There are three vital moments in the scientific journey of Pep Canadell, member of the international scientific committee of CREAF, executive director of the Global Carbon Project consortium and chief researcher of the CSIRO Climate Science Centre, both in Canberra (Australia). Of course there are more, but the ones that stand out from his forceful, friendly and leisurely conversation are: studying at the Faculty of Biology at the Universitat Autònoma de Barcelona (UAB) in the 1980s; expanding his research with stays at Stanford University (USA) and the Smithsonian Tropical Research Institute (Panama) in the 90s and finally getting involved as a researcher for the IPCC (Intergovernmental Panel on Climate Change) does more aged 18 when, he claims, advising political decision-making on climate change was not considered scientific prestige.

These are three decisive decisions of one of the world's most heard voices on climate change, coordinator of the annual Global Carbon Budget report, which advocates a green industrial revolution to implement the transition to renewable energies.

"The Ecology I learned at the UAB is perhaps the most powerful tool of all my studies to do what I do now globally"

Studying at the UAB opened his eyes to ecology and to meeting the then professor Jaume Terradas, now professor emeritus of Ecology and CREAF researcher. And, in return, to be deeply aware that this discipline is a pillar. "The Ecology I learned at the UAB is perhaps the most powerful tool of all my studies to do what I do now globally. For the last 25 years I have only worked with specialists in mathematics, in modelling, very numerical professionals and no one knows anything about this discipline", he says. "The way we think about ecosystems - whether it's Montseny or the world - is similar, although it contemplates processes at different scales".

And it goes back to the beginnings of CREAF with Terradas, to the awareness of providing scientific knowledge and rigor, and to the need to act as a global society in the face of climate change. "The ecological context is everything. Climate change won't be solved in 50 years: if we don't become global citizens and believe it, we won't solve it. We are only thinking about 2030 when nuclear power is turned off. Catalonia must do more, as a developed, rich and intelligent country, because the emissions it records are from 200 years ago. Climate change is cumulative, it is not a problem of today". And with both the geographical and temporal perspective given by experience and the world view, he drops a reflection that is as decisive as it is not very encouraging: "in Catalonia I don't see a strong leadership, there are remarkable people who come and go are going".

Science and policy, a work in progress

The second vital moment comes when he observes how collaboration between science and political action is valued at Stanford University and the Smithsonian Tropical Research Institute. "It wasn't interesting, it wasn't considered science", he recalls, "but let's compare it to the current situation in which many centers are ahead and, in fact, need to interact with governments. We need a type of scientific profile capable of maintaining this exchange and, in fact, I consider that CREAF has been able to do this and there has been a directed will to be relevant for Catalan society and for science in general".

"CO2 has been accumulating in the atmosphere for thousands of years and remains irreversible: we must act to tend to zero. However, if we reduce or stop the amount of methane in the atmosphere, we will see a reduction in global warming"
Pep Canadell, member of CREAF's International Scientific Committee

The third key experience has to do with the Intergovernmental Panel on Climate Change and is shaped by the realization that the scientific knowledge based on triggering political action and profound changes has been available for at least 20 years. "The IPCC is a fantastic model owned by 196 governments around the world, which indicate what they need advice on. We have no other model as genuine. Perhaps it is naive, but more than the governments we must surely reach society, although it is certain that the IPCC must continue to improve". And he mentions the recent scientific advisory committee that the Spanish central government has recently created and the need to structure its processes, beyond becoming an external corpus to which advice is sought.

Stop the problem

As a scientific and vital axis, climate change has a constant presence in Pep Canadell's speech. How could it not be otherwise, after all. He studies the warming of the planet and proposes alternatives to stop emitting carbon dioxide from what he calls the green technological revolution, which involves electrification. "Carbon dioxide has been accumulating in the atmosphere for thousands of years and we must act to tend to zero", he says. "The important thing about climate change is not to solve the problem, but to stop it. And therefore end emissions. In addition, among the fossil fuels we must take into account methane, much more powerful than carbon dioxide, which continues to be concentrated in the atmosphere. The big difference between CO2 and methane is that if we reduce or stop the amount of the latter in the atmosphere, very soon we will see a reduction in global warming. CO2 remains on the planet for thousands of years in an irreversible way, although both emissions continue to grow".

"We have a problem of lack of water that affects a very large number of people and the solution must be technical, powered by renewable energies. We need to electrify, dispense with fossil fuels and make the transition to renewable energies"

The technology powered by renewable energies is one of Canadell's strong arguments that points, for example, to the critical moment of water scarcity. "We have a problem of lack of water that affects a very large number of people and the solution must be technical. Another thing are solutions based on nature, the role of carbon sinks, the landscape, forests, crops... All nature-based solutions will contribute to a more restored, resilient, renewable landscape while capturing residual emissions. Here is the big problem: we mark 2050 as the year of zero emissions, but it will not be because some sectors of the industry will not be able to undertake the transition to renewables due to its high cost in this context. This is when the carbon sinks intervene for the 10 to 15% of emissions that cannot be eliminated. Now, it depends on where we are, we don't know to what extent Catalonia will continue to dry out in 50 years...".

Far from a pessimistic tone, the veteran scientist welcomes local and multilateral initiatives such as the international consortium Mediterranean Climate Action Partnership (MCAP), promoted by the sub-national governments of California and Catalonia, which represents 14 Mediterranean climate bioregions of 5 continents and presented at COP28. "Everyone is involved in the transition because all economic sectors and social actors have a role", he says forcefully. "We need to see multiple ways to relate, to exchange information and lessons learned. In this, NGOs have been very active and they must be taken into account for their ability to relate, for example, Renovem-nos".