Measuring the climate impact of reflective cooling
Carbon emissions are measured in tonnes of CO₂. Reflective and radiative cooling is measured in watts per square metre. The Reflective–Emissive Carbon Offset (RECO) is the framework MEER uses to express the two on the same scale, so the climate benefit of surface cooling can be compared directly with conventional carbon mitigation.
Current global-average relationship
A first-order approximation. Local values vary with latitude, solar radiation, atmospheric transmission and surface energy balance — MEER is developing location-specific RECO values for every region.
Tonnes of CO₂, or watts per square metre?
Climate mitigation has historically been quantified in two very different languages. Emissions inventories, national targets and carbon markets are expressed in tonnes of CO₂-equivalent. Surface energy balance — the physics that governs how reflective and radiative cooling actually work — is expressed in watts per square metre of radiative forcing. Both are physically correct. Neither translates cleanly into the other without a defined conversion.
Used by IPCC inventories, national reporting, offsets, ESG disclosures and carbon markets. Intuitive for policymakers and the public.
Used by atmospheric physicists, radiative-transfer models and engineers designing cool-roof and passive radiative cooling materials.
RECO does not replace either system. It provides a defined equivalence between them, grounded in global mean radiative forcing, so that a square metre of reflective surface can be discussed alongside a tonne of CO₂ in a scientifically consistent way.
How much cooling does one square metre provide?
Enter a reflective area to see its equivalent climate impact in tonnes of CO₂, calculated using the current global-average RECO conversion. Location-specific conversion factors are in active development.
CO₂-equivalent offset
CO₂e over the deployment lifetime · global-average conversion
Where the number comes from.
One tonne of excess atmospheric CO₂ produces roughly 856 watts of additional surface heating, integrated across its climate lifetime.
One square metre of highly reflective surface prevents approximately 112 watts of solar heating from being absorbed by the Earth system — on the global average.
Dividing the two gives the current global-average conversion factor: ~7.6 m² ≈ 1 tonne CO₂e. Actual values are location-specific.
Technical derivation & assumptions
The metric is derived from global mean radiative forcing. A radiative forcing of 1 W/m² applied over Earth's surface area (≈5.1 × 10¹⁴ m²) corresponds to a well-characterised heating rate. Converting the marginal forcing of atmospheric CO₂ (≈1.66 W/m² per 100 ppm at present concentrations, with airborne fractions and lifetime integrated) yields an equivalence of roughly 856 W per additional tonne of CO₂ over a canonical accounting horizon.
For a highly reflective surface with an albedo increase of Δα ≈ 0.5 under a global-mean insolation of ~340 W/m² (top-of-atmosphere) — accounting for atmospheric transmission and cloud attenuation — approximately 112 W/m² of solar heating is prevented. This is a global-mean value; local values scale with the actual insolation, atmospheric transmission and surface albedo at each site.
The ratio 856 / 112 ≈ 7.6 m² per tonne CO₂e is used directly, without rounding. The per-square-metre value follows: 1000 kg / 7.6 ≈ 131.58 kg CO₂e per m².
What the measurement looks like in practice.
Applying the current global-average conversion to real deployments shows the CO₂-equivalent climate value of the surfaces that shade a school, cool a hospital or protect a reservoir. Location-specific RECO values will refine these estimates for every region.
One classroom block
Mid-sized regional hospital
Typical distribution centre
Shade-tolerant crops
Water-saving float array
Cool-roof deployment
From one global number to a global map.
One tonne of CO₂ has the same climatic effect wherever it is emitted. Reflective cooling is fundamentally different — the solar energy reaching Earth's surface varies with latitude, atmospheric transmission, cloud cover and surface energy balance. RECO is therefore evolving from a single global-average value into a spatially resolved climate metric, with a location-specific conversion factor for every region.
Low-latitude, high-insolation regions where each square metre of reflective surface prevents the most solar heating.
Every location on Earth has its own conversion factor, derived from solar radiation, atmospheric transmission and local surface energy balance.
High-latitude and persistently cloudy regions where less solar radiation reaches the surface, so reflective cooling delivers less climate benefit per m².
Building the first physically based global framework for surface cooling.
MEER is developing the next generation of climate cooling metrics by combining satellite observations, atmospheric physics and radiative-transfer modelling to produce geographically specific RECO values. This work aims to establish the first physically based global framework for comparing surface cooling with conventional carbon mitigation.
The current value is a global-average estimate — and it's evolving.
The current RECO metric uses a global-average conversion to enable direct comparison between surface cooling and conventional carbon accounting. In reality, cooling performance varies by location. MEER's ongoing research is producing location-specific RECO values for every region of the world, allowing cooling benefits to be calculated with much greater precision.
RECO is not a carbon credit and does not claim that reflective surfaces permanently remove carbon dioxide from the atmosphere. It is a physically grounded, comparative metric for expressing the cooling impact of reflective and radiative surfaces in CO₂-equivalent terms — a shared unit for policy, engineering and public understanding.
Using the framework in research, policy and planning.
Provides a consistent unit for comparing radiative-forcing studies of reflective and radiative cooling with the broader climate-mitigation literature expressed in CO₂-equivalent terms.
Lets policymakers evaluate cool-roof mandates, urban albedo programmes and reflective infrastructure alongside emissions-reduction commitments using a single scale.
Supports municipal heat plans, adaptation strategies and infrastructure investment decisions by quantifying the climate value of surface cooling in familiar units.