Climate Change Future

Hansen to Obama Pt 1 – the Now or Never plan

It would be an understatement of epic proportions to say that President-elect Barack Obama has a big job ahead of him come January 2009. Plenty of people will be giving him ‘advice’ – some good, most not (if the history of vested interests twisting the political process over the last few decades is any guide).

Scientists have something particularly important to communicate to Obama on climate change and energy. It’s based on hard-won, peer-reviewed evidence – not spin and denial – and it’s a super urgent message. In broad terms, it’s the policy implications of the Sustainability Emergency.

One of the most respected climate change scientists, Dr James Hansen of NASA, has drafted a statement which Obama should definitely read. I think BraveNewClimate readers should study it too. It is perhaps the single best succinct summary of the problems and solutions of global warming and related issues that I’ve read.

As such, I’ve decided to republish it here on BNC in full over the next week, and invite feedback from readers. As Jim says, “This is a first draft. Criticisms would be much appreciated.” I’ll make sure he gets to see them. To access the original PDF, click here. Or wait and follow it here on BNC. I’ve enhanced the original slightly by adding some judicious hyperlinks, which will allow readers to explore these ideas further.

First up, it’s an overview of the core problem – the threats of inaction (or weak progress), the urgency of the problem and the fallacy of part-solutions, and the principle implication – coal emissions must stop ASAP.


Tell Barack Obama the Truth – The Whole Truth (Part I of IV)

Dr James E. Hansen

Embers of election night elation will glow longer than any prior election. Glowing even in other nations, and for good reason. We are all tied together, more than ever, like it or not. Barack Obama’s measured words on election night, including eloquent recognition of historic progress, from the viewpoint of a 106-year-old lady, still stoke the embers. But he was already focusing on tasks ahead, without celebratory excess. Well he should.

The challenge he faces is unprecedented. I refer not to the inherited economic morass, as threatening as it is. The human toll due to past failures and excesses may prove to be great, yet economic recessions, even depressions, come and go. Now our planet itself is in peril. Not simply the Earth, but the fate of all its species, including humanity. The situation calls not for hand-wringing, but rather informed action.

Optimism is fueled by expectation that decisions will be guided by reason and evidence, not ideology. The danger is that special interests will dilute and torque government policies, causing the climate to pass tipping points, with grave consequences for all life on the planet. The President-elect himself needs to be well-informed about the climate problem and its relation to energy needs and economic policies. He cannot rely on political systems to bring him solutions – the political systems provide too many opportunities for special interests.

Here is a message I think should be delivered to Barack Obama. This is a first draft. Criticisms would be much appreciated.

Climate threat. The world’s temperature has increased about 1°F over the past few decades, about 2°F over land areas. Further warming is “in the pipeline” due to gases already in the air (because of climate system inertia) and inevitable additional fossil fuel emissions (because of energy system inertia). Although global warming to date is smaller than day-to-day weather fluctuations, it has brought global temperature back to approximately the highest level of the Holocene, the past 10,000 years, the period during which civilization developed. Effects already evident include:

1. Mountain glaciers are receding worldwide and will be gone within 50 years if CO2 emissions continue to increase. This threatens the fresh water supply for billions of people, as rivers arising in the Himalayas, Andes and Rocky Mountains will begin to run dry in the summer and fall.

2. Coral reefs, home to a quarter of biological species in the ocean, could be destroyed by rising temperature and ocean acidification due to increasing CO2.

3. Dry subtropics are expanding poleward with warming, affecting the southern United States, the Mediterranean region, and Australia, with increasing drought and fires.

4. Arctic sea ice will disappear entirely in the summer, if CO2 continues to increase, with devastating effects on wildlife and indigenous people.

5. Intensity of hydrologic extremes, heavy rains, storms and floods on the one hand, and droughts and fires on the other, are increasing.

Some people say we must learn to live with these effects, because it is an almost godgiven fact that we must burn all fossil fuels. But now we understand, from the history of the Earth, that there would be two monstrous consequences of releasing the CO2 from all of the oil, gas and coal, consequences of an enormity that cannot be accepted. One effect would be extermination of a large fraction of the species on the planet. The other is initiation of ice sheet disintegration and sea level rise, out of humanity’s control, eventually eliminating coastal cities and historical sites, creating havoc, hundreds of millions of refugees, and impoverishing nations.

Species extermination and ice sheet disintegration are both ‘non-linear’ problems with ‘tipping points’. If the process proceeds too far, amplifying feedbacks push the system dynamics to proceed without further human forcing. For example, species are interdependent – if a sufficient number are eliminated, ecosystems collapse. In the physical climate system, amplifying feedbacks include increased absorption of sunlight as sea and land ice areas are reduced and release of methane, a powerful greenhouse gas, as permafrost melts.

The Earth’s history reveals examples of such non-linear collapses. Eventually, over tens and hundreds of thousands of years, new species develop, and ice sheets return. But we will leave a devastated impoverished planet for all generations of humanity that we can imagine, if we are so foolish as to allow the climate tipping points to be passed.

Urgency. Recent evidence reveals a situation more urgent than had been expected, even by those who were most attuned. The evidence is based on improving knowledge of Earth’s history – how the climate responded to past changes of atmospheric composition – and on observations of how the Earth is responding now to human-made atmospheric changes. The conclusion – at first startling, but in retrospect obvious – is that the human-made increase of atmospheric carbon dioxide (CO2), from the pre-industrial 280 parts per million (ppm) to today’s 385 ppm, has already raised the CO2 amount into the dangerous range. It will be necessary to take actions that return CO2 to a level of at most 350 ppm, but probably less, if we are to avert disastrous pressures on fellow species and large sea level rise.

The good news is that such a result is still possible, if actions are prompt. Prompt action will do more than prevent irreversible extinctions and ice sheet disintegration: it can avert or reverse consequences that had begun to seem inevitable, including loss of Arctic ice, ocean acidification, expansion of the subtropics, increased intensity of droughts, floods, and storms.

Principal implication. CO2 is not the only human-made gas that contributes to global warming, but it is the dominant gas and it has the longest lifetime. Much of the CO2 increase caused by burning fossil fuels remains in the air more than 1000 years. So CO2 must be the focus of efforts to stop human-caused climate change.

It would be easy to jump to the conclusion that solution of global warming is to phase down total fossil fuel emissions by some specified percentage. That approach will not work as a strategy. The reason for that conclusion and an outline of a better strategic approach follow immediately from geophysical boundary constraints.

are provided in the published paper.”]

Figure 1a shows oil, gas and coal reserves, with the purple portion being the amount that has already been burned and emitted into the atmosphere. Despite uncertainty in the magnitude of undiscovered reserves, their amounts are certainly enough to yield atmospheric CO2 greater than 500 ppm. That amount would be disastrous, assuring unstable ice sheets, rising sea level out of humanity’s control, extermination of a large fraction of the species on Earth, and severe exacerbation of climate impacts discussed above.

Oil is used primarily in vehicles, where it is impractical to capture CO2 emerging from tailpipes. The large pools of oil remaining in the ground are spread among many countries. The United States, which once had some of the large pools, has already exploited its largest recoverable reserves. Given this fact, it is unrealistic to think that Russia and Middle East countries will decide to leave their oil in the ground. A carbon cap that slows emissions of CO2 does not help, because of the long lifetime of atmospheric CO2. In fact, the cap exacerbates the problem if it allows coal emissions to continue. The only solution is to target a (large) portion of the fossil fuel reserves to be left in the ground or used in a way such that the CO2 can be captured and safely sequestered.

Coal is the obvious target. Figure 1b shows that if there were a prompt moratorium on construction of new coal plants, and if existing ones were phased out linearly over the period 2010-2030, then atmospheric CO2 would peak during the next few decades at an amount somewhere between 400 and 425 ppm. The peak value depends upon whose estimate of undiscovered reserves is more accurate. It also depends upon whether oil in the most extreme environments is exploited or left in the ground, and thus it depends on the carbon tax (see next post).

This coal-phase-out scenario yields the possibility of stabilizing climate. Overshoot of the safe CO2 level is sufficiently small that improved agricultural and forestry practices, including reforestation of marginal lands, could bring CO2 back below 350 ppm, perhaps by the middle of the century. But if construction of new coal plants continues for even another decade it is difficult to conceive a practical, natural way to return CO2 below 350 ppm.


Part II of IV will focus on policy options…

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By Barry Brook

Barry Brook is an ARC Laureate Fellow and Chair of Environmental Sustainability at the University of Tasmania. He researches global change, ecology and energy.

9 replies on “Hansen to Obama Pt 1 – the Now or Never plan”

Dear James Hansen,

Thanks for telling the truth as you see it and for speaking out loudly, clearly and often about what everyone knows but precious few will say.

As you know better than most of us, “denial” is not only a river in Egypt. However we choose to look at the taxonomy of denial, you help us easily see that many too many leaders are collusively engaged in its practice. Even though it is perverse, denial is consensually validated behavior. If enough elite people remain in denial, something more attractive…ie, something illusory…can be put in place of what is more real and somehow likely to be more truthful.

Doing good work along the path toward a good enough future for children will not be an easy task for anybody. Evidently, everybody wants to be a somebody, but nobody in a position of power willingly assumes the requisite responsibilities and performs the duties of office. Such so-called ‘leadership’ is both ubiquitous and woefully inadequate.

Occasionally a great person like you can be found who goes against the tide of people with power…who disputes the elitists who uniformly favor whatsoever is politically convenient, economically expedient, socially agreeable and religiously tolerated.

Certainly I share the view that everyone-in-power’s silence with regard to what is happening in any “here and now” moment of space-time is the most formidable foe that the family of humanity faces.



Steven Earl Salmony
AWAREness Campaign on The Human Population,
established 2001


Welcome back from China Barry.

Joseph Romm at Climate Progress is not happy with Hansen’s policy recommendations:

He concludes: “I am not entirely convinced that 350 ppm is needed this century from a purely scientific perspective. But I am utterly unconvinced that you have a technology and policy strategy needed to achieve 350 ppm or come anywhere close. For now, I’ll stick with 450 ppm.”

I agree with Hansen on the science but Romm’s critique of the policy issues is very worthwhile reading.


Chris @2: I’ve read Romm, and think he is wrong on this, or at least has not read all of what Hansen has to say, especially about energy alternatives. But I’ll leave comment on that until I’ve posted the four parts. Suffice to say, if we all choose to “stick with 450 ppm” as Romm says, then we may as well not bother, because we’ll be pursuing a solution that only half-fixes the problem and therefore ultimately fails — because it still leads to a transformed planet the likes of which humanity has ever experienced.


Since Obama is, ultimately, a politician responsible to voters, I think he should list the impacts on humans (and specifically american humans) first (eg. mass flooding of new york, failing crops driving up food prices, cities in the mid west being abandoned as drinking water dries up), even if in an absolute scheme of things these are smaller than mass species extinction. Obama has to sell this message to congress and the american people.


[…] Coal is the dirtiest fuel. Coal burning has released and spread around the world more than 100 times more radioactive material than all the nuclear power plants in the world. Mercury released in coal burning contaminates the world ocean as well as our rivers, lakes and soil. Air pollution from coal burning kills more than 100,000 people per year. If such consequences were occurring from nuclear power, nuclear plants would all be closed. Mining of coal, especially mountaintop removal, causes additional environmental damage and human suffering. It is time for all the coal plants to be closed, indeed, averting climate disasters demands that all coal plants be phased out. Coal is best left in the ground. […]


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