Ozone Column & UV-B Impact

Dobson Unit trajectories WMO 2022 Montreal Protocol baseline Rocket NOx/HCl coupling UV-B economic impacts

Reference year for KPIs: 2040

293.1 DU

Ozone column (2040)

3.3%

Depletion vs pre-industrial (303 DU)

+6.5%

UV-B surface increase (erythemal)

$57B/yr

Total UV-B economic cost (2040)

10 yr

Recovery delay vs WMO baseline

2.2 DU

Rocket-induced ozone loss (2040)

Global Mean Ozone Column (Dobson Units) — 2024 to 2070

Pre-industrial baseline: 303 DU. 2024 observed: 291 DU (~4% depletion). WMO 2022 projects recovery to 303 DU by ~2066 under Montreal Protocol alone. N₂O from agriculture and rocket emissions push full recovery to 2076 (10 year delay) under Orderly transition / Moderate scenario.

Ozone Hole Status (2040)

Severe

Antarctic ozone hole severity assessment based on DU column, N₂O loading, and rocket NOx injection.

Recovery Progress (2040)

60%

Percentage of recovery from 1994 Antarctic minimum (~269 DU) back toward pre-industrial (303 DU).

N₂O Contribution (2040)

0.70 DU

Ozone depletion from rising agricultural N₂O — the dominant ODS not covered by the Montreal Protocol.

UV-B Radiative Amplification: Each 1% decrease in ozone column amplifies erythemal UV-B by 2%, DNA damage by 3%, plant growth inhibition by 2.5%, and phytoplankton productivity loss by 1.8% (RAF factors, WMO 2022).

Agricultural Yield Losses (2040)

Wheat -0.79%

Soybean -1.18%

Phytoplankton -1.18%

Health Risk Indicators (2040)

Melanoma risk increase: +6.5% vs pre-industrial UV-B levels

UV-B surface increase (erythemal): +6.5%

Note: Risk increase is cumulative over lifetime UV-B exposure at current depletion level, relative to a pre-industrial ozone column (303 DU). Geographical variation is large; high-latitude populations benefit from ongoing recovery, tropical populations face highest absolute UV-B flux.

Economic Cost Breakdown (2040, Orderly transition / Moderate)

$26B

Health costs
(melanoma, cataracts)

$17B

Agricultural yield
losses (crops)

$14B

Marine fisheries
(phytoplankton loss)

Total: $57B/yr

Ozone Depletion Attribution (2040)

The current ozone column of 293.1 DU represents a depletion of 3.3% from pre-industrial (303 DU). The causes are split between legacy ODS under Montreal Protocol control, rising unregulated N₂O, and rocket-induced depletion.

CFC/HCFC residual — 70.6%

N₂O (agriculture) — 7.1%

Rocket launches — 22.2%

Global mean ozone column 293.1 DU in 2040 (3.3% below pre-industrial baseline of 303 DU). Montreal Protocol recovery trajectory contributes +5.0 DU of recovery since 2024; partially offset by N2O depletion (0.70 DU) and rocket emissions (2.20 DU under 'moderate' scenario). Full recovery delayed by ~10 years vs WMO 2022 projection. UV-B erythemal dose is 6.5% above pre-industrial baseline.

CFC / HCFC Legacy

Peak stratospheric chlorine loading was ~3.7 ppb in the late 1990s. The Montreal Protocol and its amendments have driven a steady decline; chlorine loading reached ~3.3 ppb by 2024. Full recovery to pre-industrial chlorine levels is expected around 2060–2070 for most CFC compounds, though some very long-lived species (CFC-11, CFC-113) delay recovery.

N₂O — The Unregulated Threat

Nitrous oxide (N₂O) from agricultural fertilisation and livestock is now the primary ozone-depleting substance not covered by any international treaty. N₂O is converted to NO in the stratosphere, where it catalyses ozone destruction via the NO-NO₂ cycle. Projected to contribute an additional 1.2–2.0 DU of depletion by 2050–2080, delaying full recovery by 5–15 years beyond the WMO baseline.

Rocket NOx & HCl

Rocket engines inject NOx directly into the stratosphere where it catalyses ozone depletion. Solid rocket motors (HTPB/AP composite) additionally release HCl — a direct chlorine source. Under the moderate scenario, rocket launches account for ~22.2% of the total ozone depletion in 2040. Under the aggressive scenario this rises substantially.

Regulatory Status

Rocket emissions are currently unregulated under any international ozone-protection instrument. The Chicago Convention governs aviation emissions but explicitly excludes space launch. FAA environmental reviews assess surface-level impacts but not stratospheric chemistry. WMO and UNEP have called for monitoring; no binding controls exist as of 2024.

Gap: Regulatory framework absent for stratospheric ozone impacts of commercial space launches at scaled launch rates.

Ozone Column Recovery Scenarios (DU)

Montreal Protocol baseline (WMO 2022): Full recovery to 303 DU expected ~2066 in Antarctica, ~2040 in mid-latitudes, if no new ODS threats emerge. N₂O and rocket emissions delay this timeline.

Recovery Delay by Driver (vs WMO 2022 Baseline)

Driver	Scenario	Delay (years)	Mechanism
N₂O from agriculture	Current trajectory	5–8 yr	NO catalytic cycle; no Montreal Protocol coverage
Rocket launches	Conservative	1–2 yr	NOx + HCl injection; limited total volume
Rocket launches	Moderate	3–7 yr	Significant NOx at 25,000 launches/yr by 2050
Rocket launches	Aggressive	10–15 yr	Large NOx + HCl burden; potential for localised ozone holes
Combined (N₂O + rockets)	Moderate	10 yr (model est.)	Compound effect; non-linear interaction of NOx sources

Scientific Basis

Source	Key Finding
WMO/UNEP Ozone Assessment 2022	Montreal Protocol on track; full global recovery ~2066. N₂O now dominant unregulated ODS. Calls for monitoring of new threats.
Ryan et al. (2022) GRL	First comprehensive radiative forcing assessment of full rocket fleet; ozone coupling via NOx deposition quantified at current launch rates.
Jackman et al. (1998) J. Geophys. Res.	NOx ozone sensitivity in the stratosphere — calibration for NOx depletion contribution per launch.
Toohey et al. (2019)	Solid rocket motor HCl emissions and ozone depletion; scaling with launch rate; flags regulatory gap.
Solomon et al. (2016) Science	Detection of Antarctic ozone healing — first statistical evidence that Montreal Protocol is working.
Chipperfield et al. (2017) Nature	Quantification of ozone layer recovery progress; multi-model assessment framework.
Ravishankara et al. (2009) Science	N₂O as most important ODS in 21st century under current emission trends.

Key Physical Constants Used in This Model

Parameter	Value	Source
Pre-industrial ozone column	303 DU	WMO 2022
Observed 2024 ozone column	291 DU	NOAA GML
1994 Antarctic minimum	~269 DU	Dobson network
Erythemal UV-B RAF	2.0 per 1% ozone decrease	WMO 2022 Table 3
DNA damage RAF	3.0 per 1% ozone decrease	WMO 2022
Economic cost per 1% depletion	$17.5B/yr	Derived from ~$70B/yr at 4% depletion