Tag: Hansen

China: ready to pay the price

ames Hansen was in China when the American midterm elections were held, and he reports that while the rest of us were feeling pessimistic he was becoming optimistic. Not because of what was happening in the US, but because of China. He found two reasons for optimism, the first of which he has explained in a poston his website. The second will follow, but there’s enough in the first to warrant notice here.

In the activist dimension of his life – which he always makes clear is an expression of personal opinion and in this respect differentiated from his scientific work – Hansen opposes cap and trade approaches to limiting carbon emissions as ineffective and instead advocates a steadily rising carbon fee collected from fossil fuel companies and returned to the public on a per capita basis to allow lifestyle adjustments and spur clean energy innovations.

 

He considers there are signs that China is ready to consider a rising carbon price as part of a clean energy transition. At the Beijing Forum he attended he was impressed by what he described as the focused rational approach to dealing with the challenges, epitomized by Dr. Jiang Kejun (pictured), the lead speaker in the session “Global Environmental Policies and National Strategies”.

“Jiang Kejun laid out sector-by-sector projections of transitions to low-carbon and no-carbon energies and improved energy efficiency that would allow CO2 emission growth to be slowed and then reversed over the next few decades. Technology development is supported, and, when lower carbon technology becomes available, efficiency standards are promptly ratcheted downward. Most encouragingly, there is recognition that this strategy requires a rising carbon price for most successful results. The Chinese authorities appear to grasp that rapid attainment of the tipping points at which clean energies quickly displace dirty energy requires an economic incentive.”

Hansen remarks the advantages of the scale of manufacturing in China. It is so great that the unit price of new technologies can be quickly brought down, putting China in a position to sell carbon-efficient technologies to the rest of the world.

He compares the prevention of effective legislation by vested interests in the US with his impression that China has the capacity to implement policy decisions rapidly. He notes that the leaders seem to seek the best technical information and do not brand as a hoax that which is inconvenient. The power of fossil fuel interests is not as strong as in the US.

Hansen’s earlier view was that global action to stem climate change required agreement between China and the United States for a rising carbon fee. He acknowledges this is not realistic as the dysfunctional Congress would not approve such a treaty.

However, he sees a way around that. He envisages China finding agreement with other nations such as the European Union to impose rising internal carbon fees. And here’s the crunch:

“Existing rules of the World Trade Organization would allow collection of a rising border duty on products from all nations that do not have an equivalent internal carbon fee or tax.”

And the consequence:

“The United States then would be forced to make a choice. It could either address its fossil fuel addiction with a rising carbon fee and supportive national investment policies or it could accept continual descent into second-rate and third-rate economic well-being. The United States has great potential for innovation, but it will not be unleashed as long as fossil fuel interests have a stranglehold on U.S. energy policies.”

Nicholas Stern doesn’t share Hansen’s impatience with emissions trading schemes, but it is worth noting that he sounded very similar trade warnings in Auckland in September where he was delivering the Douglas Robb lectures. The world is embarking on a “new industrial revolution” of renewable energy and cleaner innovation, he told the Herald. Countries which don’t embrace it will find other countries reluctant to trade with them. Ten or fifteen years from now, those that produce in dirty ways are likely to face trade barriers.

However it is obtained, a rising price on carbon is an essential element in the transition to clean energy, and trade concerns may well play a part in making it global. Hansen insists that only a tax can achieve it, but there are indications that China is also considering a cap-and-trade system. Either way contributes to the seriousness Hansen discerns in China’s planning towards the transformation of its currently carbon-dependent economy.

World leaders pretend

Apparently the American Geophysical Union’s readiness to speak out on climate change which I reported in a recent post was not as the LA Times portrayed it.  Joseph Romm has written of his disappointment that the AGU is constrained by a determination to veer away from anything that could be construed as advocacy. They state that the email exchange forum they have set up for journalists is designed to answer questions about the current state of scientific knowledge, with a special emphasis on the physical sciences that relate to climate change. Non-science questions such as those relating to policy, ethics, or economics will be returned to sender for refinement.

One example they provide is the question, “Is current U.S. infrastructure adequate for sea level rise?”  Such a question will be returned to sender on the grounds that judgments of adequacy involve tradeoffs in risk and in policy. The scientists will only answer the question if it is changed to “What amount of sea level rise might occur this century?”

It’s a stark contrast with climatologist  James Hansen, who recently delivered an open lecture in Japan on the occasion of his being awarded the prestigious Blue Planet Prize. The text and powerpoint charts can be accessed on his website. He doesn’t hold back. Here are the opening words:

 

“Human-made climate change is a moral issue. It pits the rich and the powerful against the young and the unborn, against the defenseless and against nature.

“Climate change is a political issue. But politics fails when there is a revolving door between government and the fossil fuel-industrial complex.

“Climate change is a legal issue. The judiciary provides the possibility of holding our governments accountable for their duty to protect the public interest.”

The accompanying slide has a footnote that statements relating to policy are personal opinion.

Of course Hansen then proceeds with the science of climate change, explaining the current position with his usual clarity.

“It is difficult for the public to recognize that we have a crisis, because human-made global warming, so far, is small compared to day-to-day weather fluctuations. Yet the fact is: we have an emergency. Because of the great inertia of the ocean, which is four kilometers deep, and the ice sheets, which are two to three kilometers thick, the climate system responds slowly to climate forcings such as increasing greenhouse gases. But this inertia is not our friend, because it increases the danger that we may pass tipping points, beyond which the dynamics of the climate system takes over and rapid changes occur out of humanity’s control.”

He offers three examples of tipping points. The ice sheets of Greenland and Antarctica, especially the West Antarctic ice sheet, are one. If an ice sheet is weakened to the point that it begins to collapse then the dynamics of the process take over. Another non-linear problem is the extermination of species which can accelerate because of the interdependencies among species. A third is methane hydrates, essentially frozen methane. If they begin to disintegrate the process could become self-sustaining. He notes these tipping points have all occurred during Earth’s history in conjunction with warming climates.

At this point in his lecture he again crosses into the kind of territory that the AGU eschews for its scientists.

“Climate inertia and tipping points give rise to potential intergenerational injustice. Today’s adults enjoy the benefits of fossil fuel use, but the impacts will be borne by young people and future generations. Our parents did not know that their actions would affect future generations. We do not have that excuse. We can only feign ignorance. It is called denial.”

There was a lengthy period following Hansen’s testifying to Congress in the 1980s during which he decided to concentrate on research and leave public communication to others. He tells how  it was the arrival of his grandchildren combined with the growing gap between what was understood of the science and what was known by the public that brought him back to public communication. In 2004 he gave a carefully prepared public talk titled “Dangerous anthropogenic interference: a discussion of humanity’s Faustian climate bargain and the payments coming due”.

His public lecture in Japan is the latest example of his readiness to couple the communication of the science with clear assessment of the risk and with concrete recommendations as to how that risk may yet be avoided.  As his lecture proceeds he explains the basis of our current scientific understanding. It depends most of all on Earth’s paleoclimate history, then on ongoing global observations showing how climate is responding to rapid changes of atmospheric composition, and finally on climate models and theory which are helpful in interpreting what is happening and needed to predict future changes. There’s a pile of interesting material which follows which I won’t try to summarise here, save to say that he points out that the human-caused rise in atmospheric carbon dioxide is occurring at a rate 10,000 times faster than the natural geologic change of the Cenozoic era of the past 65 million years. He also explains his assessment that a level of no more than 350ppm of atmospheric carbon dioxide is required if we wish to preserve the planet on which civilisation developed.

He’s not backward in spelling out policy implications. We must halt all coal emissions in 20 years, not develop tar sands, oil shale or methane hydrates, and not pursue the last drops of oil in polar regions, deep sea drilling or pristine land. “In other words, we must move on to the clean energy future now, rather than using all the remaining fossil fuels.”

There’s as yet no sign of our doing so:

“But what is really happening? The United States has signed an agreement with Canada for a pipeline to carry tar sands oil to Texas. New coal plants are being built all around the world, some being financed by the World Bank. Environmentally destructive mountaintop removal continues. Oil is pursued in pristine places. The environmentally destructive practice of shale fracturing is being developed and implemented to find the last bits of gas.

“There is a huge gap between government rhetoric and policy reality. Leaders say that we have a ‘planet in peril’, yet their proposed policies barely differ from business-as-usual. Greenwash is plentiful, but the leaders follow a path of appeasement of fossil fuel special interests. There is no Winston Churchill willing to stand up and tell the truth about what is needed.”

Hansen then moves to his policy prescriptions which include a rising price on carbon, government regulation, and technology development driven by the certainty of the carbon price. He is not diffident in offering them, but his audience would have no difficulty recognising when he has moved from presentation of the science to advocacy of a particular response.

The notion that a scientist’s responsibility ends where a politician’s begins is simplistic. Politicians often enough show little sign of fully appreciating the reality of the science, and even if they do they appear to have an endless capacity to shy away from appropriate action. Are scientists like Hansen supposed to stay in their sanctums and be satisfied with issuing bulletins on the state of the science? And when they see the mayhem created by industry denial and media confusion and political timidity are they supposed to just shrug their shoulders and get on with their research? Even though they know what that research indicates for the human future if we carry on as usual?

Hansen’s record makes it quite clear that advocacy doesn’t mean compromising research. His scientific work continues and wins respect in its own right. Joe Romm has  reason to be disappointed that the AGU has put such stringent limits on its scientists’ communication with journalists.

[REM]

Licking lignite

Jeanette Fitzsimons raised the alarm in a recent Herald op-ed over Solid Energy’s plans for Southland lignite. A very justified alarm. She wrote of well-advanced plans to use more than 3 billion tonnes of economically recoverable lignite from three fields in Southland. Big plans, of which New Zealanders are hardly aware. First off is the transformation of lignite, by drying it, into briquettes for Fonterra’s milk-processing plants and for export. Only 100,000 tonnes a year in the pilot plant to be built next year, followed by a full-scale plant many times larger. Next are plans to convert lignite to diesel, with the claim that all New Zealand’s diesel could be produced this way. The third big plan is the conversion of lignite to urea.

 

It’s the increase in greenhouse gas emissions associated with this vast development that concerns Fitzsimons. Her article rests on the arguments of James Hansen that the use of coal must be phased out over the next couple of decades. And she’s not buying the claim of carbon compliance:

“Solid Energy says all the emissions will be ‘offset’. But increasing the amount of biological carbon that cycles between atmosphere and plants can’t compensate for putting more fossil carbon into the system, even if our ETS scheme pretends it can.

“Paying money is, in the end, not a get-out-of-jail-free card for increasing pollution.

“These huge lignite developments are close – Solid Energy intends to start building next year. Any hope we had of reducing our greenhouse emissions would be lost.”

Her conclusion is robust:

“As citizens, we need to refocus our domestic action to tell Solid Energy and the Government by every means available to us to keep the coal in the hole. Every tonne of lignite New Zealand keeps in the ground is 1.5 tonnes of carbon dioxide that doesn’t get into the atmosphere.”

I agree entirely, and wonder what is going on in the mind of the Minister of Energy and others in government as they contemplate the proposed activity of the government-owned company. It’s not as if there is any requirement for lignite in something essential like our electricity generation, no lingering imperative that we carry on using it until we can replace it with renewables. The only imperative in the proposed lignite exploitation is that we not leave any resource stone unturned in the drive to greater economic wealth.

I don’t know how much thought the Minister gives to the counter imperative that we take every step open to us to prevent the continuing build-up of greenhouse gas emissions in the atmosphere. There is perhaps a cautionary note in the reference to coal in the Draft Energy Strategy, but it’s far from specific:

“New Zealand’s extensive coal resources currently contribute to electricity supply security. Coal is also utilised by industry and is exported. Coal could potentially contribute to the economy in other ways, such as through the production of liquid fossil fuels, methanol or fertiliser such as urea.

“This potential is more likely to be fully realised if an economic way to reduce high levels of greenhouse gas emissions is found. Carbon capture and storage technology (CCS) will potentially be an effective way of utilising resources while reducing CO2 emissions.”

Moreover there’s nothing in Solid Energy’s plans which suggests that the lignite development is going to wait on CCS (if the technology is ever developed successfully). Meeting the slack requirements of the ETS is all they appear to have in mind, and that’s clearly no impediment to proceeding.

The Minister has a wide embrace. He welcomes every renewable energy development that comes along. In the same breath he waxes enthusiastic at the prospect of the discovery and urgent development of fossil fuel resources. If the Draft Energy Strategy is as close to his and the government’s philosophy as we’re going to get it appears the thinking is that we can fully exploit the fossil fuel resources while alternatives are being developed. And we should be getting on with it smartly while it’s profitable. It’s an opportunity which we would be foolish to miss. Indeed according to Chris Baker, CEO of the mining and exploration lobby Straterra, who followed up Jeanette Fitzsimons’ article the very next day, the lignite resource could be worth $3 trillion. He didn’t say to whom, but no doubt there would be trickle down.

How does this wealth stack up against the release of more atmospheric carbon as a result of exploiting the lignite? That’s a rhetorical question. It doesn’t matter how many trillions of dollars we gain if we lose a habitable world for our descendants in doing so.

If the government is serious about tackling climate change it should instruct Solid Energy not to pursue the lignite plans and relieve them of whatever dividend expectations that makes them unable to fulfil. If regulation is necessary it should legislate for it. It should tell the public that unless full carbon capture and storage technology is possible there can be no exploitation of the lignite fields because of the seriousness of the threat of increased greenhouse gases. That threat, it should explain, far outweighs the transient economic gain of fossil fuel development.

We can’t have it both ways. We can’t reduce emissions by increasing them. We can’t say we recognise the threat of global warming and at the same time expect to carry on with all activities which give rise to it. If Gerry Brownlee and the government think we can, they are deceiving themselves and us. Jeanette Fitzsimons is absolutely right. Keep the coal in the hole.

PS. Take a few minutes to send Gerry Brownlee an email to that effect. Remind him that he has a responsibility to the future. I’ve done so.

The Flooded Earth

The Flooded Earth: Our Future in a World without Ice Caps

Paleontologist Peter D Ward is scared and not afraid to admit it. He doesn’t mince matters in his latest book The Flooded Earth: Our Future in a World Without Ice Caps. His own study of Earth’s geological past makes him well aware of what changes to the ice caps can mean for sea level and also of how closely past temperature rises and falls have been tied to levels of atmospheric carbon dioxide. He is alarmed by the prospect for this century and also for the centuries ahead if we keep loading the atmosphere with carbon dioxide from fossil fuels. Over coming centuries we can expect metres of sea level rise at a minimum, and much more if there is rapid disintegration of one or more ice sheets. His example of how rapid change can be is a rise which occurred during the most recent ice melt 14,000 to 16,000 years ago when the sea appears to have risen by nearly 50 feet over 300 years.

Scientific reticence is not for him. He discusses it at one point in the book. In relation to sea level rise he considers the fear of being wrong is inhibiting the sounding of the alarm that new discoveries call for. He refers to James Hansen on the question of caveats and caution. Hansen regards caveats as essential to science, but warns that there is a question of degree and “gradualism” as new evidence comes to light may not be appropriate when an issue is pressing. Ward welcomes the robustness of Hansen who says he expects more than 3 feet sea level rise by century’s end. Ward also notes climatologist Stephen Rahmstorf’s recent estimate, based on a new kind of model, of a minimum of 2 feet and a maximum of almost 5 feet this century. Ward doesn’t himself settle on a particular figure for this century, but has no doubt that the rise will continue so long as carbon dioxide levels are permitted to continue to rise, and that it will be very difficult for human society to cope with.

The book has many warnings to give about what rising sea levels will mean. They are pitched to the understanding of non-specialist readers and they bring into focus the work of a wide range of researchers in a variety of fields. One area of major concern is how even a modest increase in sea level will dramatically affect world agricultural yields. Some land will be drowned, but Ward draws particular attention to salt intrusion from the sea in agricultural areas near to oceans. A detailed examination of the Sacramento Delta region in California illustrates just one highly susceptible area. Ward considers the world overpopulated, and the prospect of feeding 9 billion or more people is certainly not enhanced by encroaching sea water.

It is estimated that even an 8-inch rise in the Bay of Bengal will displace 10 million Bangladeshis in an already heavily populated country.

The flooding of threatened countries and cities as sea level rise gathers pace is the focus of another chapter of serious warning. Bangladesh and Holland are two countries he discusses. It is estimated that even an 8-inch rise in the Bay of Bengal will displace 10 million Bangladeshis in an already heavily populated country. A 3-foot rise in sea level will put Holland on the ropes; a 16-foot rise will knock it out, flooding huge areas and displacing millions. Venice and New Orleans feature in his discussion of cities, but he points to myriad coastal cities which will face neighbourhood triage – deciding which areas to fight for and which to give up. If sea level rises much beyond 5 feet expensive infrastructure will be threatened and some enormous economic blows suffered. Airport runways in San Francisco, Honolulu, and Sydney will be the first to go. In many cases it will be more cost-effective to abandon coastal cities rather than try to protect them.

Ward frequently offers imaginary scenarios at various stages of the future, ranging from twenty years through to several hundred or even thousand years. They are not comforting, but they are all too possible if we refuse to take seriously the effects our fossil fuel habits are having on the global environment. His picture of what effect the Canadian operations to extract oil from tar sands will have had by 2030 if they continue is shocking – the desolate, devastated landscape, the health and environmental hazards visited on the First Peoples, the vast increase in carbon dioxide emissions. Another imaginary picture in 2045, with carbon dioxide levels at 450 ppm, portrays the last visit of tourist divers to Osprey Reef in the Coral Sea. The reef has changed tenants. Its once-numerous corals have been replaced by microbes that thrive in hot, acidic water. No longer a coral reef in the Coral Sea, it has become a bacterial reef in the Bacteria Sea. A more distant scenario is in 2400 on the Bangladesh-India border. Carbon dioxide levels are at 1200 ppm. More than half of Bangladesh is under water. He pictures a mass border breakthrough of a tide of humanity met by tactical nuclear weapons killing fifty thousand Bangladeshis instantly and many more in weeks to come.

One can hear the scoffing of denialists and delayers. But I found nothing alarmist in the scenarios.  What else do we think is going to happen as the seas continue an inexorable rise brought on by the gradual or more than gradual disintegration of the ice sheets? Ward knows what the ice sheets mean for sea level. He also knows what elevated carbon dioxide means for global temperature. Earth has been through this before. The difference this time is that it is our own doing and that it is happening to a planet heavily populated with human beings.

The book includes a chapter titled “Extinction?”. The question mark was a small relief. Here he discusses his concern at the eventual possibility of a slow changeover of the oceans through global warming from their current “mixed” states to a stratified state which in the past has always been a prelude to biotic catastrophe. The chapter recapitulates briefly the argument of his previous book Under a Green Sky, reviewed here, and emphasises the contributory role of sea level rise to the process of slowing oceanic currents and interrupting the mixing of oxygenated top waters with those below. In his view this is a point where we need to see a vital connection between ancient climates and impending climate change. He observes that the media have not allowed scientists to make this case, not because they disbelieved it but because the past scenarios were too horrifying for us to contemplate their happening again, and soon.

There’s an element of understandable desperation in Ward’s final chapter. It considers carbon sequestration possibilities through afforestation, charcoal burial, acceleration of natural weathering processes and other measures. Also, albeit with not much conviction and some trepidation, it canvasses major geo-engineering proposals to which we may be driven in extremity.

I found Ward’s book hard to put down. He draws out the implications of what we already know with clarity and force. That is a most valuable service. The more scientists will overcome their inclination to reticence and share their fears with the general population the better. Any risks in doing so pale beside the consequences of not doing so.  We must be faced with the full reality of what we are doing to the climate while we can still escape the more extreme consequences.

[Buy via Fishpond (NZ), Amazon.com, Book Depository (UK, with free shipping worldwide).]

Days of future passed

The idea that a rise in global temperature of no more than two degrees above pre-industrial levels is a safe target for the world to aim for is widely accepted in political forums where the measures needed to stay within that range are considered. Not universally accepted though. The small island states and many others of the least developed countries already impacted by climate change are adamant that 1.5 degrees is the highest rise that should be considered safe.

Indeed one wonders what the reasoning of the more powerful nations has been in settling on the two degree target. When Mark Lynas trawled through predictions in scientific journals for his book Six Degrees (review here) he found plenty to disturb at two degrees, including  possible desertification and abandonment of agriculture over millions of square kilometres in the US, an extremely hot and drought-ridden Mediterranean Europe, an ice-free Arctic ocean with implications difficult to measure, the bleaching and likely death of many coral reefs, major loss of food production in India, serious population displacement in Bangladesh.

Now Chris Turney (pictured) and his University of Exeter colleague Richard Jones have reported their attempt to reconstruct the temperature during the Last Interglacial between 130,000 and 116,000 years ago. Their paper is published in the Journal of Quaternary Science.  Turney explains its significance in his blog, where he writes:

“Temperatures appear to have been more than 5˚C warmer in polar regions while the tropics only warmed marginally; strikingly similar to recent trends. Not only this, but taken together, the world appears to have been some 1.5˚C warmer when compared to the 1961 to 1990 average. If we take into account the rise in temperature that has happened since industrialization, we find the Last Interglacial was around 1.9˚C warmer. Furthermore, this period also shows the warming in the Indian and Southern oceans took place before that of the northern hemisphere, suggesting these regions may cause further global warming beyond that directly forced by increasing greenhouse gas levels.”

It’s important to recognise what impacts that level of temperature rise brought. Turney points out that we know there was a dramatic decrease in polar sea ice coverage while large parts of the Antarctic and Greenland ice sheets melted. Critically, he says, the warmer temperatures appear to have helped global sea levels become some 6.6 to 9.4 metres higher than today, with a rate of rise of between 60 to 90 millimetres per decade, more than double that recently observed.

Let’s return to today’s “safe target” notion of no more than two degrees above pre-industrial levels.  Here’s one of the key messages from the EU reference document explaining the scientific background for that target:

“Global mean temperature increases of up to 2°C (relative to pre-industrial levels) are likely to allow adaptation to climate change for many human systems at globally acceptable economic, social and environmental costs. However, the ability of many natural ecosystems to adapt to rapid climate change is limited and may be exceeded before a 2°C temperature increase is reached.”

If Turney and Jones’ estimation of the temperature in the Last Interglacial is correct it suggests that  sea levels will rise significantly higher than anticipated. How a sea level rise six to nine metres higher than today could be adapted to “at globally acceptable economic, social and environmental costs” rather beggars the imagination.

So far as Turney is concerned, “The inevitable conclusion is emission targets will have to be lowered further still. Not a popular message.”

It has been apparent for some time that ice sheets are showing signs of less stability than was expected. It is not news that sea level rise this century looks likely to be higher than the IPCC estimates (a possibility recognised in the IPCC report itself). But what Turney and Jones add is evidence that the past may be offering us a specific guide as to what sea level rise we would need to  prepare for if we allowed a two degree temperature rise.

Turney is a geologist whose interest is in researching the past, particularly in relation to climate. His excellent book Ice, Mud and Blood was reviewed on Hot Topic last year. He has continued to figure from time to time on the site because of his connection with the New Zealand firm Carbonscape. We noted his recognition last year by the Sunday Times as one of the modern-day heroes of science and technology.

He finishes his blog with these words:

“Crucially, the scientific and policy implications of the Last Interglacial demonstrate it pays to look back to yesteryear. As the great poet and playwright Thomas Eliot once wrote, ‘Time present and time past, are both perhaps present in time future, and time future contained in time past.’ Fingers crossed these words are heeded.”

Fingers crossed indeed. Against the seemingly unstoppable drive to exploit fossil fuels we need some signs of hope that society’s leaders are going to wake up to the dangers we are heading for. There are glimmers, as I pointed to in my post yesterday, perhaps even gleams if William Hague is representative, but a far wider section of our political and economic leadership needs to become fully acquainted with the lessons from the past.

Gareth adds (because he was going to blog this, but Bryan got his post in first)]: The period that Turney and Jones are considering — the last interglacial (LIG), better known (at least to me, though Turney’s blog provides other names) as the Eemian, is interesting because it provides an example of where we may be heading. During the LIG CO2 peaked at under 300 ppm, and sea levels were 6m to 9m higher than present, with rates of sea level rise of at least 6cm to 9cm per decade. The last time CO2 was at 300 ppm was before Dave Keeling started taking accurate measurements in the late 50s (it was about 312 ppm in 1958, and we’re nudging 390 ppm at present). In other words, the equilibrium response (that is, the long-term — century to millennial scale — response, when the oceans and ice sheets have had a chance to catch up) to the greenhouse gas levels more than 50 years ago is sea level at least 6 metres higher than now — and as Turney and Jones find, a global average temperature 1.9ºC above pre-industrial. The 2ºC “target” being bandied around as “achievable” (50% odds only) at 450 ppm is likely to be a mirage — it might hold true in the short term, but 450 ppm commits us to something well beyond the LIG/Eemian, when, as you will not need reminding, there were crocs and hippos in the Thames. When James Hansen was looking at long term targets, he selected 350 ppm as compatible with a planet with ice sheets at both poles. Turney and Jones synthesis of data on the Eemian suggests that if that’s our goal we need to be looking at 300 ppm — and a much bigger task. Over to Bill…

Turney, C. S. and Jones, R. T. (2010), Does the Agulhas Current amplify global temperatures during super-interglacials?. Journal of Quaternary Science, 25: 839–843. doi: 10.1002/jqs.1423

[Moody Blues]