Climates of the Future

Predicting future climate changes is a fundamental challenge with critical practical implications. These implications arise because climate change causes significant shifts in environmental conditions, impacting the economy and ecology. Ignoring these changes is not an option. As a result, climate change has become one of the top global concerns today.

How Climate Change is Forecasted

To predict climate changes, scientists use mathematical modelling. Based on the equations of thermo-hydrodynamics, oceanic and atmospheric circulation models have been developed. These models consider the entire circulation system and the energy balance of heat gain and loss and are combined with models of land and glacier processes. They include biogeochemical transformations, which affect the dynamics of critical atmospheric components, such as carbon dioxide, a significant driver of the greenhouse effect. This complex system, often called a “mathematical Earth system model,” integrates not just oceans and atmosphere but also biogeochemistry and terrestrial vegetation. All of these components interact and evolve within the models.

These models are highly sophisticated. To understand their complexity, imagine a video game—but one that’s incomparably more intricate. Developing such models requires hundreds of person-years of work. With these models, we can attempt to forecast future climate changes by starting from past or current conditions. Typically, the models begin in the mid-18th century, and through time integration, they simulate the evolution of meteorological, oceanic, and vegetation conditions up to the present and beyond.

Climate Scenarios

Climate scenarios are used to drive these models forward. These scenarios represent projections of greenhouse gas emissions or the intensity of contributing activities over time. Creating such scenarios is complex and involves entire institutions working on projections considering demographics, energy use, and the potential (or lack thereof) for transitioning to alternative fuels. These scenarios are then fed into the climate models to predict future changes.

Because of the uncertainties, scenarios are typically categorized as either “hard” or “soft.” A hard scenario, for instance, projects a significant rise in global temperatures by the end of this century, with the most dramatic increases occurring in the Arctic. As the Arctic loses its perennial ice cover, large previously frozen areas will become exposed, raising temperatures even further. Another significant consequence is rising sea levels, estimated to increase by 50–70 cm globally, leading to substantial coastal flooding, including areas like Florida. Mountain glaciers are expected to continue their retreat, with Greenland’s ice sheet degrading, particularly on its western side. The fate of Antarctica is less clear, but some scenarios suggest that it may remain stable, as temperatures in many regions won’t rise above freezing. However, increased precipitation due to warmer air masses could lead to a growth in Antarctica’s ice volume.

The thawing of permafrost is already underway and will continue. While the disappearance of permafrost may seem advantageous, much infrastructure—roads, airstrips, bridges—is built on it. Significant investment will be required to prevent structural damage as the ground thaws.

Global warming intensifies the heat in cities, making urban living increasingly challenging. As global temperatures rise, some diseases, like malaria, are expected to spread into northern regions where they previously did not exist. Although malaria is primarily a social disease, it has a strong climatic component, following global temperature patterns as it moves northward.

International Agreements and Geoengineering

Addressing climate change requires international cooperation, as evidenced by protocols limiting greenhouse gas emissions, such as the Kyoto Protocol. However, the Kyoto Protocol was insufficient in curbing emissions, as its targets were too small, and key countries like the U.S. did not participate. A new protocol may be developed soon, but its success remains uncertain.

Aside from international agreements, adaptation and mitigation efforts are critical. One potential avenue is geoengineering—technological interventions designed to counteract global warming. One idea involves placing a reflective “mirror” in space to block some of the sun’s rays, reducing Earth’s heat intake. Another idea mimics the cooling effect of volcanic eruptions by injecting sulfur into the atmosphere to create a global aerosol cloud, which could lower temperatures. While these approaches have been shown to reduce temperatures in model simulations, they carry significant risks. For example, geoengineering would not restore the regional climate conditions we are accustomed to, and the ecological effects, such as acid rain from sulfur aerosols, remain unknown.

Geoengineering ideas remain largely theoretical, with many unanswered questions about their feasibility and potential side effects.