There’s plenty of bad news around these days, and that’s true of climate policy as of many other things. Turnbull (or Abbott, pulling Turnbull’s strings) has already imposed massive cuts in climate science research in Australia and it seems certain that Trump will do the same in the US.
Happily, it looks as if they have come too late to do real damage. The fact of climate change is now well established. Cutting research will impose all kinds of costs, but it’s not going to change the conclusions of science. Of course, the right will reject inconvenient science as they have done for decades, but more of less research won’t change that.
The big news is that the problem has turned out to be much easier to solve than anyone thought. We’ve long known that, to have a 50-50 chance of limiting warming to 2 degrees C, emissions should peak in 2015, and decline at an annual rate of at least 2.2 per cent thereafter. Hardly anyone thought a peak could happen before 2020 at the earliest, and this would imply a decline so steep (4.6 per cent per year) as to be just about impossible.
It now seems pretty clear, however, that fossil fuel emissions did in fact peak, or at least flatten out in 2015, and have remained stable through 2016.
Of course, stabilization is not enough. Is it possible for emissions to decline at the required rate. We can look at an identity
e = g – t – r
where e is the rate of growth of emissions, g is the rate of growth of output, t is the annual technological improvement in energy efficiency (the ratio of energy use to output, and r is the reduction in emissions per unit of energy, due to renewables).
Currently, these are just about in balance. But installations of renewables (and therefore r) are growing rapidly, while g is declining in the developed world, and probably also in China. It follows that we can expect e to become negative in the near future.
Policy matters, and it is important that the Paris Agreement should go ahead, with or without Trump and Turnbull. But the goals to which governments are willing to commit depend on what they think they can credibly promise. So, the fact that stabilizing the global climate looks to be feasible within the current economic framework is really good news.
UPDATE: A couple of commenters have questioned the math above. So, let’s spell it out. Let
E = Emissions (tonnes CO2)
G = Gross World Product (constant $)
J = Energy used (joules)
T (for technology) = G/J ($/joules)
R (for reduction) = J/E (joules/tonne CO2)
Then
E = G / (T*R)
Taking logs
log (E) = log (G) – log (T) – log (R)
Differentiating with respect to time
e = g – t – r
as stated.
Anyone wishing to debate this further should do so in the Sandpit
John Quiggin 
@Ikonoclast
We’ll take this to the sandpit.
Oh dear, my above comment sounds terribly precious doesn’t it? J.Q. can strike it out or leave it up there for me to garner the full embarrassment and pillorying I deserve.
However, I do still believe that we need a tough message about emergency climate being required now, along with strong dirigist (state) action to make it happen.
“emergency climate action” I meant.
If there is cause for optimism it is arising from low emissions alternatives crossing below price parity thresholds. Besides the direct effects of that – more energy investment decisions choosing those options – I think it will have an increasing effect of easing the economic alarmist fears that underpin mainstream reluctance and resistance to commit to strong and effective policy. It has the potential to break the unanimity within the lobbying by commerce and industry for obstruction and delay – the kind of unanimity that sees peak business groups like the BCA have maximising the growth of export fossil fuels as a key element of their climate policy! (I kid you not).
Whilst I doubt Australian business owners and managers have ever been unanimous about this, at the level of their most influential collective lobbying it may as well be and whilst there are some fine sounding in principle statements of preference for carbon pricing and policy certainty these groups are amongst the fiercest opponents of either in practice. I don’t know how tight a strangle hold the fossil fuel industries have over such bodies or how readily a shift away from resisting and obstructing strong climate policy can proceed, but the renewable success story may be more significant in the near term for enabling such an attitude change than for the (still inadequate) emissions they mitigate.
I’d like to think the energy transition we need can happen without clear, strong, committed policy, just because RE can compete and win in an open energy market, but I seriously doubt it. We need that committed policy more than ever. If the Business sector ceases to be a primary source of resistance and economic fearmongering in this the mainstream political base denial and obstruction has relied upon can have it’s foundations pulled from under it and serious policy may manage to get up – and without being so compromised, to please stakeholders, that it’s ineffectual.
This really is FUBAR.
Conceptually it is all over the place.
Why not just say global warming is determined by the balance between emissions and sinks.
Then the necessary policy objective is simply:
S (inks) = E (missions)
UNits LHS are: k s[-1] ie tonnes per year
Units RHS are: k s[-1]
As soon as you insert G, “rate of growth of output,” you self-destruct all reason and logic.
When rate of growth of output is zero, your equation [E = G / (T*R)] all goes to zero but carbon emissions will still be accumulating in the atmosphere.
E as defined will still be positive or negative?
The whole modelling attempt is wrong.
Why not just say – we need to reduce carbon emissions to the capacity of sinks.
Produce the necessary number – from the available data, and then produce parameters
per joule
per $
per capita
or what ever.
This is much safer ground.
@Ivor
We don’t want to limit emission to the capacity of sinks. Sinking CO2 into the ocean is destructive to the health of the biosphere. The world ocean has an enormous capacity for CO2 but we really don’t want to use it. What we want (now) is declining emissions.
I have a somewhat jaded view of this which is that humans are collectively unable to manage CO2 but fortunately technology has saved us, pretty much via basic cost economics, perhaps with a little bit of intentional action thrown in. No one really predicted the massive drop in the cost of solar energy to the point where it outcompetes coal; the situation has improved radically over the last decade or so. Everyone – including the dreaded capitalists – are converting to RE because it is cheaper. If solar had hit a brick wall of cost we were fried.
@Jim Birch
Yes, that makes sense.
Good program on renewables on RN.
Importantly, after the experience of Germany and Denmark, the base load argument has evaporated. Also, Australia has the largest/longest grid which means we can shift power here there and anywhere – if the wind ain’t blowing one place it’s blowing at another.
Link to above http://www.abc.net.au/radionational/programs/rearvision/renewable-energy-and-the-national-grid/7987134#transcript
The correct equation is:
e = g * t * r
e emissions (kg)
g output ($)
r energy intensity in output (Joules/$)
t emissions per unit of energy (kg/Joule)
The dimensions are:
kg = $ * kg/J * J/$
and the LHS = RHS.
All very simple, provided you define your terms properly based on international standards and show your working
It is so nice to hear you being optimistic in these posts, Professor Quiggin, keep it up!
alex
Ivor, you’re wrong. e, for example, is not “emissions” but “RATE of emissions (ie dE/dT)”, g is not “output” but “rate of output”, etc. As John said, learn some elementary calculus.
@alex
As previously advised, arguments based on estimated co2 concentrations should be posted in the sandpit
Looking at human emissions only may be taking one’s eye off the ball.
Many others above have already commented on and reiterated the dwindling capacity for sinks to continue to absorb emissions, but it’s worth noting too that natural sources of carbon dioxide are being opened/enhanced as a consequence of human emissions, and secondarily by positive feedings-back. Clathrates and permafrost methane are immediately obvious components, but soil carbon loss from altered hydrological and/or fire regimes are also a concern, as are biomass loss from vegetation and warming (and possibly deoxygenating) water. Amongst other things…
At this point the issue is not so much whether the second derivative of anthropogenic emissions is zero, but whether the first derivative of cumulative emissions is negative, and how rapidly human emissions can possibly be reduced to make it as negative as possible.
There’s the rub.