Weatherdem's Weblog

Bridging climate science, citizens, and policy

Leave a comment

Some Short Notes on the US-China Climate Deal

The US-China climate deal announced in December 2014 generated big news.  It was yet another diplomatic success for the Obama administration and John Kerry’s State Department.  Nothing I say below takes away from that success.  In terms of climate action success, the deal ranks pretty low to me.  I’ll quickly summarize what I understand of the deal and then share why I think it isn’t a significant climate deal.

The Deal

Here is a quick summary (emphasis mine):

China, the world’s biggest emitter of greenhouse gases, pledged in the far-reaching agreement to cap its rapidly growing carbon emissions by 2030, or earlier if possible. It also set an ambitious goal of increasing the share of non-fossil fuels to 20 percent of its energy mix by 2030.

Obama announced a target to cut U.S. emissions 26 to 28 percent below 2005 levels by 2025 – eight years after he leaves office — the first time the president has set a goal beyond the existing 17 percent target by 2020.

The bolded portions highlight the agreement’s big news.  China agreed to a carbon emissions cap and the U.S. pushed its emissions reduction target out 5 years and increased the target by ~11% below 2005 levels.

Those are good goals.  Are they sufficient goals?  It depends on what you consider sufficient.  I consider goals that will actually achieve the stated climate target of <2C warming by 2100 as sufficient.  These goals won’t achieve that target.  But then, as I’ve written for some time now, I don’t think we can set goals that achieve the <2C by 2100 target.  There are technical and political hurdles that we chose not to surmount during the past 30+ years.  Why won’t this agreement achieve that target?  Let’s take a quick look from the same International Business Times article:

China completes a new coal plant every eight to 10 days, and while its economic growth has slowed, it is still expanding at a brisk rate exceeding 7 percent.

The scale of construction for China to meet its goals is huge even by Chinese standards. It must add 800 to 1,000 gigawatts of nuclear, wind, solar and other zero-emission generation capacity by 2030 — more than all the coal-fired power plants that exist in China today and close to the total electricity generation capacity in the United States.

And to meet its target, the United States will need to double the pace of carbon pollution reduction from 1.2 percent per year on average from 2005 to 2020 to 2.3 to 2.8 percent per year between 2020 and 2025.

Who out there truly believes that China can deploy 800 GW of zero-emission generation capacity in less than 15 years?  Remember before you answer in the affirmative that China’s deployment of coal-fired plants exceeded anything in history and that coal remains an extremely cheap energy resource.  All the other technologies currently cost more in terms of deployment.  What incentives does China, as a developing nation, have to spend more money for intermittent power sources?  They’re more interested in growing their economy, as the U.S. is.  Speaking of the U.S. – I emphasized part of that quote quite purposefully to highlight the scale of the issue.  China must, in 15 years, deploy as much generation infrastructure as exists in the entire U.S. today.  Our infrastructure took decades and decades to build out.  China needs to do the same thing, with more expensive infrastructure, in 15 short years!?  I will be among the first to congratulate China if they accomplish this daunting task and I don’t think China should shy away from working towards it.  I just don’t think they have a realistic chance of actually accomplishing it.

What about the U.S.?  We need to more than double the decarbonization rate of our economy to achieve our emissions goals.  Remember that most of the decarbonization achieved since 2005 was due first to the Great Recession and second to the natural gas boom.  The Great Recession is finally behind us, though effects linger.  The natural gas boom?  It’s currently experiencing strong headwinds as OPEC pushes the cost of oil down to the $50 range from the $100-110 range last year.  It’s economically unfeasible to frack for natural gas with $50 per barrel of oil.  While the natural gas industry won’t collapse (at least I hope it doesn’t), it won’t support additional decarbonization for the foreseeable future either.

I believe we are well on our way toward 3-4C warming by 2100 and must plan and act accordingly.  This deal, while diplomatically ambitious, is not climate ambitious enough to drive us away from those thresholds.


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.

Leave a comment

Newest Climate Change Consensus Document Won’t Matter…

It won’t matter unless and until physical scientists leverage expertise outside of their silos and stop executing failed strategies.  In addition to summary after summary of government sanctioned peer-reviewed scientific conclusions, scientists now think they need to report on the perceived consensus on individual bases of those conclusions in order to spur the public to action.  Regardless of their personal political leanings, scientists are very conservative job actors.  They have long-held traditions that are upheld at every turn, which reduces the urgency of their statements.  As an analogy, think of a bunch of people sitting down who think for long time periods before any action is ever taken.  First, they calmly say there is a situation that requires near-immediate action.  Then they say it a little louder.  Then a handful start yelling because you’re not responding to their carefully crafted words and they think that you just didn’t hear them or you just aren’t smart enough to understand those carefully crafted words.  Then they start screaming because they’re convinced you’re an idiot and screaming will definitely work where yelling and saying those words didn’t work before.

Well, the screaming isn’t helping, is it?  You’re not an idiot.  The volume of words isn’t the issue.  The issue is you are motivated by things outside of the climate realm – things like having a job; a job that pays a living wage so you can pay for your mortgage and car payment and keep your children educated and happy.  An existence in an affluent world that allows you the time and energy to think of complex problems beyond your perceived immediate needs.  If those needs aren’t met – if you have insecure affluence – you place climate change and the environment far down on a list of priorities – just like a majority of other Americans.

But the newly released “American Association for the Advancement of Science, the world’s largest general scientific society with a membership of 121,200 scientists and “science supporters” globally” report won’t change this dynamic.  While it is important that the AAAS engages scientists and the society it serves, this report is unfortunately just the latest effort by a group of physical scientists that ignores science results outside of their discipline to try to convince Americans that immediate and drastic action is necessary.  Like previous efforts, this one will not spur people to action, mostly because the actions listed are about limits, stopping, restricting, reversing, preventing, and regulating.  The conceptual model from which these words arise works in direct contrast to the fundamentals of American culture.  We are a people who are imaginative, who innovate, who invest.

As I have written before, there is no way we will achieve greenhouse gas emissions reductions without substantial investment into innovation of new technologies that we research, develop, and deploy at scale.  There is nothing limiting or restrictive about this framework.  It it the opposite of those things.  This framework recognizes and sets out to achieve opportunities; it allows for personal and cultural growth; it is in sync with the underlying cultural fabric of this country.  It directly addresses people’s perception of the security of their affluence in the same way that developing countries’ economic growth allows people to move beyond basic material needs to higher order needs.

The reality of insecure affluence among many Americans today might be an indirect outcome of the 1%’s efforts to increase wealth disparity, but it is real.  We have to address that disparity first in order to address the real, valid perceptions of insecure affluence.  Only after Americans feel their personal wealth is secure will they have the resources to devote to higher order needs such as global climate change.  That can happen with concerted focus on investing and innovating a post-carbon economy.  But you won’t see that at the top of any policy prescription from the majority of climate scientists.


NOAA Sea-Level Rise Report Issued – Dec 2012

This is a busy time of year for the sciences with the annual American Geophysical Union’s and the international Conference of Parties meetings occurring simultaneously.  NOAA has issued a number of reports in recent days, none of which are overflowing with good news.  Today, NOAA released their Global Sea Level Rise Scenarios for the United States National Climate Assessment.  It was produced in response to a request from the U.S. National Climate Assessment Development and Advisory Committee and consists of a review and synthesis of recent scientific publications examining global sea level change.

Why is this report important?  “More than 8 million people in the US live in areas at risk of coastal flooding. Along the Atlantic Coast alone, almost 60 percent of the land that is within a metre of sea level is planned for further development, with inadequate information on the potential rates and amount of sea level rise.”  The public, policymakers and planners need to know what to expect with respect to sea-level rise this century: where should development occur or be restricted and why?

The report is based on four plausible scenarios.  Scenario 1 is simply a linear extrapolation of the historical sea-level rise (SLR) rate out to 2100.  Scenario 2 is based only on projected ocean warming.  Scenario 3 builds on 2 by adding recent ice sheet loss (land-based).  Scenario 4 reflects ocean warming and the maximum plausible contribution of ice sheet loss and glacial melting.  Scenario 1 is appropriate for communities which can assume high risk or for short-term projects.  Scenario 4, in contrast, is meant for places which can’t accept risk.

Here are the scenario SLR values by 2100:


Note that these values are not predictions, but are projections.  That is, NOAA isn’t saying that if X and Y happen, then the Intermediate-High scenario is a prediction.  The scenarios present a framework for policymakers and the public to use to make decisions.

Here is a time series graph of historical and projected SLR:


The range of potential SLR shown in the table and figure above might lead some to conclude that ‘high confidence” in that range is misplaced by NOAA.  This is a gross misinterpretation of what is presented.  The level of uncertainty, which will always exist, is actually useful to policymakers.  Given this range of projections, people can leverage local and regional knowledge to come to better decisions than they would without this range.  Something quantified is better than a big shrug when planning, after all.

With the governors of New York, New Jersey, and Connecticut requesting $80 Billion to clean up and rebuild (better) after Hurricane Sandy, future projections of sea-level rise can obviously provide guidance regarding what and how to rebuild in addition to where to rebuild.  Policy development and planning will have to take these and other projections into heavier account this century than they did last century.  An estimate of how many billions of dollars can potentially be saved by incorporating this information would also be useful.


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).


Research: Climate Change Permanency

I’ve written a couple of posts on climate change basics (Gases, Forcing & Surface Temperature and Energy & Projections) that described how energy enters and moves through the climate system and some physical ramifications of emitting greenhouse gases.  This post will build on those in an important way by examining what is very likely to happen to the base climate system in response to increasing carbon emissions.  The operative word that is used throughout is: permanency.  The climate system has so far been slightly altered by our species’ emissions.  Most of the effects of that alteration won’t go away for hundreds of years.  As humans emit additional emissions, the effects grow.

For all intents and purposes, as far as our species is concerned, the climate system’s alteration will not go away for a long, long time – on the order of thousands of years.  That’s permanency as far as we’re concerned.  Or, as the paper I cite puts it: it’s irreversible.  Conditions will very likely not return to those we’ve experienced in our lifetimes and in the past few thousand years for many thousands of years into the future.  That’s the cold, hard scientific truth of the situation.  Now, people can decide for themselves whether such irreversibility or permanency is a “good” or “bad” thing – I won’t make normative judgments for anyone else but myself.  I don’t consider such a change a “good” thing.  The effects I will describe here are significant, but they are only those that are easily projected.  Many other effects that haven’t been considered or experienced by our species will almost certainly fall out as a result of projections discussed here.  Our civil institutions are not well equipped to handle even the first-order effects, let alone the compounding influence of effects upon effects.

On a personal note, I will not describe things as ‘catastrophic’ anymore.  I have hinted at this in some posts I’ve written in the past few months without much explanation.  The primary reason for this is using such language simply turns people off from considering the material.  I think we need more people engaged on this topic, not less, and will consider scientific results of language and framing as much as I consider climate science results (a post dealing with this specifically is in the works).  That said, I will continue to not spend many resources to engage the ideologically driven skeptic community.  They simply have a different worldview than I do and neither party will convince the other that their side is “correct”.  One goal of this blog is to inform those who are interested and to have civil, productive discussions of peer-reviewed climate science and the political/policy implications of that science.

So, before I delve into some details, words like `permanency` and `irreversible` will be used more frequently on this blog in the future.  I will not use words like catastrophic.  On that note…

Susan Solomon and her coauthors published a paper in 2008 entitled, “Irreversible climate change due to carbon dioxide emissions.”  The primary finding: climate change resulting from anthropogenic carbon dioxide emissions is largely irreversible for 1,000s of years after the emissions stop.  As a result, atmospheric temperatures are likely to remain higher than present-day values, rainfall reductions during dry seasons are likely to occur across the planet, and sea level rise is likely to continue to occur for thousands of years even though the models they used did not include every physical process involved in the hydrologic cycle in addition to the noted lack of all first-order forcings.  The study gives us an idea of the type of temperature trends we are likely to experience for the next few thousand years as well as a conservative estimate of how high average global sea level rise will be.

In similar fashion as other modeling work, Solomon et al. allow CO2 concentrations to rise, then halt suddenly at some level in the future (reflecting a dramatic shift in human behavior such as radical technological innovation, etc.  I characterize this treatment of behavior as “magical” because there is never robust reasoning to adequately describe such behavior shifts).  Concentrations in the study rose at 2%/year to peak CO2 values of 450, 550, 650, 750, 850, and 1200 ppmv, followed by zero emissions after hitting each peak.  For reference, current annual CO2 concentrations average just over 390pppmv.  What occurs after the peaks is the interesting part of this paper, as the following graph shows:


The x-axis shows time in years out to the year 3000.  Pre-industrial CO2 concentrations are indicated by the dashed line near the bottom of the graph.  Without any effort at emissions’ mitigation, any one of these peaks is well within the realm of possibility. What happens after each peak?  An extended period of time during which CO2 concentrations remain much higher than pre-industrial levels.  Concentrations remain at levels between ~300 to ~800ppmv for the next thousand years, decreasing at decreasing rates during and after they reach their respective peaks.  What effect might this have on temperature?  The next graph in the paper demonstrates the simulated effects:


Each curve in this graph corresponds to the emissions lines in the previous graphs.  Temperatures remain at least 1°C warmer (and up to 4°C warmer) than those of the year 1800 for the next thousand years.  Temperatures do not decline at nearly the rate that CO2 concentrations do in the latter part of the millenium.  While CO2 concentrations remain higher throughout the period, “permanency” is evident by temperature trends through the year 3000.  What does that mean for the real world?  Whatever temperature shift takes place through the end of rising emissions stays in place for all intents and purposes for our species permanently.

Rising temperatures have many other effects on different earth systems, including sea levels.  Here are the sea level change projections from the Solomon et al. study:


Again, each line in this plot corresponds to an emissions scenario and a temperature trace in the two previous plots.  Note the y-axis on this plot: it only shows sea level rise due to thermal expansion.  Any additional water entering the world’s oceans resulting from melting glaciers or land-based ice sheets are not included in this projection.  Therefore, the reader can interpret this plot as a minimum of sea level rise through 3000.  The greatest rise obviously corresponds to the highest emissions scenario and the highest temperature rise.  0.4m rise in the minimum projected by this study and 1.9m is the maximum.  Similarly to the previous plots, sea level doesn’t decrease once emissions and temperatures stabilize.  Instead, they continue to slowly increase throughout the next millenium and remain high in essence in a permanent sense.

What’s obviously inaccurate with this study is the instantaneous cessation of CO2 emissions.  Many studies treat future emissions in similar fashion.  How emissions decrease in the future is of course a large unknown and therefore impossible to model with high accuracy.  Solomon et al. do acknowledge that their treatment of emissions is not meant to be realistic, but to “represent a test case whose purpose is to probe physical climate system changes”.  The primary lesson from this paper is relevant no matter the specific future emissions pathway: the longer emissions continue at any level close to 20th century levels, the longer it will take before concentrations stop rising and begin their slow descent in a planet with full carbon sinks, and temperatures and sea levels stabilize.  The point at which all of these conditions peak is, in the end, almost entirely up to us.

The policy implications of this and other studies are obvious and not-so-obvious.  Among the former: the willingness of coastal residents to incur higher infrastructure and other costs in future years versus their desire to implement policies designed to mitigate their situation; the willingness of non-coastal residents to keep funding federal insurance programs that allow others to live in high-risk zones; the way in which municipalities write zoning laws: for developers or for citizens; policy development that will help populations adapt to climate change effects in their region and/or that address mitigation on a larger scale; the priority assigned to programs that may or may not generate technological innovations that would lead to adaptive or mitigative strategies at some undefined point in the future (via government or business); how to address the need that policymakers have for information that will facilitate a balanced approach between short-term gain and long-term risk management.  Other implications exist, as I’m sure most readers can attest.  One result of this study is clear: we have locked in a certain amount of costs just as we’ve locked in a certain amount of warming and subsequent changes in multiple earth systems.

1 Comment

2011 CO2 Emissions Up

In 2011, global emissions of carbon reached an all-time high of 31.6 Gigatonnes, according to preliminary IEA estimates.  That was 3.2% (1.0 Gt) higher than 2010 emissions.  The IEA has developed an energy pathway consistent with a 50% chance of limiting global temperature increases to only 2°C, which requires CO2 emissions to peak at 32.6 Gt no later than 2017.  This reinforces statements I’ve made in the past year that a maximum of 2°C warming is no longer feasible.  There is no reason short of worldwide economic collapse that emissions will peak at or below 32.6 Gt prior to 2017.  As emissions continue, more warming and additional effects are locked into Earth’s climate system.  The good news is due to transfer of power generation from coal to natural gas (more natural gas plants as gas prices fell in 2009 and 2010), US CO2 emissions fell by 92 Mt (1.7%) from 2010 to 2011.  Indeed, emissions have fallen 7.7% from 2006 levels in the US.  A significant portion of that decrease was due to the economic troubles from which we still haven’t recovered, of course.  Do market forces exist to help reduce those emissions?  Absolutely they exist: taxes and permit systems.  Note that the second article includes a brief discussion of why previous environmental action was taken.  It cites the immediate identification of the causality behind environmental disasters.  I disagree with the author’s assessment that such an event will ever occur with respect to climate change.  I further disagree that such a “Climate Pearl Harbor” (as it has been described elsewhere) is the only means by which bottom-up action and support can be generated.


Get every new post delivered to your Inbox.

Join 331 other followers