Science & Policy

The Carbon Budget

How much more carbon can we emit before we lock in dangerous levels of climate change? Or in other words, how much carbon can we have in the atmosphere before we are no longer able to keep temperature rise to below 2oC, as agreed globally?

Enter the global carbon budget. Just like a financial budget, this tells us how much carbon we have left to ‘spend’ before we run out. Unlike a financial budget, we won’t be physically prevented from spending any more once it runs out, but we will certainly be going into overdraft.

A safe climate

The Paris climate agreement, negotiated in 2015 by nearly all governments in the world, commits to keeping global temperature to below 2oC which is what majority of scientists agree is a ‘safe’ limit. Learn more about that historic agreement here.

Science tells us that if we want to stay below 2oC, the carbon budget is reached once we emit another 805 gigatonnes of carbon dioxide (GtCO2e). If we want to stay below 1.5oC, the aspirational target of the global climate agreement, we have even less leeway: 205 GtCO2e12. But this only gives us a 66% chance of limiting the temperature increase to 2oC or 1.5oC respectively.

We’ve already used up our budget for a 100% chance of limiting warming to 1.5oC3.

That means that even if the world did everything needed to keep the temperature rise to 1.5oC, we cannot guarantee that it will be enough – we have already emitted too much. So whatever we do now, we can only hope.

5 years left

So what does this mean? And how long do we have left before we make our climate unsafe?

Today, we emit a total of about 53.2 GtCO2e per year, of which the bulk comes from fossil fuels (about 36 GtCO2e or 68%). Agriculture, forestry, and other land use changes are the second largest source of emissions, at about 12 GtCO2e or roughly 24% of global emissions4.

You can see the sources of current emissions by sector below. For more information, read about the causes of climate change here.


At current emissions levels, we only have 5 years left to have even a 66% chance of keeping climate change below 1.5oC. We have more time for 2oC but we must change course quickly; every increase in temperature brings with it more uncertainty and more financial, ecological, and human costs.


Mind the gap

And that’s not all. We are seeing a huge gap between the reality of the emissions path we’re on and the emissions path we need to be on.

Science tells us that annual emissions in 2030 need to be as low as 42 GtCO2e to stay below 2oC. That’s 12-14 GtCO2e less than what we expect if current policies including country commitments from the Paris Agreement are successfully implemented.

To stay below 1.5oC, total annual emissions would have to be around 39 GtCO2e – this is a massive 15-17 GtCO2e less than currently projected.

These are huge emissions gaps, see figure below, that need to be addressed and solutions found if we are to meet our climate commitments.


The Carbon Tracker Initiative follows this budget closely for the energy sector and has advocated for investors to ensure there is plan to stop supporting industries that burn fossil fuels that will ‘break the bank’ as far as the carbon budget is concerned. For more on how investors influence global emissions read here.

Critical climate solutions

We need game-changing technologies that are ready for immediate large-scale deployment, that are available and cost-effective in all countries, and that deliver real, measurable, effective and near-term emission reductions.

And that’s why the way that we use our land is so important for our climate and life on earth. Forests, peatlands and grasslands are the most important carbon sink on land: together they store about 2,000 Gt of carbon, and every year, forests and other natural ecosystems absorb about 11 GtCO2e5.

To really understand the carbon budget and what it means for the energy sector we need a deep understanding of the whole carbon cycle.


This amazing ability to remove carbon dioxide from the atmosphere makes land carbon sinks a safety net for the climate – a buffer against catastrophic climate change.

That’s why protecting and enhancing natural ecosystems is a cost-effective climate solution that can absorb 5.2 GtCO2 from the atmosphere per year (that’s about a third of the emissions gap), and perhaps as much as 7 Gt (54% of the emissions gap) with large scale restoration of degraded lands6. But we’re losing 4.3-5.5 GtCO2 per year from ecosystems7.

Destruction and degradation of forests are approximately 10% of total global emissions.

Once these sinks are gone, the climate safety net is gone forever, and the budget will be blown.

At Ecosphere+

At Ecosphere+ we are working to scale up investment into the world’s most valuable natural technology – trees.

While many ingenious technological solutions for reducing carbon emissions are being developed and deployed, forests are the most valuable and effective natural asset that we have – and their potential is ready to be harnessed today. Forests also deliver many other benefits beyond just carbon!

That is why we at Ecosphere+ work to protect forests.

[1] 66% chance of staying under the respective temperatures.

[2] Carbon Brief (2016) Analysis: Only five years left before 1.5C carbon budget is blown Accessed April 4, 2017 

[3] Carbon Tracker 2016

[4] UNEP (2016) The Emissions Gap Report 2016.

[5] Global Carbon Project (2016) Global Carbon Budget 2016.

[6] UNEP (2015) The emissions gap report 2015, Nairobi.

[7] IPCC (2014) ‘Agriculture, forestry and other land use (AFOLU)’. In: IPCC AR5, WG3.