"In the past two years, the world has come together around the climate and ecological crises through the U.N. Climate Change and Biodiversity Conferences. But we should remember that the causes of the crises are interlinked – that they have already collided - and that inaction over both may result in dire consequences." Dr Gregory Cooper, University of Sheffield's Institute for Sustainable Food.
U.K. research teams have used computer models to examine four ecosystems under threat to determine what factors lead to tipping points, a point of no return in the climate system.
Since 1980, climate disasters have increased, and the researchers conclude that crossing 1.5 Celsius set by the IPCC and the Paris Accords as a threshold that must not be crossed will only exacerbate climate catastrophes in an already dire situation even more. They found that one-fifth of global ecosystems are at risk of collapse and taking neighboring ecosystems down with them.
From the University of Sheffield press release:
Extreme weather events such as wildfires and droughts will accelerate change in stressed systems leading to quicker tipping points of ecological decline, according to a new study.
Using computer modelling, the UK research team, which includes scientists from the University of Sheffield, looked at four ecosystems under threat to work out what factors might lead to tipping points, beyond which collapse was inevitable. In some systems, the combination of adding new extreme events on top of other ongoing stresses brought the timing of a predicted tipping point closer to the present by as much as 80 per cent.
Ultimately, say the authors, a “perfect storm” of continuous stress from factors such as unsustainable land use, agricultural expansion and climate change, when coupled with disruptive episodes like floods and fires, will act in concert to rapidly imperil natural systems.
“Previous studies of ecological tipping points suggest significant social and economic costs from the second half of the 21st century onwards. Our findings suggest the potential for these costs to occur much sooner,”added co-author Professor John Dearing, Emeritus Professor at the University of Southampton.
"When the world decides upon a red line we shouldn't cross, I think it should be communicated clearly and widely when there are first signs of this line being crossed." Leon Simons
Fred Pearce writes in Yale 360, Mind the Gaps: How the U.N. Climate Plan Fails to Follow the Science:
On the 1.5-degree target, British meteorologists reported in the journal Nature that a lack of agreement on how to measure global average temperatures is likely to delay formal recognition that the threshold has been exceeded by up to a decade. The result, warns lead author Richard Betts of the U.K. Met Office’s Hadley Centre, will be “distraction and delay just at the point when climate action is most urgent,” resulting in temperature “overshoot” and a need for highly expensive — and unproven — actions later to reverse warming.
Meanwhile a study headed by Matthew Gidden, a climate modeler at the International Institute for Applied Systems Analysis (IIASA) in Austria, found that the rules governing how countries can declare they have reached net-zero emissions are fixed so that governments will be able to claim compliance years ahead of scientific reality.
Critical issues have been under the radar because scientists have not wanted to naysay policymakers building support for climate action.
These critical technical issues have been largely under the radar until now — in part, say concerned researchers, because scientists have not wanted to confuse or naysay policymakers looking to build public support for climate action. But the discrepancies raise serious questions about whether governments are truly committed to abiding by the science. “Politicians are trying to find an easy way to meet their pledges,” said IIASA forest ecologist Dmitry Shchepashchenko.
Scientists are concerned that the system agreed by negotiators for calculating offsets is contradictory and wide open to abuse.
Climate scientists have traditionally assessed temperature trends averaged over the three previous decades. The U.N.’s Intergovernmental Panel on Climate Change (IPCC), which assesses climate science for the international community, now favors two decades. But in either case, calculations based on recent past temperatures mean the average will always lag behind reality, kept low by the cooler early years of the period. The results won’t reflect the current situation, says Betts in the Nature article published during the Dubai conference.
Most are unaware that one of three data sets has shown that 2023 breached 1.5 C above the Paris threshold for the first time. Copernicus EU first reported an average temperature of 1.48 Celsius. NASA Hadley at 1.4 Celsius. Berkely Earth at 1.54 Celsius.
Berkeley Earth, a California-based non-profit research organization, has been preparing independent analyses of global mean temperature changes since 2013. The following is our report on global mean temperature during 2023.
We conclude that 2023 was the warmest year on Earth since 1850, exceeding the previous record set in 2016 by a clear and definitive margin.
The global annual average for 2023 in our dataset was estimated as 1.54 ± 0.06 °C (2.77 ± 0.11 °F) above the average during the period 1850 to 1900, which is traditionally used a reference for the preindustrial period. This is the first time that any year has exceeded the key 1.5 °C (2.7 °F) threshold. The significance of this is discussed below. Also, please note that given the uncertainties and differences in methodologies, other groups are expected to report 2023 as slightly less than 1.5 °C above preindustrial. The differences between Berkeley Earth’s analysis and that of other groups is discussed at the end of this report.
The last nine years have included all nine of the warmest years observed in the instrumental record.
The long-term trend towards higher temperatures is being driven by man-made global warming. However, year-to-year rankings are likely to reflect short-term natural variability. In 2023, an emerging El Niño event combined with other natural and man-made factors discussed below to create a record-breaking warm year. By contrast, 2021 and 2022 had somewhat lower temperatures due to a persistent a La Niña event. The cyclic warming and cooling due to El Niño and La Niña is one of the largest sources of year-to-year internal variability in the global average temperature, often adding or subtracting 0.1 °C from the global average.
Worst-case climate scenarios are not being studied, yet all trends indicate a worst-case is where we are heading.
Assuming the world stays on its current warming trajectory, IPCC projections suggest that 1.5 °C will be breached around 2030, give or take a decade3. But, on the basis of 20-year averages, the passing of 1.5 °C would not be formally recognized until around 2040.
Shortening the period over which the average is calculated doesn’t help much. Ten-year averages4 are reasonably representative of longer-term averages5 and reduce the delay to five years. But that is still a long time when action is needed urgently. Shortening the average period further isn’t useful, because natural variability then dominates.
A more instantaneous indicator of the current level of long-term warming is needed. Several such methods are already in use. These include: finding the end point of a linear trend over the past 30 years (see go.nature.com/3ssvpwx); using more sophisticated methods for statistical smoothing over short time frames (see go.nature.com/3mqsr7g); and calculating the human contribution to warming from data on changes in the concentrations of greenhouse gases and aerosols6.
“A Miracle Will Occur” Is Not Sensible Climate Policy 07 December 2023 James Hansen, Pushker Kharecha, Makiko Sato
The COP28 Chairman and the United Nations Secretary General say that the goal to keep global warming below 1.5°C is alive, albeit barely, implying that the looser goal of the 2015 Paris Agreement (to keep warming well below 2°C) is still viable. We find that even the 2°C goal is dead if policy is limited to emission reductions and plausible CO2 removal. IPCC (the Intergovernmental Panel on Climate Change, which advises the UN) has understated global warming in the pipeline and understated fossil fuel emissions in the pipeline via lack of realism in the Integrated Assessment Models that IPCC uses for climate projections. Wishful thinking as a policy approach must be replaced by transparent climate analysis, knowledge of the forcings that drive climate change, and realistic assessment of policy options. The next several years provide a narrow window of time to define actions that could still achieve a bright future for today’s young people. We owe young people the knowledge and the tools to continually assess the situation and devise and adjust the course of action.