Claim: “Climate Change Will Cause Lots of Extinctions, but “we do not know exactly when”
Abundant evidence biosphere is doing just fine, deserts are shrinking, warm conditions and rising CO2 levels are good for life, it would be unwise to put a timeframe on a prediction of mass extinction
Claim: “Climate Change Will Cause Lots of Extinctions, but “we do not know exactly when”
Essay by Eric Worrall
I thought science was supposed to be falsifiable?
December 10, 2024 | Elaina Hancock – UConn Communications
Climate Change Extinction Risk
A global meta-analysis of climate change extinction risk emphasizes that we are at a crucial point and drastic action is needed
The impacts of climate change are intensifying, and according to the most recent United Nations Emissions Gap Report, we need to take dramatic action if we are to remain below 1.5C of warming. The climate crisis significantly threatens global biodiversity, and effective conservation policies and efforts to mitigate disastrous outcomes rely on accurate models and predictions. To increase certainty in available models, UConn Department of Ecology and Evolutionary Biology Professor Mark Urban analyzed 485 studies, comprising over 5 million projections, to create a global assessment of climate change extinctions. The study is published in Science. Urban met with UConn Today to discuss his findings.
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Read more: https://today.uconn.edu/2024/12/climate-change-extinction-risk/#
What were your findings, and did anything surprise you?
Whereas past assessments indicated high uncertainties, this analysis suggests with increasing certainty that climate change has caused and will cause global extinctions. Climate change results in an accelerating risk of global extinction, rising from 2% currently to 30% under the highest-emission scenario. Current policies and actions place the world on a path to a 2.8 degrees Celsius rise in global temperature, which would still result in 5% of species being at risk. This study presents a choice for decisionmakers: Will we curb emissions now and only need to protect 2% of species at risk, or will we choose another path that will fundamentally alter the nature of our world.
Can you discuss extinction debt and how Earth’s hidden biodiversity impacts extinction risk assessment?
Extinction risk estimates indicate how many species could eventually become extinct at some point in the future. The analogy I like to give is a water jug with a crack in it. We know that the water will eventually flow out, but we do not know exactly when. Extinction debt characterizes all those species that are declining toward extinction (losing water) and will eventually become extinct without interventions. The bad news is that many species might be declining or about to decline due to climate change impacts, but we have not yet recognized these threats. The good news is that we could still mitigate climate change or deploy successful conservation measures to ensure that the debt is not paid.
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Read more: https://today.uconn.edu/2024/12/climate-change-extinction-risk/#
The referenced study;
Climate change extinctions
SCIENCE
5 Dec 2024
Vol 386, Issue 6726
pp. 1123-1128Editor’s summary
Because it is clear that human activities are altering the global climate, researchers have been studying potential effects and predicting declines and extinctions. Understanding the consequences globally requires the synthesis of many studies. Following up on an initial effort nearly 10 years ago, Urban found that we can expect, with increased certainty, that rising temperatures will lead to an increasing number of extinctions, with the highest emission scenario leading to extinction of nearly a third of the Earth’s species, especially those from particular vulnerable taxa or regions. —Sacha Vignieri
Abstract
Climate change is expected to cause irreversible changes to biodiversity, but predicting those risks remains uncertain. I synthesized 485 studies and more than 5 million projections to produce a quantitative global assessment of climate change extinctions. With increased certainty, this meta-analysis suggests that extinctions will accelerate rapidly if global temperatures exceed 1.5°C. The highest-emission scenario would threaten approximately one-third of species, globally. Amphibians; species from mountain, island, and freshwater ecosystems; and species inhabiting South America, Australia, and New Zealand face the greatest threats. In line with predictions, climate change has contributed to an increasing proportion of observed global extinctions since 1970. Besides limiting greenhouse gases, pinpointing which species to protect first will be critical for preserving biodiversity until anthropogenic climate change is halted and reversed.
Read more: https://www.science.org/doi/10.1126/science.adp4461
The Paleo evidence does not support the hypothesis that warmer temperatures create hostile conditions for life.
Our monkey ancestors also did well in a much hotter world. The Palaeocene-Eocene Thermal Maximum, 5-8C hotter than today, was the age of monkeys. Our monkey ancestors thrived on the abundance of the hothouse PETM, and colonised much of the world, only retreating when the encroaching cold drove them from their new homes.
There is also abundant evidence that rising CO2 levels in the modern age are good for the biosphere.
Let’s not forget the coral reefs.
Obviously in the face of abundant evidence that the biosphere is doing just fine, that deserts are shrinking, that warm conditions and rising CO2 levels are good for life, it would be unwise to put a timeframe on a prediction of mass extinction. Without a timeframe, a prediction that 30% of species will one day die is about as safe as scientific predictions get.