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Climatic change and ecology

30 years of R+D CSIC

In 1990 the first IPCC report on climate change was presented. What has changed in these years? Among other things, scientists found out the limits of vegetation to sequester CO2, and have study how it influences the nitrogen/phosphorus balance and other soil elements. Also, a recent work has revealed that Arctic temperatures are reaching a critical threshold.

With integrated models, climate change is studied in ecosystems as a whole, with physical, biological, chemical, economic and sociological variables. In the picture, goats and sheep graze last summer in the middle of a drought. Image: M.Fernández/CSIC Cataluña

One of the changes is the large amount of data available and the capacity to analyse it. Also the emergence of integrated models, which go beyond climate and take into consideration climate change in ecosystems as a whole, with physical, biological, chemical, economic and sociological variables.

"We have more powerful tools than a few years ago, we have satellite data, with higher spatial, temporal and spectral band resolution. We have a large number of databases and machine learning tools to work with them," explains ecologist Josep Peñuelas, CSIC researcher at CREAF.

“Tenemos herramientas más potentes que hace unos años, tenemos datos de satélite, de mayor resolución de banda espacial, temporal y espectral. Tenemos una gran cantidad de bases de datos y herramientas de machine learning para trabajar con ellas”, explica el ecólogo Josep Peñuelas, investigador del CSIC en el CREAF. He is one of the most internationally recognised ecologists, awarded with the Rey Jaime I Prize for Environmental Protection (2015) and the Ramón Margalef Ecology Prize (2016).

Worse scenarios are becoming a reality

In reference to the IPCC's first report years, Peñuelas says that " the science we had at the time it was good. In that report we defined different possible scenarios, of which, unfortunately, the most pessimistic ones are becoming a reality”. Peñuelas, who currently heads the CREAF-CSIC-UAB Global Ecology Unit, participated in the first IPCC report.

Then, scientists were aware not only of the global temperature increase, but also of the alterations in land use, in the vegetation cover and nitrogen/phosphorus balance in the soil, all of them factors that affect plant productivity.

Limits to the ability of sinks to trap CO2

It was also clear that it was necessary to take action as soon as possible, but there was a certain fear of being catastrophic and "we were too optimistic, relying on the ability of plants to trap carbon". Over the years, researchers have found that this capacity is limited.

This was shown in a paper in Nature Ecology in 2017, led by Josep Peñuelas. There is a limit on the positive effects of fertilisation by the CO2 and nitrogen emissions in the environment, the paper said, which lead to vegetation growth which in turn increases capacity to trap carbon. The capacity of carbon sinks is reduced by new nutrient limitations, climate change, changes in land use, high temperatures and an unprecedented drought.

Figuring out the big laws of ecology

Peñuelas points out that "we still have room for improvement in the development of the science of ecology". There are many interacting variables that can lead to unexpected results. We must find out, he says, the basic scientific laws of ecology, similarly to mathematics or physics.

In this sense, in 2019, he proposed five biological laws for the Earth's vital processes, processes that cannot exceed the natural limits of the available resources of space, matter and energy. "Biology builds on what is possible within these physicochemical limits," he said in the paper.

Plants also need phosphorus, and if there is insufficient phosphorus, there is no growth of plant cover, which in turn reduces the capture of atmospheric carbon dioxide and thus feeds back into global warming and reduces the ability to produce food. Image:  M.Fernández/CSIC Cataluña

Economics and sociology included in the integrated environmental models

Climate change research now addresses not only climatic variables. Integrated models are being developed that also include physical, biological, chemical, economic and sociological variables. The aim is to consider the impact of climate change on society and the effectiveness of possible solutions.

For example, in a recent paper scientists estimated the detrimental effects on the yield of food and biomass crops. They warned that mitigation measures, including CO2 capture and storage, are urgently needed, preferably before 2040, to avoid irreversible climate change and severe food crises.

Imbalance of nitrogen, phosphorus and other elements

A few years ago, it was thought that the more nitrogen fertilisers were used the more productivity would increase. But in recent years scientists have seen that nitrogen excess has broken the nitrogen/phosphorus balance in soils. As a matter of fact, nitrogen excess can also lead to health problems in people, according to a study in 2021.

What does this have to do with climate change? Plants also need phosphorus and with too much nitrogen and insufficient phosphorus, plants cannot growth well, which in turn reduces the capture of atmospheric carbon dioxide, thus feeding back into global warming and reducing the ability to produce food.

Ecological niche occupied by different species of animals or plants is defined by their use and content of bioelements such as carbon, nitrogen, phosphorus, potassium, magnesium, sodium, zinc, among others

But it is not just phosphorus: there is a whole range of elements whose balance is essential for the survival of plants and ecosystems in general. Each organism needs these elements in specific quantities. In 2019, Peñuelas proposed in a paper that the ecological niche occupied by different species of animals or plants is defined by their use and content of bioelements such as carbon, nitrogen, phosphorus, potassium, magnesium, sodium, zinc, among others.

On the other hand, a CSIC and CREAF project proposed the need to take advantage of the properties of wild plants to improve agricultural yields and to reduce the impact of pesticides and industrial fertilisers.


Arctic fire with a front 30 kilometres wide. The fire was detected on 6 August 2020 at a latitude of 69.31°N. Sentinel-2 infrared colour image. Satellite photo processed by Adrià Descals and acquired by the European Space Agency.


The unexpected permafrost fires

Today's satellite data and computer tools make it possible to analyse the evolution of climate change with a high level of precision. In a recent paper published in Science, the team analysed four decades of satellite observations in the Arctic.

"The results caught us off guard," says Peñuelas, "because we tend to think in linear progressions and we saw that this is not the case. The work revealed that temperatures are reaching a critical threshold where "small increases above a summer average of 10 °C can exponentially increase the area burned and the associated emissions", explains Josep Peñuelas.

The study, whose first author is Adrià Descals, from CSIC and CREAF, reveals that 2020 was the warmest summer in four decades. In 2019 and 2020 alone, almost the same area burned in the Arctic as in the previous four decades, which meant total emissions of 412.7 million tonnes of CO2.

"Unfortunately, we are not reacting. It is not only the indifference of governments, it is also the indifference of society. We only take action when we are harmed, as it happened with Covid"

"This area is extremely important because there are huge amounts of carbon stored in the permafrost," says Peñuelas. Fires in the permafrost accelerate CO2 emissions into the atmosphere, but fires have not only increased in the Arctic, there are more fires everywhere; everything is linked to the conditions resulting from warming: it is warmer, water evaporates earlier, there is more drought… We have to take action urgently," Peñuelas concludes.

"Unfortunately, we are not reacting. It is not only the indifference of governments, it is also the indifference of society. We only take action when we are harmed, as it happened with Covid. The positive side is that now we are a larger scientific community working on this and we have made great steps in knowledge".



Penuelas, J., Ciais, P., Canadell, JG., Janssens, I., Fernandez-Martinez, M., Carnicer, J., Obersteiner, M., Piao S., Vautard, R., Sardans, J. (2017). Shifting from a fertilization-dominated to a warming-dominated period. Nature Ecology & Evolution 1, 1438–1445. doi:10.1038/s41559-017-0274-8.

Penuelas, J., Baldocchi, D. 2019. Life and the five biological laws. Lessons for global change models and sustainability. Ecological Complexity 38 (2019), 11-14. doi: 10.1016/j.ecocom.2019.02.001.

Penuelas, J., Fernández-Martínez, M., Ciais, P., Jou, D., Piao, S., Obersteiner, M., Vicca, S., Janssens, I.A., Sardans, J. 2019. The bioelements, the elementome and the “biogeochemical niche”. Ecology 100(5), 2019, e02652. doi: 10.1002/ecy.2652

Xu, S., Wang, R., Gasser, T. et al. Delayed use of bioenergy crops might threaten climate and food security. Nature 609, 299–306 (2022).

Descals, A., Gaveau, D., Verger, A., Sheil, D., Naito, D., Peñuelas, J., 2022. Unprecedented fire activity above the Arctic Circle linked to rising temperatures, Science.