How much must a country's net CO2 emissions be reduced to meet the Paris Agreement?
Equitable Carbon Budgets per Country
The total global carbon budget can be divided per country. Dividing the global country
budget into country budgets can be done in many different ways. One way of doing it is to divide the global
budget into a budget per person, and then assigning a budget to a country based on its population. This is often
considered an equitable way of dividing the budget. This way to divide the budget is used on this page.
The current population is 7.7 billion, which means
that the global budget to limit warming to 1.5°C above pre-industrial (1850-1900) levels with a 66% probability of
420 GtCO2 implies a personal carbon budget of 54.5 tCO2. (1 tCO2 = 1 billion
tonnes (metric tons) CO2.)
Only fossil fuels and cement are included in the country carbon budgets in the reduction scenario below, which
means that they exclude e.g. emissions due to land use changes. The reason is that I have not found any recent and
complete data for country emissions which include land use changes (LULUCF). Aviation and maritime emissions
are also excluded, since they are not reported per country in the data set used for country emissions (GCP 2018).
How big is a country's equitable carbon budget?
Same emission reduction amount every year
One way of modelling emissions reductions is to reduce the emissions with the same amount every year.
Every year of delay in action means that the emissions must reach net zero one year earlier.
How much (in MtCO2) must country emissions be reduced per year to reach net zero emissions before
the carbon budget runs out?
Note: This scenario can't tell what the warming will likely be, only when the budget runs
out, since net zero emissions are not reached before the budget runs out.
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Same percentage of emission reductions every year
Another possible way of modelling emissions is to reduce the emissions by the same percentage amount every year,
e.g. a 10% reduction of emissions every year.
In the calculations below, all years with emissions above 1/100th of the emissions the start year are counted.
How much (in percent) must country emissions be reduced per year to reach net zero emissions before the carbon
budget runs out?
Note: This scenario can't tell what the warming will likely be, only when the budget runs
out, since net zero emissions are not reached before the budget runs out.
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2030 goal vs net zero goal
The Emission Gap Report 2019 state
that global GHG emissions would need to be 55% lower in 2030 than in 2018, to limit global warming to below 1.5ºC.
The SR15 report state that net zero CO2 emissions must be reached in 2050
to be able to limit global warming to below 1.5ºC.
Since the total warming is depending on the total amount of CO2 emitted, there is a relationship between the 2030
goal and the net zero goal. If emissions are reduced more to 2030, the net zero point can happen later in time.
Conversely, if emission are not reduced enough in 2030, the net zero point must happen a lot sooner.
What is the relationship between the 2030 and the net zero goals?
Note: This scenario can't tell what the warming will likely be, only when the budget runs
out, since net zero emissions are not reached before the budget runs out.
How long does the budget last if country emissions continue increasing or stay flat?
Note: This scenario can't tell what the warming will likely be, only when the budget runs
out, since net zero emissions are not reached before the budget runs out.
