The Science of Heat Reduction

Did you know that 45% of anthropogenic global warming isn’t caused by carbon dioxide, but by methane, black carbon, tropospheric ozone, and HFCs? 

In the near-term, these supercharged, short-lived climate pollutants (SLCPs) are up to thousands of times stronger than CO₂. While the warming effect of CO₂ builds slowly, these pollutants act fast, trapping large amounts of excess atmospheric heat as soon as they are emitted.

In addition, man-made alterations of the earth’s surface and feedback loops have led to serious reductions in the Earth’s albedo – its ability to reflect heat.

As disturbing as these facts are, they also point to a great opportunity to make a big difference:

If we can curb these SLCPs and protect and restore the earth’s albedo at scale, we can begin to slow down the rise in excess heat trapped in atmosphere in the crucial next ten years, build a bridge to net zero by 2050, and move more rapidly toward a sustainable climate.

Read on to learn how.

• Earth, unbalanced: Why the atmosphere is heating up
  

  The Earth’s energy balance is the difference between incoming shortwave infrared radiation from the sun and outbound longer-wave infrared radiation from the Earth. It is influenced primarily by clouds, surface reflectivity (albedo), the atmosphere, and increasingly by climate pollutants. This balance is measured in terms of “radiative forcing,” a metric reported in units of watts per square meter (W/m²).

  Our atmosphere is heating up because increasing greenhouse gas emissions have shifted the Earth’s energy balance. As humans continue injecting climate pollutants into the atmosphere, the Earth is retaining more energy – that is, heat – than it has for tens of thousands of years.

  The result is higher global temperatures and more extreme weather, including heat waves, droughts, floods, bigger storms, atmospheric rivers, melting ice, sea-level rise, and massive ecosystem disruptions. The pace of the climate crisis continues to accelerate.  

  Despite our best efforts, we are losing ground. By applying what we know about radiative forcing, we can start to catch up. 

• Not all greenhouse gases are created equal

  The best-known driver of global warming is carbon dioxide (CO₂). More than a trillion metric tons have accumulated in the atmosphere since the start of the Industrial Revolution because of human activities.  

  Carbon dioxide:

  • Is the most ubiquitous greenhouse gas (GHG)
  • Has the greatest cumulative effect over time
  • Stays in the atmosphere for centuries to millennia
  • Has the weakest warming effect among all GHGs per ton in any given year

  This makes carbon dioxide the ideal reference gas for comparing the global warming potency of other GHGs. The standard metric for current-day climate accounting is GWP-100: each GHGs’ “Global Warming Potential” over a period of 100 years, compared to that of CO₂.  

  But here’s the problem:

  While GWP-100 works well for GHGs that stay in the atmosphere for centuries, it undervalues emissions which dissipate much faster but which can be thousands of times more potent in heating the planet in the near-term. Yet it is precisely in the near-term that we need to take decisive action to stabilize our climate. 

  

  The methane example

  According to NASA, methane is responsible for 20-30% of global warming since the onset of the Industrial Revolution, and its atmospheric concentration is rising every year. 

  

  By accounting for methane only in terms of GWP-100, conventional carbon footprint accounting and markets fail to provide the critical data we need to stem the near-term climate crisis.  

• How to accelerate the fight against global warming

  If we stopped all SLCP emissions today:

  • Methane and HFCs would rapidly break down in the atmosphere and stop entrapping heat within 15-20 years  
  • Black carbon emissions and tropospheric ozone from emitted pollutants would completely dissipate within days or weeks

  Even under this scenario, the excess heat already baked into the atmosphere from past emissions of CO₂ and other long-lived greenhouse gases will continue to drive feedback loops, so warming effects will continue to worsen for a time before they start receding.

  But the sooner we can mitigate these drivers of climate change, the better. 

  

  The same is true for Earth’s albedo (i.e., its heat reflectivity). Currently, we are losing snow, ice, clouds, and other light-colored surfaces, which reflect about 30 percent of incoming solar radiation back into space. Every reflective surface we preserve, restore, or add, whether it’s natural or manmade, has an immediate effect.  

  Bottom line: If we tackle these factors at scale, we can significantly lower the amount of heat trapped in the atmosphere in the near-term.

  Just by reducing SLCPs, we can avoid 0.6°C of global warming by 2050. In that same timeframe, CO₂ reductions, which make their biggest impact in the long-term, yield 0.1°C in avoided warming. 

  

  Source: CCAC 

• We can’t manage what we don’t measure

  We need to measure and manage more than carbon dioxide emissions over the next 100 years. We must track and reduce all atmospheric heat drivers now.

  This can be done by assessing all contributors to climate change at their full strength, over any time timespan, including:  

  • CO₂ and other long-lived well-mixed GHGs
  • SLCPs, including methane, black carbon, HFCs, and tropospheric ozone
  • Surface conditions such as loss of climate-critical ecosystems and albedo
  • The influence of “negative” climate forcers such as sulfate and nitrate aerosols that have a cooling effect on the atmosphere, but have detrimental effects on air quality and human health.

  Through this type of comprehensive accounting, we can help our partners:

  • Create full climate footprints for their organizations, facilities, and projects
  • Choose targeted mitigation actions that make sense for business and the planet
  • Assess and fund projects aimed at near-term heat reduction
  • Account for social and environmental co-benefits and tradeoffs
  • Help bring down excess atmospheric heat and get to net zero faster

  The Global Heat Reduction Initiative offers the following options:

   

  • Registry

    Our groundbreaking climate registry supports critical heat reduction projects, focusing on currently undervalued or overlooked climate pollutants to enable your organization to offset its carbon footprint while reducing near-term atmospheric heat.

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  • Footprinting

    We can measure and verify your business/organization and facilities for their full climate footprint, including all climate drivers. This enables you to invest in mitigation investments (internal abatement, insetting, or offsetting) that support near-term heat reduction and provide co-benefits.

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  • Advisory

    We help private, public, and NGO partners tackle excess heat through heat impact assessments for current and future facilities and infrastructure, planning, project design, and training on heat reduction science and methodologies.

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• CO₂ remains crucial

  None of the above means that mitigating CO₂ is less important going forward.

  Carbon dioxide remains the dominant long-term driver of climate change. We must work to achieve long-term and short-term goals at the same time. While we take action to reduce excess atmospheric heat in the near term, we must accelerate efforts to cut and remove CO₂ to bring the Earth’s climate back into balance over the long term.  

  That’s how we can:

  • Blunt the sharpest edges of the climate crisis
  • Buy time to let CO₂ cuts and removals reach their full effect over decades
  • Build a livable bridge to net zero in 2050
  • Stabilize our climate and begin to restore it to its pre-industrial equilibrium

  We welcome projects aimed at reducing or removing CO₂ emissions.