Human-caused global warming has continued to increase at an “unprecedented rate” since the last major assessment of the Earth’s climate system published just two years ago, 50 leading scientists warned on Thursday.
Their analysis shows over the past decade a record level of greenhouse gases is being emitted each year; equivalent to 54 billion tonnes of carbon dioxide – with human-induced warming averaging 1.14 degrees.
The remaining carbon budget – how much carbon dioxide can be emitted to have a better than 50 per cent chance of holding global warming to 1.5 degrees (a key Paris Agreement target) – has halved over three years.
The scientists including leading climatologists in Ireland and the UK have launched a project to update key climate indicators every year, so people can be kept informed about critical aspects of global warming and act in a more timely manner.
The analysis, published to coincide with climate negotiations in Germany this week, is described as a “timely wake-up call” indicating the pace and scale of climate action has been insufficient.
Climate experts including the UN Intergovernmental Panel on Climate Change (IPCC) are meeting in Bonn to prepare the ground for the Cop28 climate conference in the UAE next December. It will include a stocktake of progress towards keeping global warming to 1.5 degrees by 2050.
IPCC author and director of ICARUS climate research centre at Maynooth University Prof Peter Thorne, who contributed to the research, said it was critical that policymakers and the general public be made aware of “how quickly we are changing the climate through our collective activities”.
“Already since the IPCC assessment of the physical science basis [of climate change] in 2021 key numbers have changed markedly and we remain well off track globally to avert warming above 1.5 degrees,” he added.
Asked if he was surprised by the extent of deterioration within such a short period, Prof Thorne said: “The deterioration in these key metrics of climate change at such a pace is consistent with expectations of an accelerating climate system response as we continue to increase global GHG emissions.”
‘This is the critical decade for climate change. Decisions made now will have an impact on how much temperatures will rise and the degree and severity of impacts we will see as a result’
The latest data “increases the urgency of Cop28, if we have any hope of ‘keeping 1.5 alive’ although, in reality, the best we can now hope for is probably 1.5 degrees with little or low overshoot”.
“If we pass 1.5 the next best thing we can do is stop warming reaching 1.6 and so on and so forth. At no point should we throw up our hands in despair. Every saved emission is a reduced climate impact,” he underlined.
On implications for the Government, Prof Thorne said: “The findings increase yet further the urgency of meeting our legal obligations under the amended Climate Act. That means taking seriously recent warnings from EPA and others that we are currently off-course and redoubling efforts to get back on track. Ultimately the climate system will respond to our collective emissions and does not care a whit about special pleading from every sector as to why they can’t reduce emissions.”
Last week the EPA projected that Ireland would achieve a reduction of only 29 per cent in greenhouse gas emissions by 2030, far short of a legally binding target of 51 per cent, a core part of the Government’s climate policy. The agency’s latest projections show that almost all sectors are on a trajectory to exceed their national ceilings, including agriculture, industry, electricity and transport.
Given the speed at which the global climate system is changing, the scientists argue that policymakers, climate negotiators and civil society groups need to have access to up-to-date and robust scientific evidence on which to base decisions.
The IPCC is the most authoritative source of scientific information on the state of the Earth’s climate but turnaround time for its major assessments is five or 10 years, which creates an “information gap”, particularly when climate indicators are changing rapidly, the scientists warn.
In an initiative led by the University of Leeds with researchers including Prof Thorne, they have developed an open data, open science platform – including the Indicators of Global Climate Change dashboard and website igcc.earth – which will be updated on key climate indicators annually.
“This is the critical decade for climate change. Decisions made now will have an impact on how much temperatures will rise and the degree and severity of impacts we will see as a result,” said Prof Piers Forster, who is co-ordinating the project.
“Long-term warming rates are currently at a long-term high, caused by highest-ever levels of greenhouse gas emissions. But there is evidence that the rate of increase in greenhouse gas emissions has slowed,” he added.
“We need to be nimble footed in the face of climate change. We need to change policy and approaches in the light of the latest evidence about the state of the climate system. Time is no longer on our side. Access to up-to-date information is vitally important.”
Writing in the journal Earth System Science Data, the scientists outline how key indicators have changed since publication of the IPCC’s Sixth Assessment Working Group 1 report in 2021- which provided key data that fed into the subsequent landmark IPCC synthesis report this year.
‘Even though we are not yet at 1.5 degrees warming, the carbon budget will likely be exhausted in only a few years’
Human-induced warming, largely caused by the burning of fossil fuels, reached an average of 1.14 degrees for 2013 to 2022 above pre-industrial levels. This is up from 1.07 degrees between 2010 and 2019. Human-induced warming is now increasing at a pace of over 0.2 degrees per decade.
The analysis also found emissions were “at an all-time high”, with human activity resulting in the equivalent of 54 billion metric tonnes (a margin of error of +/-5.3) of carbon dioxide being released into the atmosphere on average every year over the 2012-2021 period.
There has been a positive move away from burning coal, yet this has come at a short-term cost in that it has added to global warming by reducing particulate pollution in the air, which has a cooling effect.
Minister of environment in Chile, Prof Maisa Rojas Corradi, who is an IPCC author and was involved in the study, said: “An annual update of key indicators of global change is critical in helping the international community and countries to keep the urgency of addressing the climate crisis at the top of the agenda and for evidence-based decision-making.”
In line with the ratchet-mechanism of increasing ambition envisioned by the Paris Agreement “we need scientific information about emissions, concentration, and temperature as often as possible to keep international climate negotiations up to date and to be able to adjust and if necessary correct national policies”, she added.
In 2020, the IPCC calculated the remaining global carbon budget was around 500 gigatonnes of carbon dioxide. By the start of 2023, the figure was roughly half that at around 250 gigatonnes of CO2.
The reduction in the estimated remaining carbon budget is due to a combination of continued emissions since 2020 and updated estimates of human-induced warming.
“Even though we are not yet at 1.5 degrees warming, the carbon budget will likely be exhausted in only a few years as we have a triple whammy of heating from very high CO2 emissions, heating from increases in other GHG emissions and heating from reductions in pollution,” Prof Forster explained.
“If we don’t want to see the 1.5-degree goal disappearing in our rear-view mirror, the world must work much harder and urgently at bringing emissions down,” he said. “Our aim is for this project to help the key players urgently make that important work happen with up-to-date and timely data at their fingertips.”
Dr Valérie Masson-Delmotte from the Université Paris Saclay who co-chaired Working Group 1 of the IPCC’s Sixth Assessment report and was involved in the climate indicators project, said: “This robust update shows intensifying heating of our climate driven by human activities. It is a timely wake up call for the 2023 global stocktake of the Paris Agreement – the pace and scale of climate action is not sufficient to limit the escalation of climate-related risks.”
Recent IPCC reports have conclusively shown, with every further increment of global warming, the frequency and intensity of climate extremes, including hot extremes, heavy rainfall and agricultural droughts, increases.
The indicators website extends a successful climate dashboard called the climate change tracker which was created by software developers who took ideas from the finance industry on how to present complex information to the public.