News of record-breaking temperatures, longer droughts, bigger storms and larger wildfires have become commonplace in our headlines. Each year is seemingly the hottest, driest or wettest somewhere in the world but what does this mean for wild fish and the water environment they rely on?
It is almost unbelievable to think that all these climate milestones (many of which use datasets that go back to the 1800s) are now suddenly smashing records year after year while here in the UK we have made it to the end of 2024 seemingly without a summer! But you’re not going crazy. Unlike politicians, oligarchs and business moguls, climate recording does not deal in opinion or speculation – only data.
Climate data for this year is now almost all gathered in and it will likely come as no surprise that 2024 is ‘virtually certain’ to be the hottest year in recorded history (Copernicus, 2024; Poynting, 2024). If that sounds like a familiar headline, it’s because it is- the previous 10 years have all been the hottest ever recorded (NOAA, 2024b).
While the UK had a cooler summer, other regions faced extreme heat, droughts, and wildfires which have devastating impacts on wildlife. The UK is not immune to these risks either. The increasing unpredictability of our climate alongside population growth is placing increasing strain on our water resources. Hotter temperatures will continue to drive the demand for water abstractions, water which we do not have to spare, both in the UK and globally.
Migratory freshwater fish populations have plummeted due to climate change, with mass fish kills becoming alarmingly common, and increased water demand further adding to these pressures. These conditions are destabilising ecosystems and livelihoods, underscoring the urgent need for meaningful climate action. Despite international pledges, the continued rise in global temperatures threatens biodiversity and human survival, demanding immediate response.
Summer 2024 was the hottest summer period recorded in human history across the globe. Perhaps even more surprising was that this was also the case in Europe (King, 2024). Whilst we have bemoaned the lack of sunshine here in the UK – with the British summer being the coolest since 2015 – the rest of the continent experienced a far hotter summer, with wildfires raging across the Peloponnese and droughts in southern Italy and the Iberian Peninsula.
2024 also marks another significant climate milestone and will most likely break the 1.5 C warming threshold for global temperatures, agreed upon by all countries who signed the 2015 Pairs Climate Agreement (NOAA, 2024a). The landmark treaty explicitly stated that the worlds nations would “hold the increase in the global average temperature to well below 2°C above pre-industrial levels and pursue efforts to limit the temperature increase to 1.5°C above pre-industrial levels”. It is becoming evident that we have now failed to meet this target. Although apparently, all hope is not lost.
Right now, the world’s leaders are once again meeting to discuss efforts to tackle climate change at COP29, the UN Climate Change Conference. You may be forgiven for wondering how much good these UN conferences really do. Last year, COP28 was held in the United Arab Emirates, a country in which fossil fuel production (the largest driver of anthropogenic climate change) accounts for 30% of its GDP, raising questions about the legitimacy of the conference (ITA, 2023). The UN quite sensibly this year chose Azerbaijan to host COP29. A country where oil and gas production make up almost 50% of the country’s GDP, and account for 90% of its export revenue (IEA, 2024). Perhaps a smarter choice?
At WildFish, we have reported extensively about the negative impacts of record-breaking temperatures on wild fish populations here in the UK (click here to read more about the effects of increasing temperatures on freshwater wildlife) but how are wild fish faring across the globe as fresh and coastal waters continue to heat up.
The Living Planet Index (LPI) for Migratory Freshwater Fishes has published their 2024 update, which lays bare the unprecedented decline of migratory freshwater fish across the globe (Deinet et al., 2024). The report shows a staggering 81% decline in migratory freshwater fish populations from 1970 to 2020, driven by habitat loss, degradation, overfishing, pollution, and climate change. Latin America and the Caribbean experienced the most severe decrease at 91%, while Europe saw a 75% decline. North America showed a 35% decrease, and Asia-Oceania reported a 28% decline. Overall, 61% of all migratory freshwater fish species were in decline across the globe, painting a bleak picture for the future of these climatically sensitive species.
Across the world we have seen the now all too familiar sight of mass fish kills, often either the direct result of climate warming, or from extreme weather events such as floods and droughts. In August, hundreds of thousands of dead fish washed into the port in Volos, Greece, (The Guardian, 2024). The incident was linked to historic flooding last year in the Thessaly plain, which refilled a nearby lake drained in 1962. As the lake receded, freshwater fish were forced toward the Volos port and died upon reaching the saltwater. A 2024 journal article has also linked population collapses of capelin in the Barents Sea with changes in ecosystem structure as a result of warming temperatures (Olsen et al., 2024). On September 4, around 24,000 fish, mainly menhaden, were found dead in Baltimore Harbour due to a combination of seasonal temperature shifts, pollution, algal blooms, and oxygen-depleting dead zones (Keefer, 2024). Thermal inversion lifted oxygen-consuming sulfur bacteria to the surface while algae, fuelled by nutrient-rich pollution and climate-warmed waters, thrived, worsening oxygen depletion.
El Niño, a natural climatic event in the Pacific Ocean, which has been growing stronger in frequency and intensity as a result of rising sea and air temperatures due to climate change came to an end in 2024, having begun in 2023. First reports into its impact on fish populations have shown major ecological shifts, affecting fisheries productivity (Castrejón et al., 2024). Species responses have varied; some have increased biomass due to changing sea temperatures, while others remain uncertain. Key fisheries, such as sailfin grouper and spiny lobster, show mixed impacts, worsened by overfishing and climate change. The knock-on socio-economic effects have included reduced catches, higher costs and livelihood instability as many people rely on stable and predictable fish stocks for their livelihood in this part of the world.
List of references
Castrejón, M., Pittman, J., Ramírez-González, J., & Defeo, O. (2024). An overview of social-ecological impacts of the El Niño-Southern Oscillation and climate change on Galapagos small-scale fisheries. Ocean & Coastal Management, 259, 107436. https://doi.org/10.1016/j.ocecoaman.2024.107436
Copernicus. (2024). Copernicus: 2024 virtually certain to be the warmest year and first year above 1.5°C | Copernicus. Copernicus. https://climate.copernicus.eu/copernicus-2024-virtually-certain-be-warmest-year-and-first-year-above-15degc
Deinet, S., Flint, R., Puleston, H., Baratech, A., Royte, J., Thieme, M. L., Nagy, S., Hogan, Z. S., Januchowski-Hartley, S. R., & Wanningen, H. (2024). The Living Planet Index for Migratory Freshwater Fishes: 2024 update.
IEA. (2024). Overview – Azerbaijan energy profile – Analysis. IEA. https://www.iea.org/reports/azerbaijan-energy-profile/overview
ITA. (2023, November 25). United Arab Emirates—Oil and Gas. US Department of Commerce – International Trade Administation. https://www.trade.gov/country-commercial-guides/united-arab-emirates-oil-and-gas
Keefer, V. (2024). Massive Baltimore Harbor Fish Kill Highlights Need for Further Pollution Reduction. https://www.cbf.org/news-media/newsroom/2024/maryland/massive-baltimore-harbor-fish-kill-highlights-need-for-further-pollution-reduction.html
King, S. (2024, September 6). Summer 2024 was world’s hottest on record. BBC Weather. https://www.bbc.com/weather/articles/c93p5kz9elro
NOAA. (2024a, January 9). What’s in a number? The meaning of the 1.5-C climate threshold | NOAA Climate.gov. http://www.climate.gov/news-features/features/whats-number-meaning-15-c-climate-threshold
NOAA. (2024b, January 12). 2023 was the world’s warmest year on record, by far | National Oceanic and Atmospheric Administration. https://www.noaa.gov/news/2023-was-worlds-warmest-year-on-record-by-far
Olsen, T., Stige, L. C., Dupont, N., Durant, J. M., & Langangen, Ø. (2024). Repeated large declines in the Barents Sea capelin population are associated with different ecosystem conditions. ICES Journal of Marine Science, 81(8), 1584–1593. https://doi.org/10.1093/icesjms/fsae101
Poynting, M. (2024, November 7). 2024 ‘virtually certain’ to be world’s warmest year on record. BBC News. https://www.bbc.com/news/articles/c1dpnxnvv2go
The Guardian. (2024, August 29). Greece tourist port flooded with hundreds of thousands of dead fish. The Guardian. https://www.theguardian.com/environment/article/2024/aug/29/greece-tourist-port-flooded-with-hundreds-of-thousands-of-dead-fish
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