Realistically it is not possible to keep within 1.5C of
global warming without the use of carbon dioxide removal from our atmosphere on
a massive scale. Is it realistic to keep within a 2C limit with no carbon
removal technology in face of a growing world energy demand? The mathematics of
this is explored.
This is part 1 of a four part series.
Part 3. Where we were
at the end of 2015. 2015 progress report.
Part1:-Realism.
Whether we stay within the 2 C limit of global world
temperatures agreed as targets by the Paris climate conference 2015 (COP21)
depends on many factors. Do we have grounds for pessimism or optimism?
Certainly I have seen both of these outlooks expressed recently. Our ultimate
goal should be staying within the 1.5C limit requiring us to find ways of
removing future emissions of CO2 (as I will show in part 2), but here I look at
how realistic it is stay within 2C by limiting our emissions.
Figure 1. Alternatives chasing a growing economy. G(e) is the
growth rate in total energy per annum, g(a) is the growth rate in alternatives.
In this post I look at what
needs to be mathematically done (as opposed to how we may technically achieve this) to achieve decarbonisation as
energy demand grows at different possible rates, if it is achievable
realistically, and to quantify in terms of temperature reached for different growth
pathways that exceed our limits. The growth pathways that are used to estimate
the outcome will not directly be the fossil fuel emission pathways but rather
the growth in alternatives and the total energy related growth. These pathways will of course largely determine
the fossil fuel pathways but are better to identify in order to evaluate the
realism, pessimism or optimism of the situation. Mathematically what action is
needed to be to be taken will be clarified indicating that yes it can be done
but again mathematically how urgent this needs to be done will be seen.
What I present is standard hypothetical pathways to be
applied to the situation now or in the future that enable us to evaluate if we
are likely to stay within the limit and a plausible temperature anomaly reached
if we cannot.
These are not expected to be forecasts of our growth rates
and hence not forecasts of the temperature anomaly reached. Rather an approach
with simplifying assumptions (explained in the page. A mathematical task) is used
so that a realistic estimate can readily be calculated and then a means of
comparison in future years can be readily achieved to provide way of tracking
progress. (Temperature locked in will be
indicated for different growth pathways).
To achieve what seems an overwhelming hurdle we must
identify the scale of the problem and tackle it with hope. Being overly-pessimistic
can lead to despair and giving up. Being unrealistically optimistic can equally
lead to complacency in the belief that someone will somehow solve the problem
and in the meantime we can put it to one side and compartmentalize our thinking
to block out the reasoning required to tackle the task in hand.
On the one hand we see the enormous challenge of creating
the necessary infra- structure of alternative emission free means of obtaining
energy. We also see the need for our energy to grow for the many in dire need.
We have more people living in extreme poverty today than the entire global
population living in pre-industrial times. We see that for many the energy
related growth must increase and hence our task of creating the emission free
energy infra structure is increasing as our alternatives chase a growing economy.
See figure 1 repeated below. On the other hand we see that it is possible to
have exponential growth in technological commodities as has happened in
telecommunication systems. We have seen this with the proliferation of say
mobile phones based on miniaturisation of electronics systems with advances in
semiconductor technology but can this happen with the large needs of power
consumption? (Our advances, performance related to cost, in information
technology have been somewhere in excess of 50% per annum for over half a
century).
Figure 1. Alternatives chasing a growing economy. G(e) is the
growth rate in total energy per annum, g(a) is the growth rate in alternatives.
Figure 1 above shows the estimated global energy consumed
per year against time and is drawn precisely to scale for the growth rates
shown. This is in units of Eo where Eo is the total energy delivered per year
at the present time.
The black line, Tx, represents the total energy related
growth and starts thus at a value 1. In this hypothetical and hopefully
extreme case Tx grows at 3% per annum. The green line, Ax, shows the growth
in alternatives and at the present day has a value Ao =0.186 or 18.6% and in
this hypothetical case grows at 7% until it catches the total energy growth rate
after 44 years. The red line, Fx, represents the fossil fuel consumption as the
difference between these (see assumptions) and reaches zero after 44 years when
decarbonising is complete.
The blue shaded area shows the amount of carbon related
energy (28 years at today’s rate, see calculations) that would ensure we stay
within 2C if the climate sensitivity for doubling CO2 is 2.8C.
(The 2C increase would not be observed in 28 years time but would be locked in if concentrations were stabilised, the increase becoming apparent in a few decades after this time).
The area between the red line, Fx, and the axes represents the carbon related energy. Compared to the blue shaded area which should not be exceeded this comes to an equivalent of 48 years for the arbitrary values shown in fig. 1 at today’s rate of emissions.
(The 2C increase would not be observed in 28 years time but would be locked in if concentrations were stabilised, the increase becoming apparent in a few decades after this time).
The area between the red line, Fx, and the axes represents the carbon related energy. Compared to the blue shaded area which should not be exceeded this comes to an equivalent of 48 years for the arbitrary values shown in fig. 1 at today’s rate of emissions.
Clearly to stay within the limits we can see that for these
growth rates we overshoot the budget by a factor of 1.7 (48/28). We need to
exceed this massive exponential 7% per annum growth in alternatives or decrease
the growth in the energy related economy.
Creating a progress report.
Want I want is a system based on clear and stated
assumptions to identify how well we are doing based on essential measurements
and indicators keeping these to a minimum (this will help in later estimating
uncertainties) and provide a system for future use.
The same system (with the same assumptions) can be applied to
future dates (for example in 5 or 10 years time) using data (the updated
indicators) when it becomes available in the future, or now for expected new
data based on assuming certain pathways
from the present.
I estimate the global increase in temperature reached for
various pathways. I identify the indicators needed to do this calculation from
information from credible sources like the World Bank, NOAA and the
International Energy Agency.
Knowing our current percentage use of energy from sources
that don’t contribute to CO2 building up in the atmosphere, the concentration
of CO2 in the atmosphere today and the rate that CO2 is building up then the
temperature anomaly that becomes locked in (that will likely be evidenced in
decades to come) can be estimated for different growth scenarios. Initially for
simplicity I will assume we can build up all our alternatives exponentially at
a constant compound annual percentage increase. Later and more realistically I
will consider that for the present time there are many of our alternatives that
cannot be expected to rise exponentially but a small base of wind and solar and
some other alternatives can hopefully do so.
Progress report 2015.
For a fuller 2015 progress report see part three
For equations and assumptions see part two
Year ending
|
2015
|
|||||||
The
indicators
|
||||||||
Total
Ao
|
Wind
Solar
Others
A1
|
Hydro
Nuclear
Biomass
|
||||||
Alternatives today /%
|
18.6
|
1.2
|
17.4
|
|||||
CO2 concentration/ppm
|
400
|
|||||||
..rising at/ppm per year
|
2.13
|
|||||||
Consequences for
staying within 2C:-
(assuming a climate sensitivity of 2.8C
for doubling CO2 concentrations)
and
( pre-industrial concentration of CO2 at
280ppm)
|
||||||||
1. Years left at today’s rate of emissions
|
28
|
|||||||
2. And for the following growth pathways:-
|
||||||||
G(e)
|
g(a)
|
year decarbonised
|
Pulse:- No of years of
emissions at today’s rate
|
Overshoot factor
|
Possible T anomaly
|
|||
%
|
%
|
year
|
years/factor
|
factor
|
C
|
|||
2
|
4
|
2102
|
115
|
4.11
|
3.36
|
|||
2
|
5
|
2073
|
59
|
2.11
|
2.54
|
|||
2
|
6
|
2059
|
39
|
1.41
|
2.21
|
|||
2
|
7
|
2050
|
29
|
1.05
|
2.03
|
|||
3
|
5
|
2102
|
180
|
6.47
|
4.16
|
|||
2
|
5
|
2073
|
59
|
2.11
|
2.54
|
|||
1
|
5
|
2058
|
32
|
1.16
|
2.08
|
|||
0.7
|
5
|
2055
|
28
|
1.02
|
2.01
|
|||
0
|
5
|
2049
|
22
|
0.78
|
1.89
|
|||
0
|
4
|
2058
|
27
|
0.98
|
1.99
|
|||
G(e)
|
g(a)
|
Ao
|
A1
|
g (lin)
|
T
|
|||
1
|
15
|
18.6
|
1.2
|
2% of 0.174
|
2
|
|||
2
|
19
|
18.6
|
1.2
|
2% of 0.174
|
2
|
|||
Table. 2015 progress
report
It is seen that if our energy related economic growth, G(e),
increases at 2% per annum then from 2015 we can decarbonise staying within 2C
if we manage to increase on average all our alternatives by at least a massive 7% per annum for the
next 35 years! If in 2025 we have not increased the percentage share of
alternatives and the CO2 concentration rates increase in a similar manner as in
the last ten years then we will need to decarbonise in less than 22 years from 2025
and increase our alternatives by more
than 10% per annum to stay within the limit for the same energy related
economic growth, G(e). (see part 4)
Alternatively.
If we can only manage to have a growth in alternatives,
g(a), by 5% per annum due to technical
difficulties then we would have to limit our total energy related economic
growth to 0.7% or less to be sure of staying within the 2C limit. However with this
same restriction and no progress until 2025 we would be faced with having to cut world economic growth by 1.5% or
more per annum for at least 26 years.
Figure 2. The curves represent the energy from fossil fuels
as we decarbonise for different growth rates in Energy related growth from a base in alternatives of 18.6% and if
growth in alternatives is limited to 5%. The light blue shaded area represents
the energy budget from fossil fuels at todays’rate (2015) of emissions to stay
within the 2C limit.
From Figure 2 above we can see how our chances of staying
within the 2C target decreases rapidly as the energy related economic growth
rate increases. The area underneath the red fossil fuel curve should not exceed
the blue area otherwise we are taking a risk, the greater the area the greater
the risk.
Our present day percentage of alternatives other than
nuclear, biomass and waste or hydro is about 1.2%. If it is this component that
can only increase exponentially then the situation is more severe. This is
discussed more fully in my 2015 progress report. With certain assumptions it
may be that if we rely on these renewables and not nuclear we are likely to
require global exponential increases in the order of 15% per annum but if we delay action for 10 years we will
require these renewables to grow at 26%
per year for a 1% rate of growth of energy consumption and at 30% per year! for a 2% rate of growth of energy consumption.
(See part 4)
Conclusions.
The estimates
achieved here are based on mathematical reasoning on the basis that the
assumptions are realistic. The reader can thus determine their own opinion on
realism. I point out the minimum requirements in terms of growth that are
needed to be reasonably sure of staying
within a 2C limit, whether or not that is something to which we can be expected
to adapt.
I consider that we
can stay within the 2C limit but this will require changes based on addressing
the reasons that are preventing us from taking action. Time is clearly running
out but the more we do the less the negative impacts will be. If our action is
inadequate we can see the massive expansion of alternatives that future
generations will be faced with and the simultaneous problem of finding ways to
provide additional energy to remove CO2 from our atmosphere if it is indeed
technically feasible.
If we can rely on
alternatives other than nuclear, hydro or biomass to grow exponentially we
require them to grow at an average of 15% per annum on the assumption that we
can limit global energy growth to below 1% per annum. This means at least
doubling these renewables every 5 years seven times over.
References:-
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