The climate agreement, 2 degrees, and your children’s future

Not too long ago, just after the Paris COP21 climate meeting, I read two interesting articles that contradicted each other.  The first said “COP21: Paris deal far too weak to prevent devastating climate change, academics warn.”  The second was more optimistic, “Rapid switch to renewable energy can put Paris climate goals within reach.”

“So which is it?”, I wondered.

The Independent

The first one discussed a letter sent by eleven supposedly prominent climate scientists to The Independent that warned that the climate deal reached at the COP21 gives “false hope” and will result in insufficient action being taken.

A few choice quotes from the letter sent to The Independent include: “ The hollow cheering of success at the end of the COP21 agreement proved yet again that people will hear what they want to hear and disregard the rest.”  Also, “Given that we can’t agree on the climate models or the CO2 budget to keep temperatures rises to 2 deg C, then we are naive to think we will agree on a much tougher target in five years…”  And, “Our backs are against the wall and we must now start the process of preparing for geoengineering.”  As you will see, this last part of this quote is telling.

The Independent’s article is a bit sensational, and maybe that was their intention, however, no first round of any diplomatic agreement is ever quite enough, and this may be the first time in modern history where every nation in the world agreed on anything.  Also, climate models are typically analyzed together as a group — a standard practice that does not specifically require exact agreement between models.  Also, the CO2 budget to keep warming below 2 degrees centigrade (2 C) is a simple matter of physics, not politics — so no “agreement” needed there.

What’s REALLY interesting is the background of the so-called “world’s top climate scientists”, as The Independent calls them.  A simple search of the names of the signatories shows a motley crew, with nary a “top climate scientist” among them.  Their occupations range from oceanography, to engineering, to urban planning, to politics, music, and book writing.  Of those that were actual scientists, they are all “B players” at best.  However, one common thread is that most of them seem to be proponents of geoengineering to some degree or another.

Geoengineering is the use of heroic measures to cool the Earth’s climate.  Such measures include seeding the upper atmosphere with sulfate particles to reflect a portion of the sun’s energy, and other drastic and dangerous measures to cool the Earth.

Geoengineering is generally thought to be a horrible idea, and if it does come to that, then we humans are truly screwed.  Not to say that it won’t come to that, and that we shouldn’t research every option, but it is not yet the time to put it into practice.  Let’s try a bit of prevention before we go for radical surgery — which brings us to the second article.

The Guardian

According to The Guardian, a “Rapid switch to renewable energy can put Paris climate goals within reach.”  The Guardian reports that the COP21 is shooting for a 2 C cap on warming, while also aiming to go lower to 1.5 C.  The premise of the article is that a rapid increase in renewable energy to 36% of total energy production worldwide by 2030 would give half of the CO2 reduction needed to limit global warming to 2 C, with the rest made up by conservation and efficiency.  This is based on a recently released report by the International Renewable Energy Agency (IRENA).

The good thing about the rapid scale-up of renewables according to the IRENA is that it would increase the global GDP by about $1.3 trillion dollars and add 24 million jobs to the renewable energy sector.  That seems reasonable given the current rapid growth in the U.S. renewable energy industry.  The Guardian article goes on to say that these changes are well under way, with $329 billion invested last year in renewables — and that despite cheap oil!

Unlike The Independent, The Guardian writes articles backed by reputable sources, and this one was no different.  So I’d say that the COP21 goals are definitely within reach… BUT is the 2 C goal itself where we should be heading?


Is 2C of warming the best target to limit the worst impacts of global warming?

I have always wondered where the 2 C (3.6 degrees Fahrenheit) limit came from, and after a little bit of googling I found out.  The 2 C target came from a now famous paper by the Yale economist William Nordhaus back in the early 1970s.  Two centigrade was proposed as the upper limit to acceptable economic losses based on historical climate data and certain assumptions made at the time.

After the initial proposal several other academics and politicians took the 2 C number and ran with it until it became the accepted upper limit on warming.  So the question remains, is this really the goal we should be aiming for, especially considering it’s based on outdated information and very little actual climate science?

A recent paper in the January 2016 issue of the scientific journal Nature Geosciences tackles this question.  It’s titled “A scientific critique of the two-degree climate change target” by Reto Knutti, Joeri Rogelj, Jan Sedlacek, and Erich Fischer, from the Institute for Atmospheric and Climate Science, in Zurich, Switzerland.

According to this well written and comprehensive paper, the 2 C limit was first adopted at the 2009 Copenhagen climate conference.  It was a “…political decision, informed by science, but no scientific assessment ever defended or recommended a particular target.”  They further state, that “Ultimately, the 2C target is a political consensus that takes into account what policymakers at that time considered to be both realistically achievable and tolerable.”

The goal of this paper was to see if there is any scientific evidence to support the 2 C limit.  As you will see the risks are on a sliding scale, just like life in general, there is no black or white, no best answer.  It all comes down to what you consider an acceptable level or risk of destruction, displacement and death — “acceptable risk” for yourself versus all those billions of “other” people out there.


Is temperature the right target to aim for?

According to the article any metric that we use should be: 1) related to our end goals, 2) observed with accuracy both in the present and the past, 3) understood how humans influence it, and it should be 4) easy to communicate.  They state that temperature fulfills most of these goals.

Temperature has been well recorded over wide areas for over a century, and the link between the burning of fossil fuels, the release of carbon dioxide, and global temperature change has also been well understood for over a century.

However, they also state that global surface temperatures do not capture important effects of increased carbon dioxide concentrations such as ocean acidification, or the rate of change for example.  Both of which have widespread implications for the health of the environment and us humans living within it.


What other targets might we use?

Some other targets that could be used include atmospheric CO2 concentration (e.g., sea level rise, ocean acidification, rate of temperature change, regional climate changes (e.g. the Arctic is changing much faster than the rest of the world), avoiding of tipping points (e.g. west antarctic ice sheet collapse), emission reduction targets, date of zero emissions, or maybe some combination of targets.  The authors point out that whatever is chosen has to be measurable, scalable and actionable at the global level.

The authors conclude that global temperature is the metric that meets most goals, and has already gained the widest acceptance, although it’s hard to set the preindustrial baseline.  Setting the pre-industrial baseline is important so that attributing what damage has already been done, and by what countries, can be determined.  This is also important for determining who should pay the most to fix it.


Are there any points of no return we should be thinking about?

Some adverse outcomes of climate change happen in a linear fashion, for example, a certain amount of warming correlates with a fixed increase in precipitation.  However, some changes are non-linear, meaning small changes result in bigger effects.  For example, a small amount of warming will cause an exponential increase in heat waves.  Some other examples of thresholds or tipping points may include the melting of Greenland’s ice cap, or collapse of the West Antarctic Ice sheet.  Once we’ve crossed one of these thresholds changes will happen at a fast rate, possibly over decades, and become essentially irreversible.

Back many years ago when I was a geologist, a somewhat new theory was being advanced, that of punctuated equilibrium which replaced the old theory of graduated equilibrium or gradual change.  Geologists and paleontologists used to think that big changes happened slowly over millions of years.  However, they couldn’t square that with massive shifts in whole fossil ecosystems and strata of rock that showed huge changes happening over incredibly short time spans.  As usual, eventually the theory caught up with the data.


A figure from the Nature Geosciences article illustrates both linear (one to one) and nonlinear (exponential) effects of climate change.  The first part of the figure is shown below and the second half further down.

Box a) shows increase in rain and Box b) shows an exponential increase in heat waves with increasing overall global temperature.  Box c) shows a dramatic “punctuated” jump in sea levels at a given temperature, while Box d) shows a linear decrease in Arctic ice with increasing temperature.  The different grey lines and shaded areas represent the range of error.  I added two lines to the graph… the blue line on each graph shows the current level of global warming of about 0.87 C (1.5 F), while the red line is the 2C (3.6F) proposed limit to global warming.


As the authors of our article point out, we have a “better understanding of the consequences of crossing such (climate) thresholds than exactly where these thresholds may be.”  And in a quote that I think sums the whole mess up… “In our view, the current 2C UNFCCC target is a compromise between what is deemed possible and desirable, rather than a ‘planetary boundary’ that clearly separates a ‘safe’ from a ‘dangerous’ world.”

That’s a profound statement.

As warming increases, the affected area of the planet’s surface increases, and the magnitude of change increases.  However, the uncertainties about the extremes also increase.  In other words, we are entering into unknown territory, to a place that will likely be hostile to human life on this planet.  The second part of the figure seen below, shows the increase in risks with increasing temperature.

This graph shows how the risk for different adverse events (each bar) increase with increasing global temperature.  The first bar “Unique and threatened systems” includes sensitive ecosystems such as the world’s alpine regions and Arctic.  “Extreme weather” includes such things as Super Storm Sandy, Typhoon Haiyan, and the 2003 European heat wave.  “Distribution of impacts” goes from local to widespread with increased risk.  “Large-scale singular events” would include collapse of the West Antarctic ice sheet, or halting of the Atlantic Meridional Current that keeps Northern Europe warm.  The vertical line on each graph shows the current level of global temperature increase at about 0.8 C (1.4 F).  The blue vertical line on each graph shows the current level of global temperature increase, at about 0.87 C (1.5 F), while the red line is the 2C (3.6F) proposed limit to global warming.


So what sort of time do we have to act?

The authors make the important point that even if CO2 emissions stopped today, the changes already set in motion will persist for hundreds to thousands of years.  And any decisions made and plans executed now have implications for many generations to come.  Further, these decisions and plans are not reversible if they are insufficient or failed.  So it seems that the sooner we act, the better off we will be.  And our actions have to be proportional to the risk if we hope to avert the worst of it.

So back to picking a target

According to the article, “Defining a climate target, and deciding who needs to do how much to achieve it… depend on values and worldviews, on arguments about fairness and on ethics.”  They also state that the role of scientists should be to analyze and discuss the consequences of different proposals;  a role scientists have been reluctant to take due to the politicized nature of the discussion.

They sum up by saying that “the choice of any target is ultimately a compromise between costs, benefits, trade-offs, and risks, where scientific evidence is combined with moral and ethical argument… “, and that “The 2C target is ‘focal point’ or ‘anchoring device’ that can guide climate policy.”

So the bottom line is that given the CO2 that’s already been released, what’s already baked into the system, we are in deep trouble.  However, that doesn’t mean we should give up.  The COP21 was a huge accomplishment.  Of course it won’t be perfect, and of course it is not near enough.  BUT it does show that the world’s governments are in agreement, and it does lay the foundation for future gains.  What we should be doing is pursuing aggressive change in our relationship with energy and our environment so that we don’t end up going from “deep trouble” to extinct.  Big difference there I think.

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