Guest essay by Eric Worrall
According to a new study, the ocean and land ecosystem collapses have already started, and will become significant by 2030
Climate change could cause abrupt biodiversity losses this century
Christopher Trisos, University of Cape Town, Alex Pigot, UCL
April 9, 2020 1.37pm SAST
The impacts of climate change on species and ecosystems are already evident. Poleward shifts in the geographic distributions of species, catastrophic forest fires and mass bleaching of coral reefs all bear the fingerprints of climate change.
But what will the world’s biodiversity look like in the future?
Risk of abrupt biodiversity loss early this century
Abrupt biodiversity loss due to marine heatwaves that bleach coral reefs is already under way in tropical oceans. The risk of climate change causing sudden collapses of ocean ecosystems is projected to escalate further in the 2030s and 2040s. Under a high greenhouse gas emissions scenario the risk of abrupt biodiversity loss is projected to spread onto land, affecting tropical forests and more temperate ecosystems by the 2050s.
These dire projections use historical temperature models to find the upper limit that each species can survive under, as far as we know. Once temperatures rise to levels a species has never experienced, scientists have very limited evidence of their ability to survive.
It’s possible some species, such as those with very short generation times, may be able to adapt. For species with longer generation times – such as most birds and mammals – it may be only a few generations before unprecedented temperatures occur. When this happens the species’ ability to evolve out of this problem may be limited.
…Read more: https://theconversation.com/climate-change-could-cause-abrupt-biodiversity-losses-this-century-135968
The abstract of the study;
The projected timing of abrupt ecological disruption from climate change
As anthropogenic climate change continues the risks to biodiversity will increase over time, with future projections indicating that a potentially catastrophic loss of global biodiversity is on the horizon. However, our understanding of when and how abruptly this climate-driven disruption of biodiversity will occur is limited because biodiversity forecasts typically focus on individual snapshots of the future. Here we use annual projections (from 1850 to 2100) of temperature and precipitation across the ranges of more than 30,000 marine and terrestrial species to estimate the timing of their exposure to potentially dangerous climate conditions. We project that future disruption of ecological assemblages as a result of climate change will be abrupt, because within any given ecological assemblage the exposure of most species to climate conditions beyond their realized niche limits occurs almost simultaneously. Under a high-emissions scenario (representative concentration pathway (RCP) 8.5), such abrupt exposure events begin before 2030 in tropical oceans and spread to tropical forests and higher latitudes by 2050. If global warming is kept below 2 °C, less than 2% of assemblages globally are projected to undergo abrupt exposure events of more than 20% of their constituent species; however, the risk accelerates with the magnitude of warming, threatening 15% of assemblages at 4 °C, with similar levels of risk in protected and unprotected areas. These results highlight the impending risk of sudden and severe biodiversity losses from climate change and provide a framework for predicting both when and where these events may occur.Read more (paywalled): https://www.nature.com/articles/s41586-020-2189-9
I’m not paying 209 Euros to look at a RCP 8.5 study, but from what I can see, what the researchers did is really funny.
The researchers appear to have taken lots of wild predictions of individual species extinction or the demise of narrow ecological niches, and grouped them into one big wild prediction.
They completely disregarded the point of why scientists making wild predictions keep their focus narrow.
Nobody notices if a prediction of the demise of an obscure orchid fails to manifest. Narrow predictions incur minimal reputational risk.
But the abrupt disappearance of an entire ecosystem is another matter entirely.
By grouping all the individual wild predictions together, the study authors have stripped away the cover which comes from keeping predictions narrow, and magnified the reputational risk for everyone they cited.
Everyone worried about their reputation now has to pay 209 Euros to look at the full study to see how their work has been used.
If nothing bad happens after 2030, there is no risk for the authors of this study, all the risk is on the researchers they cited.