The 16 vital signs that tell us the world is reaching a climate catastrophe
Scientists have identified 16 “vital signs” that show climate change has already imperiled life on Earth beyond anything humans have ever seen.
A major research project, involving Exeter University and cosigned by 15,000 scientists in 163 countries, sounds the alarm on climate change louder than ever before.
It shows that 16 of the 32 vital indicators that “convey the effects of human activities on greenhouse gas emissions and the consequent impacts on climate, our environment, and society,” including human population and oil consumption, are at record levels.
“Life on our planet is clearly under siege,” said Professor William Ripple, of Oregon State University.
“These trends show deeply alarming patterns of climate-related variables and disasters. We also found little progress to report as far as humanity combating climate change,” he said.
The 16 signs
Human population: A growing population can contribute to increases in fossil fuel and resource use, although per capita consumption is also a major factor.
Ruminant livestock population: Cows, pigs and other ruminants contribute greatly to emissions of methane and other greenhouse gasses.
Per capita meat production: This continues to grow sharply. Plant-based diets can reduce emissions associated with deforestation and other land use pressures.
World gross domestic product: Although GDP growth is needed in less wealthy countries, overall GDP is an indicator of consumption and greenhouse gas emissions.
Oil consumption: The production and use of oil contributes significantly to greenhouse gas emissions.
Gas consumption: The production and use of natural gas contributes significantly to greenhouse gas emissions.
CO2 emissions: CO2 emissions are one of the greatest contributors to global warming.
Fossil fuel subsidies: Subsidies for the fossil industry support the continued use of fossil fuels and slow adoption of renewable energy.
Atmospheric CO2: CO2 is an important greenhouse gas, which contributes greatly to warming.
Atmospheric methane: Methane is an important greenhouse gas, which contributes greatly to warming.
Atmospheric nitrous oxide: Nitrous oxide is an important greenhouse gas, which contributes to warming.
Surface temperature: Rising global average temperatures can contribute to increased climate-related disasters and feedback loops.
Earth’s energy imbalance: Energy imbalance is an important indicator of global heating.
Ocean heat content: The oceans absorb a large share of warming, making ocean heat content another important indicator of global heating.
Ocean acidity: Ocean acidification can lead to coral bleaching and have other negative impacts on sea life, endangering the livelihoods of millions of people.
Sea level change: Rising sea levels could make many low-lying coastal areas uninhabitable over the course of time.
Four vital signs that are at record levels and could help the climate
Fertility: Births per woman are directly linked to human population size and are at their lowest level in at least 40 years.
Solar/Wind consumption: Renewable energy sources are at record levels and tend to have lower greenhouse gas emissions.
Divestment: Pension funds and other institutions are selling off their fossil fuel investments in increasing numbers, helping curtail the use of climate-destructive fossil fuels.
Climate emergency declarations: National and other climate emergency declarations are growing every year and are an important step toward effective climate policies.
In 2023, there have already been 38 days with global average temperatures more than 1.5°C above pre-industrial levels. Until this year, such days were a rarity, the study found.
Meanwhile, the highest average Earth surface temperature ever recorded came this July, and there’s “reason to believe it was the highest surface temperature the planet has seen in the last 100,000 years”, adds the study, published in the journal BioScience.
And so far this year wildfires in Canada have pumped more than a 1 billion tonnes of CO2 into the atmosphere – greater than Canada’s total 2021 greenhouse gas emissions of 0.67 billion tonnes.
Yet still the world is not waking up, the researchers warn.
They point out, for example, that global fossil fuel subsidies roughly doubled between 2021 and 2022, from $531 billion (£434 billion) to a record of just over $1 trillion.
Christopher Wolf, of Oregon- based Terrestrial Ecosystems Research Associates, said: “As scientists, we are hugely troubled by the sudden increases in the frequency and severity of climate-related disasters.”
“The frequency and severity of those disasters might be outpacing rising temperatures. By the end of the 21st century, as many as 3 to 6 billion people may find themselves outside the Earth’s livable regions, meaning they will be encountering severe heat, limited food availability and elevated mortality rates.”
“Without actions that address the root problem of humanity taking more from the Earth than it can safely give, we’re on our way to the potential collapse of natural and socioeconomic systems and a world with unbearable heat and shortages of food and freshwater,” Dr Wolf said.
Professor Tim Lenton, at the University of Exeter, said: “These record extremes are alarming in themselves, and they’re also in danger of triggering ‘tipping points’ that could do irreversible damage and further accelerate climate change.”
Tipping points include the melting of key ice sheets and the loss of the Amazon rainforest, which trigger further warming – by reflecting less sunlight back into the atmosphere and releasing CO2 into the atmosphere, respectively. This further increases warming and the process repeats itself.
The study also finds four vital signs that will help curb climate change that are at record levels. They are increasing use of renewable energy, an increasing recognition among governments the the world is facing a climate emergency, and growing divestments by pension funds of fossil fuel investments.
The number of births per woman are also falling significantly.
