Data from the World Meteorological Organization (WMO) show that in 2024 the concentration of carbon dioxide (CO₂) in the atmosphere reached the highest level in the history of measurements. The main driver was not a surge in emissions as such, but above all a decline in the ability of natural ecosystems to absorb CO₂—from warming oceans to droughts and wildfires. Despite the rapid growth of renewable energy, global warming is accelerating and the risk of crossing climate tipping points in the Earth system is rising steadily.
According to the WMO, the annual average CO₂ level measured by the Global Atmosphere Watch monitoring network was 377.1 ppm in 2004. In 2024 it had already reached 423.9 ppm, and in 2025—according to the Global Carbon Budget published in November last year—it was 425.7 ppm.
“In recent years, as the World Meteorological Organization’s report shows, the concentration of carbon dioxide in the atmosphere has been rising at a record pace. This does not happen because emissions are rising at a record pace—recently their growth has slowed due to the energy transition in Europe and China. The faster increase in concentration mainly results from the fact that natural ecosystems are absorbing less and less CO₂,”
explains Marcin Popkiewicz, a physicist and editor of the Nauka o Klimacie (Science of Climate) portal, in an interview with Newseria.
Almost half of global CO₂ emissions each year remains in the atmosphere, while the rest is absorbed by land ecosystems and the world’s oceans. However, this storage is not permanent. As ocean temperatures rise, oceans absorb less CO₂. Meanwhile, the effectiveness of land carbon sinks declines as vegetation dries out and forest fires become more frequent. A lower absorption capacity means global warming accelerates further.
“At their current concentration in the atmosphere, carbon dioxide and other greenhouse gases would already ‘want’ to raise the planet’s temperature by about 3 degrees. But because the oceans warm slowly, and because part of the warming impact of greenhouse gases is offset by sulfate aerosol emissions, the temperature increase so far is about 1.4 degrees. The goal of the Paris Agreement is to limit warming to 1.5–2 degrees Celsius so that we don’t cross various tipping points and so that we avoid very serious problems linked to a changing climate. We need to bring CO₂ emissions to zero—not cut them by half or by 80%, but to zero. That is a huge challenge,”
says Popkiewicz.
“We must replace fossil fuels, because they account for about 70% of the climate-change problem.”
The Global Carbon Budget 2025 indicates that global CO₂ emissions from fossil fuels in 2025 will rise by about 1%, reaching a record 38.1 billion tonnes. Increases are expected not only in the European Union but also in China, the United States, and India—linked to higher emissions from specific fuels: coal, natural gas, and oil.
“In the long run, we are capable of replacing fossil fuels with renewable energy sources. However, it is a process that will take many years—and we don’t have much time. We should take many steps to accelerate this transition,”
the Nauka o Klimacie editor explains.
The United Nations reports that fossil fuels still account for nearly 60% of electricity generation globally, but cleaner sources are gaining ground. Between 2015 and 2024, annual renewable generation capacity increased by roughly 2,600 gigawatts (GW)—about 140%. Over the same period, fossil-fuel power capacity rose by only about 640 GW (16%).
According to the International Energy Agency (IEA), wind and solar are now among the cheapest sources of electricity in many countries, and in most regions their costs are lower than those of new investments based on fossil fuels. The report also notes that the expansion of renewables is constrained mainly by regulatory barriers—such as lengthy permitting procedures, grid-connection delays, and broader network infrastructure bottlenecks.
“There are many interest groups that want to at least slow the transition—and ideally block it. We are talking about Russia and Saudi Arabia, but also the current U.S. administration. These are countries that have fossil fuels and earn very well from selling them. Europe is in a completely different position: we do not have cheap fossil fuels to extract on our territory, so we must think about alternatives—not only in terms of climate protection, but also our trade balance related to fossil-fuel and energy imports, energy security, and Europe’s energy sovereignty,”
Popkiewicz says.
According to the WMO’s update State of the Climate Update for COP30, 2025 could turn out to be one of the warmest years on record. Analyses by the U.S. National Oceanic and Atmospheric Administration (NOAA) confirm that the deep component of the Atlantic Meridional Overturning Circulation (AMOC) has weakened over the last two decades, linked to increasing inflows of fresh water from melting glaciers. Reports on the cryosphere also emphasize that accelerating thaw of permafrost leads to the release of additional CO₂ and methane—an extra feedback that intensifies global warming.
“There are many tipping points in Earth’s climate system. Some are associated with very serious threats, such as the destabilization of permafrost, which could disrupt the climate balance to the point that the Earth system ‘jumps’ into an entirely different, hotter state. We do not want to experiment with that, because it would bring geopolitical destabilization,”
Popkiewicz assesses.
“Countries in Africa, the Middle East, and India would become uninhabitable. We don’t want experiments involving billions of people who would have to flee because of such massive climate change.”
Research published in Nature in 2024 shows that rising temperatures, droughts, deforestation, and wildfires reinforce one another and increase the risk that parts of the Amazon could cross a tipping threshold, triggering an abrupt ecosystem shift.
“It is estimated that with 4 degrees Celsius of warming, the Amazon rainforest would begin to turn into savanna. That change is strictly climatic, but because we are also deforesting the Amazon—cutting off the flow of moisture deeper into the rainforest after coastal forests are cleared—it may turn out that the Amazon could shift into a savanna state already at 2 degrees Celsius of warming,”
the expert explains.
