Hansen: Climate science and moral responsibility


Calling climate change an issue of intergenerational justice on a par with ending slavery, James Hansen will argue in his lecture on being awarded the Edinburgh Medal that current generations have an overriding moral duty to their children and grandchildren to take immediate action, the Guardian reported.  Hansen et al.’s paper, “Scientific Case for Avoiding Dangerous Climate Change to Protect Young People and Nature,” is forthcoming in the Proceedings of the  National Academy of Sciences. “This situation raises profound moral issues as young people, future generations, and nature, with no possibility of protecting their future well-being, will bear the principal consequences of actions and inactions of today’s adults,” Hansen et al. conclude.

The UK Guardian reported on April 6:

Nasa scientist: climate change is a moral issue on a par with slavery

Prof Jim Hansen to use lecture at Edinburgh International Science Festival to call for worldwide tax on all carbon emissions

Averting the worst consequences of human-induced climate change is a “great moral issue” on a par with slavery, according to the leading Nasa climate scientist Prof Jim Hansen. …

Hansen, who will next Tuesday  be awarded the prestigious Edinburgh Medal for his contribution to science, will also in his acceptance speech call for a worldwide tax on all carbon emissions. …

He said humanity faces repeated natural disasters from extreme weather events which would affect large areas of the planet. “The situation we’re creating for young people and future generations is that we’re handing them a climate system which is potentially out of their control,” he said. “We’re in an emergency: you can see what’s on the horizon over the next few decades with the effects it will have on ecosystems, sea level and species extinction.” …

Hansen will argue in his lecture that current generations have an over-riding moral duty to their children and grandchildren to take immediate action. Describing this as an issue of inter-generational justice on a par with ending slavery, Hansen said: “Our parents didn’t know that they were causing a problem for future generations but we can only pretend we don’t know because the science is now crystal clear. …

He has co-authored a scientific paper with 17 other experts, including climate scientists, biologists and economists, which calls for an immediate 6% annual cut in CO2 emissions, and a substantial growth in global forest cover, to avoid catastrophic climate change by the end of the century.

The paper … has passed peer review and is in the final stages of publication by the US journal Proceedings of the National Academy of Sciences…

Hansen et al., “Scientific Case for Avoiding Dangerous Climate Change to Protect Young People and Nature,” forthcoming in the Proceedings of the  National Academy of Sciences, revised as of March 23, is posted here.

Scientific Case for Avoiding Dangerous Climate Change to Protect Young People and Nature

Authors:  James Hansen, Pushker Kharecha, Makiko Sato, Frank Ackerman, Paul J. Hearty, Ove Hoegh-Guldberg, Shi-Ling Hsu, Fred Krueger, Camille Parmesan, Stefan Rahmstorf, Johan Rockstrom, Eelco J. Rohling, Jeffrey Sachs, Peter Smith, Konrad Steffen, Lise Van Susteren, Karina von Schuckmann, James C. Zachos

(Submitted on 6 Oct 2011 (v1), last revised 23 Mar 2012 (this version, v3))


Global warming due to human-made gases, mainly CO2, is already 0.8{\deg}C and deleterious climate impacts are growing worldwide. More warming is ‘in the pipeline’ because Earth is out of energy balance, with absorbed solar energy exceeding planetary heat radiation. Maintaining a climate that resembles the Holocene, the world of stable shorelines in which civilization developed, requires rapidly reducing fossil fuel CO2 emissions. Such a scenario is economically sensible and has multiple benefits for humanity and other species. Yet fossil fuel extraction is expanding, including highly carbon-intensive sources that can push the climate system beyond tipping points such that amplifying feedbacks drive further climate change that is practically out of humanity’s control. This situation raises profound moral issues as young people, future generations, and nature, with no possibility of protecting their future well-being, will bear the principal consequences of actions and inactions of today’s adults.

Dr. Hansen and colleagues also have a new paper, “Public Perception of Climate Change and the New Climate Dice,” that was submitted to Proceedings of the National Academy of Sciences on April 5.  The paper as submitted is posted here.

Public Perception of Climate Change and the New Climate Dice

Authors:  James Hansen, Makiko Sato, Reto Ruedy


“Climate dice”, describing the chance of unusually warm or cool seasons relative to climatology, have become progressively “loaded” in the past 30 years, coincident with rapid global warming. The distribution of seasonal mean temperature anomalies has shifted toward higher temperatures and the range of anomalies has increased. An important change is the emergence of a category of summertime extremely hot outliers, more than three standard deviations (3{\sigma}) warmer than climatology. This hot extreme, which covered much less than 1% of Earth’s surface in the period of climatology, now typically covers about 10% of the land area. It follows that we can state, with a high degree of confidence, that extreme anomalies such as those in Texas and Oklahoma in 2011 and Moscow in 2010 were a consequence of global warming, because their likelihood in the absence of global warming was exceedingly small. We discuss practical implications of this substantial, growing, climate change.

Also see the video of Dr. Hansen’s TED talk, given in February 2012:  “Why I must speak out about climate change.”

Earlier posts:

Jim Hansen arrest at White House tar sands pipeline protest: “We had a dream”

10/10/10 global warming rally at the White House

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5 Responses to Hansen: Climate science and moral responsibility

  1. John Shade says:

    While the Edinburgh Science Festival was degrading the Edinburgh Prize by giving it to an unhinged zealot, a letter from very experienced former employees of NASA was in the in-tray of the NASA Administrator expressing great concern over the way in which he is bringing that Agency into disrepute. Details here: http://climatelessons.blogspot.co.uk/2012/04/experienced-former-nasa-employees.html

    • Rick - Climate Science Watch says:

      We don’t normally post references to whatever global warming ‘skeptics’ are lionizing at the moment, nor uninformed and disrespectful comments about eminent scientists. But there’s a point to be made here. With all due respect, the signers of the letter are not intellectually qualified to critique the work of James Hansen and his colleagues at the NASA Goddard Institute for Space Studies, and the rest of the leading climate scientists. I’ll be surpirsed if you can point me to any publications in the climate science peer-reviewed literature by any of the letter-signers. They couldn’t give you a meaningful exposition of Hansen’s analysis, nor a meaningful critique of it. I also note that they appear to be predominantly connected with the Johnson Space Center, i.e., the human space flight portion of the NASA budget. They are interested in protecting the Johnson Space Center budget, but this seems sort of an ignorant way of going about it. I have nothing in principle against human space flight, though I think its foreseeable future is seriously limited by distances. But I wouldn’t spend another dollar on astronauts if it in any way compromised funding for the more important NASA Earth Science program, in particular the remote-sensing satellite global climate observing system and associated data systems and scientific research.

      • John Shade says:

        I admire your willingness to publish contrary views from time to time, and I hope a further comment from me will not try your patience too much.

        I think you may well be right about the signees lack of publications in the climate science literature, but that does not automatically render them, nor little old me for that matter, intellectually unqualified to criticise at least some aspects of the work of those who do have such publications. For example, a history of failed predictions, a neglect of the scientific method’s emphasis on observational tests of hypotheses, a penchant for science by press release, and emotive, value-laden, histrionics.

        On the observational front, I notice a well-qualified IPCC reviewer has recently said this: ‘There is currently no evidence that increased human-based emissions of carbon dioxide or other “greenhouse gases” have any measurable effect on the climate. This view is based upon my experience as an expert reviewer of all of the Reports of the Intergovernmental Panel on Climate and an intimate knowledge of everything in them.’ [http://www.investigatemagazine.co.nz/Investigate/?p=2692]

        • Rick - Climate Science Watch says:

          In selecting Vincent Gray, a non-climate-scientist from New Zealand as your preferred expert to put up against, not only James Hansen, but virtually all of the leading climate scientists and their in-depth scientific assessments of climate change, you are cherry-picking to suit your preferences. Gray, it has been noted [ http://en.wikipedia.org/wiki/Vincent_R._Gray ], calls himself an “Expert Reviewer for the IPCC” since 1990, although this consideration has been challenged and considered misleading since it does not require any expertise at all, but only that “he asked to see the draft report” and signed an agreement not to publicly comment on the draft report. Gray has never been published in a peer-reviewed journal on the subject of climate change.

          It is evident from the technical publicationss by Dr. Hansen and his colleagues that his analysis does not depend fundamentally on models and their predictions/projections, but is based on the observational record and a scientific understanding of the Earth’s energy imbalance, its magnitude, causes, and implications. You can call his presentations “emotive, value-laden histrionics” if you wish, but I suggest readers actually read Dr. Hansen’s scientific papers and his memoir, Storms of My Grandchildren, and judge for themselves. In my opinion they represent science and scientist-citizenship at its best.

  2. Henry says:

    Thanks for taking the time to produce this website and to patiently dig into the denialist’s methods. One of the most infuriating things that they throw at those who don’t follow their agenda blindly, is the accusation that those doubting them are not “openminded”, as if being so includes giving equal weight to nonsense against scientific evidence and logical deductive methods, a la creationism’s false embracing of scientific “debate” as their rationale for bringing myth and religion into the science classroom. I am a month away from a BS in Environmental Science, and I would like to help you in your mission, if you can use me. Reply by email if interested. Thanks.

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