally, they have improved their analysis of the sea surface temperature anomalies (a perennial issue) which leads to an increase in the recent trends. Finally, they have started to produce an infilled data set which uses an extrapolation to fill in data-poor areas (like the Arctic – first analysed by us in 2008…) that were left blank in HadCRUT4 (so similar to GISTEMP, Berkeley Earth and the work by Cowtan and Way). Because the Arctic is warming faster than the global mean, the new procedure corrects a bias that existing in the previous global means (by about 0.16ºC in 2018 using a 1951-1980 baseline). Combined, the new changes give a result that is much closer to the other products:

Differences persist around 1940, or in earlier decades, mostly due to the treatment of ocean temperatures in HadSST4 vs. ERSST5.

In conclusion, this update further solidifies the robustness of the surface temperature record, though there are still questions to be addressed, and there remain mountains of old paper records to be digitized.

The implications of these updates for anything important (such as the climate sensitivity or the carbon budget) will however be minor because all sensible analyses would have been using a range of surface temperature products already.

With 2020 drawing to a close, the next annual update and intense comparison of all these records, including the various satellite-derived global products (UAH, RSS, AIRS) will occur in January. Hopefully, HadCRUT5 will be extended beyond 2018 by then.

In writing this post, I noticed that we had written up a detailed post on the last HadCRUT update (in 2012). Oddly enough the issues raised were more or less the same, and the most important conclusion remains true today:

First and foremost is the realisation that data synthesis is a continuous process. Single measurements are generally a one-time deal. Something is measured, and the measurement is recorded. However, comparing multiple measurements requires more work – were the measuring devices calibrated to the same standard? Were there biases in the devices? Did the result get recorded correctly? Over what time and space scales were the measurements representative? These questions are continually being revisited – as new data come in, as old data is digitized, as new issues are explored, and as old issues are reconsidered. Thus for any data synthesis – whether it is for the global mean temperature anomaly, ocean heat content or a paleo-reconstruction – revisions over time are both inevitable and necessary.


  1. , 2021.

Shellenberger’s op-ad

Filed under: — group @ 9 July 2020

Guest commentary by Michael Tobis

This is a deep dive into the form and substance of Michael Shellenberger’s promotion for his new book “Apocalypse Never”. Shorter version? It should be read as a sales pitch to a certain demographic rather than a genuine apology.

Michael Shellenberger appears to have a talent for self-promotion. His book, provocatively entitled “Apocalypse Never” appears to be garnering considerable attention. What does he mean by that title? Does it mean we should do whatever we can to avoid an apocalypse? Does it mean that no apocalypse is possible in the foreseeable future? For those of us who haven’t yet read the book (now available on Kindle), Shellenberger provides an unusual article (at first posted on Forbes, then at Quillette and the front page of the Australian) which appears less a summary than a sales pitch, an “op-ad” as one Twitter wag put it.

It’s called “On Behalf Of Environmentalists, I Apologize For The Climate Scare”. In short, Shellenberger lands clearly on the naysayer soil. Not much to see, everyone. Cheer up, carry on, these are not the droids you’re looking for.


In support of this insouciance, Shellenberger offers twelve “facts few people know”. Most of the points are defensible to some extent, and most of them raise interesting topics. A main purpose of this article is to provide references to the relevant discussions. But in going through it, it’s worth keeping an eye on the rhetorical purposes of the items, which appear a bit scattershot, and to the rhetorical purpose of the list, which might appear rather obscure.

Clearly labeling the list “facts that few people know” implies that all these points unambiguously refute common beliefs that are widely. And the “apology for the climate scare” indicates further that these beliefs are widely held by a supposedly misguided community of “climate scared”. A defender of the list, Blair King suggests that “[Shellenberger] identified false talking points used repeatedly by alarmists to misinform the public and move debate away from one that is evidence-based to one driven by fear and misinformation”. That does seem to be a fair reading of the stated intent of the list, but it just doesn’t ring true as a whole.

Speaking as a verteran “climate scared” person, the items don’t seem especially familiar. It’s hard to imagine a conversation like this:“Gosh, climate change is an even bigger threat to species than habitat loss.”“I know, and the land area used for producing meat is increasing!”As Gerardo Ceballos said:

This is not a scientific paper. It is intended, I guess, to be an article for the general public. Unfortunately, it is neither. It does not have a logical structure that allows the reader to understand what he would like to address, aside from a very general and misleading idea that environmentalists and climate scientists have been alarmist in relation to climate change. He lists a series of eclectic environmental problems like the Sixth Mass Extinction, green energy, and climate disruption. And without any data nor any proof, he discredits the idea that those are human-caused, severe environmental problems. He just mentions loose ideas about why he is right and the rest of the scientists, environmentalists, and general public are wrong.

What causes the strange incoherence of these “facts few people know”? At the end of this review I’ll propose an answer. Meanwhile, I will consider several questions regarding each item:

  • VALIDITY Is the claim unambiguously true? Unambiguously false? Disputed?
  • RELEVANCE TO CLIMATE Is the claim directly relevant to climate concern/”climate scare” or is it more of interest to tangentially related environmental issues?
  • SALIENCE Is the contrary of the claim widely believed by environmental activists? Does widespread belief in the claim contribute materially to an excess of climate concern?
  • IMPLICATION What is the rhetorical purpose of the question?
  • REALITY To what extent is the rhetorical purpose justified?
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Coronavirus and climate

Filed under: — gavin @ 20 March 2020

As we collectively reel from the changes wrought by the current pandemic, people are being drawn by analogy to climate issues – but analogies can be tricky and often distort as much as they illuminate.

For instance, in the Boston Globe, Jeff Jacoby’s commentary was not particularly insightful and misquoted Mike Mann pretty egregiously. Mike’s response is good:

I am relieved to see policy makers treating the coronavirus threat with the urgency it deserves. They need to do the same when it comes to an even greater underlying threat: human-caused climate change.

In a recent column (“I’m skeptical about climate alarmism, but I take coronavirus fears seriously,” Ideas, March 15), Jeff Jacoby sought to reconcile his longstanding rejection of the wisdom of scientific expertise when it comes to climate with his embrace of such expertise when it comes to the coronavirus.

In so doing, Jacoby took my words out of context, mischaracterizing my criticisms of those who overstate the climate threat “in a way that presents the problem as unsolvable, and feeds a sense of doom, inevitability, and hopelessness.”

As I have pointed out in past commentaries, the truth is bad enough when it comes to the devastating impacts of climate change, which include unprecedented floods, heat waves, drought, and wildfires that are now unfolding around the world, including the United States and Australia, where I am on sabbatical.

The evidence is clear that climate change is a serious challenge we must tackle now. There’s no need to exaggerate it, particularly when it feeds a paralyzing narrative of doom and hopelessness.

There is still time to avoid the worst outcomes, if we act boldly now, not out of fear, but out of confidence that the future is still largely in our hands. That sentiment hardly supports Jacoby’s narrative of climate change as an overblown problem or one that lacks urgency.

While we have only days to flatten the curve of the coronavirus, we’ve had years to flatten the curve of CO2 emissions. Unfortunately, thanks in part to people like Jacoby, we’re still currently on the climate pandemic path.

Michael E. Mann

State College, Pa.

The writer is a professor at Penn State University, where he is director of the Earth System Science Center.

Direct connections

There are some direct connections too. The lockdowns and travel restrictions are having a material effect on emissions of short-lived air pollutants (like NOx, SO2 etc.), water discharges and carbon dioxide as well. The impacts on air and water quality are already being seen – perhaps allowing people to reset their shifted baselines for what clean air and water are like.

Business-as-usual is kaput

Obviously, nothing is going to be quite the same after this. We will soon be describing prior norms and behaviours as “that is so BC” (before coronavirus). Already, when watching pre-recorded TV shows, I internally cringe when seeing the handshaking and hugging.

But it should also be obvious that for worst-case scenarios to materialise, it is a combination of factors that drive the results. Luck, good or bad, and decisions, wise or unwise, combine to create the future. Luck drives the specific potency of the virus, it’s incubation period and lethality, but societal decisions determined the preparation (or lack thereof), the health care system design or capacity (or lack thereof), and governmental responses (adequate or not).

Indeed, every possible future can only be reached by a specific track of what is (the science) and what we do about it (the policy). That is no different with climate as it is with pandemics. There is no possible future in which no-one made any decisions.

BAU wow wow

How should we discuss scenarios of future emissions? What is the range of scenarios we should explore? These are constant issues in climate modeling and policy discussions, and need to be reassessed every few years as knowledge improves.

I discussed some of this in a post on worst case scenarios a few months ago, but the issue has gained more prominence with a commentary by Zeke Hausfather and Glen Peters in Nature this week (which itself partially derives from ongoing twitter arguments which I won’t link to because there are only so many rabbit holes that you want to fall into).

My brief response to this is here though:

Mike Mann has a short discussion on this as well. But there are many different perspectives around – ranging from the merely posturing to the credible and constructive. The bigger questions are certainly worth discussing, but if the upshot of the current focus is that we just stop using the term ‘business-as-usual’ (as was suggested in the last IPCC report), then that is fine with me, but just not very substantive.


  1. Z. Hausfather, and G.P. Peters, "Emissions – the ‘business as usual’ story is misleading", Nature, vol. 577, pp. 618-620, 2020.

IPCC Special Report on Land

Thread for discussions of the new special report. [Boosting a comment from alan2102].

Climate Change and Land
An IPCC special report on climate change, desertification, land degradation, sustainable land management, food security, and greenhouse gas fluxes in terrestrial ecosystems

Land degradation accelerates global climate change. Al Jazeera English
Published on Aug 8, 2019

New UN report highlights vicious cycle of climate change, land degradation. CNA
Published on Aug 8, 2019

New IPCC Report Warns of Vicious Cycle Between Soil Degradation and Climate Change. The Real News Network
Published on Aug 8, 2019

Absence and Evidence

Guest commentary by Michael Tobis, a retired climate scientist. He is a software developer and science writer living in Ottawa, Ontario.

A recent opinion piece by economist Ross McKitrick in the Financial Post, which attracted considerable attention in Canada, carried the provocative headline “This scientist proved climate change isn’t causing extreme weather – so politicians attacked”.

In fact, the scientist referenced in the headline, Roger Pielke Jr., proved no such thing. He examined some data, but he did not find compelling evidence regarding whether or not human influence is causing or influencing extreme events.

Should such a commonplace failure be broadly promoted as a decisive result that merits public interest?

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