In a new study released today, UCS attributes substantial temperature and sea level rise to emissions traced to the largest fossil fuel producers and cement manufacturers. And for the first time, we extend sea level projections into the future, quantifying how past heat-trapping emissions from the fossil fuel industry will impact the world for centuries to come.
The world’s largest fossil fuel and cement producers have known for decades that their products cause climate change, yet they spread disinformation to misinform the public and have profited as people around the world have suffered from ever-worsening climate impacts. Previous attribution research published by my Union of Concerned Scientists colleagues have allowed us to draw causal connections between sources of heat-trapping emissions and resulting impacts, like present day increases in atmospheric greenhouse gas concentrations, air temperatures, sea levels, ocean acidification, and wildfire burned area. At the same time, social science research has shed light on what the industry knew and when they knew it.
In our new study, we bring together those two lines of research to understand what would have happened if fossil fuels had been phased out following key developments throughout history. We found that heat-trapping emissions traced to major carbon polluters have contributed to nearly half of present day surface air temperature rise and nearly a third to the observed global mean sea level rise. And critically, we demonstrate how these emissions will cause harm for centuries to come.
The past haunts the future
Our new research quantifies how sea levels will rise for hundreds of years as a result of past emissions traced to products produced and sold by the Carbon Majors. By comparing scenarios, with and without industrial fossil fuel development and its associated emissions, we find that past emissions from the Carbon Majors are projected to lead to an additional 0.26-0.55 m (10-21 inches) of sea level rise by the year 2300. While the magnitude of future sea level rise will depend on how emissions evolve this century our results attributing additional future sea level rise to past emissions are largely unchanged, regardless of what future emissions trajectories the world follows.
If the Carbon Majors emissions had ceased after 1990, the long-term sea level rise just from past emissions traced to their products is projected to be an additional 0.17-0.35 m (6-14 inches), showing how just a few decades of emissions can have a big impact on the future. Every delay in phasing out fossil fuels will burden future generations who need to adapt to rising seas and recover from loss and damage due to sea level impacts.
The world that could have been
To represent versions of the world that could have been if different actions had been taken and the world had acted in a timely manner to address the harms of fossil fuels, we develop several different counterfactual scenarios. We use the newly updated Carbon Majors database which quantifies annual emissions associated with coal, oil, gas, and cement production by each of the 122 largest fossil fuel and cement producers from 1854-2022. We explore 3 counterfactual scenarios, where we remove the emissions from these companies starting in a particular year:
- 1854 counterfactual: A world where industrial fossil fuel development never occurred. In this scenario we remove emissions from the world’s largest fossil fuel and cement producers starting in the year 1854. This is the earliest time period we can reliably know how much fossil fuels were being produced by different companies.
- 1950 counterfactual: A world where fossil fuels had been phased out when the industry knew that fossil fuels were harming the climate system. In this scenario we remove fossil fuel industry emissions after 1950 when research has shown that companies were internally aware of the harms of their products.
- 1990 counterfactual: A world where the international community had acted swiftly to phase out fossil fuels at the start of international efforts to address climate change. In this scenario we remove industry emissions after 1990, when the international community was first forming the Intergovernmental Panel on Climate Change and the United Nations Framework Convention on Climate Change.
In each set of simulations, we subtract emissions traced to the largest producers from the full emissions that actually occurred, and use a climate model, the MAGICC model, to determine what would have happened if the emissions from these companies never entered the atmosphere. MAGICC (Model for the Assessment of Greenhouse Gas Induced Climate Change) is a publicly accessible model that been widely used, including in the Intergovernmental Panel on Climate Change (IPCC) reports to understand how future climate could respond to different heat-trapping emissions scenarios.
Across all scenarios, we find that the world would have been cooler and the sea levels lower if fossil fuel emissions had been phased out earlier. We find that heat-trapping emissions traced to the Carbon Majors during 1854-2020 have contributed to as much as 57% to present day surface air temperature rise and as much as 37% to the observed global mean sea level rise. In the 1950 counterfactual scenario, modern temperatures (averaged from 1990-2020) would have been 0.41-0.66°C above the preindustrial (1850-1900) average and global sea levels would have risen by 0.12-0.17 m. This implies that these companies are responsible for as much as 57% of the present-day air temperature rise and as much as 36% of the present day sea level rise in this scenario. Impacts are similar in the 1854 and 1950 counterfactuals due to the relatively small amount of heat-trapping emissions released 1854-1950 relative to the enormous amount of emissions released after 1950.
In the 1990 counterfactual, the Carbon Majors are responsible for as much as 26% of the present-day air temperature rise and as much as 17% of the present-day sea level rise. The 1990 scenario has full historical emissions from 1854-1990 and then emissions from the fossil fuel industry removed 1990-2020. The climate impacts from emissions in recent decades are not yet fully realized, meaning this scenario underestimates the industry’s responsibility.
How does this study compare to what was found in previous UCS research?
The findings of our new research corroborate those of previous UCS studies, affirming the strength of our methods and accuracy of models used. By using the newest available emissions data for the Carbon Majors, this study extends this type of attribution research to present day. The main advancement of this particular study is the look to the future, which the updated methodology allowed us to do.
This research uses the same climate modeling approach used in the 6th IPCC report (2021) to project future temperatures under different emissions scenarios. Previous UCS research had used methods derived from the 5th IPCC report, released in 2014.
One of the biggest differences between these two approaches is how they determine sea level rise. The previously used model was only backward looking, meaning it could describe sea level rise in the past. The new model accounts for different drivers of sea level change, including ice sheet models and glacier models, capturing dynamics that were not happening in the recent past and allowing us to project into the future.
Using research to motivate action
Our research shows that emissions traced to the world’s largest fossil fuel and cement manufacturers have caused global temperatures and sea levels to rise, and that sea levels will continue to rise for hundreds of years in response to heat-trapping emissions which have already occurred. The fossil fuel industry knew by the 1950s that their products were causing climate change and at any time in the intervening decades they could have changed their business model to phaseout fossil fuels, yet they chose to keep producing, and profiting from, these harmful products. These actions have led to worsening climate change which will impact people in the future for centuries to come.
As the people around the world experience the devastating impacts of stronger storms, more destructive wildfires, sea level rise, and other detrimental changes they are calling for those who are responsible to be held accountable. Communities around the world are pursuing accountability through court cases based on the fact that the fossil fuel industry knowingly deceived the public while producing products that would increase risks of climate change. Research that can trace specific climate impacts to the heat-trapping emissions produced by these companies can help inform this litigation. Researchers can help play a role by designing research questions that inform global action. It is long past time the world to phaseout fossil fuels and to get accountability for the harms that have occurred—and will occur in the coming years. The time to take action is now.