James Hansen: Scientific reticence and the fate of humanity

Desdemona Despair

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.

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