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Bridging climate science, citizens, and policy


What About That 2 °C Warming Goal?

David G. Victor and Charles F. Kennel, who are researchers in International Relations and Oceanography, respectively, wrote a Comment article for Nature at the beginning of October.  In it, they argued that climate and policy folks should stop using 2 °C as the exclusive goal in international climate policy discussions.  I agree with them on principle, but after reading their paper and numerous rebuttals to it, I also agree with their reasoning.

I’ll start with what they actually said because surprise, surprise, tribal and proxy arguments against their commentary focused on very narrow interpretations.

Bold simplicity must now face reality. Politically and scientifically, the 2 °C goal is wrong-headed. Politically, it has allowed some governments to pretend that they are taking serious action to mitigate global warming, when in reality they have achieved almost nothing. Scientifically, there are better ways to measure the stress that humans are placing on the climate system than the growth of average global surface temperature — which has stalled since 1998 and is poorly coupled to entities that governments and companies can control directly.

I agree with their political analysis.  What have governments – including the US – done to achieve the 2 °C goal?  Germany for instance largely switched to biomass to reduce GHG emissions while claiming that renewables (read: solar and wind) are replacing fossil fuels.  The US established more robust vehicle emissions and efficiency requirements, but the majority of US emission reductions in recent years result from cheap natural gas and the Great Recession.  No country will meet its Kyoto Protocol emissions goal – hence the hand-wringing in advance of the Paris 2015 climate conference.  And by the way, even if countries were meeting Kyoto goals, the goals would not lead to < 2 °C warming.

More from the authors:

There was little scientific basis for the 2 °C figure that was adopted, but it offered a simple focal point and was familiar from earlier discussions, including those by the IPCC, EU and Group of 8 (G8) industrial countries. At the time, the 2 °C goal sounded bold and perhaps feasible.

To be sure, models show that it is just possible to make deep planet-wide cuts in emissions to meet the goal. But those simulations make heroic assumptions — such as almost immediate global cooperation and widespread availability of technologies such as bioenergy carbon capture and storage methods that do not exist even in scale demonstration.

We will not achieve either of the last two requirements.  So we will very likely not achieve <2 °C warming, a politically, not scientifically, established goal.

A single index of climate-change risk would be wonderful. Such a thing, however, cannot exist. Instead, a set of indicators is needed to gauge the varied stresses that humans are placing on the climate system and their possible impacts. Doctors call their basket of health indices vital signs. The same approach is needed for the climate.

Policy-makers should also track ocean heat content and high-latitude temperature. [...]

What is ultimately needed is a volatility index that measures the evolving risk from extreme events — so that global vital signs can be coupled to local information on what people care most about. A good start would be to track the total area during the year in which conditions stray by three standard deviations from the local and seasonal mean.

So the authors propose tracking a set of indicators including GHG concentrations, ocean heat content, and high-latitude temperature.  What is most needed? An index that measures evolving risk from extreme events.  That’s pretty cut and dry reading to me.

Of course, climate scientist activists took umbrage that somebody left their tribe and tried to argue for something other than a political goal that they didn’t have any input on that, by the way, we won’t meet anyway.

RealClimate (RC) starts by attacking the authors personally for not describing why the recent surface global warming pause isn’t really a pause – which is a tangential discussion.  RC also writes that “the best estimate of the annual cost of limiting warming to 2 °C is 0.06 % of global GDP”.  Really?  The “best” according to whom and under what set of assumptions?  These aren’t details RC shares, of course.  Cost estimates are increasing in number and accuracy, but this claim also misses the fundamental point the authors made: “technologies such as bioenergy carbon capture and storage methods that do not exist even in scale demonstration”.  RC confuses theoretical calculations of economic cost with the real-world deployment of new technologies.   To achieve the 2 °C goal requires net removal of CO2 from the atmosphere.  That means we need to deploy technologies that can remove more CO2 than the entire globe emits every year.  Those technologies do not exist today.  Period.  IF they were available, they would cost a fraction of global annual GDP.  It’s the IF in that sentence that too many critics willfully ignore.

RC then takes the predictable step toward a more stringent goal: 1.5 °C.  Wow.  Please see the previous paragraph to realize why this won’t happen.

RC also dismisses the authors’ claim that the 2 °C guardrail was “uncritically adopted”.  RC counters this wildness by claiming a group came up with the goal in 1995 before being adopted by Germany and the EU in 2005 and the IPCC in 2009.  Um, what critical arguments happened in between those dates?  RC provides no evidence for its own claim.  Was the threshold debated?  If so, when, where, and how?  What happened during the debates?  What were the alternative thresholds and why were they not accepted?  What was it about the 2 °C threshold that other thresholds could not or did not achieve in debates?  We know it wasn’t the technological and political features that demanded we choose 2 °C.  Diplomats and politicians don’t know the scientific details between IPCC emission scenarios or why 2 °C is noteworthy other than a couple of generic statements that a couple of climate-related feedbacks might start near 2 °C.  Absent that scientific expertise, politicians were happy to accept a number from the scientific community and 2 °C was one of the few numbers available to use.  Once chosen, other goals have to pass a higher hurdle than the status quo choice, which faced no similar scrutiny.

RC then rebuts the authors’ proposed long-term goal for a robust extreme events index, claiming that such an index would be more volatile than global temperature.  The basis for such an index, like any, is its utility.  People don’t pay much attention to annual global temperatures because it’s a remote metric.  Who experienced an annual mean global temperature?  Nobody.  We all experienced local temperature variability and psychological research details how those experiences feed directly into a person’s perception of the threat of climate change.  Nothing will change those psychological effects.  So the proposed index, at least in my mind, seeks to leverage them instead of dismissing them.  Will people in Miami experience different climate-related threats at a different magnitude than mid-Westerners or Pacific Islanders?  Of course they will.  2 °C is insufficient because the effects of that threshold will impact different areas differently.  It’s about a useful a threshold as the poverty level or median wage.  Those levels mean very different things in rural areas compared to urban areas due to a long list of factors.  That’s where scientific research can step in and actually help develop a robust index, something that RC dismissed at first read – a very uncritical, knee-jerk response.

Also unsurprisingly, ClimateProgress (CP) immediately attacks the authors’ legitimacy.  It’s telling that the same people who decry such tactics from the right-wing so often employ them in their own discourse with people who are trying to achieve similar goals.  CP also spends time hand waving about theoretical economic analyses while ignoring the basic simple real-world fact that technologies don’t exist today that do what the IPCC assumes they will do starting tomorrow on a global scale.  It’s an inherent and incorrect assumption which invalidates any results based on it.  I can cite lots of theoretical economic analyses in any number of discussions, but the theory has to be implemented in the real world to have any practical meaning.  I want carbon capture technologies deployed globally tomorrow too because I know how risky climate change is.  Wishing doesn’t make it so.  It’s why I’ve been critical of the Obama administration for putting all of their political capital into a plan to drive millions of US consumers into for-profit insurance markets instead of addressing the multitude of problems facing the country, including the desperate need to perform research and development on technologies to help alleviate future climate change.

The authors responded to RC and CP in a DotEarth piece.  I agree with this statement:

The reality is that MOST of the debate about goals should centrally involve the social sciences—more on that below.

What I find interesting about this statement is that if we were to follow RC’s and CP’s heavy-handed criticism, they shouldn’t have a seat at the climate goal-setting table because they don’t have the requisite expertise to participate.  What social science credibility do physical scientists have?  Too many activists like those at RC and CP don’t want anyone else to have a seat at the table, but have they staked out a legitimate claim why they get one while nobody else does?  They continue a little later on:

This is where a little bit of political science is helpful. I can’t think of any complex regulatory function that is performed according to single indicators. Central bankers don’t behave this way when they set (unilaterally and in coordination) interest rates and make other interventions in the economy. Trade policy isn’t organized this way. In our article we use the example of the Millennium Development Goals because that example is perhaps closest to what the UN-oriented policy communities know—again, multiple goals, many indicators. That’s exactly what’s needed on climate.

They also note that different perspectives leads to different types of goals – which directly contradicts the climate community’s acceptance of 2 °C as the only goal to pursue.  They push back against their critics’ denouncement for not including enough about how people set the 2 °C threshold:

The reason it is important to get this story right is not so that the right community gets “credit” for focusing on 2 degrees but so that we can understand how the scientific community has allowed itself to get lulled into thinking that it is contributing to serious goal-setting when, in fact, we have actually not done our jobs properly.

They identify what I think is the real critical issue which people bury with the proxy battles I present above:

That means that for nearly everyone, the question of goals is deeply intertwined with ultimate impacts, adaptability and costs.  Very quickly we can see that matter of goal-setting isn’t some abstract number that is a guardrail but it is bound up in our assessments of risk and of willingness to pay for abatement as well as bear risk.

The point here is perhaps most salient: the 2 °C threshold is but one value in a very large set.  Different people have different goals for different reasons – based on their value system.  As well they should.  The 2 °C threshold is treated as a sacred cow by too many in the climate community.  What happens when, as I now believe will happen, the globe warms more than 2 °C?  Will folks finally stop cherry picking statistics and brow-beating other folks who are really their allies in this effort?  Will folks set aside tribalism and accept expertise from other researchers, you know, acceptance of other sciences?

There are many more pieces written about this Nature Comment that I didn’t get into here.  They all serve as interesting exhibits in the ongoing effort to get our heads around the wicked problem of climate change and design efficient policies to change our emissions habits.  This unfortunately won’t be the final example of such exhibits.


CO2 Emissions Continue to Track At Top of IPCC Range

A new Nature Climate Change editorial (subs. req.) has a very useful graph (2 variants) that I have been looking for:


Note first the y-axis: global CO2-emissions in Petagrams of carbon per year.  This unit is different from the other common unit used: CO2 concentrations.  The emissions eventually lead to the concentrations.  This is only the CO2 emissions, not CO2-equivalent, which might be a better variable but introduces more complexity in analysis.

Let’s go through the lines on the graph before we discuss them.  The “IS92″ lines (a-f; light blue dashed) were the emission scenarios developed for the 1992 Supplementary Report to the IPCC Assessment.  There are 40 SRES scenarios shown (thin green lines) and 6 illustrative scenarios (thick green dashed lines) that the IPCC developed for the 4th Assessment Report (AR4).  These are the scenarios most people discuss: A1B, B2, etc.  For the upcoming AR5, CO2 emissions form the basis of the scenarios.  There are ways to convert from one to the other, which is how all of these different scenarios can be plotted together.  The AR5 scenarios are labeled according to the anomalous forcing value expected in the year 2100 and a “Representative Concentration Pathway”.  Thus, RCP3 represents 3 W/m^2 forcing due to CO2 concentrations.  You can see what has to happen to global emissions to achieve this relatively low forcing value by the end of the century.  Alternatively, there is an RCP4.5, RCP6, and RCP8.5 pathway.  As a side note, my work will likely utilize the RCP8.5 pathway because we will most likely continue to move down this pathway for the foreseeable future.

Historical emissions are the black dots/line.  The estimate for 2012 emissions is the red dot.  It is obvious to see that our historical emissions has tracked near the top of any set of emissions scenarios (IS92-E, IS92-F, A1FI, A2, and A1B) and not the middle or bottom.  That has implications in climate policy because most scientific studies performed to date have focused on the low to moderate scenarios.  The reason is simple: most climate scientists thought there would be no chance of inaction once people saw what was likely to happen using even low or moderate emission scenarios.  In general, scientists were wrong.  The world has continued to increase the amount of CO2 emitted into the atmosphere, with “average annual growth rates of 1.9% per year in the 1980s, 1.0% per year in the 1990s, and 3.1% per year since 2000,” as I’ve covered in 2011 and earlier in 2012.  The post-2000 increase is largely due to China and India.

The lead author of the report posted different form of this graph and included yet another call to action that the world will ignore:


A quick note: the RCP3 scenario’s absurdity becomes more clear post-2060: emissions have to turn negative to achieve 3 W/m^2 by 2100!  Is anyone aware of technologies that remove emissions from the atmosphere in excess of what we emit to the atmosphere?  Put another way, emissions would have to decrease to near-zero in addition to deployment of removal infrastructure.  I obviously wasn’t involved scenario development, but it strikes me as incredibly myopic to include this pathway in climate scenarios: it exists only as a fantasy, especially when you realize that important feedback processes are still not understood well enough to include them in modeling efforts.

The main point of this graph is valid though: on our current emissions trajectory, global warming of 4–6.1 °C is likely.  Given recent studies showing more sensitivity to temperature changes one order of magnitude less than this that has already started to generate real-world changes, no one can say with certainty what a 4°C rise in global temperature above the pre-industrial average will cause.

Now, I must make a very important point here.  This does not mean the end of civilization or the world.  Our species is remarkably adaptive to a wide range of conditions.  While our species has never lived in a world that warm, we have enormous advantages over our ancestors: technology.  The world might not look like it does today, and we will of course not live in the same way, but I firmly believe that whatever changes we make will allow the great majority of us to continue to live.

That is not to say that we should do nothing at all.  I have made quite clear that the current approach (UNFCCC & IPCC) has proven itself to not work.  I do not know exactly what the correct approach will be, but I think remaining in a failed paradigm is a bad idea moving forward.  We must make new efforts – the more the merrier in the short-term so we can evaluate what does and does not work.  My line of thought has developed to this: I think groups must initiate smaller efforts, and indeed I think in some cases they already have.  Regional cohesive groups generally know better what works for them and why.  A good place to start on a larger scale would be to work to understand why certain actions work in some places better than others and put policies in place to exploit those opportunities.

But 2°C is not achievable by any means that I can see.  Neither is 350ppm CO2 concentration.  Scientists and activists alike should cast aside these hard to understand numbers.  A focus on other goals: energy portfolios, land use, and adaptation plans make more sense (different numbers since we tend to operate that way).


Beyond 4 Degrees – Catastrophic Double-Digit Temperature Increases by Mid-Century?

The UK Met Office hosted a conference in last month (Sep 2009) titled, “4 Degrees and Beyond” at Oxford University.  The bottom-line message is confirmation of what many climate activists have been saying for years: there is a much higher potential for much more warming than commonly thought.  The numbers are staggering in their implications, as I’ll detail below.

First, what did these climatologists do?  They ran the IPCC  high emissions scenario (i.e. business as usual (BAU)) in one of the few global climate models capable of analyzing strong carbon cycle feedbacks, a necessary test to truly reveal details of what our current emissions path could bring to the planet.  The reason this test is necessary was apparent in the results: the same warming that resulted from a BAU scenario without the feedbacks by 2099 occurred instead around 2060 in the BAU scenario with the feedbacks.  What implications does that level of warming by 2060 have for the globe by 2099?  Substantially higher temperatures, especially for some regions:

  • The Arctic could warm by up to  27.4°F [15.2 °C] for a high-emissions scenario, enhanced by melting of snow and ice causing more of the Sun’s radiation to be absorbed.
  • For Africa, the western and southern regions are expected to experience both large warming (up to 18 °F [10 °C]) and drying.
  • Some land areas could warm by 12 degrees [7C] or more.
  • Rainfall could decrease by 20% or more in some areas, although there is a spread in the magnitude of drying. All computer models indicate reductions in rainfall over western and southern Africa, Central America, the Mediterranean and parts of coastal Australia.
  • In other areas, such as India, rainfall could increase by 20% or more. Higher rainfall increases the risk of river flooding.

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