A recently published article calls for an “international mobilization” in the study of Earth’s geophysical and biological processes that can enhance the climate change. According to the work, it is necessary to obtain a better evaluation of the operation and impact of those phenomena in order to be able to make a more accurate estimate of carbon dioxide carbon (CO2) that humanity can still emit before the Earth’s average temperature definitely exceeds 1.5 degrees Celsius compared to pre-industrial values.
“We believe that there must be a massive and immediate international mobilization to advance climate science, which includes an increase in research priorities and funding, in order to rapidly improve knowledge of the interactions and impacts of climate change. feedbacks [climáticos] in the context of the remaining carbon budget,” reads in the comment published in the magazine One Earthauthored by William J. Ripple and Christopher Wolf, both from Oregon State University, in the United States, and five other scientists working in the US, UK and Germany.
The carbon budget is an important concept in the context of climate change policy. Knowing the value of the amount of CO2 that can still be emitted gives an idea of how close we are to a point of no return and makes it possible to develop climate policies that avoid reaching that limit.
But the calculation of this value is complex because it has to take into account the terrestrial processes that interact with the climate, which are many. The most recent carbon budget figures released give a taste of this complexity.
120 gigatons of difference
On 11 November last, the Global Carbon Project (GCP) – a recognized international research project that provides baseline information for climate policy – published an article on the 2022 carbon budget.
According to that work, 380 gigatons of CO2 remained to be emitted, in order to avoid with 50% probabilities that the earth’s average temperature exceeds 1.5 degrees, the value from which it is estimated that the effects of climate change are more violent. If you consider that annual CO2 emissions will be around 40 gigatons, that budget will be spent in just nine years.
That same day, an article published in site CarbonBrief released a much smaller estimate. According to the text, humanity had, as of January 2023, only 260 gigatons of CO2 to spend, 120 gigatons less than the value of the GPC, according to authors from the University of Leeds and Imperial College London, in the United Kingdom. . This value is equivalent to six and a half years of emissions. That is, if emissions do not decrease, it would be exceeded in the middle of 2029.
The figure obtained by Piers Forster of the University of Leeds and colleagues took into account, like the GPC, the carbon budget calculations of the Intergovernmental Panel on Climate Change (IPCC) published in August 2021 and the which has already been issued in 2020, 2021 and 2022.
The big difference is that it also incorporated the most recent improvements on the calculation of the carbon budget that took into account the impact of normally polluting aerosols in the air. Although the effect is small, these aerosols reflect some of the sunlight.
“As we reduce carbon emissions, those aerosols will also decline, causing the relative warming effect”, reads in the CarbonBrief article. This warming effect, however small, has an impact on the amount of CO2 that can still be emitted.
“Assessing what remains of the carbon budget is complex because a large part of the total budget has already been issued, and relatively minor improvements in scientific knowledge can have large consequences on those estimates”, explain those authors.
Insufficient climate models
It is precisely this aspect that the authors of the commentary published in One Earth fear. The article published last Friday tries to gather for the first time all the processes of feedback known actors involved in climate change in a single list. In all, there are 41 processes, 27 of which amplify climate change, seven have a dampening effect and there are seven more that it is not known whether they accelerate global warming or mitigate it.
A very simple example of a positive phenomenon is that of the polar ice caps. The heating of the planet causes these large white areas located at the two poles to decrease due to the melting of ice, this means that there will be a smaller area reflecting the sun’s rays. If the sea ice area of the arctic decreases, part of the light ends up entering directly into the ocean, warming it and enhancing the warming of the Earth.
There are feedback phenomena linked to the formation of clouds, water vapor in the atmosphere, atmospheric dust, forest fires, desertification, the reduction of forest cover, among many others, that link climate, geology and the living world of ecosystems. According to the authors, this complexity has not been fully studied or integrated into climate models.
“To our knowledge this is the most extensive list of cycles of feedback of climate, and not all of them are fully accounted for in climate models. What we urgently need is more research, modeling and an acceleration in cutting emissions. [de gases com efeito de estufa]”, says Christopher Wolf, quoted in a press release from Oregon State University.
Despite the improvement of those models in recent decades, the researcher argues that more needs to be done: “The accuracy of climate models is crucial because they help guide efforts to mitigation by telling policy makers about the expected effects caused by human emissions of greenhouse gases.”
In 2018, a scientific article that had a lot of impact showed that there was a risk that, even if the temperature of the planet only increased by two degrees due to emissions of greenhouse gases, this warming would trigger a series of uncontrollable phenomena that would make the Earth much hotter. Despite being seen as an extreme scenario, the risk of not understanding those systems cannot be ignored, say the authors.
“In the worst case scenario, if the amplification of feedbacks is strong enough, the result will be tragic climate change far beyond anything humans can control,” says William J. Ripple, in the same statement. “We need a rapid transition towards an integrated Earth system science, because climate can only be fully understood by considering the state and functioning of all Earth systems together. This will require a large-scale collaboration.”