We have a climate emergency on our hands, and the timeliness of our action is the critical factor determining the consequences.
Put simply, we must reduce greenhouse gas emissions 50% by 2030. If we fail, we are on a track to trigger “dangerous interference with the climate system.”1 50×30 is the short-term emission reduction target that complies with the pathway to limit warming to 1.5 degrees Celsius.
If the long-term goal is carbon-neutral, or Zero CO2 emissions by 2050, then the short-term target required to meet that goal is a 50% reduction by 2030 – 50×30 – otherwise the time-frame for phasing out carbon emissions must be sooner than 2050.
In order to meet the 1.5 degrees Celsius target agreed upon in 2015 by all signing nations (the Paris Agreement commits to “limited global temperature increase well below 2 degrees Celsius, while pursuing efforts to limit the increase to 1.5 degrees”), the world can only emit a limited amount of CO2. That’s called the global CO2 emissions budget.
According to the IPCC, the total CO2 budget2, starting in 2020, is about 340 GtCO2 for a 67% probability of staying below 1.5 degrees C, and about 500 GtCO2 for a 50% probability of staying below 1.5 degrees C.
We are currently emitting about 40 GtCO2 per year. With a linear phase-out from our current emissions rate to 2050, we would emit 600 GtCO2, or 20% more emissions than a 50% probability of meeting the 1.5 degree C target(Figure 1).
Figure 1. Zero by 2050 – linear phase-out from today’s levels equals 600 GtCO2.
To stay within a 500 GtCO2 budget and reach zero emissions by 2050, we must peak global CO2 emissions by 2020 and reach a 50% emissions reduction by 2030 (see Figure 2).
Figure 2. Zero by 2050 and 50% by 2030 equals 500 GtCO2.
If we only reduce CO2 emissions 25% by 2030, then to stay within a 500 GtCO2 budget, we would need to reach zero emissions by 2040 (Figure 3).
Figure 3. Zero by 2040 and 25% by 2030 equals 500 GtCO2.
And, with a 40% CO2 emissions reduction by 2030, we would need to reach zero emissions by 2045, or five years earlier (Figure 4) to stay within the 50% probability carbon budget.
Figure 4. Zero by 2040 and 25% by 2030 equals 500 GtCO2.
Some organizations and companies adopting emissions commitments that result in exceeding the carbon budget – 25×30, 30×30, or 40×30 – are rationalizing their actions by stating “if we’re less aggressive more will join the battle.” Well, that’s not the way it works with climate change.
Confronting climate change means taking science-based actions now. The notion that watering down actions invites more people in is reckless. We cannot afford to be timid at a time when addressing climate change is a global emergency.
We know that change happens when real pressure is applied, when we take on the heavy lifting. To do our part, we must reduce emissions in the built environment by the following near-term targets:
A 50% reduction in embodied carbon for all new buildings, infrastructure and major renovations as soon as possible and no later than 2030.
A 50% building operationsreduction for all existing buildings as soon as possible and no later than 2030.
*Eliminating CO2 emissions from new building operations ensures that annual building sector emissions do not increase. It does not in and of itself yield reductions.
Unquestionably, all CO2 emissions must then be phased out by 2050. However, we cannot attach too much credibility to only “zero emissions by 2050” commitments without science-based intermediate targets. The longer we postpone serious reductions, the less of the carbon budget we have left to work with, and the sooner and more difficult it will be to reach zero.
We have been forced to face, and can no longer avoid, the near-term actions we must take. Being accommodating and timid isn’t working. We are simply running out of time.
We are the gatekeepers of decisive action in the built environment, and we are the hope for real change. It’s 50×30 or bust!