Global Carbon Budget

If global carbon emissions continue to grow as they have in the last decade we will burn through the 2°C carbon budget by 2035.

That is the grim reality of extending historical emissions growth into the IPCC’s cumulative carbon budgets.

In its new report the IPCC stated that to have an even chance of limiting warming to less than 2°C (since the period 1861–1880) it will require keeping cumulative CO2 emissions from all anthropogenic sources to less than 840 GtC.

By 2011 mankind had already emitted 531 GtC.  (See our carbon emissions and sinks piece)

If global carbon emissions continue to grow at 2% each year, as they have done over the last decade, we will blow through the 840 GtC carbon budget at the start of 2035.

The more stringent target of 800 GtC, that gives us a 66% chance of limiting warming to 2°C, is exhausted in 2032.  The more lax goal of 880 GtC, that gives us a 33% of limiting warming to 2°C, follows shortly afterwards in 2037.  If non-CO2 greenhouse gas concentrations increase, aerosols are reduced or the permafrost begins to melt these dates will be dragged forward.  The reverse will push them back.

Our current emissions path will leave us committed to more than  2°C of warming in just 22 years.  It would also commit us to much more warming beyond that given the economic inertia of global carbon emissions.

In fact the 2°C carbon budget is so stringent that even if global carbon emissions stopped growing and remained flat for the coming decades we would still break the 2°C budget in 2041, less than 30 years from now.

In the graphic above we show the speed at which we exhaust the 2°C  budget based on different annual emissions growth rate scenarios.

The first one is the same as our initial chart and shows that if emissions grow at 2% each year we break the 2°C budget in 2035.  In the second we see that if annual emissions remain constant at a 2011 level we break the 2°C budget in 2041.  The third shows that if annual emissions decline at 2% per year we will break the 2°C budget in 2058.

To reach 2100 within the 840 GtC budget (>50%) emissions need to decline at 3.5% per year, beginning immediately.  If action is delayed until 2020 annual reductions of  6%/year are required.  Such reductions would be largely dependent on the deployment of negative emission technologies.

The gap between where we are and where we need to be is enormous.

This is the nature of our problem:

We have a coal problem.  We have an oil problem.  We have a gas problem.  We have a deforestation problem.


And our lack of ambition in dealing with it is quite astonishing

Lindsay Wilson
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I founded Shrink That Footprint in November 2012, after a long period of research. For many years I have calculated, studied and worked with carbon footprints, and Shrink That Footprint is that interest come to life.

I have an Economics degree from UCL, have previously worked as an energy efficiency analyst at BNEF and continue to work as a strategy consultant at Maneas.  I have consulted to numerous clients in energy and finance, as well as the World Economic Forum.

When I’m not crunching carbon footprints you’ll often find me helping my two year old son tend to the tomatoes, salad and peppers growing in our upcycled greenhouse.

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