Carbon dioxide is vital to all life on Earth. Without it, plants wouldn’t be able to grow and produce the oxygen we breathe. Yet an excess of CO2 is posing a real threat to the livability of the planet. As a greenhouse gas it traps heat in the Earth’s atmosphere and CO2 levels have increased dramatically since the Industrial Revolution, driven primarily by the burning of fossil fuels for energy and transportation.This is leading to a steep rise in global temperatures, with ever more severe consequences, including storms, flooding, drought and days of extreme heat. There is overwhelming consensus among scientists that reducing CO2 is critical to avoiding the most catastrophic impacts of climate change. But how do we actually achieve it? What goals exist for CO2 reduction?The COP30 summit in Belem marks a decade since the historic Paris Agreement, the world’s first legally binding climate deal to keep global temperatures rising more than 1.5 degrees Celsius (2.7 degrees Fahrenheit) above pre-industrial levels. CO2 reduction is central to this. It requires a 43% cut in emissions by 2030 compared to 2019 levels and reaching net zero by 2050.While this applies to all greenhouse gases — methane and nitrous oxide are also potent polluters — CO2 is the focus, as it is responsible for around 80% of temperature rise since 1990.Despite these global aspirations, CO2 emissions hit a new high in 2024, which was recognized as the hottest year on record.China, the US, India, the EU and Russia are the biggest polluters. The energy sector produces by far the most emissions, followed by agriculture and then industrial processes such as chemical and cement production.While there has been some progress in reducing emissions — in the EU, for example, they have dropped 37% compared to 1990 levels — the world is still falling behind global targets. Recent research shows the biggest economies and polluters are not on track to meet the Paris Agreement.Ditching fossil fuels is keyAs the primary source of CO2 emissions, the world urgently needs to transition away from fossil fuels.This requires reshaping how our societies function, from how we power economies, grow food and travel, to what we buy and how we dispose of it. Some of the biggest cuts so far have been made in the energy sector, through expanding electrification, improving efficiency and, crucially, moving toward renewables.Renewables have made enormous strides with clean power sources, led by solar, accounting for 40% of global electricity generation last year. The International Energy Agency, an independent intergovernmental organization, predicts by 2030 renewable capacity will grow by 2.7 times and provide more than half of global electricity demand. Other methods of reducing CO2 include the expansion of electric vehicles , shifts to a more plant-based diet, sustainable agricultural practices, and the use of heat pumps to warm homes.How far can forests help?Forests are vital to climate protection. They act as “carbon sinks,” absorbing CO2 from the atmosphere through the process of photosynthesis and locking it down in trees, roots and soil. Land-based ecosystems — which include forests, grassland and tundras — are estimated to absorb around 30% of carbon dioxide emissions each year. The key role of planting and maintaining forests in climate protection was recognized in the Paris Agreement. This became more concrete at the 2021 climate conference in Glasgow, when countries representing 90% of the world’s forests signed an agreement to halt and reverse deforestation and land degradation by 2030.From Costa Rica and Pakistan, to the Great Green Wall initiative across Africa’s Sahel region, many ambitious projects have set out to plant billions of trees. Yet tree planting projects have also been criticized for failing to match the species that are able to survive in specific local environments.So far, countries are way off track to reach the 2030 target. In 2024 global forest loss hit record highs, largely due to a spike in fires. An estimated 17 of the 20 countries with the biggest primary forests that signed the agreement in Glasgow now have a higher loss than in 2021. There are also concerns forests could shift from “carbon sinks” to “carbon sources.” Trees can release CO2 when they are cleared, burned or degraded. In 2023 and 2024, extreme wildfires meant forests absorbed only a quarter of their normal annual CO2.What technologies can remove CO2?In addition to nature-based approaches, there is also a market for technological solutions.Carbon capture and storage (CCS) is a process that aims to prevent excess carbon dioxide from entering our atmosphere in the first place.It works either by separating the CO2 from other gases before combustion, or once it is released by burning fossil fuels in power plants or from places such as steel mills, refineries and cement plants. Once captured, it is then compressed into a liquid and usually stored underground in places such as disused oil and gas reservoirs and abandoned coal mines.Why carbon capture needs a reality checkThe greenhouse gas can also be directly sucked from the atmosphere using filters and chemicals in a process known as direct air capture and storage, while another method captures carbon dioxide from plants burning biomass. Yet these technologies remain expensive and energy intensive.The UN has recognized CCS as an important technology for reducing emissions in the long term, saying they will be “unavoidable” if the world wants to reach net-zero goals.However, the technologies have also faced widespread criticism, with estimates suggesting they only capture 0.1% of global emissions. Critics argue the technology can be used by the fossil fuel industry as a cover to keep burning oil, gas and coal. They say limiting the worst impacts of the climate crisis requires phasing out fossil fuels as fast as possible. Under current climate policies, emissions are expected to peak this decade before falling, putting the world on track for 2.6 Celsius warming — or more — by the end of the century.
