Thursday, July 10, 2025
Would-be dictator names three climate deniers to Energy Department
Thursday, November 28, 2024
The Antarctic stratospheric ozone hole in 2024
by OnymousGuy
Abstract
The data says 2024 was pretty average, and "far from being fully healed", but NASA's press office says "relatively small". So which is it? "Relatively small", or "far from being fully healed"?
Background
We are approaching the end of season for this year's Antarctic stratospheric ozone hole, as the increasing springtime sunlight stimulates the Chapman cycle to produce more ozone.
NASA's ozone watch documents the status of the Antarctic stratospheric ozone hole, with updates about every week or so, but less frequently at the end of the season. Certain parameters are tracked:
The data for the ozone hole area, the minimum ozone, and the minimum stratospheric temperature are available. Also available is a table of values showing the maximum ozone hole area and the minimum ozone values for each year...
The graphs ... show the progress of the ozone hole for 2024. The gray shading indicates the highest and lowest values measured since 1979. The red numbers are the maximum or minimum values. The stratospheric temperature and the amount of sunlight reaching the south polar region control the depth and size of the Antarctic ozone hole. The dashed line in the minimum temperature plot indicates the temperature below which Type I (NAT) PSCs can form.
Ozone concentrations are reported in Dobson units.
The Dobson Unit (DU) is the unit of measure for total ozone. If you were to take all the ozone in a column of air stretching from the surface of the earth to space, and bring all that ozone to standard temperature (0 °Celsius) and pressure (1013.25 millibars, or one atmosphere, or “atm”), the column would be about 0.3 centimeters thick. Thus, the total ozone would be 0.3 atm-cm. To make the units easier to work with, the “Dobson Unit” is defined to be 0.001 atm-cm. Our 0.3 atm-cm would be 300 DU.
Here are some recent images.
- ozone hole area, minimum ozone, minimum stratospheric temperature,
- annual maximum ozone hole area, annual minimum ozone.
Here is a recent false color image of the ozone hole.
Discussion
From these figures, I would say that the 2024 ozone hole has been pretty close to its average over the satellite era. So I was a bit surprised to read this puffery from NASA:
Healing continues in the atmosphere over the Antarctic: a hole that opens annually in the ozone layer over Earth's southern pole was relatively small in 2024 compared to other years.
During the peak of the ozone depletion season from Sept. 7 through Oct. 13, the 2024 area of the ozone hole ranked the seventh smallest since recovery began in 1992, when the Montreal Protocol, a landmark international agreement to phase out ozone-depleting chemicals, began to take effect...
The improvement is due to a combination of continuing declines in harmful chlorofluorocarbon (CFC) chemicals, along with an unexpected infusion of ozone carried by air currents from north of the Antarctic, scientists said.
A little bit of realism creeps into the blurb from NASA, lower down in the press release.
In previous years, NASA and NOAA have reported the ozone hole ranking using a time frame dating back to 1979, when scientists began tracking Antarctic ozone levels with satellite data. Using that longer record, this year's hole ranked 20th smallest in area across the 45 years of observations.
IMO, 20th out of 45 sounds pretty average. One of the GML scientists spills the beans:
"For 2024, we can see that the ozone hole's severity is below average compared to other years in the past three decades, but the ozone layer is still far from being fully healed," said Stephen Montzka, senior scientist of the NOAA Global Monitoring Laboratory.
So which is it? "Relatively small", or "far from being fully healed"?
Ozone Depleting Substances
The ozone hole, of course, depends on the concentration of stratospheric chlorine and bromine; sources of atomic Cl and Br in the stratosphere are called ozone depleting substances. The Trump administration excised EPA information about ozone depletion and the like, so one must look to the European Union for such things.
A compound that contributes to stratospheric ozone depletion. Ozone-depleting substances (ODS) include CFCs, HCFCs, halons, methyl bromide, carbon tetrachloride, and methyl chloroform. ODS are generally very stable in the troposphere and only degrade under intense ultraviolet light in the stratosphere. When they break down, they release chlorine or bromine atoms, which then deplete ozone.
These species have one thing in common: they contain halogens, specifically chlorine or bromine. Each halogenated compound is associated with an ozone-depleting potential (ODP), a direct measure of its ability to destroy ozone. More from the EU:
The ozone-depleting potential (ODP) of a substance refers to the relative amount of ozone depletion caused by it. It is the ratio of the impact on ozone of the emission of a chemical substance to the impact of a similar emission by mass of CFC-11. The quantity in metric tonnes of a particular controlled substance is multiplied by its ODP to give its overall potential to deplete the ozone layer. For instance, 1 metric tonne of CFC-11 corresponds to 1 ODP tonnes (as its ODP is equal to 1), whilst for bromotrifluoromethane or halon 1301 (with an ODP = 10), 1 metric tonne corresponds to 10 ODP tonnes. The ODPs of controlled and new substances are listed in Annexes I and II of the Ozone Regulation (Regulation (EC) No 1005/2009). Some new substances have a range, rather than a single ODP value. In this online data viewer, the highest value of the ODP value range is used.
What are the current levels of atmospheric chlorine? NOAA's Global Monitoring Laboratory reports this trend.
It seems that the most that one could say, based on the data, is that mid-latitude amounts of ozone-depleting substances have dropped below half of their pre-Montreal Protocol maximum. Yes, the world is still on track to see Antarctic mounts of ozone-depleting substances have dropped below half of their pre-protocol maxima by 2076 or so, provided that we remain vigilant in observing the protocols and their amendments. HCFCs are the issue.
And then NOAA scientists weigh in on the minimum.
NOAA scientists also release instrumented weather balloons from the South Pole Baseline Atmospheric Observatory to observe ozone concentrations directly overhead in a measurement called Dobson Units. The 2024 concentration reached its lowest value of 109 Dobson Units on October 5. The lowest value ever recorded over the South Pole was 92 Dobson Units in October 2006.
NASA and NOAA satellite observations of ozone concentrations cover the entire ozone hole, which can produce a slightly smaller value for the lowest Dobson Unit measurement.
"That is well below the 225 Dobson Units that was typical of the ozone cover above the Antarctic in 1979," said NOAA research chemist Bryan Johnson. "So, there's still a long way to go before atmospheric ozone is back to the levels before the advent of widespread CFC pollution."
There you have, at the very end of the puff piece: "There's still a long way to go before atmospheric ozone is back to the levels before the advent of widespread CFC pollution."
Wednesday, November 27, 2024
Putting current radiative forcing in context
Current radiative forcing from all greenhouse gases, omitting aerosols from nonmetal oxides and the like, is now just under 3.5 W/m2, with an Annual Greenhouse Gas Index of about 1.52. This represents approximately 1.5% of average surface insolation. Unlike solar energy, which rises and falls with the sun, this infrared energy captured from the earth itself accumulates second by second, day and night.How significant is this? Consider this analogy. A typical adult on a 2000 kcal/day diet ingesting daily 1.5% calories in excess will gain 31 pounds per decade, with profound consequences. Now we have been burning fossil fuels at the same high rate as our over-eater for more than two decades. How can we possibly imagine that the consequences for the planet will be less severe?
Background
On the average, the earth reflects 31 units of solar radiation back to the space for every 100 units received (thus, the total earth albedo is 0.31). The cloud albedo accounts for 23 units of the 31. For individual clouds, local albedo may be in excess of 0.7.
Comparison with diet
Obesity in children and adults increases the risk for the following health conditions:
- High blood pressure and high cholesterol which are risk factors for heart disease.
- Type 2 diabetes.
- Breathing problems, such as asthma and sleep apnea.
- Joint problems such as osteoarthritis and musculoskeletal discomfort.
- Gallstones and gallbladder disease.
"If left untreated, class III obesity may shorten life expectancy up to 14 years. In addition to contributing to potentially serious health problems, class III obesity is associated with reduced economic and social opportunities and reduced quality of life."
As stated in the abstract, we have been burning fossil fuels at the same high rate as our over-eater for more than two decades. How can we possibly imagine that the consequences for the planet will be less severe?
Wednesday, November 13, 2024
Current Composition of the Atmosphere, November, 2024
Guest post by Jim
NOAA has once again released its monthly updates to CO2, CH4, and N2O. See the data section for each gas.
Here are the updated results. Little has changed. By 2030 the atmosphere will have such a high concentration of greenhouse gases that the effective radiative forcing will be twice that of the pre-industrial era.
The 2x crossing is now estimated to occur 1 April, 2030 (no joke!), give or take a month; changes in this estimate over the last year are more likely due to month-to-month fluctuations, not long term changes in trends.
Here is the combination of historic data, satellite era data, and the most recent updates from NOAA:
Sunday, October 06, 2024
Recent trends in atmospheric methane.
A guest post from Jim
Over the last year, the global increases in methane emissions have begun to raise alarms.
Here's a brief sample:
- Sarah Kaplan's report in the Washington Post, reporting 10 Sept 2024, "Emissions of methane — a powerful greenhouse gas — are rising at the fastest rate in recorded history, scientists said Tuesday, defying global pledges to limit the gas and putting the Earth on a path toward perilous temperature rise."
- The European Space Agency's post, also on 10 Sept 2024, "The Global Methane Budget 2024 paints a troubling picture of the current state of global methane emissions. The new report reveals that human activities are now responsible for at least two-thirds of global methane emissions. This marks a significant increase in human-produced methane sources over the past two decades, with emissions rising by 20%, with the fastest rise occurring over the last five years."
- NOAA's summary of 5 Apr 2024, No sign of greenhouse gases increases slowing in 2023, reports that "Atmospheric methane, less abundant than CO2 but more potent at trapping heat in the atmosphere, rose to an average of 1922.6 parts per billion (ppb). The 2023 methane increase over 2022 was 10.9 ppb, lower than the record growth rates seen in 2020 (15.2 ppb), 2021(18 ppb) and 2022 (13.2 ppb), but still the 5th highest since renewed methane growth started in 2007. Methane levels in the atmosphere are now more than 160% higher than their pre-industrial level,"
"I haven't followed methane much because I couldn't find a good data source, but now I have, from NASA. And even better source is the Global Carbon Project, which is updated every 7.6 days.After that weird lull in the mid-aughts, methane is on the rise again and is the highest it's been in 800,000 years.Methane's radiative forcing has increased by about 0.4 W/m^2 since 1979, while CO2's has jumped about 1.6 W/m^2 in the same interval...It's incredible that the world, despite all the rhetoric and (token) efforts, keeps allowing this to happen. Clearly, I think, these trends will only be taken seriously once some catastrophic effects happen, and by then it will be too late. So human and we can't even help ourselves."
- " The primary reference ...(pre-print) Global Methane Budget 2000–2020 Here's an excerpt from the abstract: "Understanding and quantifying the global methane (CH4) budget is important for assessing realistic pathways to mitigate climate change. Emissions and atmospheric concentrations of CH4 continue to increase, maintaining CH4 as the second most important human-influenced greenhouse gas in terms of climate forcing after carbon dioxide (CO2). The relative importance of CH4 compared to CO2 for temperature change is related to its shorter atmospheric lifetime, stronger radiative effect, and acceleration in atmospheric growth rate over the past decade, the causes of which are still debated. "
- Additional Analyses for Methane Budget 2024:Human activities now fuel two-thirds of global methane emissions. "Methane is rising faster in relative terms than any major greenhouse gas and is now 2.6-fold higher than in pre-industrial times. Global average methane concentrations reached 1931 parts per billion (ppb) in January of 2024 (Lan et al 2024). Annual increases in methane are also accelerating for reasons that are debated..."
Wednesday, October 02, 2024
Current Composition of the Atmosphere, September, 2024
Guest post by Jim
NOAA has once again released its monthly updates to CO2, CH4, and N2O. See the data section for each gas.
Here are the previous results.
Here are the updated results; changes are more likely due to month-to-month fluctuations, not long term changes in trends:
Here are recent month to month variations from the moving average and its best fit.The crossing is now estimated to occur early March, 2030, give or take a month.
Here is the combination of historic data, satellite era data, and the most recent updates from NOAA:
Sunday, June 23, 2024
CO2 eq update June, 2024
NOAA has released its monthly updates to CO2, CH4, and N2O. See the data section for each gas.
Here are the previous results.
Here are the updated results; changes are more likely due to month-to-month fluctuations, not long term changes in trends:
Here are recent month to month variations from the moving average and its best fit.
The crossing is now estimated to occur mid-February, 2030, give or take a month.

Here is the combination of historic data, satellite era data, and the most recent updates from NOAA: