Post-COP30, more aggressive policies needed to cap global warming at 1.5°C

Read the 2025 Outlook  |  Read Executive Summary  |  Download Data Tables

The latest United Nations Climate Change Conference (COP30) concluded without a roadmap to phase out fossil fuels and without significant progress in strengthening national pledges to reduce climate-altering greenhouse gas emissions. In aggregate, today’s climate policies remain far too unambitious to meet the Paris Agreement’s goal of capping global warming at 1.5 degrees Celsius, setting the world on course to experience more frequent and intense storms, flooding, droughts, wildfires and other climate impacts. A global policy regime aligned with the 1.5°C target would almost certainly reduce the severity of those impacts. 

In the 2025 Global Change Outlook, researchers at the MIT Center for Sustainability Science and Strategy (CS3) compare the consequences of these two approaches to climate policy through modeled projections of critical natural and societal systems under two scenarios. The Current Trends scenario represents the researchers’ assessment of current measures for reducing greenhouse gas (GHG) emissions; the Accelerated Actions scenario is a credible pathway to stabilizing the climate at a global mean surface temperature of 1.5°C above pre-industrial levels, in which countries impose more aggressive GHG emissions-reduction targets.  

By quantifying the risks posed by today’s climate policies—and the extent to which accelerated climate action aligned with the 1.5°C goal could reduce them—the Global Change Outlook aims to clarify what’s at stake for environments and economies around the world. Here we summarize the report’s key findings at the global level; regional details can also be accessed in several sections and through MIT CS3’s interactive global visualization tool.   

Emerging headwinds for global climate action  

Projections under Current Trends show higher GHG emissions than in our previous 2023 Outlook, indicating reduced action on GHG emissions mitigation in the upcoming decade. The difference, roughly equivalent to the annual emissions from Brazil or Japan, is driven by current geopolitical events. Additional analysis in this report indicates that global GHG emissions in 2050 could be 10% higher than they would be under Current Trends if regional rivalries triggered by U.S. tariff policy prompt other regions to weaken their climate regulations. In that case, the world would see virtually no emissions reduction in the next 25 years.

Energy and electricity projections 

Between 2025 and 2050, global energy consumption rises by 17% under Current Trends, with a nearly ninefold increase in wind and solar. Under Accelerated Actions, global energy consumption declines by 16%, with a nearly 13-fold increase in wind and solar, driven by improvements in energy efficiency, wider use of electricity, and demand response. In both Current Trends and Accelerated Actions, global electricity consumption increases substantially (by 90% and 100%, respectively), with generation from low-carbon sources becoming a dominant source of power, though Accelerated Actions has a much larger share of renewables.   

“Achieving long-term climate stabilization goals will require more ambitious policy measures that reduce fossil-fuel dependence and accelerate the energy transition toward low-carbon sources in all regions of the world. Our Accelerated Actions scenario provides a pathway for scaling up global climate ambition,” says MIT CS3 Deputy Director Sergey Paltsev, co-lead author of the report. 

Greenhouse gas emissions and climate projections 

Under Current Trends, global anthropogenic (human-caused) GHG emissions decline by 10% between 2025 and 2050 but start to rise again later in the century; under Accelerated Actions, however, they fall by 60% by 2050. Of the two scenarios, only the latter could put the world on track to achieve long-term climate stabilization.  

Median projections for global warming by 2050, 2100 and 2150 are projected to reach 1.79, 2.74 and 3.72°C (relative to the global mean surface temperature (GMST) average for the years 1850-1900) under Current Trends and 1.62, 1.56 and 1.50°C under Accelerated Actions. Median projections for global precipitation show increases from 2025 levels of 0.04, 0.11 and 0.18 millimeters per day in 2050, 2100 and 2150 under Current Trends and 0.03, 0.04 and 0.03 mm/day for those years under Accelerated Actions. 

“Our projections demonstrate that aggressive cuts in GHG emissions can lead to substantial reductions in the upward trends of GMST as well as global precipitation,” says CS3 Deputy Director C. Adam Schlosser, co-lead author of the Outlook. “These reductions to both climate warming and acceleration of the global hydrologic cycle lower the risks of damaging impacts, particularly toward the latter half of this century.” 

Implications for sustainability 

The report’s modeled projections imply significantly different risk levels under the two scenarios for water availability, biodiversity, air quality, human health, economic well-being and other sustainability indicators.  

Among the key findings: policies that align with Accelerated Actions could yield substantial co-benefits for water availability, biodiversity, air quality and health. For example, combining Accelerated Actions-aligned climate policies with biodiversity targets, or with air-quality targets, could achieve biodiversity and air quality/health goals more efficiently and cost-effectively than a more siloed approach. The Outlook’s analysis of the global economy under Current Trends suggests that decision-makers need to account for climate impacts outside their home region and the resilience of global supply chains.  

Finally, CS3’s new data-visualization platform provides efficient, screening-level mapping of current and future climate, socio-economic and demographic-related conditions and changes—including global mapping for many of the model outputs featured in this report.  

“Our comparison of outcomes under Current Trends and Accelerated Actions scenarios highlights the risks of remaining on the world’s current emissions trajectory and the benefits of pursuing a much more aggressive strategy,” says CS3 Director Noelle Selin, a co-author of the report. “We hope that our risk-benefit analysis will help inform decision-makers in government, industry, academia and civil society as they confront sustainability-relevant challenges.”  

On July 1, 2024, the MIT School of Science launched the MIT Center for Sustainability Science and Strategy (CS3). The purpose of CS3 is to advance knowledge and computational capabilities in the field of sustainability science, and support decision-makers in government, industry and civil society in their efforts to achieve sustainability goals. Researchers at CS3 develop and apply expertise from across the Institute to improve understanding of sustainability challenges, and thereby provide actionable knowledge and insight to inform strategies for enhancing human well-being for current and future generations.