We have no time to contrast biodiversity loss
By Federico Citterich
As negotiations at the COP28 Climate Conference in Dubai wrapped up with the “UAE Consensus”, contradicting voices were raised in criticism or in celebration for the wording of the non-binding agreement on a global “transition away from fossil fuels in energy systems, in a just, orderly, and equitable manner."
The Consensus calls for the acceleration of action "in this critical decade, to achieve net zero by 2050 in keeping with the science,” but many experts agree, current commitments of countries are insufficient to stop the emergency.
Pope Francis, who was unable to attend the UN Summit because of health reasons, released his Apostolic Exhortation in the run-up to the event noting that since the release of in 2015, the principles agreed on at the key COP15 Summit have not yet been implemented, and national interests are too often placed before the common good.
Thus, Laudate Deum is an urgent call to tackle the climate crisis, recognising that time is running out, and irreversible damage, caused by human activity, has already been done.
In line with this conviction and despite increased awareness of the need for decision-making in the context of climate change, a recent study carried out by a team of scientists from University College London (UCL) highlights the fact that more action is urgently needed.
Species populations could decline abruptly
The team, whose research was published in the journal Nature Ecology and Evolution, used climate projections to compare current and future temperatures of particular areas around the world to appreciate whether a set of more than 35,000 species will be likely to experience harsh conditions.
They found that the area of the geographic range that becomes unsuitable for particular organisms is likely to increase abruptly – rather than gradually – in the future.
Initially, most populations may appear to be safe. Yet, over the course of just a single decade, large areas of the species’ geographical range would suddenly switch to becoming unsuitable.
“And a decade is an incredibly short period of time”, highlighted Alex Pigot, lead author of the study. “Many species persist for millions of years on the planet, and we are hence dealing with extremely rapid changes”.
According to the researchers, this could lead organisms’ populations to decline abruptly, rather than to steadily decrease as the climate changes.
No time to respond
Since the pre-industrial period, the world has warmed by around 1.2°C, and the effects of this on ecosystems around the world are already visible.
“Many organisms are dying out in the hottest parts of their geographic distributions, and many others are dispersing and moving towards colder locations, tracking the sets of conditions they are adapted to”, explained Pigot. “We are also observing behaviour modifications, as organisms are changing the times of the year when they are undertaking key events of their life cycle”.
According to the scientists, climate change has already been responsible for the global extinction of various organisms.
“The Costa Rican golden toad was last recorded in 1989 after the population crashed due to a series of droughts in the region”, said Pigot. “But this is just one of the many potential examples”.
Furthermore, the researchers suggest that, as the climate warms up, the number of threatened species will increase exponentially, rather than linearly.
“According to the Intergovernmental Panel on Climate Change (IPCC), at 2°C of warming we will be at risk of losing more than 20% of the species on the planet”, warned Pigot.
Combining these factors with the results obtained by Pigot and colleagues accentuates a concerning scenario. “We are not prepared for the changes that are already happening and to those coming down the road”, said Pigot. “The fact that these changes are happening and will happen abruptly challenges us even further because it leaves us with a very limited amount of time to study and respond to these situations”.
Current examples: coral bleaching
“The idea that the responses and impacts of climate change on biodiversity are going to be abrupt, as our model suggests, shouldn’t be very surprising, because we often see these abrupt changes in modern ecological systems”, added Pigot.
An example, the researchers proposed, is the bleaching of coral reefs, which occurs when sea surface temperatures get around 1 °C above the average maximum surface temperature of that particular location.
“A couple of decades ago, these events were very rare and localised”, explained Pigot. “In the space of just 20 years, however, mass bleaching events have been recorded all across the oceans, occurring every few years if not every year”.
According to the scientists, roughly 70% of the world’s coral reefs will be degraded by climate change when 1.5 °C of warming will be reached, and this percentage will increase to 99% at 2 °C of warming.
“I think it’s imperative that we are monitoring these changes”, said Pigot. “Just as we, as humans, monitor our health, we need to be monitoring the health of our oceans to see what the state of our planet is and how it is changing”.
Future directions
The researchers hope that they can also use this information to develop better conservation and management strategies with the aim of more sensibly conserving biodiversity.
“Some coral reefs are doing better than others and suffered less bleaching or mortality”, highlighted Pigot. “It’s really important that we identify the characteristics of the locations where this is the case so that we can try to replicate them in different areas”.
The scientists suggest that coral reefs that are impacted by additional stresses – such as fishing or the runoff of agricultural fertilisers – are particularly vulnerable to bleaching events.
“Minimising these additional threats would boost coral reefs’ resilience to climate change”, added Pigot.
As proposed by the researchers, however, reducing these other stresses is not enough. “There really is no alternative to rapidly and permanently cutting our greenhouse gas emissions if we want to save these ecosystems”, explained Pigot.
Coral reefs are not the only case where an abrupt loss of biodiversity has been recorded. Another example resides in the spectacled flying fox, a species of fruit bat that inhabits Australia’s north-eastern regions of Queensland.
“In 2018, Queensland was hit by very intense heat waves of over 42 °C in temperature”, said Pigot. “These killed a third of the entire population of the spectacled flying fox – more than 25,000 individuals – over the course of a single day”.
The scientists stress that it’s the abruptness of the change that prevents the ability of organisms to adapt.
Hence, to effectively tackle the current climate change and biodiversity loss crises in light of the potentially abrupt decline of species populations, the researchers call for advanced warning systems and forecasts.
“What we really need is predictions of how organisms will be impacted by climate change in the future so that we can anticipate when these abrupt collapses might happen”, explained Pigot.
Additionally, the scientists propose that we further need to protect nature. “We need to do what we are doing now, but we need to do it bigger and better”, said Pigot. “We need to protect larger areas of intact ecosystems because this will mitigate climate change by locking up the carbon dioxide stored there and will give organisms the capacity to adapt, to move to cooler locations, and to have larger population sizes”.
Interrelation between climate change and biodiversity loss
“The world is currently facing two major crises, climate change and the loss of biodiversity”, highlighted Pigot. “These are inherently interlinked and to some extent driven by the same processes, such as land use change and deforestation”.
The researchers explained that land use change and deforestation are major drivers of climate change – being responsible for around 20% of the greenhouse gas emissions – but have also historically been the major drivers of biodiversity loss.
The scientists also suggested that the impacts of climate change on biodiversity loss are going to be accelerated in the future.
“As we heat up the planet, we are increasingly going to lose species”, argued Pigot. “We think that over the course of this century, climate change is going to become the major driver of biodiversity loss”.
And although the climate has already changed many times in the past, it is its pace that is nowadays worrying. “1.2 °C of warming doesn’t sound very much, but if we continue along our current trajectory we will face 2.5-3 °C of warming by the end of the century”, said Pigot.
The researchers warn that the last time we experienced similar temperatures was around 3 million years ago.
“We are essentially rewinding 3 million years of Earth history into the next few decades”, explained Pigot. “It’s an extremely rapid pace of change, a pace of change that organisms have not had to deal with and are not ready for”.
“Furthermore, these 8 million species that inhabit the planet are also living alongside around 8 billion humans”, underlined Pigot. “We have converted vast tracts of habitats for agriculture and for our cities, and this loss of habitat has been a major driver of biodiversity decline”.
According to the scientists, habitat loss will prevent species from adapting in the future.
“Where species would have been able to shift their distributions to colder temperatures in response to climate change, this would now be impossible because there is a road or agricultural fields in the way”, said Pigot.
“We always have to remember that biodiversity provides a huge number of benefits to human society”, he concluded. “Losing these systems inevitably means losing these benefits as well”.
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