International Day of Climate Action 2024

I remember the day I realised that extinction did not begin - and did not end - with the meteorite fall that ended the reign of the dinosaurs on Earth.  It was 2004 and the headliner in a science magazine (probably National Geographic) made my younger self feel completely overwhelmed. The first Global Amphibian Assessment (GAA1)¹ had been published, showing amphibians were going extinct faster than any other vertebrate, and that some of the major drivers of their rapid extinction were the loss of their habitat and its overexploitation. I was shocked reading the lines that, out of the 435 amphibian species being at higher risk of extinction, 207 species are rapidly declining due to unknown or poorly understood causes. I was too young at that time, and access to information was not as easy as it is today, to take further action.

In 2023, almost 20 years after the first Global Amphibian Assessment, the second Global Amphibian Assessment (GAA2) was published ². The report stated that amphibians remain the most threatened vertebrates on earth, with 41% of the species listed on the Red List of Threatened Species of the International Union for Conservation of Nature (IUCN). Since the first release of the GAA1, numerous studies have been carried out to better comprehend the causes of the rapid disappearance of amphibians. Amongst many potential threats that have been identified in the GAA2, climate change, and human activities were considered major drivers of the ongoing extinction event.

_{IUCN. (2024). The proportion of extant (i.e., excluding Extinct) species in The IUCN Red List of Threatened Species. The numbers to the right of each bar represent the total number of extant species assessed for each group. EW - Extinct in the Wild, CR - Critically Endangered, EN - Endangered, VU - Vulnerable, NT - Near Threatened, DD - Data Deficient, LC - Least Concern. [Version 2024-1. Accessed September 6, 2024. https://www.iucnredlist.org/resources/summary-statistics]}

Unfortunately, climate change is not only affecting amphibians and many other animal and plant species. It is also a major threat to agriculture, freshwater availability and quality, and human health. We hear every day that air and water temperatures are rising around the world, that entire human settlements are being damaged or destroyed by fluvial and pluvial floods, that coastal settlements are expected to disappear in the next few decades due to rising sea levels, and that extreme weather events will become more frequent and intense in the future. It is worth noting that the list of adverse effects of climate change continues.

The effects of climate change are becoming more apparent every day. We only need to check our social media accounts or any news portal to see that more and more people around the world are facing water shortages every day, or that glaciers are retreating at dramatic rates. However, the effects of climate change are much more difficult to identify and measure when they interact with other environmental perturbations. For example, various studies have reported an increased risk of elevated temperatures and chemicals due to unknown interactive effects that are difficult to predict. These chemicals include synthetic compounds, such as pesticides, which are widely used to control pests in crops around the world. Compounds that are currently considered safe may alter their toxic behaviour under different climate change scenarios^3,4,5,6. For example, higher temperatures may accelerate the transformation and degradation of pesticides into substances that are equally or more toxic to plants and animals, including humans, than their parent compound^7,8.

In recent years, scientists from different disciplines around the world have raised their voices in recent years to warn of the need to take better action against climate change, for example by improving climate mitigation strategies. However, a lack of information and understanding of the effects and interactions of climate change and other anthropogenic factors, such as pesticides, can lead to under- and/or overestimation of the potential environmental threats and thus hamper the goals set. Owing to the past and current scientific efforts to provide support in the development of climate mitigation strategies and actions to protect our planet, research plays a fundamental role in combating the adverse effects of climate change. We must therefore better understand the processes underlying the effects of climate change to ensure a healthy planet for future generations.

As part of the collective effort to tackle climate change, and in my role as DC10 of the QTOX project, my research focuses on developing models that describe and quantify the effects of changes in temperature and the presence of pesticides on aquatic communities. This will allow us to simulate different scenarios of both climate change and pesticide use and evaluate their interactive effects on different ecosystems from our computers, enabling us to test several different scenarios and communities in a small fraction of the time and resources that an equivalent experiment (e.g., mesocosm experiments) would take. It is important to note, however, that the development of accurate and useful models is only possible thanks to the enormous amount of work carried out by scientists around the world over the years, and that any new insights gained from the research will only improve the accuracy and broaden the applications of the models.

References:

1. _{Stuart SN, Chanson JS, Cox NA, Young BE, Rodrigues ASL, Fischman DL, Waller RW. 2004. Status and trends of amphibian declines and extinctions worldwide. Science 306:1783-1786. https://doi.org/10.1126/science.1103538}
2. _{Luedtke JA, Chanson J, Neam K, Hobin L, Maciel AO, Catenazzi A, et al. 2023. Ongoing declines for the world’s amphibians in the face of emerging threats. Nature. 622:308-14. https://doi.org/10.1038/s41586-023-06578-4}
   
3. _{Hermann M, Peeters ETHM, Van den Brink PJ (2023). Heatwaves, Elevated Temperatures, and a Pesticide Cause Interactive Effects on Multi-Trophic Levels of a Freshwater Ecosystem. Environmental Pollution 327: 121498. https://doi.org/10.1016/j.envpol.2023.121498}
   
4. _{Huang A, Mangold-Döring A, Guan H, Boerwinkel MC, Belgers D, Focks A, Van den Brink PJ (2023). The Effect of Temperature on Toxicokinetics and the Chronic Toxicity of Insecticides towards Gammarus Pulex. Science of The Total Environment 856: 158886. https://doi.org/10.1016/j.scitotenv.2022.158886}
   
5. _{Mangold-Döring, A, Huang A, van Nes EH, Focks A, Van den Brink PJ (2022). Explicit Consideration of Temperature Improves Predictions of Toxicokinetic–Toxicodynamic Models for Flupyradifurone and Imidacloprid in Gammarus Pulex». Environmental Science & Technology 56, nº2215920-29. https://doi.org/10.1021/acs.est.2c04085}
   
6. _{Sinclair T, Craig P, y Maltby LL (2024). Climate Warming Shifts Riverine Macroinvertebrate Communities to Be More Sensitive to Chemical Pollutants». Global Change Biology 30, nº4: e17254. https://doi.org/10.1111/gcb.17254}
   
7. _{Fenner K, Canonica S, Wackett LP, Elsner M (2013). Evaluating Pesticide Degradation in the Environment: Blind Spots and Emerging Opportunities. Science 341,752-758. https://doi.org/10.1126/science.1236281}
8. _{Reedich LM, Millican MD, Koch PL (2017). Temperature Impacts on Soil Microbial Communities and Potential Implications for the Biodegradation of Turfgrass Pesticides. Journal of Environmental Quality 46, n^o3: 490-97. https://doi.org/10.2134/jeq2017.02.0067}