Reviewed by Lexie CornerJun 5 2024
According to the University of Leeds' second annual Indicators of Global Climate Change study, human-induced warming has increased to 1.19 °C during the past ten years (2014–2023), up from 1.14 °C seen in 2013–2022 (detailed in the previous year’s report).
When 2023 is considered separately, global warming caused by human activities reaches 1.3 °C. This is less than the 1.43 °C overall warming observed in 2023, suggesting that El Niño and other natural climate variability also contributed to 2023’s record temperatures.
The research also reveals that only around 200 gigatonnes (billion tonnes) of residual carbon dioxide can be emitted, or roughly five years’ worth of current emissions, before committing us to 1.5 °C global warming.
In 2020, the Intergovernmental Panel on Climate Change (IPCC) estimated that, with a central estimate of 500 gigatonnes of carbon dioxide, the remaining carbon budget for 1.5 °C was in the range of 300 to 900 gigatonnes. Global warming and CO2 emissions have persisted since then. By the beginning of 2024, the remaining carbon budget for 1.5 °C was estimated to be between 100 and 450 gigatonnes, with a central estimate of 200.
Professor Piers Forster, Director of the Priestley Centre for Climate Futures at the University of Leeds, leads the Indicators of Global Climate Change Project.
Our analysis shows that the level of global warming caused by human action has continued to increase over the past year, even though climate action has slowed the rise in greenhouse gas emissions. Global temperatures are still heading in the wrong direction and faster than ever before.
Piers Forster, Professor and Director, Priestley Centre for Climate Futures, University of Leeds
Forster added, “Our analysis is designed to track the long-term trends caused by human activities. Observed temperatures are a product of this long-term trend modulated by shorter-term natural variations. Last year, when observed temperature records were broken, these natural factors were temporarily adding around 10 % to the long-term warming.”
The warning comes as climate experts convene in Bonn to prepare for the COP29 climate summit, which will be held in Baku, Azerbaijan, in November.
The UN’s Intergovernmental Panel on Climate Change (IPCC) is the authoritative source of scientific information on the state of the climate; however, since its next major assessment will not take place until around 2027, there is an “information gap,” especially since climate indicators are changing rapidly.
The new study is supplemented by an open data, open science platform—the Climate Change Tracker’s Indicators of Global Climate Change dashboard—which enables quick access to the most recent information on essential climate indicators.
The most recent Indicator study, published in Earth System Science Data by over 50 scientists, also sheds fresh light on the consequences of sulfur emission reductions in the global shipping industry. Sulfur cools the climate by directly reflecting sunlight into space and causing more reflective clouds to develop. However, ongoing emissions reductions have diminished this effect.
Although this was compensated last year by aerosol emissions from Canadian wildfires, the study says the longer-term pattern shows that the amount of cooling expected from aerosol emissions is decreasing.
Other Key Findings:
- Human-induced warming has increased to 1.19 °C over the last decade (2014-2023), up from 1.14 °C in 2013-2022 (as stated in last year’s study)
- Human-induced warming has been growing at an unprecedented rate in the instrumental record, averaging around 0.26 °C each decade from 2014 to 2023
- The high rate of warming is due to high greenhouse gas emissions (53 billion tonnes of CO2 per year) and improved air quality, which reduces the impact of human-caused cooling from particles in the atmosphere
- High levels of greenhouse gas emissions are also having an impact on the Earth's energy balance: ocean buoys and satellites are monitoring unprecedented heat fluxes into the Earth's oceans, ice caps, soils, and atmosphere. This flow of heat is 50 % more than the long-term average
Forster added, “Fossil fuel emissions are around 70 % of all GHG emissions and clearly the main driver of climate change, but other sources of pollution from cement production, farming and deforestation and cuts to the level of sulfur emissions are also contributing to warming.”
He further stated, “Rapidly reducing emissions of greenhouse gases towards net zero will limit the level of global warming we ultimately experience. At the same time, we need to build more resilient societies. The devastation wrought by wildfires, drought, flooding, and heat waves the world saw in 2023 must not become the new normal.”
The report is expected to play an important role in informing new Nationally Determined Contributions, which are improved climate plans that every country has promised to submit to the United Nations Framework Convention on Climate Change (UNFCCC) by 2025 to reduce emissions and adapt to climate impacts.
Journal Reference:
Forster, P. M., et al. (2024) Indicators of Global Climate Change 2023: annual update of key indicators of the state of the climate system and human influence. Earth System Science Data. doi:10.5194/essd-16-2625-2024