Article adapted from the original source: Considering sectoral warming and cooling emissions and their lifetimes can improve climate change mitigation policies (published July 30, 2025)
Authors/organizations: B. Buma, I. Ocko, B. Walkowiak, Y. Xu, M. Lackner, S. S. Sartzetakis, A. Alpert, and S. Dhungel. Environmental Defense Fund (New York) and Texas A&M University. Published in npj Climate and Atmospheric Science (Nature Portfolio), in partnership with King Abdulaziz University’s CECCR. DOI 10.1038/s41612-025-01131-8.
Rights: Creative Commons Attribution – NonCommercial – NoDerivatives 4.0 International (CC BY-NC-ND 4.0), license of the published version. This text is an original analysis by WasteOlas: the study’s numerical data are used, tabulated, and commented on, with author attribution and a link to the publication. No text, tables, or figures from the source are reproduced or translated.
Visual credit: illustration taken from the main source.
What if part of the warming we are already experiencing remains invisible? A study published in npj Climate and Atmospheric Science quantifies, sector by sector, what 33 substances emitted since 1750 are actually doing to the climate: some warm, others cool, and they do not persist in the atmosphere at the same rate at all. The results reshuffle the usual hierarchy of responsibilities and point to a much faster lever for action than anticipated.
One-Third of Warming is Masked, and the Mask is Fading
Warming emissions accumulated since 1750 alone account for approximately 2.18 °C (± 0.14), of which 1.25 °C is from long-lived species and 0.93 °C from short-lived species. CO2 accounts for 47% of this gross warming, methane 29%. Conversely, cooling species, primarily aerosol precursors, remove approximately 0.83 °C (± 0.15), with 68% of that attributed to sulfur dioxide alone. The net balance, approximately 1.35 °C (± 0.21) in 2022, thus conceals one-third of warming already emitted but temporarily offset.
This compromise is unstable: aerosols disappear in a few days to weeks, while CO2 acts for centuries. Cleaning the air, which is perfectly justified for public health, mechanically unmasks warming that has already occurred. The authors also note that the surge in temperatures in 2023 and 2024 is partly explained by this phenomenon.
Sectors with the Highest CO2 Load Also Self-Cool
The study highlights a strong inverse correlation (p = 0.001, r² = 0.91): the higher the share of CO2 in a sector’s warming, the more that sector co-emits cooling species. Here is what this looks like for the period 1750-2022, in terms of average surface temperature variation.
| Sector | Gross Warming (°C) | Co-emitted Cooling (°C) | Net Effect (°C) |
|---|---|---|---|
| Agriculture (incl. forests and fishing) | +0.34 | -0.03 | +0.31 |
| Fossil fuel production and distribution | +0.35 | -0.05 | +0.30 |
| Industry | +0.44 | -0.22 | +0.22 |
| Buildings | +0.31 | -0.11 | +0.20 |
| Transport | +0.29 | -0.15 | +0.14 |
| Waste | +0.14 | -0.02 | +0.12 |
| Electricity production | +0.31 | -0.26 | +0.05 |
The table demonstrates two things. Industry and electricity production show a flattering net balance only because their own aerosols mask half, and over 80% in the case of electricity, of their gross warming. Conversely, agriculture, the fossil fuel sector, and waste have almost no cooling to lose: every tonne avoided in these sectors translates into an almost integral thermal gain.
Time Reshuffles the Cards: From 12% to 34% in a Century
The temporal dimension is also striking. Current agricultural emissions will account for approximately 16% of the warming felt in 2032, but only 6% in 2122, because methane dissipates. Electricity production emissions follow the inverse trajectory: approximately 12% in 2032, then 34% in 2122, once aerosols have dissipated and CO2 remains. By reallocating fossil fuel emissions to their end uses, the gap widens further: agriculture goes from 25% to 8%, electricity from 25% to 37%.
In other words, no single strategy works for both horizons. We must act quickly on short-lived warmers to limit the rate of warming, and simultaneously accelerate action on CO2 to limit its final level, taking into account the loss of the aerosol mask.
What This Means for WasteOlas
This is precisely the niche where resource and waste management and local CO2 valorization are situated. The waste sector accumulates 0.14 °C of gross warming for only 0.02 °C of co-emitted cooling: it ranks, along with agriculture and the gas sector, among the targets the authors consider most promising for rapid and inexpensive climate gain. Capturing methane and carbon flows at the source produces a measurable effect within a decade, with no unmasking rebound effect. The priority given by the FOGA fund to reducing CH4 emissions in Swiss gas networks, which we noted in the spring, finds its quantified climate justification here.
The second lesson concerns the long term. Since CO2-induced warming accumulates for centuries and its compensation by aerosols is set to disappear, carbon ambition must be raised, not just maintained. Transforming local, biogenic CO2 into a resource rather than a discharge—the logic validated by the first federal ITINERO funding for a Swiss capture and valorization project—directly addresses this requirement. Combined with the potential of domestically produced biomethane, 25% to 50% of future gas needs according to the Paul Scherrer Institute, the loop closes: reduce fugitive methane today, valorize biogenic carbon sustainably.
Key Takeaways
- One-third of already emitted warming, approximately 0.83 °C, is masked by short-lived aerosols that dissipate with air purification.
- The waste sector shows 0.14 °C of gross warming for only 0.02 °C of cooling: acting on methane here yields an almost integral thermal gain within a decade.
- For WasteOlas, the study validates the dual approach: rapid capture of short-lived warmers at the source and valorization of local CO2 for the long term, two horizons that climate policies still treat separately.
Conclusion
This publication provides quantified evidence of what WasteOlas monitoring observes in the field: the most effective deposits are not always the most visible, and flows from waste and fermentation concentrate immediate climate potential that CO2 equivalent inventories structurally underestimate. The next step, for companies as well as regulators, will be to valorize this temporal dimension in financing and certification mechanisms, so that speed of action counts as much as the volume avoided.