Information & Computational Sciences

Beyond greenwishing: facing the hard truths of climate change

By on 17/12/2023 in News

At every year’s climate negotiations, a crucial question looms: what are the odds that we can limit global warming to the critical threshold of 1.5°C?

The answer depends on the “safe” carbon budget concept, which represents the cap on total emissions that humanity can afford to release, while still having a chance to stay below the critical threshold(s) of temperature rise. Net Zero, while important, is not per se sufficient: the path to net zero is crucial.

A fundamental role is played by the Nationally Determined Contributions (NDCs) agreed by countries under the Paris Agreement and their (not legally binding) implementation.

Unfortunately, the projected global greenhouse gas (GHG) emission levels are expected to be only 2% below the 2019 level by 2030 – falling short of the much more substantial reductions needed to align with the Intergovernmental Panel on Climate Change (IPCC) scenarios for limiting global warming.

Credit: U.S. Department of Agriculture (USDA(link is external)) photo by Bob Nichols (Public Domain)

This is the context in which the COP28 deal should be judged. But, “Transitioning away from fossil fuels in energy systems, in a just, orderly and equitable manner, accelerating action in this critical decade, so as to achieve net zero by 2050 in keeping with the science…” is open to interpretation. Proof of this is that Saudi Arabia has already declared that the deal will not affect its fossil fuels exports.


As a reminder that “keeps with the science”:  the IPCC scenarios indicate that to have a 50% chance of limiting warming to 1.5°C, global GHG emissions need to fall 43-60% by 2030. Trebling renewables is essential, but would not be sufficient, if they mainly went to satisfy growth in energy demand. Current emissions reduction efforts are insufficient to respect that limit.

What’s more, while warned by IEA and the Production Gap Report that we cannot afford to emit the majority of the carbon contained in active fossil fuel fields, and that opening new fields is incompatible with the 1.5°C goal, several countries intend to approve ones. It’s no surprise, therefore, that “phasing out” fossil fuels did not make it into the final COP28 text.

What has been agreed, is the path of least resistance, in the short term. Namely a very gradual transition. This is understandable. Overhauling the energy system will be very expensive and could mean significant adjustments to infrastructure and daily life. But we don’t have the time for a very gradual transition. The longer we avoid reality and seek comfort in naïve optimism, in “greenwishing” (where overly optimistic policies and strategies are believed to provide solutions), the more expensive and damaging the consequences will be.



It’s a greenwish to believe sustainability will be warmly welcomed by everyone. Setting aside strong opposition from vested interests, a just transition that is both well-funded and well planned, focusing on economic diversification and social inclusion, is crucial. Political leadership here will be crucial. Without it, overcoming grassroots populist resistance may be difficult and could be exploited by those seeking to maintain the status quo.

Greenwishing is underestimating the limitations of carbon removal form the atmosphere. An example of this is  land-based and “nature-based solutions”. They are essential for adaptation and biodiversity conservation, but not sufficient to remove carbon at the scale needed. Staying within a safe carbon budget requires rapid and substantial net CO2 capture, but studies like the “Land Gap Report” highlight the impracticality of achieving this at the global scale and, moreover, within a few decades (see a more in-depth explanation here).

While restoring forests ecosystems is crucial for multiple reasons, and has a large theoretical potential to capture carbon in the long term, their actual contribution by 2050 is likely to be a few gigatons per year, as the major soil contribution can only be realised rather slowly.

Forests often play a crucial part in the voluntary carbon market, a related area of concern. Integrity issues within the voluntary carbon market are often highlighted, but the primary challenges lie elsewhere: in the mismatch between a potentially high demand for carbon offsets and the limited capacity of ecosystems to quickly capture enough carbon, in the inability of offsetting schemes to decrease global emissions permanently,  because of the transient nature of carbon storage within the biosphere through offsets, as opposed to permanent carbon removal.

Continuing to emit while offsetting implies that carbon, once securely stored in fossil fuels deep within the Earth, and effectively removed from the atmospheric cycle, is being extracted, released back into the atmosphere, and only temporarily offset by e.g. tree growth. This carbon will be stored in forests and other ecosystems for a limited period, rather than being permanently sequestered away as it was in fossil forms.  The storage in the biosphere is vulnerable to environmental disturbances, as seen, for example, in the massive forest fires in Canada in 2023 (18 million ha, or more than the entire total surface of England, Wales and Northern Ireland.). Also, if warming continues, heat stress will lower the global capacity to store carbon. It is therefore probable that many forest ecosystems will succumb to the risks they are supposed to mitigate.

Still, voluntary offsetting schemes are often marketed as “natural climate solutions”. These might be a “solution” for those buying offsets, but they are not, per se, bringing us closer to the goal of halving emissions every 10 years.

If, by 2050, ecosystems cannot offset more than a few gigatons of CO2 per year, perhaps carbon removal technologies – mentioned in the COP28 deal – will help keep us withing the safe carbon budget and have the notable advantage to remove carbon permanently?

We cannot rule out breakthroughs and indeed they would be welcome, but we risk more greenwishing.

Carbon capture and storage (CCS) and direct air capture (DAC) present significant difficulties. CCS, in particular, has shown underwhelming performance and high costs. CCS captured only about 0.03% of global emissions from 1996-2020, raising doubts about its scalability and impact on global emissions levels. Planned flagship projects in the UK will capture yearly roughly 1% of the territorial emissions and can store permanently less than one year of present UK territorial emissions.  A recent study by Oxford University pointed out that the costs of a “high CCS pathway” to net zero would be an extra £1 trillion/yr compared to a renewables-based one. The vast majority of fossil fuels are therefore likely to be “unabated” and therefore is a legitimate target for phasing out.

DAC, though theoretically feasible, and technically possible, demands an enormous amount of energy. The first plant that opened in the US, in November 2023, illustrates the scaling up problem. We would need some several million plants of that capacity to absorb half of the current yearly CO2 emissions. A lot of optimism is required here.

Governments that oppose the phasing out of fossil fuels while endorsing the 1.5°C limit are optimistic at best. Greenwishing, stemming from a misplaced confidence in our ability to reverse the effects of releasing hundreds of gigatons of fossil carbon into the atmosphere, poses a serious risk. This complacency threatens to drive global temperatures far beyond that limit, potentially reaching as high as 3°C, which would have severe and irreversible consequences for our planet.

As the Global Stocktake has pointed out, the window for keeping global warming within the 1.5°C limit is rapidly closing. And, admittedly, after COP28 the odds we can still squeeze through are low. But, all the more, to stray as little as possible from the 1.5oC limit, we need immediate, decisive and adequately funded action to decarbonise the whole economy – justly.

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