(a) Greenhouse gas scenarios in 1988 GCM simulations, (b) Observed temperature compared with simulations for scenarios A, B, C.  Shaded range was based on estimated global temperature at peaks of the current and prior interglacial periods, about 6,000 and 120,000 years ago. Graphic: Hansen, 2017 / Earth Institute

By James Hansen
26 October 2017

(Earth Institute) – Frank Dentener, an editor of Atmospheric Chemistry and Physics, in a recent note to me observed that Ice Melt, Sea Level Rise, and Superstorms[4], hereafter Ice Melt, was not highly cited or mainstream in climate impact discussions.  He was concerned because he thought it important for peer-reviewed extreme scenarios to be included in the upcoming IPCC AR6 cycle[5].

In Ice Melt, summarized in a video, we use paleoclimate analyses, climate modeling, and modern observations to expose a global climate emergency: fossil fuel emissions must be reduced as rapidly as practical.  A proposed 2°C global warming target is not a safe “guardrail” – 2°C warming would lock in unconscionable climate impacts on young people and future generations. Earth’s present energy imbalance, with most of the excess energy pouring into the ocean, assures continued ocean warming for decades and threatens to lock in amplifying climate feedbacks, melting of ice shelves and nonlinearly growing sea level rise.  Earth’s energy imbalance also assures continued long-term warming of land areas, with increasingly extreme droughts, floods and storms.  Subtropics in summer and the tropics year-round are becoming uncomfortably warm; these areas will become less habitable if warming continues, increasing immigration pressures and global governance problems.  Responsibility for these affairs will lie with the developed world.  Our related Young People’s Burden[6]  paper shows that continued high fossil fuel emissions unarguably sentences young people to either a massive, implausible cleanup of atmospheric CO2 or growing deleterious impacts or both.

Below I examine whether recent observations support the conclusions in the Ice Melt paper.

Greenhouse gas (GHG) climate forcing annual growth rate.  IPCC scenario RCP2.6 keeps maximum global warming <1.5°C.  Annual addition to future warming (right hand scale) assumes climate sensitivity 3°C for 2×CO2.  Actual GHG growth exceeds RCP2.6 by at least 0.01 W/m2 in 2015 and 2016. Graphic: Hansen, 2017 / Earth Institute

First, however, I address “scientific reticence,” which I suspect affects consideration of our Ice Melt and Young People’s Burden papers – more important, it affects public understanding of climate change and the prospects for avoiding disastrous climate impacts.  I once wrote about Scientific Reticence and Sea Level Rise[7] from an academic perspective, concluding, in agreement with Eipper[8], that scientists should not shrink from exercising their rights as citizens and responsibilities as scientists.  Here it may be more informative if I describe two personal examples, papers I published in 1981[9] and 1988[10], each with many co-authors and each with receptions similar to that of the Ice Melt paper.  Those two papers probably had the most impact of all papers I have written, yet neither was greeted with citations or approval by the community.  Even after 3-4 decades their cumulative citations rank only #16 and #17 among papers on which I am lead author or co-author.  They rank #11 and #12 among papers on which I am lead author. [more]

SciScientific Reticence and the Fate of Humanity


  1. Anonymous said...

    An interesting article by Hansen, which will not... be widely read.

    The climate change narrative has failed to garner the attention and interest required. It's still burbling along (kinda like methane bubbles in the Arctic), but it has lost the larger audience.

    The term scientific reticence very much applies to the scientist themselves - who have still failed to coalesce as a urgent (read "emergency") group of concerned experts. That is to say, they're continuing to follow the same failed processes for funding, attention, recognition and acknowledgement.

    It's not working. Certainly not under the Trump Administration, but I've brought this all up many times before.

    Somehow, they still do not grasp the meaning that the "rules have changed" and moreover, they have always been rigged to support climate pollution and more greenhouse gas contributions. Well, we all know what that leads (or are supposed to).

    The inflexibility of the scientific community to break the mold and call forth emergency sessions (even if they have to do this on their own) will result in what we've already got - little interest, little real action, little real effort, lots of "greenwashing" and plenty of ink and paper (bits and bytes) being burned up wasting irreplaceable time and money.

    In other words - they're not calling enough attention to their work and their results because they continue to play by the rules established for them. It hasn't worked - and it will not work.

    Few people seem to understand that we do not need permission to change the game. We can still do what we want - if we want. If we can find the path and the courage and the fortitude to make it happen. But as long as scientists - and the public - continue to accept the established "rules" on climate change - we're basically fucked. Pure and simple.

    It has been addressed by others before. Either we acknowledge the real global climate emergency - in our actions, papers, attitudes and practices - or we continue to pretend that it's not urgent and there is not present emergency. But the data says otherwise, over and over and over again. So it is up to us to act like it matters, act like we believe it, act like we must change and change very, very fast.

    Scientists are procedure driven, by training and by institutional expectations. I get that, but now that we have sufficient data, there isn't any more time for this slow, long, drawn out "lets just stick to the science" approach. They have GOT TO BECOME ACTIVISTS because they are indeed, the real experts on the science - we should believe them. But they need to take charge on this and not wait around for political leadership because it isn't going to happen.

    I have no hope for our future unless something radical is done. Human survival is what is at stake here. ~Survival Acres~  


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