Demystifying science-speak

Here is a great table of word substitutions for scientists to make when talking to non-scientists, or for non-scientists to mentally make when reading scientific articles. I saw it on Real Climate and, like the person who posted it there, thought that it deserved a wider audience. It comes originally from a lecture by Richard Somerville at UC San Diego on communicating climate science, part of this course.

Terms that have different meanings for scientists and the public

Scientific term  Public meaning  Better choice
enhance improve intensify, increase
aerosol spray can tiny atmospheric particle
positive trend good trend upward trend
positive feedback good response, praise vicious cycle, self-reinforcing cycle
theory hunch, speculation scientific understanding
uncertainty ignorance range
error mistake, wrong, incorrect difference from exact true number
bias distortion, political motive offset from an observation
sign indication, astrological sign plus or minus sign
values ethics, monetary value numbers, quantity
manipulation illicit tampering scientific data processing
scheme devious plot systematic plan
anomaly abnormal occurrence change from long-term average


Warning: climate change ahead

climate-crisis-aheadThe really short version of the climate change story hasn’t changed much for the last ten years or more, of course: we know we are cooking the earth and things are going to get very uncomfortable, if not catstrophic, unless we stop pumping CO2 into the atmosphere. (NASA’s version is one of the simplest, clearest and most authoritative if you need to direct anyone to such a resource.) However, the scientific work continues to improve our knowledge every year. Two significant recent publications are discussed in not-too-technical terms in two highly regarded blogs, RealClimate and ThinkProgress.

Should we trust the bloggers? These bloggers, yes. Stefan Rahmstorf, who discusses Marcott’s paper in Science, teaches physics of the oceans as a professor at Potsdam University, is a member of the Advisory Council on Global Change of the German government and is a lead author of the paleoclimate chapter of the 4th assessment report of the IPCC. Joe Romm, who discusses Hansen’s paper, worked at the highest levels of the US Department of Energy in the 1990s before moving into full-time environmental campaigning. (For more about them, see Wikipedia: Rahmstorf, Romm.) From here on, this summary uses their words, drastically condensed; follow the links at the end for the full versions.

Marcott study: The End of the Holocene

by Stefan Rahmstorf

Recently a group of researchers from Harvard and Oregon State University has published the first global temperature reconstruction for the last 11,000 years – that’s the whole Holocene (Marcott et al. 2013). The results are striking.

Over the last decades, numerous researchers have painstakingly collected, analyzed, dated, and calibrated many data series that allow us to reconstruct climate before the age of direct measurements. Such data come e.g. from sediment drilling in the deep sea, from corals, ice cores and other sources. Shaun Marcott and colleagues for the first time assembled 73 such data sets from around the world into a global temperature reconstruction for the Holocene [i.e. the 11,700 years since the last Ice Age].

Marcott s

Global temperature reconstruction from proxy data by Marcott et al, Science 2013

The climate curve looks like a “hump”. At the beginning of the Holocene global temperature increased, and subsequently it decreased again by 0.7 ° C over the past 5000 years. The well-known transition from the relatively warm Medieval into the “little ice age” turns out to be part of a much longer-term cooling, which ended abruptly with the rapid warming of the 20th Century. Within a hundred years, the cooling of the previous 5000 years was undone. (One result of this is, for example, that the famous iceman ‘Ötzi’, who disappeared under ice 5000 years ago, reappeared in 1991.)


The curve of Marcott et al. will not be the last word on the global temperature history during the Holocene; like Mann et al. in 1998 [the famous “Hockey Stick” which was a similar temperature record for the last 1,000 years] it is the opening of the scientific discussion. There will certainly be some corrections and improvements. However, I believe that (as was the case with Mann et al.) the basic shape will prove correct: a relatively smooth curve with slow cooling trend lasting millennia from the Holocene optimum to the “little ice age”, mainly driven by the orbital cycles. At the end this cooling trend is abruptly reversed by the modern anthropogenic warming. …

Just looking at the known drivers [factors affecting climate change] and the actual temperature history shows it directly, without need for a climate model: without the increase in greenhouse gases caused by humans, the slow cooling trend would have continued. Thus virtually the entire warming of the 20th Century is due to man. This May, for the first time in at least a million years, the concentration of carbon dioxide in our atmosphere has exceeded the threshold of 400 ppm. If we do not stop this trend very soon, we will not recognize our Earth by the end of this century.

Hansen study: Climate Sensitivity is High, Burning All Fossil Fuels Would Make Most of Planet ‘Uninhabitable’

by Joe Romm, Sept 17, 2013

James Hansen, the country’s most prescient climatologist, is out with another must-read paper, “Climate sensitivity, sea level and atmospheric carbon dioxide,” … co-authored by a number of Hansen’s former colleagues at NASA. … The key findings are:

• The Earth’s actual sensitivity to a doubling of CO2 levels from preindustrial levels (to 550 ppm) — including slow feedbacks — is likely to be larger than 3–4°C (5.4-7.2°F).
• Given that we are headed towards a tripling (820 ppm) or quadrupling (1100 ppm) of atmospheric CO2 levels, inaction is untenable.
• “Burning all fossil fuels” would warm land areas on average about 20°C (36°F) and warm the poles a stunning 30°C (54°F). This “would make most of the planet uninhabitable by humans, thus calling into question strategies that emphasize adaptation to climate change.”

Burning all or even most fossil fuels would be a true scorched Earth policy.

Given that James Hansen has been right about global warming for more than 3 decades, his climate warnings need to be taken seriously. [The] whole paper is worth reading. The authors conclude:

Most of the remaining fossil fuel carbon is in coal and unconventional oil and gas. Thus, it seems, humanity stands at a fork in the road. As conventional oil and gas are depleted, will we move to carbon-free energy and efficiency—or to unconventional fossil fuels and coal?

If fossil fuels were made to pay their costs to society, costs of pollution and climate change, carbon-free alternatives might supplant fossil fuels over a period of decades. However, if governments force the public to bear the external costs and even subsidize fossil fuels, carbon emissions are likely to continue to grow, with deleterious consequences for young people and future generations.

It seems implausible that humanity will not alter its energy course as consequences of burning all fossil fuels become clearer. Yet strong evidence about the dangers of human-made climate change have so far had little effect. Whether governments continue to be so foolhardy as to allow or encourage development of all fossil fuels may determine the fate of humanity.

That’s the end of my quote from Romm’s blog, and now you know the considered opinion of the experts. But we will be all right here in Oz, of course:



Realclimate post on Marcott:

Marcott’s paper on Science:
Science 8 March 2013
A Reconstruction of Regional and Global Temperature for the Past 11,300 Years
Shaun A. Marcott1, Jeremy D. Shakun, Peter U. Clark, Alan C. Mix

ThinkProgress post on Hansen:

Defining a rapidly changing climate

If the climate is changing, what is it that’s changing? Climate, they say, is what you expect, while weather is what you get. But if climate is changing, how do we know what to expect?

That may sound flippant but it has become quite a serious question in climate science circles of late, for two reasons: communicating climate science to the public, and dealing with the statistical problem of defining a moving target.

On the first question, for instance, we have a typical member of the public asking on the RealClimate open thread“One thing that has confused me is how long it takes for weather to become climate.”

One of the regulars replied: “WMO (World Meteorological Organization) states that climate is 30 or more years of weather data.” Another backed him up, saying, “The traditional answer is 30 years or thereabouts.” ‘SecularAnimist’, another regular, answered at greater length:

I think this question is increasingly irrelevant, and the “traditional” answer is becoming obsolete.

The question was relevant when we were asking whether the various atmospheric conditions, processes, events and patterns of events that comprise “climate” are in fact changing, and wanted to know over what length of time we’d need to observe those phenomena as ever-changing, short term “weather” to be able to conclude that the changes are sufficiently long-term to be considered “climate” change. But we already know that the climate is changing, and will continue to change, as a result of our CO2 emissions. We don’t need 30 more years of observations to tell us that, now.

And the “traditional” answer is obsolete because it presumes that the Earth’s climate is sufficiently stable, and changing so slowly, that it really does take 30 or more years of observations to detect any long-term, large-scale change. That’s no longer the case, because the climate system is being driven to change more rapidly and extremely than it has ever done in human history. It’s unlikely to take another 30 years for the American midwest to become desert. It’s unlikely to take another 30 years for the Arctic sea ice to disappear completely during summer — with all of the prodigious effects that implies.

There is every reason to expect that permanent, large-scale, dramatic changes, which cannot reasonably be called anything but “climate change”, may now occur on time scales of a few years, rather than a few decades, as would have been expected in the pre-AGW world.

The more technical problem with the definition of climate is that weather needs to be averaged over enough annual cycles to iron out the bumps caused by specific weather events (that’s where the ’30 years’ comes from) but if, for instance, the averages of the 1980s, 1990s, and 2000s are successively quite different from each other then a ‘climate’ defined by the 1980-2010 average becomes meaningless.

Should we just average over a shorter period, then? No, because known multi-year cycles such as El Nino will distort the result too much. As far as I know, the experts are still working out what to do about that. Meanwhile they tend to define our baseline climate by the period from 1951-1980. James Hansen, whom I have mentioned before, presents the reasons very sensibly in a very recent discussion of his recent ‘climate dice’ paper:

Studies of climate change generally use some base period to define an average climate and calculate “anomalies” relative to that average, i.e., climate anomalies are the deviations from that average climate. In our papers we used 1951-1980 as the base period.

Global temperature change over the past century (Fig. 1) helps us discuss possible effects of the choice of base period. Our choice of 1951-1980 as a base period has several merits:

1) The period 1951-1980 is prior to the large warming of the past few decades. If we wish to examine the effect of that global warming on climate, we must compare with the climate that existed prior to that warming.

2) The 1951-1980 period has the best global data coverage and can best characterize climate variability. Spatial coverage of data was poorer at earlier times.

3) 1951-1980 was the base period used by the National Weather Service and other researchers when we made our first analyses of observations and climate simulations. For comparison with these early analyses and climate simulations we should use the same base period.

4) Many of today’s adults, baby-boomers, grew up during 1951-1980, so it is recent enough for many people to remember what the climate was like.

The whole discussion is well worth reading, since it presents the key findings of the longer and more technical paper in a very approachable way. Download it (pdf) from here.

Climate Change – Picturing the Science

Cover of Climate Change – Picturing the ScienceClimate Change – Picturing the Science
Gavin Schmidt and Joshua Wolfe, Norton, 2009

This is the perfect book to give someone who doesn’t know much about climate change but  is interested in knowing more. It is authoritative but non-technical, uncompromising but never shrill or aggressive, and lucid but not simplistic.

Schmidt is a climate scientist at NASA and co-founder of RealClimate, and in the latter role he has patiently explained climate science to all comers from school children to fellow experts, for years. He is very, very good at it and here he has recruited similarly well-qualified people to write on specific topics. Any single chapter can stand alone, making the book simultaneously very browsable and a useful fill-the-gaps reference.

Schmidt’s over-arching metaphor for the book is the health of our planet: Symptoms, Diagnosis and Cure. It’s a good metaphor (the Buddha used it 2500 years ago, so it has a good long track record!) and it lets him organise a complicated mass of material into a coherent story about how we know what’s going on around us, why it’s happening and what’s likely to happen, and how we might avert the worst of the likely consequences.

So far, so much better than most books on the subject, but it gets better still. His co-author is a photographer and the book is copiously illustrated with excellent photos – scientists at work, hurricanes, threatened species, Arctic houses subsiding into thawing permafrost, air pollution in Beijing … all sorts of images, and all relevant and memorable.

Longer reviewsNature and Daily Kos.