change and the loss of biodiversity
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? Projections indicate that unless emissions are
rapidly reduced, the climate crisis will get substantially worse. Up to
50% of species are forecast to lose most of their suitable climate
conditions by 2100 under the highest greenhouse gas emissions scenario.
But we still
lack answers to some basic questions. When will species be exposed to
potentially dangerous climate conditions? Will this occur in the next decade or
only later in the century? Will the exposure of species accumulate gradually,
one species at a time? Or should we expect abrupt jumps as the climate limits
of multiple species are exceeded?
understanding of when and how abruptly climate driven disruptions of
biodiversity will occur is limited because biodiversity forecasts typically
focus on individual snapshots of the future. We took a different route. We used
annual projections of temperature and precipitation from 1850 to 2100 across
more than 30,000 marine and terrestrial species to estimate the timing of
species exposure to potentially dangerous climate conditions.
Based on these
projections, we estimate that climate change could cause sudden biodiversity
losses. These could occur much sooner this century than had been expected.
This new analysis indicates that a high percentage of species in
local ecosystems could be exposed to potentially dangerous climate conditions
simultaneously. Rather than slowly sliding down a climate change slope, many
ecosystems face a cliff edge.
There is a
high 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.
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.
But why does this matter so much?
losses of biodiversity from climate change represent a significant threat to
human well-being. In many countries a large percentage of people rely on their
immediate natural environment for their food security and income. Sudden
disruption of local ecosystems would negatively affect their ability to earn an
income and feed themselves, potentially pushing them into poverty.
instance, marine ecosystems in the Indo-Pacific, Caribbean and the west coast
of Africa are at high risk of sudden disruption as early as the 2030s. Hundreds
of millions of people across these regions rely on wild-caught fish
as an essential source of food. Eco-tourism revenues from coral reefs are also
a major source of income. In Latin America, Asia and Africa, large parts of the
Andes, Amazon, Indonesian and Congo forests are projected to be at risk from
2050 under a high emissions scenario. Sudden loss of animal communities could
negatively affect the food security of people in these regions. It could also
reduce the long-term ability of tropical forests to lock up carbon if the birds
and mammals that are important for dispersing seeds are lost.
findings highlight the urgent need for climate change mitigation. Rapidly
reducing greenhouse gas emissions this decade will help save thousands of
species from extinction, and protect the life-giving benefits they provide to
humans. Keeping global warming below 2°C flattens the curve of climate change
risk to biodiversity. It does this by massively reducing the number of species
at risk and buys more time for species and ecosystems to adapt to the changing
climate, whether that’s by finding new habitats, changing their behaviour, or
with the help of human-led conservation efforts. There’s also an urgent need to
ramp up efforts to help people in high risk regions adapt their livelihoods as
climate change alters local ecosystems.
where and when species will be exposed to dangerous climate change throughout
the century could provide an early warning system, identifying those areas most
at risk of abrupt ecological disruption. In addition to highlighting the urgent
need for reducing fossil fuel usage, these results could help guide
conservation efforts, such as designating new protected areas in climate
also inform resilient ecosystem-based approaches for helping people adapt to
changing climates. An example would be planting mangroves to protect coastal
communities against increasing flooding. The potential to continuously update
and validate these near-term projections as ecological responses to climate
change unfold should further refine projections of future climate risks to
biodiversity that are so central to managing the climate crisis. Our planet is
still teeming with life. With the right political leadership and daily actions
that we take as citizens, we still have the power to keep it that way.