The Transition to 1.5
Jae Edmonds

DRAFT PRESENTATION—COMMENTS WELCOME

United Nations

Framework Convention
on Climate Change

Article 2(a) Holding the increase in the global average temperature to well below 2 °C above pre‐industrial levels and topursue efforts to limit the temperature increase to 1.5 °C above pre‐industrial levels,….
Article 4: In order to achieve the long‐term temperature goal set out in Article 2, Parties aim to […], achieve abalance between anthropogenic emissions by sources and removals by sinks of greenhouse gases in the secondhalf of this century, on the basis of equity, and in the context of sustainable development and efforts to eradicate
poverty.
Courtesy: Jan Sigurd Fuglestvedt

United Nations

Framework Convention
on Climate Change• When the Paris Agreement was negotiated no scenario pathways had beendeveloped that showed that 1.5 was possible.
• That literature has grown rapidly since.

All CO2 emissions scenarios are alike—They all end at zero
• Cumulative emissions of CO2 will
determine climate CO2 climate forcing—and climate—for the next century.
• Non‐CO2 emissions will become moreimportant as CO2 emissions decline to zero
• CO2 has no atmospheric sink—it doesn’tdisappear• Carbon that was removed from theatmosphere over millions of years, canonly be partitioned between atmosphere,ocean and land
• Atmosphere (~20% on average will remain
permanently)• Oceans (~80% on average will end up inoceans)

4 Representative Concentration
Pathways and Extensions

Getting to Zero—Five strategy elements• Energy efficiency—reduce demand for energy as much as economical• Decarbonize power generation• Fossil fuel with CCS• Renewable power• Nuclear power• Bioenergy• Bioenergy with CCS• Electrify Buildings and Industry

DRAFT PRESENTATION—DO NOT QUOTE, SUBJECT TO CHANGE

as much as economical• Decarbonize transport• Electrify• Biofuels• H2Source: http://www.energy.gov/science‐innovation/energy‐sources/renewable‐energy/wind• Halt deforestation/afforestation and continue improving crop yields
DRAFT PRESENTATION—COMMENTS WELCOME

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Getting to zero—ALL sectors need to get close
to zero or less

DRAFT PRESENTATION—DO NOT QUOTE, SUBJECT TO CHANGE

Source: IPCC, AR5, SPM

DRAFT PRESENTATION—COMMENTS WELCOME

6

The Challenge of Getting to 1.5• CO2 is measured in bothtons of CO2 and tons of C
• 3.667 ton CO2 = 1 tons C• $1/tCO2 = $3.67/tC
CO2 May 2019414.7 PPM at NOAA’s

Mauna Loa Atmospheric Baseline Observatory

Preindustrial ~280 ppm

CO2‐equivalent(ppm)

RadiativeForcing(W/m2)

Avg. Global Temp.
Change Long‐term
(T)*

1360

8.5 (RCP)

6.8 oC1030

7.0

5.6 oC850

6.0 (RCP)

4.8 oC650

4.5 (RCP)

3.6 oC550

3.7

2.9 oC450400

2.6 (RCP)
1.9

2.1 oC
1.5 oC* Assumes a climate sensitivity of 3oC. Climate sensitivity is the number of degrees theplanet would warm in the long term if the concentration of CO2 doubled.

Remaining Carbon Budget• By the end of 2017, 2200 ± 320 GtCO2 has been emitted by human activities• Currently, emitting 42 ± 3 GtCO2/yr

Choice of the measure of global temperature affects the estimatedremaining carbon budget
Using global mean surface air temperature, as in IPCC AR5:580 GtCO2 left (50% chance of 1.5 °C)
420 GtCO2 left (66% chance of 1.5 °C)
Using global mean surface temperature (GMST)
770 GtCO2 left (50% chance of 1.5 °C)
570 GtCO2 left (66% chance of 1.5 °C)
Courtesy: Jan Sigurd Fuglestvedt

Global emissions pathway characteristics

Rapidreductions
Net zero

Courtesy: Jan Sigurd Fuglestvedt

Negative emissions

Global emissions pathway characteristics
Delayed action

 Negative emission

Courtesy: Jan Sigurd Fuglestvedt

Global emissions pathway characteristics

Courtesy: Jan Sigurd Fuglestvedt

Characteristics of Four Illustrative Pathways

Low‐energy
demandSource: Figure 2.5, IPCC SR1.5

Sustainability
focus

Middle of the road– follows historicalpatterns

Resource‐ andenergy‐intensiveSource: Figure 2.15, IPCC SR1.5

The energy system will need to transform

2020 Primary Energy

Sustainability
focus

Middle of the road –Resource‐ andfollows historical patterns energy‐ intensive

Low‐energy
demandIEA Fast Trransition

Progress to Date
• Current policies andmeasures are not adequate
to meet Nationally
Determined Contributions(NDC) to Paris Agreement.
• NDCs are inadequate tomeeting either 2o or 1.5olong‐term stabilization
goals.

Source: https://www.carbonbrief.org/look‐beyond‐emissions‐gap‐to‐see‐full‐force‐of‐climate‐pledges‐says‐unep‐reportFinal Thoughts• Limiting climate change to any level involves eventually transitioning to azero CO2 emissions world– All sectors of energy and land systems must also decline toward zero or lower– All regions of the world must also decline toward zero or lower• Lower limits of global temperature require faster transitions• The challenge to achieving the 1.5o goal should not be underestimated.
– Global emissions must begin to decline before 2030
– Global carbon emissions must reach zero around 2050
– And then go negative.

• Technology, policy and institutions will shape the mix of sectors and fuels.
• The world is currently NOT on track to achieve the 1.5o goal.

DISCUSSION16