05 October 2010

Is "Dangerous Interference" Inevitable?

Should We Just Throw In The Towel?

The Stern Review warned that adapting to climate change would be significantly more expensive than avoiding it in the first place (see this earlier post). But the opportunity to slow or reduce ("mitigate") climate change may have been lost. It may already be too late. Now we have to start facing the costs of adaptation to inevitable changes.

At least that is the gist of a recent report by a British expert committee, and accompanying comments by the UK's new environment secretary.

And other evidence, from scientific research and from China's continued rapid economic growth, with corresponding increases in energy consumption, suggests that we will substantially overshoot the proposed target of 2°C warming above pre-industrial levels.

Yet more research suggests that the 2°C target was in the danger zone anyway.

So here is the information summarized in this post:
  • China's growth takes us past targets
  • 2°C target was too low
  • We can't stay below 2°C anyway
  • UK Environment Minister: Change inevitable

Soaring Chinese Growth

A recent article in Reuters noted that the International Energy Agency suggested that China's greenhouse gas emissions could rise to a peak of about 8.4 billion tonnes of CO2 per year by around 2020 and then begin to decline. Such a scenario would still allow global warming to be kept below about 2°C above pre-industrial levels--a supposedly "safe" level.

But the Netherlands Environmental Assessment Agency in their report "No growth in total global CO2 emissions in 2009" estimate that China's emissions from fuel burning reached 8.1 billion tonnes of CO2 in 2009, and India's reached 1.7 billion tonnes. (Press release here, PDF of report here.) China's emissions rose at 9% and India's at 6%. At that rate China will easily exceed 8.4 billion tonnes of emissions by 2010 or 2011.

The almost-global recession caused emissions to drop in developed economies, but increases in developing economies largely canceled out such reductions.

(Note that "The assessment excludes CO2 emissions from deforestation and logging, forest and peat fires, from post-burn decay of remaining above-ground biomass, and from decomposition of organic carbon in drained peat soils. The latter mostly affects developing countries. These sources could add as much as a further 20% to global CO2 emissions." Source)

Even with proposed "efficiency gains, China's expected rapid economic growth will push its absolute volume of emissions to between 9.6 and 10.1 billion tonnes of CO2 per year by 2020, compared with 5.2 billion tonnes in 2005, according to a study from the Chinese Academy of Sciences," said Reuters.

Keeping Warming Below 2°C Won't Save Us

A lot of international discussion, and the Copenhagen Accord, mention the idea that if we can keep global warming below 2°C above pre-industrial levels we will avoid "dangerous anthropogenic interference with the climate system". This target now seems dubious. Maybe it should be 1.5°C or even lower.

Chris S.M. Turney and Richard T. Jones of the University of Exeter have published "Does the Agulhas Current amplify global temperatures during super-interglacials?" in the Journal of Quaternary Science (full text here). They looked at climate during the Last Interglacial, spanning the period from about 130 to 116 thousand years ago, when sea level was 6.6–9.4 meters higher than today. The question was, what was the global temperature then? And, what were the mechanisms of regional distribution of that warming?

With the usual caveats, "Our results suggest the world was 1.5 ± 0.1°C warmer than the period AD 1961–1990". (The underlying drivers of warming at that time were changes in the amount of energy reaching the Earth from the Sun, due to variations in the Earth's orbit, and resulting changes in the carbon cycle.) They believe that warming in the southern hemisphere altered prevailing winds and thus ocean currents, allowing more upwelling of carbon-rich deep waters thus amplifying warming in the northern hemisphere.

The authors note that similar changes in southern-hemisphere winds and ocean currents seem to be happening today, and that similar feedbacks driving more warming may occur.

They go on to say, "if our estimate of global temperatures during the LIG is broadly correct and was higher than pre-industrial levels by ∼1.9°C, this leads us to question whether a 2°C target for stabilising global temperatures should be considered ‘safe’", since sea levels were so much higher back then at those temperatures.

Many others have raised similar concerns. See this review of James Hansen's book.

We're Going to Overshoot 2°C Anyway

A recent paper by Rogelj et al. in Environmental Research Letters, "Analysis of the Copenhagen Accord pledges and its global climatic impacts—a snapshot of dissonant ambitions", points out that if you total up the emission-reduction "pledges" made in the Copenhagen Accord the resulting rates of continuing emissions are very likely to take us past 2°C of warming. They find, regarding the developed countries:
Ultimately, even the optimistic interpretation of the Accord's pledges results in effective reductions by 2020 far outside the 25–40% range of aggregated emission reductions for developed countries specified in Box 13.7 of IPCC AR4. That box provided data for the lowest category of analysed mitigation scenarios which stabilize atmospheric CO2eq concentrations between 445 and 490 ppm CO2eq and have a best estimate global temperature increase of 2.0–2.4 °C at equilibrium.
Taking the countries at their word, the authors estimate global annual emissions of around 50 Gigatonnes CO2 equivalent in 2020, up from about 39 GtCO2eq in 1990 and 49 GtCO2eq in 2004. They estimate that global emissions would reach 55 GtCO2eq by 2050. To keep us under 2°C warming the estimated emissions in 2050 would have to be closer to 17 GtCO2eq. They figure that "Case 1 with reference growth after 2020 results in a likely global temperature increase of 2.5–4.2 °C above pre-industrial in 2100 and is still increasing afterwards."

Thus even if the various countries deliver on their pledges to decrease (or, in some cases, increase) their emissions those emissions are likely going to take us above 490 ppm and above 2°C. (The conclusion of the paper is too depressing to quote, but I include it in a footnote.)

The UK Sees "Unavoidable" Climate Change

The Adaptation Subcommittee of the UK Committee on Climate Change has issued a report "How well prepared is the UK for climate change?". The report says that because of current and projected future climate change, the UK should be thinking about what its inhabitants, companies and institutions should be doing to deal with the impacts of that change.
Preparing for climate change today will reduce the costs and damages of a changing climate and allow UK businesses, the public sector, the third sector and individuals to take advantage of potential opportunities. Early action will help make the UK better prepared for today’s climate and ensure that decisions made today that have long-lasting consequences do not close off options and make it harder to adapt in the future.
They go on to make various specific recommendations. Access the Adaptation Subcommittee's report here. (About the committee.)

But the really interesting development was a speech given by new UK Environment Secretary Caroline Spelman on the occasion of the report's launch. She said:
Today’s report provides a wake-up call. It recognises that there is no part of our society which is immune from the effects of climate change. Which means that every part of our society must think about its resilience. ... This Government will not give up the battle to tackle the causes of climate change. ... But while it is vital that we continue the task of drastically cutting our greenhouse gas emissions, we know that we are already facing levels of unavoidable climate change. ... And UK climate change projections suggest even higher temperatures and more severe weather in the coming years. ... If more than 75% of our businesses remain unprotected we are in danger of ending up with a two-tier commercial sector - those that have adapted successfully and those who didn’t see it coming. ... What Government can do is provide them with information and models to help them calculate the risks. ... And the transition to a low carbon, well-adapted global economy could create hundreds of thousands of sustainable ‘green’ jobs.
(PDF of the speech here. Article about the speech in The Telegraph here.)

That sounds to me like a change in emphasis. "Low carbon" efforts will not be enough. Everybody has to start thinking, and acting, to protect themselves from the negative impacts of inevitable climate change. (There is particular emphasis on getting companies and local authorities to analyze their risks and address them, using tools (but not necessarily money) provided by the government.

Get ready for a very different earth.

Graph from Netherlands Environmental Assessment Agency, June 2010, No growth in total global CO2 emissions in 2009 (pdf here) by permission.

The Chris S.M. Turney and Richard T. Jones paper is Copyright © 2010 John Wiley & Sons, Ltd.  Quotations used under fair use standards.

The Rogelj et al. is © IOP Publishing 2010. Quoted under fair use standards.

Conclusion of Rogelj et al. paper:
If the average national ambition level for 2020 is not substantially improved and loopholes closed in the continued negotiations, only low probability options remain for reaching the 2 °C (and possible 1.5 °C) ambition of the Accord. Most developed country submissions to the Accord indicate that only with a global and comprehensive agreement countries are inclined to commit to more, and likewise for developing countries the required level of support through financing, technology and capacity building is needed. With the negotiation mandates having been extended to the end of 2010, committing to higher ambitions and agreement by all Parties still remains possible. It is clear from this analysis that higher ambitions for 2020 are necessary to keep the options for 2 and 1.5 °C open without relying on potentially infeasible reduction rates after 2020. In addition, the absence of a mid-century emission goal—towards which Parties as a whole can work and which can serve as a yardstick of whether interim reductions by 2020 and 2030 are on the right track—is a critical deficit in the overall ambition level of the Copenhagen Accord.

No comments:

Post a Comment

Comments are moderated.