Certainly one needs to be forgiven, given the barbaric attack on Ukraine and democracies everywhere by the Muscovites, and the systematic dismantling of democracy here in the US by their fascist allies, for forgetting that life on this planet is under threat from climate change caused by human activity. The UN has certainly not forgotten, and this post concerns three interrelated events between November 2024 and March 2025. But first, a short diversion.
The basis for UN efforts to combat climate change is a document entitled United Nations Framework Convention on Climate Change, UNFCCC, usually referred to as the Convention, enacted in 1992 by 196 nations. [2] It is supported by annual Conferences of Parties (COPs). The Kyoto Protocol was adopted in 1997 at COP3 and came into force in 2005, extending the Convention, committing signatories to reducing greenhouse gas emissions. Conferences of the 192 parties to the Kyoto Protocol are designated as CMPs and take place concurrently with the COPs. The Paris Agreement, aka Paris Accords, was signed in 2016 and covers climate change mitigation, adaptation and finance. It instituted the mechanism of Nationally Determined Contributions, NDCs, which are non-binding national plans for climate action. At present there are three nations that have not ratified the Paris Accords and one - the USA – that has withdrawn from the agreement. Meetings of Paris Accords signatories are referred to as CMAs, and they take place concurrently with COPs. Thus the recent COP meeting in Baku was officially COP29/CMP19/CMA6. [3] It seems, however that the individual COP meetings focus primarily on one or the other of the two major climate treaties, so for example COP29's agenda was slanted toward finance while COP30's will be focused on plans to address greenhouse gas emissions.
In anticipation of COP30 (upcoming in Brazil) the UN Environment Programme published its annual Emissions Gap Report, this time subtitled “No more hot air … please!” [4]. It urged the updating of NDCs to reflect the need for more rapid progress in meeting the climate change goals, based on examination of scenarios based on various degrees of emissions reductions. These were couched in terms of the NDCs, and the scenario results focused on a single variable: land temperature increase.
In particular, if only the existing NDCs are implemented – which incidentally is by no means guaranteed - “the best we could expect to achieve is catastrophic global warming of up to 2.6°C over the course of the century” [5]. The reason for this statement is that, while signatories to the Paris Agreement pledged to reduce emissions and take other actions so as to prevent an increase in global temperatures by as much as 2°C by the end of the century, with 1.5°C as a goal, emissions in most parts of the world have been going up instead of stabilizing or decreasing. Only the EU has actually managed to decrease emissions in every sector, and even they lag in meeting the overall goal.
Overall greenhouse gas emissions reached a new record in 2023, with 57.1 Gigatons CO2 equivalent. Numbers were not available for 2024 and (as of late March 2025) are still not available, but looking at the data there is no reason to expect that they have fallen. The curves at the top of this article, referred to as “Keeling Curves” in recognition of Charles Keeling, who began systematic measurement of CO2 concentrations in 1958 [6] show how atmospheric CO2 concentrations have increased by about 35% since 1960. [7] My own analysis shows that the CO2 concentration is increasing exponentially, and that the rate of increase is itself increasing [8].
As was widely reported, COP29 was a nearly total failure; its sole accomplishment was to establish a fund to compensate especially hard-hit nations, but with a level of funding totally inadequate to achieve its objectives. The result was hardly surprising, as the host nation has a huge vested interest in the continued extraction and burning of fossil fuels, and because the conference was flooded with fossil fuel industry lobbyists. But it is difficult to ascertain these features from the summary proceedings [9], which by all standards is a masterpiece of dissembling.
By contrast, the (UN) World Meteorological Organization's State of the Global Climate 2024 [10] pulled no punches. The seven key indicators from that report are summarized below:
Atmospheric greenhouse gas concentrations
In 2023, all the main greenhouse gasses (CO2, CH4, NOx) reached their highest levels in the last 800,000 years.
Real-time data indicate further increases through 2024. {See above, and [8]]
Global mean near-surface temperature
The annually averaged global mean value was 1.55°C ± 0.13°C above the 1850-1900 average.
2024 was the warmest year in the 175 year history of direct observations, surpassing 2023, the previous warmest year by 0.1°C. Moreover, each of the past 10 years has been individually the warmest year on record.
Ocean heat content
2024 saw the highest level in the 65 year history of measurements.
Each year in the past eight has seen a record level of ocean heat content
The rate of ocean warming over the period 2005-2024 is more than twice that over the period 1960-2005.
Global mean sea level (MSL)
In 2024, the satellite-measured MSL was the highest in the 31 year history of such measurements.
The rate of MSL rise in the decade 2015-2024 is more than twice that observed in the decade 1993-2002.
Ocean acidity (as indicated by pH)
Acidification at the ocean surface has increased steadily over the past 39 years, as indicated by a decrease in the central estimate of pH from just under 8.11 to 8.045.
There is regional variability in the rate of acidification.
Glacier mass balance
“Glacier mass loss from 2021/2022 to 2022/2023 represents the most negative three-year glacier mass balance on record, and seven of the ten most negative annual glacier mass balances since 1950 have occurred since 2016.”
Sea-ice extent
The 18 lowest Arctic sea-ice area minima from satellite data all occurred in the past 18 years.
The Antarctic minimum and maximum sea ice extent for 2024 were both the second lowest on record (1979-present)
In light of recent US political developments involving the attack on science in general and that on NOAA in particular, it is worthwhile to consider the words of the WMO Secretary-General in her Foreword to [10]: “Investment in National Meteorological and Hydrological Services is more important than ever to meet the challenges and build safer, more resilient communities. Authoritative scientific information and knowledge is necessary to inform decision-making in our rapidly changing world . . .”
The foregoing represents only part of the picture, because it does not mention numerous other physical considerations, much less biological or societal ones. I will touch on but one aspect by drawing your attention to a recent finding that microplastics are implicated in reducing the efficiency of the photosynthesis process [11], [12]. Though the report focuses on implications for food production, the effect also has negative implications for the ability of vegetation to sequester carbon dioxide, leading to further increases in atmospheric greenhouse gas concentrations, resulting in further global heating, ocean heating and acidification, glacier melting, sea ice reduction and sea level rise. It is all interconnected.
Notes:
[1] https://scrippsco2.ucsd.edu/
[2] https://unfccc.int/resource/docs/convkp/conveng.pdf
[3] A list of COP conferences, together with brief summaries of the results of each, can be found at https://en.wikipedia.org/wiki/United_Nations_Climate_Change_Conference. The UN has a site also offering information about the conferences in general: https://unfccc.int/process-and-meetings/what-are-united-nations-climate-change-conferences
[4] https://www.unep.org/emissions-gap-report-2024
[5] UNEP Emissions Gap Report 2024 Key Messages. Obtainable via the link [4]
[6] https://www.aps.org/apsnews/2025/02/keeling-measurements-co2-mauna-loa
[7] The curves show the same trend but differ in detail owing to the facts that CO2 uptake and removal are geographically dependent and that the diffusion of CO2 does not occur instantaneously. There is less land mass and less vegetation in the southern hemisphere, for example. Global averages are arrived at by amalgamating data from a number of measurement sites, world wide.
[8] Linear and exponential regressions were performed on Mauna Loa data for the periods 1991-2007 and 2008-2024 with respective best fit formulas C(t) = 353.0 exp(.0049t) and C(t) = 383.8 exp(.0060t), where t is the number of years since the start of the interval, with R² values of 0.994 and 0.998, respectively. I chose the periods to be of equal length, to correspond to the 17 year periods bounded by the Paris Agreement (end of 1997). While one might be tempted to claim that this proves the Paris agreement to be ineffective, such a claim is unjustified because many developed countries have reduced their emissions while others are adopting clean energy sources at a significant rate. We could say with some confidence that were there not motivation to adopt clean energy things would be even worse. As always, I am happy to share my calculations with any paid subscriber requesting them.
[9] https://unfccc.int/sites/default/files/resource/Summary_Global_Climate_Action_at_COP_29.pdf
[10] https://wmo.int/sites/default/files/2025-03/WMO-1368-2024_en.pdf Additionally, prior to COP29 they issued a press release specifically aimed at that conference https://wmo.int/publication-series/state-of-climate-2024-update-cop29 which included a short Youtube video
[11] https://www.pnas.org/doi/10.1073/pnas.2423957122
[12] Thompson, J., Microplastics are Messing with Photosynthesis in Plants, Scientific American, March 10.2025
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