12.6: Solutions

Global Emissions

Climate change is a complex problem to solve because our modern society was built around burning fossil fuels as an energy source. We still depend heavily on fossil fuels for everything from driving our cars and washing our laundry to charging our cell phones and heating our homes. To stabilize the climate, however, we’ll need to move to near-zero carbon emissions in the long run. Thus, the challenge is to decarbonize our economy. The longer we wait for this transformation, the larger the impacts of future climate change will be, or the faster future emission reductions will need to be. And because it is a global problem, the whole world, or at least most of it, will need to cooperate to solve it. Moreover, because we’re already committed to further climate change, we'd better prepare to adapt to it. This chapter will discuss technological options, political efforts, and personal actions towards climate mitigation and adaptation to the inevitable.

Figure \(\PageIndex{1}\) illustrates the increase in carbon dioxide (CO₂) emissions since 1750. Before the Industrial Revolution, emissions were very low. Growth in emissions was still relatively slow until the mid-20th century. In 1950, the world emitted 6 billion tonnes of CO₂. By 1990, this had nearly quadrupled to more than 20 billion tonnes. Emissions have continued to grow rapidly. We now emit more than 38 billion tonnes annually. Emissions growth has slowed over the past few years, but emissions have not yet peaked. In recent years, China, the United States, and India have been the top three CO₂ emitters by total volume, with China being the largest emitter since 2006. Other major emitters include Russia, European Union (EU) member states, and Indonesia. While emissions from China and India have increased over the past few decades, their per capita emissions remain significantly lower than those of countries such as the United States and the EU.

Figure \(\PageIndex{1}\): The growth of global emissions from the mid-18th century through to today. Growth in emissions was still relatively slow until the mid-20th century. In 1950, the world emitted 6 billion tonnes of CO₂; by 2024, it had risen to over 38 billion tonnes. (CC BY 4.0; Global Carbon Budget (2025) via Our World in Data.)

Technology

Current global energy production relies heavily on fossil fuel burning, as illustrated in Fig. \(\PageIndex{2}\). The most significant energy sources are oil, coal, and natural gas, all of which are fossil fuels, whereas non-fossil fuels together account for only about 20% of total energy. In the United States, transportation is the largest source of emissions, accounting for 27%, followed by electricity generation at 25% and industry at 24%.

Figure \(\PageIndex{2}\): This pie chart illustrates the
breakdown of global greenhouse gas emissions by sector in 2019. The energy supply sector
is the most significant contributor at 34%, followed by industry (24%), agriculture (22%,
which includes forestry and land use), transportation (15%), and buildings (5.6%). (CC BY-NC 4.0; Peak CO₂ and heat trapping emissions via Climate Central)

Most oil consumption powers transportation via internal combustion engines in cars and trucks, which are very inefficient. Only about 25% of the energy input into transportation is used to move vehicles, while nearly 75% is wasted as heat. Coal is mainly used in power plants to generate electricity, and this process also results in a loss of about 50% of the total energy. Note that this loss is less than that from internal combustion engines, which makes electric cars have lower carbon footprints than internal combustion engine cars, even if the electricity is generated from coal. Most natural gas is used to generate electricity and to heat buildings. Hydro- and nuclear power are used exclusively to generate electricity, whereas biomass is primarily used for cooking and home heating in the developing world. Renewable energy sources, such as solar and wind, supply only a small fraction of total energy.

Nuclear Power

Nuclear power generates electricity by using heat from a nuclear reactor's controlled fission reaction to create steam, which drives a turbine connected to a generator. They provide fossil-free power that does not emit carbon dioxide (except during construction). Unlike intermittent sources such as solar and wind, nuclear power plants can operate 24/7, providing a steady, reliable baseload power supply. For this reason, they are viewed by some as an important future energy source. The Diablo Canyon Nuclear Power Plant depicted in Figure \(\PageIndex{3}\) is the only operational nuclear plant in California, as well as the state's largest single power station.

Figure \(\PageIndex{3}\): The Diablo Canyon Power Plant near Avila Beach in San Luis Obispo County in California. (CC BY 2.0; Tracy Adams via Flickr)

However, nuclear power has disadvantages too. Not only are they expensive to build, but they are also dangerous to operate and produce radioactive waste for which no long-term repository currently exists. Catastrophic accidents such as the nuclear meltdowns in 2011 at the Japanese Fukushima Daiichi plant and in 1986 at the Chernobyl reactor in what is now northern Ukraine have shown the dangers associated with nuclear power production. Thus, nuclear power remains a controversial topic.

Renewables

In some countries, renewable energy sources have seen a rapid increase in recent years. Germany, for example, has increased the share of renewables in total electricity production from 3% in 1990 to 45% in 2020, while its economy has been among the strongest in Europe. Denmark plans to move to 100% renewable energy by 2050. As of 2023, in the United States, renewables currently account for 9% of total energy consumption and 21% of electricity production, as illustrated in Figure \(\PageIndex{4}\). Since transportation consumes the most energy in the United States, petroleum (oil) accounts for the majority of that energy. Fossil fuels such as natural gas and coal still account for nearly 60% of electricity generation, with nuclear power and renewables accounting for the remainder.

Figure \(\PageIndex{4}\): Electricity generation in the United States comes primarily from natural gas (43.1%) and coal (16.2%). Nuclear power accounts for 18.6%, and renewable sources, including geothermal, solar, hydroelectric, wind, and biomass, account for only 21.4%. (Public Domain; Electricity Explained via U.S. EIA). Alternative Text Description.

Solar power is the conversion of sunlight into electricity, either directly via photovoltaic (PV) cells (also known as solar panels) or indirectly via concentrated solar power using mirrors. Wind power is the use of wind energy to rotate wind turbines, which are then connected to a generator to produce electricity. A renewable energy farm including solar panels and wind turbines in Germany is shown in Figure \(\PageIndex{5}\)A. Hydro power is generated by converting the gravitational potential or kinetic energy of a water source into electricity, as illustrated in Figure \(\PageIndex{5}\)B. Bioenergy is a renewable energy source derived from plants and animal waste. Unlike fossil fuels, biomass commonly used for bioenergy includes wood, food crops such as corn, energy crops, and waste from forests, yards, or farms. Geothermal power is electricity generated from Earth's core. Water or another fluid is sent down multiple miles below the surface, where the temperature increases. This boils the liquid in the pipes, which is then used to rotate a steam turbine at the surface.

A

B

Figure \(\PageIndex{5}\): A: Photovoltaic array and wind turbines at the Schneebergerhof wind farm in the German state of Rheinland-Pfalz. (CC BY-SA 3.0; Kuebi via Wikimedia Commons). B: A schematic diagram of a hydroelectric power station. (CC BY 2.5; Tomia via Wikimedia Commons). Alternative Text Description.

The advantage of renewable energy is its nearly unlimited supply potential and minimal carbon emissions. Some emissions occur during the production and installation of solar panels and wind turbines. Renewables are also not associated with the dangers of nuclear power. Their disadvantages were formerly their high up-front investment costs. Once installed, however, solar panels and wind turbines require minimal maintenance because solar energy and wind are free. During the past 10 years, the cost of solar panels has decreased dramatically by 80%. Thus, if viewed over the lifetime of a system, renewables become competitive with fossil fuels. Other renewable energy sources include geothermal, tidal, and wave energy, as well as hydropower. Another issue with renewable energy is its intermittent supply. Solar panels operate during daylight, whereas wind turbines operate only when the wind blows. However, recent studies, such as Shaner et al. (2018) have found that 80% of total electricity demand could be met by wind and solar, as quoted from the abstract of the paper:

Assuming minimal excess generation, lossless transmission, and no other generation sources, the analysis indicates that wind-heavy or solar-heavy U.S.-scale power generation portfolios could in principle provide ∼80% of recent total annual U.S. electricity demand. -Shaner et al. (2018)

Currently, many companies are moving towards more electric cars or hybrid vehicles. Due to their much higher efficiencies (80-90%), their energy use is much smaller than for vehicles with internal combustion engines, and their carbon footprint can be close to zero (some is associated with vehicle production) if renewable energy sources are used for the electricity. Even when electricity is generated from fossil fuels, the carbon footprint of electric cars remains lower than that of internal-combustion-engine vehicles. Given the substantial carbon emissions generated by the transportation sector and the significant losses it incurs, transitioning to an electric vehicle fleet could yield a substantial reduction in future emissions. Although electric cars are more expensive to purchase, their total life-cycle costs are lower than those of gasoline-powered vehicles. Electric cars have additional advantages—no oil change, no pollution, and greater torque. Manufacturing electric cars, however, is not without environmental and human impacts, including those associated with the mining of raw materials used in battery production.

Personal Actions

Each of us can take individual actions to reduce carbon emissions and the impacts of climate change. Conserving energy, e.g. by switching off lights when they are not needed. Switching to energy-efficient appliances, such as LED lights. Recycling also helps. Driving less or choosing an energy-efficient car, such as a hybrid, electric, or smaller vehicle, will reduce your carbon footprint. Even better is riding your bike. Eating less meat is another way to reduce your carbon footprint, since meat production generates more carbon emissions than vegetarian food. Homeowners can weatherize their homes or install solar panels. You can assess your carbon footprint on various websites to help you with this process.

Ultimately, however, individual actions have limited effects. Imagine, for example, that you start using less gas by riding your bike instead of driving your car. If many people did it, demand for gas would decrease, thereby lowering its price, assuming supply remains constant. Lower gas prices lead people to buy larger cars and drive more, thereby diminishing or erasing the effects of their personal emission reduction. That is not to say that we shouldn't take individual actions. However, collective action is also needed. Large-scale government actions, such as a carbon tax or a cap-and-trade system, can accelerate the transition to renewable energy sources that are necessary to avoid potentially dangerous climate change.

Adaptation

Climate change already affects us. It is not only a thing of the future or of faraway places. It is an issue of the present. Since we cannot avoid further climate change in the immediate future, we must adapt to it if we don’t want to suffer its consequences. Perhaps one of the most important things is to be aware that it is happening. This will prompt us to consider the potential implications for the region in which we live. If regional projections are available, we can consider them in planning. If not, we can still extrapolate from past changes, assuming we'll see more of what we’ve observed recently.

Figure \(\PageIndex{6}\): The Isle of Wight sea wall, in Ventnor, UK. (Public Domain; Oikos-team via Wikimedia Commons)

Adaptation can help manage impacts and risks to people and nature. The four types of adaptation actions are infrastructural, institutional, behavioural, and nature-based options. Some examples are building seawalls to combat rising sea levels, as shown in Figure \(\PageIndex{6}\), or inland flood defenses. Providing new insurance schemes to the populations under threat of climate-related disasters, changing crop planting times or varieties, depending on temperature and precipitation variation, and installing green roofs or green spaces in cities to combat the Urban Heat Island effect. Adaptation can be reactive, i.e., responding to climate impacts as they happen, or proactive, i.e, taking steps in anticipation of future climate change.

Cited Source:

Shaner, M. R., S. J. Davis, N. S. Lewis, and K. Caldeira, 2018: Geophysical constraints on the reliability of solar and wind power in the United States. Energy Environ. Sci., 11, 914–925, https://doi.org/10.1039/C7EE03029K.