2025 Global Change Outlook

Overview

In the 2025 Outlook we focus on two scenarios. 

Current Trends: Current measures for reducing greenhouse gas emissions, projected indefinitely. This scenario generally fails to stabilize climate, allowing global average temperatures to continue to rise. 

Accelerated Actions: What may happen if regions impose more aggressive greenhouse gas emissions reduction targets aligned with the Paris Agreement’s long-term goals.

By contrasting outcomes under Current Trends and Accelerated Actions, we can quantify the risks of remaining on the world’s current emissions trajectory and the benefits of pursuing a much more aggressive strategy. 

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.
 

Projections

Primary Energy

Global energy consumption exhibits different patterns—it grows in Current Trends but declines in Accelerated Actions driven by improvement in energy efficiency, wider use of electricity, and demand response. Achieving long-term climate stabilization goals will require more ambitious policy measures (e.g. Accelerated Actions) that reduce fossil-fuel dependence and accelerate the energy transition toward low-carbon sources in all regions of the world. 

Electricity

In both scenarios, global electricity consumption increases substantially, with generation from low-carbon sources becoming a dominant source of power, though Accelerated Actions has a much larger share of renewables. Variable renewables, such as wind and solar, are getting cheaper, but they make the electric grid more complicated, inducing integration costs and leading to higher electricity prices in Accelerated Actions.

Greenhouse Gas Emissions

Current policy approaches do not substantially decrease global anthropogenic greenhouse gas (GHG) emissions; without further actions, GHG emissions will start to grow again later in the century. 

Projections under Current Trends show higher 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.

The bottom line: under Current Trends, the world is not on track to achieve long-term climate stabilization. Ultimately, robust government policies aligned with Accelerated Actions will be needed for more aggressive GHG emissions mitigation.

Climate

Curtailing global mean surface temperature rise is possible with aggressive emissions cuts: the Accelerated Actions scenario offers a greater than 95% chance of staying below 2°C warming. In the Current Trends scenario, the projected continual increase in global precipitation (which is balanced by global evaporation) indicates an intensification of the global hydrologic cycle. Yet, regional shifts in weather-related storms, extreme precipitation, as well as shortages in water resources are more variable. 

For example, we project that extra-tropical storm frequency and intensity will remain constant through mid-century but may increase sharply after that. Additionally, occurrences of extreme precipitation at regional scales may increase but within a large range of possible outcomes that vary across time horizons and plausible climate sensitivities. 

Sustainability Implications

Water

Climate policies in alignment with Accelerated Actions can yield substantial co-benefits for water availability, particularly at local and regional scales. However, to identify strategies for sustainable water resources, additional complex factors that influence water quality must be incorporated.

Biodiversity

Achieving the 30x30 Biodiversity Goal—protecting 30% of land and oceans with high biodiversity and ecosystem functions by 2030—would lead to lower regional GDP losses under Accelerated Actions than it would under Current Trends. A policy that combines 30x30 with Accelerated Actions targets would require fewer subsidies to reach biodiversity targets.

Air Quality and Health

Our projections show appreciable air-quality improvements from Accelerated Actions-aligned policies aimed at reducing fossil fuel combustion, and how combining climate and air quality policies can reduce air pollution and associated health impacts.

Economic Impacts of Climate Change

Globally, our results suggest that planners need to think carefully about climate impacts in other regions and the resilience of global supply chains. Depending on a country’s position in the global economy (its supply chains, trade patterns, relative climate vulnerability, etc.), climate impacts elsewhere can either dampen country-level economic impacts or amplify them. 

Co-evolving Risks

Our new data-visualization platform, STRESS, can provide efficient, screening-level mapping of current and future climate, socio-economic and demographic-related conditions and changes. As we continue to add data and metrics from our model projections as well as supporting empirical information, the platform will provide a more comprehensive and use-inspired capability to explore co-existing and co-evolving hazards and risks. In addition to providing global mapping for many of the model outputs featured in this report, the STRESS assessment for the United States identifies focus areas for more detailed and computationally rigorous analyses.