The world emits 42 billion tonnes of CO2 a year

People put a massive 42.2 billion tonnes of carbon dioxide (CO2) into the air in 2025. About 38.1 billion tonnes came from burning coal, oil and gas and making cement, and another 4.1 billion from clearing and using land¹. At that pace the world has emitted 33.48 billion tonnes so far this year. The figures are from the Global Carbon Budget, a yearly accounting by an international group of climate scientists.

You will often see 38 billion tonnes quoted instead. That number leaves out land use. The International Energy Agency (IEA) counted 38.4 billion tonnes from energy and industry in 2025⁴, and the European Commission’s emissions database, EDGAR, just under 40 billion from fossil sources⁵. Both are within 5% of the Global Carbon Budget’s fossil figure.

The total is what the climate feels, since carbon from a cleared forest warms the planet just as carbon from a power station does. The 2025 figure is a first estimate, and its land-use part is modelled where the fossil part is measured, which leaves the total uncertain by about 3 billion tonnes either way¹.

About 1,340 tonnes of CO2 every second

Spread evenly over a year, 42.2 billion tonnes is about 1,340 tonnes of CO2 every second. Nobody measures emissions second by second, so this is the yearly total divided up, and it comes to 116 million tonnes a day.

As a gas at sea level, a year of emissions would fill a cube about 28 kilometres on each side, by our own calculation from the density of CO2¹³.

The tonnage is so large partly because CO2 weighs more than the fuel it came from. Each carbon atom picks up two oxygen atoms from the air as it burns, so one tonne of carbon becomes 3.664 tonnes of CO2¹.

Almost half of all CO2 since 1850 was emitted after 1990

In 1960 the world emitted 16.9 billion tonnes of CO2. By 1990 the figure was 28.4 billion, and in 2024 it reached a record 42.4 billion. Fossil emissions alone have quadrupled since 1960, from 9.3 to 37.8 billion tonnes².

The climate responds to the running total, and nearly half of that total is recent. People have emitted about 2,730 billion tonnes of CO2 since 1850¹. By our sum of the Global Carbon Budget’s yearly figures, 46% of that has been emitted since 1990, and 15% since 2015, the year the Paris Agreement was adopted².

Fossil fuels and cement produce nine-tenths of the world’s CO2

About nine-tenths of the world’s CO2 comes from fossil fuels and cement, and the rest from land use. In 2024 coal was the largest single source, at 41% of fossil emissions, followed by oil at 32%, natural gas at 21% and cement at 4%. Emissions from all three fuels were still growing in 2025, by 1.0% to 1.3%¹.

Sorted by what the fuel is used for, power stations come first. Generating electricity and heat produced 39% of fossil CO2 in 2025. Transport produced 22%, factories burning fuel 16%, buildings 8%, industrial processes such as cement making 8%, and producing the fuels themselves 7%⁵.

Land use is mostly deforestation. By our conversion of the Global Carbon Budget’s figures, deforestation releases about 7 billion tonnes of CO2 a year, about 4 billion of it from forest cleared permanently, and forest regrowth takes up about two thirds as much. More than half of the net land-use emissions come from three countries: Brazil, Indonesia and the Democratic Republic of the Congo¹. The forests themselves are counted on the page for the rate of deforestation.

China emits the most CO2, but the ranking depends on how you count

China emits the most CO2 of any country: 12.3 billion tonnes from fossil fuels in 2024, or 32% of the world’s fossil CO2¹. That is more than the United States, India and the European Union combined³.

Count per person, or over history, and the order changes¹.

The average American emits more than six times as much as the average Indian, and the United States has put more fossil CO2 into the air since 1850 than any other country.

Where goods are made matters too. Emissions are normally counted where the fuel is burned, so the CO2 from making a phone in China for a buyer in Europe counts as China’s. Counted by who consumes the goods, the European Union’s emissions in 2023 were 33% higher than its official total and the United Kingdom’s 58% higher, while China’s were 11% lower³.

CO2 emissions have stopped racing ahead, but they have not fallen

Fossil CO2 emissions are still rising, though far more slowly than they were, and the total with land use has barely moved in a decade. Fossil emissions grew by 2.8% a year in the 2000s and by 0.8% a year between 2015 and 2024, and the total grew just 0.3% a year in that decade¹. In 2024 it was only about 3% above the 2015 level².

Fossil emissions still set a record in 2025, rising by somewhere between 0.4% and 1.0% depending on who did the counting¹⁴. The total held level only because emissions from land use fell¹.

China, which emits a third of the world’s fossil CO2, was roughly flat: the Global Carbon Budget estimates a small rise, the IEA and EDGAR a small fall¹⁴⁵.

Behind the slow rise is a race between cleaner energy and growing demand. Over the past decade the world economy grew by about 2.4% a year, and gains in energy efficiency and cleaner energy offset most of that growth but not all of it¹.

The IEA estimates that the solar panels, wind turbines, nuclear plants, electric cars and heat pumps added since 2019 avoided about 3 billion tonnes of CO2 in 2025, around 8% of what energy use emits⁴. Demand for energy grew by more than that¹. Whether solar power has started to push coal out is the subject of a separate article.

Fossil CO2 emissions have fallen in only 11 years since 1960

Fossil emissions have fallen in only 11 of the 64 years since 1960: twice in the mid-1970s, three times in the early 1980s, then in 1992, 1998, 2009, 2015, 2016 and 2020. The largest fall by far came in 2020, when the pandemic cut them by 1.9 billion tonnes, or 5.4%. A year later 1.7 billion of that was back².

Several of those years were crises, among them the financial crash of 2009 and the pandemic of 2020, which suggests that so far the world has cut emissions by accident more than by design.

2026 may join the list. A crisis around the Strait of Hormuz had the IEA forecasting in September that world oil demand would fall in 2026 and recover all of it in 2027¹¹. Working from the IEA’s fuel forecasts, Carbon Brief, a climate news site, estimates that fossil CO2 will fall by about 0.5%¹². That would be roughly a tenth of the 2020 drop. It is a journalist’s estimate built on forecasts, not a measurement.

Staying under 1.5 °C means cutting greenhouse gas emissions about 40% by 2030

To hold warming to 1.5 °C, greenhouse gas emissions would have to be 40% below their 2019 level by 2030 and 55% below by 2035, according to the UN Environment Programme (UNEP). Countries’ current pledges, carried out in full, would deliver about 12% to 15% by 2035. For 2 °C the cuts needed are 25% and 35%⁶.

The starting point has moved the wrong way. CO2 from energy was about 5% higher in 2025 than in 2019⁴, so the cut needed from today’s level is steeper than those percentages suggest.

Those percentages cover all greenhouse gases, of which CO2 from fossil sources is a little over two thirds, by our division of UNEP’s own table⁶. For CO2 alone the sum is simpler. Reaching net zero by 2050, the point at which any CO2 still emitted is balanced by CO2 removed, means cutting about 1.7 billion tonnes every year, or 4% of 2025 emissions¹. That is close to the drop of 2020, repeated every year for 25 years, without a pandemic to cause it.

The warming follows the total emitted. Every 180 billion tonnes of CO2 adds roughly 0.1 °C¹, which at today’s rate is a tenth of a degree for every four years or so of emissions.

The world is on a different path. Policies now in force lead to as much as 2.8 °C of warming this century by UNEP’s estimate⁶, or 2.6 °C by Climate Action Tracker’s, a research group that follows national policies⁷.

CO2 emissions are already falling in 35 economies

Emissions are falling in a growing part of the world. Between 2015 and 2024, 35 economies that together produce 27% of the world’s fossil CO2 cut their emissions while their economies grew, up from 18 in the decade before¹. The European Union’s fossil emissions in 2024 were 37% below their 1990 level and the United Kingdom’s 48% below. The United States is down 20% from its peak in 2005³.

The falls hold up when imported goods are counted. Measured by consumption, emissions fell by 28% in the EU since 2007, by 37% in the UK since 2004 and by 18% in the United States since 2005, up to 2023³.

These are the falls by design that the world as a whole has not yet managed. In these economies, it seems, energy efficiency and cleaner energy have improved faster than the economy has grown.

The world average has stopped climbing too: fossil emissions per person peaked at 4.85 tonnes in 2012 and were 4.73 in 2024².

Emissions from land use have been falling since the late 1990s¹. The Global Carbon Budget’s authors credit environmental policy, and point to deforestation in the Amazon at its lowest since 2014¹⁰.

Expectations have shifted as well. In 2015 Climate Action Tracker put the warming from current policies at 3.6 °C, a full degree above its estimate today⁷.

None of this is locked in. The 35 economies produce barely a quarter of the world’s fossil CO2, and the United States, down 20% since 2005, is estimated to have risen 2.5% in 2025¹.

Nobody has called the peak in CO2 emissions yet

Nobody has yet called the peak. UNEP says countries’ pledges point to a peak and decline in global emissions, but that the uncertainty is still too large for firm conclusions⁶.

The IEA’s two main scenarios mark out the range. Under policies already in place, CO2 from energy stays near 38 billion tonnes a year all the way to 2050. If governments also carry out the policies they have formally proposed, it falls below 30 billion tonnes by mid-century⁸. Even then, by those figures, most of today’s energy emissions would remain in 2050, the year net zero needs none.

Carry the last decade’s growth of 0.8% a year forward, which is arithmetic and not a prediction, and fossil emissions alone pass 40 billion tonnes in the early 2030s. The net-zero path would have emissions falling by 1.7 billion tonnes every year instead.

Much depends on China, where three studies reviewed by UNEP have emissions peaking around 2025⁶, and on whether a fall in 2026, if it comes, outlasts the crisis behind it. A fall caused by an oil crisis would be one more accident. The year to watch for is the one in which emissions fall with no crisis to explain it, and then keep falling, as they have for a decade in 35 economies.