RealClimate

Climate science from climate scientists...

You are here: Home / Archives for Climate Science

Climate Science

How do trees change the climate?

by

Translations: (Deutsch) (English)

Guest commentary from Abby Swann (U. Washington)

This past month, an op-ed by Nadine Unger appeared in the New York Times with the headline “To save the climate, don’t plant trees”.  The author’s main argument is that UN programs to address climate change by planting trees or preserving existing forests are “high risk” and a “bad bet”. [Ed. There is more background on the op-ed here]

However, I don’t think that these conclusions are supported by the science.  The author connects unrelated issues about trees, conflates what we know about trees from different latitudes, and fails to convey the main point: tropical trees keep climate cool locally, help keep rainfall rates high, and have innumerable non-climate benefits including maintaining habitat and supporting biodiversity.

[Read more…] about How do trees change the climate?

Ocean heat storage: a particularly lousy policy target + Update

by

The New York Times, 12 December 2027: After 12 years of debate and negotiation, kicked off in Paris in 2015, world leaders have finally agreed to ditch the goal of limiting global warming to below 2 °C. Instead, they have agreed to the new goal of limiting global ocean heat content to 1024 Joules. The decision was widely welcomed by the science and policy communities as a great step forward. “In the past, the 2 °C goal has allowed some governments to pretend that they are taking serious action to mitigate global warming, when in reality they have achieved almost nothing. I’m sure that this can’t happen again with the new 1024 Joules goal”, said David Victor, a professor of international relations who originally proposed this change back in 2014. And an unnamed senior EU negotiator commented: “Perhaps I shouldn’t say this, but some heads of state had trouble understanding the implications of the 2 °C target; sometimes they even accidentally talked of limiting global warming to 2%. I’m glad that we now have those 1024 Joules which are much easier to grasp for policy makers and the public.”

This fictitious newspaper item is of course absurd and will never become reality, because ocean heat content is unsuited as a climate policy target. Here are three main reasons why. [Read more…] about Ocean heat storage: a particularly lousy policy target + Update

New developments: Climate services for health

by

I recently received a joint email from the World Meteorological and Health organisations (WMO & WHO) which I like to bring to the attention of our readers. Both because it shows the direction of some new developments, but also because the WMO and WHO are inviting people to share their experience with health and climate. We wrote a post on the subject climate and health in 2011, based on a book by Paul Epstein (who sadly pased away in November 2011) and Dan Ferber (Health on a Changing Planet), and are glad to see an increased emphasis on this topic. The call from WMO/WHO goes as follows:

Guest commentary from Joy Shumake-Guillemot

CALL FOR CASE STUDIES
Climate Services for Health
Enhancing Decision Support for Climate Risk Management and Adaptation

Climate services for health are an emerging technical field for both the health and climate communities. In 2012, WHO and WMO jointly published the Atlas on Climate and Health, drawing attention to the key linkages between climate and health, and how climate information can be used to understand and manage climate sensitive health risks. A new follow-up publication of Case Studies on Climate Services for Health is in preparation, and will take a next step to outline with greater detail how a wide range of health applications can benefit from using climate and weather information; what steps and processes can be used to co-develop and use climate and weather information in the health sector; and showcase how such partnerships and services can really make a difference to the health community. 

Submission Guidance – Deadline October 31, 2014
We invite you to share your experiences and call attention to the increasing opportunities to solve health problems with climate service solutions. Case studies should highlight existing partnerships and good practices that demonstrate the broad range of possible applications and the value of using climate information to inform health decisions. Case studies from across health science and practice are welcomed, including examples of climate services for integrated surveillance, disease forecasting, early warning systems, risk mapping, health service planning, risk communication, research, evaluation, infrastructure siting, etc. Additionally, the publication aims to highlight the full range climate-related health issues and risks (i.e. nutrition, NCDs, air pollution, allergens, infectious diseases, water and sanitation, extreme temperatures and weather, etc.) where health decision-making can benefit from climate and weather knowledge at historic, immediate, seasonal, or long-term time scales.

Case studies should be short (~600 words, 2 pages incl. images/diagrams and references) and designed to highlight the added-value that climate services have made for managing climate risks to health. Please find additional guidance on the structure and four elements to be included at http://www.gfcs-climate.org/node/579.  

For questions and submission please contact
Dr.Joy Shumake-Guillemot jshumake-guillemot@wmo.int
WHO/WMO Climate and Health Office, World Meteorological Organization, Geneva, Switzerland

Climate response estimates from Lewis & Curry

by

Guest commentary from Richard Millar (U. Oxford)

The recent Lewis and Curry study of climate sensitivity estimated from the transient surface temperature record is being lauded as something of a game-changer – but how much of a game-changer is it really?

[Read more…] about Climate response estimates from Lewis & Curry

References

  1. N. Lewis, and J.A. Curry, "The implications for climate sensitivity of AR5 forcing and heat uptake estimates", Climate Dynamics, vol. 45, pp. 1009-1023, 2014. http://dx.doi.org/10.1007/s00382-014-2342-y

Limiting global warming to 2 °C – why Victor and Kennel are wrong + update

by

In a comment in Nature titled Ditch the 2 °C warming goal, political scientist David Victor and retired astrophysicist Charles Kennel advocate just that. But their arguments don’t hold water.

It is clear that the opinion article by Victor & Kennel is meant to be provocative. But even when making allowances for that, the arguments which they present are ill-informed and simply not supported by the facts. The case for limiting global warming to at most 2°C above preindustrial temperatures remains very strong.

Let’s start with an argument that they apparently consider especially important, given that they devote a whole section and a graph to it. They claim:

The scientific basis for the 2 °C goal is tenuous. The planet’s average temperature has barely risen in the past 16 years. [Read more…] about Limiting global warming to 2 °C – why Victor and Kennel are wrong + update

Free climate science / modeling class beginning Sept. 29

by

Global Warming: The Science and Modeling of Climate Change is a free online adaptation of a college-level class for non-science majors at the University of Chicago (textbook, video lectures). The class includes 33 short exercises for playing with on-line models, 5 “number-cruncher” problems where you create simple models from scratch in a spreadsheet or programming language, and 8 “explainer” assignments where you explain some concept as you would to a smart 11-year old child (short, simple, clear), and exchange these with other students in the class for feedback. The discussion forums are very lively, as thousands of people from around the world make their way through the video lectures and exercises, lots to chat about. This is our third run of the class, so we’re getting the kinks out. We hope you find it useful. September 29 – December 31 2014.

global-warming-coursera-logo

On arguing by analogy

by

Climate blogs and comment threads are full of ‘arguments by analogy’. Depending on what ‘side’ one is on, climate science is either like evolution/heliocentrism/quantum physics/relativity or eugenics/phrenology/Ptolemaic cosmology/phlogiston. Climate contrarians are either like flat-earthers/birthers/moon-landing hoaxers/vaccine-autism linkers or Galileo/stomach ulcer-Helicobacter proponents/Wegener/Copernicus. Episodes of clear misconduct or dysfunction in other spheres of life are closely parsed only to find clubs with which to beat an opponent. Etc. Etc.

While the users of these ‘arguments’ often assume that they are persuasive or illuminating, the only thing that is revealed is how the proposer feels about climate science. If they think it is generally on the right track, the appropriate analogy is some consensus that has been validated many times and the critics are foolish stuck-in-the-muds or corporate disinformers, and if they don’t, the analogy is to a consensus that was overturned and where the critics are the noble paradigm-shifting ‘heretics’. This is far closer to wishful thinking than actual thinking, but it does occasionally signal clearly who is not worth talking to. For instance, an article pretending to serious discussion on climate that starts with a treatise about Lysenkoism in the Soviet Union is not to be taken seriously.

Since the truth or falsity of any scientific claim can only be evaluated on it’s own terms – and not via its association with other ideas or the character of its proponents – this kind of argument is only rhetorical. It gets no-one closer to the truth of any particular matter. The fact is that many, many times, mainstream science has survived multiple challenges by ‘sceptics’, and that sometimes (though not at all often), a broad consensus has been overturned. But knowing which case is which in any particular issue simply by looking for points of analogy with previous issues, but without actually examining the data and theory directly, is impossible. The point being that arguments by analogy are not persuasive to anyone who doesn’t already agree with you on the substance.

Given the rarity of a consensus-overturning event, the only sensible prior is to assume that a consensus is probably valid absent very strong evidence to the contrary, which is incidentally the position adopted by the arch-sceptic Bertrand Russell. The contrary assumption implies there are no a priori reasons to think any scientific body of work is credible which, while consistent, is not one that I have ever found anyone professing in practice. Far more common is a selective rejection of science dependent on other reasons and that is not a coherent philosophical position at all.

Analogies do have their place of course – usually to demonstrate that a supposedly logical point falls down completely when applied to a different (but analogous) case. For instance, an implicit claim that all correct scientific theories are supported by a unanimity of Nobel Prize winners/members of the National Academies, is easily dismissed by reference to Kary Mullis or Peter Duesberg. A claim that CO2 can’t possibly have a significant effect solely because of its small atmospheric mixing ratio, can be refuted as a general claim by reference to other substances (such as arsenic, plutonium or Vitamin C) whose large effects due to small concentrations are well known. Or if a claim is made that all sciences except climate science are devoid of uncertainty, this is refuted by reference to, well, any other scientific field.

To be sure, I am not criticising the use of metaphor in a more general sense. Metaphors that use blankets to explaining how the greenhouse effect works, income and spending in your bank account to stand in for the carbon cycle, what the wobbles in the Earth’s orbit look like if the planet was your head, or conceptualizing the geologic timescale by compressing it to a day, for instance, all serve useful pedagogic roles. The crucial difference is that these mappings don’t come dripping with over-extended value judgements.

Another justification for the kind of analogy I’m objecting to is that it is simply for amusement: “Of course, I’m not really comparing my opponents to child molesters/food adulterers/mass-murderers – why can’t you take a joke?”. However, if you need to point out to someone that a joke (for adults at least) needs to have more substance than just calling someone a poopyhead, it is probably not worth the bother.

It would be nice to have a moratorium on all such analogical arguments, though obviously that is unlikely to happen. The comment thread here can assess this issue directly, but most such arguments on other threads are ruthlessly condemned to the bore-hole (where indeed many of them already co-exist). But perhaps we can put some pressure on users of these fallacies by pointing to this post and then refusing to engage further until someone actually has something substantive to offer. It may be pointless, but we can at least try.