New research suggests plants might be able to absorb more CO2 from human activities than previously expected
![New research suggests plants might be able to absorb more CO2 from human activities than previously expected New research suggests plants might be able to absorb more CO2 from human activities than previously expected](/cms_media/module_img/7703/3851554_1_articlesmall_ENVIRONMENT_20Deforestation_20_2007072555.jpg)
Deforestation in Maues, Amazon Rainforest. Picture: Andre Dib/WWF/PA Wire
New research published today [Friday 17th November 2023] paints an uncharacteristically upbeat picture for the planet. This is because more realistic ecological modelling suggests the world’s plants may be able to take up more atmospheric CO2 from human activities than previously predicted.
However, the environmental scientists behind the research are quick to underline that this should in no way be taken to mean the world’s governments relax on their obligations to reduce carbon emissions as fast as possible. Simply planting more trees and protecting existing vegetation is not a golden-bullet solution but the research does underline the multiple benefits to conserving such vegetation.
A Trinity College Dublin scientist was involved in the research, led by Western Sydney University’s Dr Jürgen Knauer, Hawkesbury Institute for the Environment, and which features in international journal Science Advances.
![Dr Silvia Caldararu, Assistant Professor in Trinity’s School of Natural Sciences Dr Silvia Caldararu, Assistant Professor in Trinity’s School of Natural Sciences](https://www.irishexaminer.com/cms_media/module_img/7701/3850858_8_articleinline_Silvia_Caldararu_1_.jpg)
Dr Silvia Caldararu, Assistant Professor in Trinity’s School of Natural Sciences, explained that "there is no optimum amount of natural vegetation, the more the better, both from a climate and biodiversity point of view".
"Of course this has to be balanced with agricultural needs but we can certainly do better than we are doing now. Ireland’s natural ecosystems are in a poor state and we do have to acknowledge that. One thing to keep in mind when we talk about this is, especially in Ireland, that it’s not only forests that are important, bogs and peatlands are critical and should be conserved and restored too."
Some companies have subscribed to tree-planting schemes overseas but this can also be problematic and as Dr Caldararu explains: "The question about where to plant trees is a thorny one. From a purely scientific point of view, closer to the equator is the best because it’s sunnier and warmer and plants grow faster. But a lot of these tree planting schemes have been shown not to actually result in any forests, and come with a baggage of colonialism and are often used for greenwashing. Recently they were also shown to be connected to human rights abuse. Science and numbers aren’t the only thing when taking these kinds of decisions."
Dr Caldararu noted: “Because the majority of terrestrial biosphere models used to assess the global carbon sink are located at the lower end of this complexity range, accounting only partially for these mechanisms or ignoring them altogether, it is likely that we are currently underestimating climate change effects on vegetation as well as its resilience to changes in climate. We often think about climate models as being all about physics, but biology plays a huge role and it is something that we really need to account for."
“These kinds of predictions have implications for nature-based solutions to climate change such as reforestation and afforestation and how much carbon such initiatives can take up. Our findings suggest these approaches could have a larger impact in mitigating climate change and over a longer time period than we thought. However, simply planting trees will not solve all our problems. We absolutely need to cut down emissions from all sectors. Trees alone cannot offer humanity a get-out-of-jail-free card.”
![Dr Jürgen Knauer of the Hawkesbury Institute for the Environment at Western Sydney University Dr Jürgen Knauer of the Hawkesbury Institute for the Environment at Western Sydney University](https://www.irishexaminer.com/cms_media/module_img/7701/3850894_3_articleinline_Juergen_Knauer_portrait.jpeg)
Dr Knauer, who headed the research team led by the Hawkesbury Institute for the Environment at Western Sydney University, explains: "Plants take up a substantial amount of carbon dioxide (CO2) every year, thereby slowing down the detrimental effects of climate change, but the extent to which they will continue this CO2 uptake into the future has been uncertain."
“What we found is that a well-established climate model that is used to feed into global climate predictions made by the likes of the IPCC predicts stronger and sustained carbon uptake until the end of the 21st century when it accounts for the impact of some critical physiological processes that govern how plants conduct photosynthesis.
Photosynthesis is the scientific term for the process in which plants convert — or 'fix' — CO2 into the sugars they use for growth and metabolism. This carbon fixing serves as a natural climate change mitigator by reducing the amount of carbon in the atmosphere; it is this increased uptake of CO2 by vegetation that is the primary driver of an increasing land carbon sink reported over the last few decades.
However, the beneficial effect of climate change on vegetation carbon uptake might not last forever and it has long been unclear how vegetation will respond to CO2, temperature and changes in rainfall that are significantly different from what is observed today. Scientists have thought that intense climate change such as more intense droughts and severe heat could significantly weaken the sink capacity of terrestrial ecosystems, for example.
In the study published this week, however, Knauer and colleagues present results from their modelling study set to assess a high-emission climate scenario, to test how vegetation carbon uptake would respond to global climate change until the end of the 21st century.
The results were clear: the more complex models that incorporated more of our current plant physiological understanding consistently projected stronger increases of vegetation carbon uptake globally. The processes accounted for re-enforced each other, so that effects were even stronger when accounted for in combination, which is what would happen in a real-world scenario.
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