copenlu/druid huggingface dataset:
Claim: We do not know if CO2 is the cause of global warming (Holman W. Jenkins Jr., 2023-11-03)
Evidence (2020-10-29): Are humans causing or contributing to global warming? Yes, by increasing the abundance of greenhouse gases in the atmosphere, human activities are amplifying Earth’s natural greenhouse effect. Virtually all climate scientists agree that this increase in heat-trapping gases is the main reason for the 1.8°F (1.0°C) rise in global average temperature since the late nineteenth century. Carbon dioxide, methane, nitrous oxide, ozone, and various chlorofluorocarbons are all human-emitted heat-trapping gases. Among these, carbon dioxide is of greatest concern to scientists because it exerts a larger overall warming influence than the other gases combined. At present, humans are putting an estimated 9.5 billion metric tons of carbon into the atmosphere each year by burning fossil fuels, and another 1.5 billion through deforestation and other land cover changes. Of this human-produced carbon, forests and other vegetation absorb around 3.2 billion metric tons per year, while the ocean absorbs about 2.5 billion metric tons per year. A net 5 billion metric tons of human-produced carbon remain in the atmosphere each year, raising the global average carbon dioxide concentrations by about 2.3 parts per million per year. Since 1750, humans have increased the abundance of carbon dioxide in the atmosphere by nearly 50 percent. Learn more.
Claim: We do not know if CO2 is the cause of global warming (Holman W. Jenkins Jr., 2023-11-03)
Evidence (2020-05-23): Here, too, commenters on this blog often claim that since recent periods in Earth’s past were almost as warm as it is now, we can’t know for sure that the CO2 we’ve added to the atmosphere is responsible for the observed recent warming. But in their paper, published in the journal Scientific Reports, the scientists confirmed that our emissions of greenhouse gases, "especially CO2, are the main causal drivers of the recent warming." [...] They’ve also never contended that CO2 is the sole factor driving climate changes over geologic history. As we’ve seen, however, it plays a key role: Without the CO2 thermostat, Earth would likely be a proverbial snowball.
Claim: We do not know if CO2 is the cause of global warming (Holman W. Jenkins Jr., 2023-11-03)
Evidence (2021-10-25): Greenhouse gases - which trap the Sun's heat - are the crucial link between temperature rise and human activities. The most important is carbon dioxide (CO2), because of its abundance in the atmosphere. We can also tell it's CO2 trapping the Sun's energy. Satellites show less heat from the Earth escaping into space at precisely the wavelengths at which CO2 absorbs radiated energy. Burning fossil fuels and chopping down trees lead to the release of this greenhouse gas. Both activities exploded after the 19th Century, so it's unsurprising that atmospheric CO2 increased over the same period.
Claim: We do not know if CO2 is the cause of global warming (Holman W. Jenkins Jr., 2023-11-03)
Evidence (2022-06-15): Scientists demonstrated the heat-trapping nature of carbon dioxide and other gases in the mid-19th century.2 Many of the science instruments NASA uses to study our climate focus on how these gases affect the movement of infrared radiation through the atmosphere. From the measured impacts of increases in these gases, there is no question that increased greenhouse gas levels warm Earth in response. [...] In the 1860s, physicist John Tyndall recognized Earth's natural greenhouse effect and suggested that slight changes in the atmospheric composition could bring about climatic variations. In 1896, a seminal paper by Swedish scientist Svante Arrhenius first predicted that changes in atmospheric carbon dioxide levels could substantially alter the surface temperature through the greenhouse effect. In 1938, Guy Callendar connected carbon dioxide increases in Earth’s atmosphere to global warming. In 1941, Milutin Milankovic linked ice ages to Earth’s orbital characteristics. Gilbert Plass formulated the Carbon Dioxide Theory of Climate Change in 1956.
Claim: We do not know if CO2 is the cause of global warming (Holman W. Jenkins Jr., 2023-11-03)
Evidence (2010-05-04): The first piece of evidence that the warming over the past few decades isn’t part of a natural cycle is how fast the change is happening. The biggest temperature swings our planet has experienced in the past million years are the ice ages. Based on a combination of paleoclimate data and models, scientists estimate that when ice ages have ended in the past, it has taken about 5,000 years for the planet to warm between 4 and 7 degrees Celsius. The warming of the past century—0.7 degrees Celsius—is roughly eight times faster than the ice-age-recovery warming on average. The second reason that scientists think the current warming is not from natural influences is that, over the past century, scientists from all over the world have been collecting data on natural factors that influence climate—things like changes in the Sun’s brightness, major volcanic eruptions, and cycles such as El Niño and the Pacific Decadal Oscillation. These observations have failed to show any long-term changes that could fully account for the recent, rapid warming of Earth’s temperature. Finally, scientists know that carbon dioxide is a greenhouse gas and that it is released into the air when coal and other fossil fuels burn. Paleoclimate data show that atmospheric carbon dioxide levels are higher than they have been in the past 800,000 years. There is no plausible explanation for why such high levels of carbon dioxide would not cause the planet to warm.
Claim: We do not know if CO2 is the cause of global warming (Holman W. Jenkins Jr., 2023-11-03)
Evidence (2022-06-15): A vital component of the atmosphere, carbon dioxide (CO2) is released through natural processes (like volcanic eruptions) and through human activities, such as burning fossil fuels and deforestation. [...] In its Sixth Assessment Report, the Intergovernmental Panel on Climate Change, composed of scientific experts from countries all over the world, concluded that it is unequivocal that the increase of CO2, methane, and nitrous oxide in the atmosphere over the industrial era is the result of human activities and that human influence is the principal driver of many changes observed across the atmosphere, ocean, cryosphere and biosphere. [...] - If a more active Sun caused the warming, scientists would expect warmer temperatures in all layers of the atmosphere. Instead, they have observed a cooling in the upper atmosphere and a warming at the surface and lower parts of the atmosphere. That's because greenhouse gases are slowing heat loss from the lower atmosphere.
Claim: We do not know if CO2 is the cause of global warming (Holman W. Jenkins Jr., 2023-11-03)
Evidence (2024-01-01): - How do scientists know that recent climate change is largely caused by human activities? - CO2 is already in the atmosphere naturally, so why are emissions from human activity significant? [...] - Is there a point at which adding more CO2 will not cause further warming?
Claim: We do not know if CO2 is the cause of global warming (Holman W. Jenkins Jr., 2023-11-03)
Evidence (2023-09-25): American Geophysical Union "Based on extensive scientific evidence, it is extremely likely that human activities, especially emissions of greenhouse gases, are the dominant cause of the observed warming since the mid-20th century. There is no alterative explanation supported by convincing evidence." (2019)5 - [...] The Geological Society of America "The Geological Society of America (GSA) concurs with assessments by the National Academies of Science (2005), the National Research Council (2011), the Intergovernmental Panel on Climate Change (IPCC, 2013) and the U.S. Global Change Research Program (Melillo et al., 2014) that global climate has warmed in response to increasing concentrations of carbon dioxide (CO2) and other greenhouse gases ... Human activities (mainly greenhouse-gas emissions) are the dominant cause of the rapid warming since the middle 1900s (IPCC, 2013)." (2015)9 [...] Intergovernmental Panel on Climate Change "It is unequivocal that the increase of CO2, methane, and nitrous oxide in the atmosphere over the industrial era is the result of human activities and that human influence is the principal driver of many changes observed across the atmosphere, ocean, cryosphere, and biosphere.
Claim: We do not know if CO2 is the cause of global warming (Holman W. Jenkins Jr., 2023-11-03)
Evidence (2024-01-01): Scientists have determined that, when all human and natural factors are considered, Earth’s climate balance has been altered towards warming, with the biggest contributor being increases in CO2. [...] Based just on the physics of the amount of energy that CO2 absorbs and emits, a doubling of atmospheric CO2 concentration from pre-industrial levels (up to about 560 ppm) would by itself cause a global average temperature increase of about 1 °C (1.8 °F). In the overall climate system, however, things are more complex; warming leads to further effects (feedbacks) that either amplify or diminish the initial warming. [...] Fingerprinting is a powerful way of studying the causes of climate change. Different influences on climate lead to different patterns seen in climate records. This becomes obvious when scientists probe beyond changes in the average temperature of the planet and look more closely at geographical and temporal patterns of climate change. For example, an increase in the Sun’s energy output will lead to a very different pattern of temperature change (across Earth’s surface and vertically in the atmosphere) compared to that induced by an increase in CO2 concentration. Observed atmospheric temperature changes show a fingerprint much closer to that of a long-term CO2 increase than to that of a fluctuating Sun alone. Scientists routinely test whether purely natural changes in the Sun, volcanic activity, or internal climate variability could plausibly explain the patterns of change they have observed in many different aspects of the climate system. These analyses have shown that the observed climate changes of the past several decades cannot be explained just by natural factors.
Claim: We do not know if CO2 is the cause of global warming (Holman W. Jenkins Jr., 2023-11-03)
Evidence (2021-02-25): With CO2 and other greenhouse gases, it’s different. Carbon dioxide, for example, absorbs energy at a variety of wavelengths between 2,000 and 15,000 nanometers — a range that overlaps with that of infrared energy. As CO2 soaks up this infrared energy, it vibrates and re-emits the infrared energy back in all directions. About half of that energy goes out into space, and about half of it returns to Earth as heat, contributing to the ‘greenhouse effect.’ [...] Before humans began burning fossil fuels, naturally occurring greenhouse gases helped to make Earth’s climate habitable. Without them, the planet’s average temperature would be below freezing. So we know that even very low, natural levels of carbon dioxide and other greenhouse gases can make a huge difference in Earth’s climate. [...] As carbon dioxide and other greenhouse gases heat up the planet, more water evaporates into the atmosphere, which in turn raises the temperature further. However, a hypothetical villain would not be able to exacerbate climate change by trying to pump more water vapor into the atmosphere, says Smerdon. "It would all rain out because temperature determines how much moisture can actually be held by the atmosphere."
Claim: We do not know if CO2 is the cause of global warming (Holman W. Jenkins Jr., 2023-11-03)
Evidence (2024-04-09): Carbon dioxide is Earth’s most important greenhouse gas: a gas that absorbs and radiates heat. Unlike oxygen or nitrogen (which make up most of our atmosphere), greenhouse gases absorb heat radiating from the Earth’s surface and re-release it in all directions—including back toward Earth’s surface. Without carbon dioxide, Earth’s natural greenhouse effect would be too weak to keep the average global surface temperature above freezing. By adding more carbon dioxide to the atmosphere, people are supercharging the natural greenhouse effect, causing global temperature to rise. According to observations by the NOAA Global Monitoring Lab, in 2021 carbon dioxide alone was responsible for about two-thirds of the total heating influence of all human-produced greenhouse gases. [...] Natural increases in carbon dioxide concentrations have periodically warmed Earth’s temperature during ice age cycles over the past million years or more. The warm episodes (interglacials) began with a small increase in incoming sunlight in the Northern Hemisphere due to variations in Earth’s orbit around the Sun and its axis of rotation. (For more details, see the "Milankovitch cycles and ice ages" section of our Climate change: incoming sunlight article.) That little bit of extra sunlight caused a little bit of warming. As the oceans warmed, they outgassed carbon dioxide—like a can of soda going flat in the heat of a summer day. The extra carbon dioxide in the atmosphere greatly amplified the initial, solar-driven warming.
Claim: We do not know if CO2 is the cause of global warming (Holman W. Jenkins Jr., 2023-11-03)
Evidence (2008-07-01): The question matters because if the ocean starts to take up less carbon because of global warming, more is left in the atmosphere where it can contribute to additional warming. Scientists wanted to understand how the ocean carbon cycle might change so that they could make more accurate predictions about global warming. Thus motivated, oceanographers began a series of research cruises, trolling across the Pacific from Japan to California, from Alaska to Hawaii, and through the North Atlantic from Europe to North America. On shore, others developed computer models. One of the largest unknowns in our understanding of the greenhouse effect is the role of the oceans as a carbon sink. Much of the carbon dioxide released into the atmosphere by the burning of fossil fuels is soaked up by the oceans, but changes in the climate are altering this absorption in surprising ways. (Photograph ©2007 *Fede*.) [...] "When we started in the 70s and 80s, we had this concept: we’ll measure [carbon dioxide concentrations in the ocean] 10 years later, and we’ll just see the anthropogenic input," says Feely. "We had very simplistic ideas that the anthropogenic changes would be the only changes we would see," he adds a little ruefully.
Claim: We do not know if CO2 is the cause of global warming (Holman W. Jenkins Jr., 2023-11-03)
Evidence (2023-08-15): Carbon dioxide (CO2) is an important heat-trapping gas, also known as a greenhouse gas, that comes from the extraction and burning of fossil fuels (such as coal, oil, and natural gas), from wildfires, and natural processes like volcanic eruptions. The first graph shows atmospheric CO2 levels measured by NOAA at Mauna Loa Observatory, Hawaii, since 1958. The second graph shows CO2 levels during Earth’s last three glacial cycles, as captured by air bubbles trapped in ice sheets and glaciers. Since the onset of industrial times in the 18th century, human activities have raised atmospheric CO2 by 50% – meaning the amount of CO2 is now 150% of its value in 1750. This human-induced rise is greater than the natural increase observed at the end of the last ice age 20,000 years ago. [...] This boom-and-bust cycle of plant growth gives the graph of CO2 a sawtooth pattern of ups and downs from year to year. At a larger scale, the upward climb of the trend line over the decades is caused by CO2 emissions, primarily from burning fossil fuels. Thus, the data illustrate both natural factors and human additions of CO2.
Claim: We do not know if CO2 is the cause of global warming (Holman W. Jenkins Jr., 2023-11-03)
Evidence (2024-10-09): Global warming is the rise in average global surface temperature caused primarily by the build-up of human-produced greenhouses gases, mostly carbon dioxide and methane, which trap heat in the lower levels of the atmosphere. [...] Science suggests that to mitigate the human contribution to global warming, we should reduce carbon dioxide and other greenhouse gas emissions. Because some additional warming is inevitable—even if we achieve significant greenhouse gas reductions quickly—we should make plans to adapt to coming climate change. If we are unable to control emissions and/or adapt to unavoidable changes quickly enough, a carefully selected geoengineering strategy could conceivably provide an emergency stopgap to slow global warming. As yet, however, several of the strategies being discussed are very risky and unproven. [...] This pattern (statisticians call it a "right-skewed distribution") suggests that if carbon dioxide concentrations double, the probability of very large increases in temperature is greater than the probability of very small increases.
Claim: We do not know if CO2 is the cause of global warming (Holman W. Jenkins Jr., 2023-11-03)
Evidence (2012-04-04): B.1.1. Evidence from attributed changes in some climate and weather extremes for a global warming of about 0.5°C supports the assessment that an additional 0.5°C of warming compared to present is associated with further detectable changes in these extremes (medium confidence). Several regional changes in climate are assessed to occur with global warming up to 1.5°C compared to pre-industrial levels, including warming of extreme temperatures in many regions (high confidence), increases in frequency, intensity, and/or amount of heavy precipitation in several regions (high confidence), and an increase in intensity or frequency of droughts in some regions (medium confidence). {3.2, 3.3.1, 3.3.2, 3.3.3, 3.3.4, Table 3.2} [...] B.4.3. The level of ocean acidification due to increasing CO2 concentrations associated with global warming of 1.5°C is projected to amplify the adverse effects of warming, and even further at 2°C, impacting the growth, development, calcification, survival, and thus abundance of a broad range of species, for example, from algae to fish (high confidence). {3.3.10, 3.4.4}
Claim: We do not know if CO2 is the cause of global warming (Holman W. Jenkins Jr., 2023-11-03)
Evidence (2009-07-14): Scientists agree that global warming is caused mainly by human activity. Specifically, the evidence shows that certain heat-trapping gases, such as carbon dioxide, are warming the world—and that we release those gases when we burn fossil fuels like coal, oil, and gas. [...] Carbon dioxide (CO2) is the heat-trapping gas in our atmosphere responsible for most of the warming measured over the past several decades. It’s released during cement manufacturing and when coal, gas, and oil are burned—something humans started doing a great deal of during the Industrial Revolution through to today. [...] We know that CO2 warms the world, that CO2 concentrations are at record-breaking levels, and that global temperatures are rising. But how do we know for certain that humans are the cause?
Claim: We do not know if CO2 is the cause of global warming (Holman W. Jenkins Jr., 2023-11-03)
Evidence (2021-08-09): However, strong and sustained reductions in emissions of carbon dioxide (CO2) and other greenhouse gases would limit climate change. While benefits for air quality would come quickly, it could take 20-30 years to see global temperatures stabilize, according to the IPCC Working Group I report, Climate Change 2021: the Physical Science Basis, approved on Friday by 195 member governments of the IPCC, through a virtual approval session that was held over two weeks starting on July 26. [...] The report shows that emissions of greenhouse gases from human activities are responsible for approximately 1.1°C of warming since 1850-1900, and finds that averaged over the next 20 years, global temperature is expected to reach or exceed 1.5°C of warming. This assessment is based on improved observational datasets to assess historical warming, as well progress in scientific understanding of the response of the climate system to human-caused greenhouse gas emissions. [...] The report also shows that human actions still have the potential to determine the future course of climate. The evidence is clear that carbon dioxide (CO2) is the main driver of climate change, even as other greenhouse gases and air pollutants also affect the climate.
Claim: We do not know if CO2 is the cause of global warming (Holman W. Jenkins Jr., 2023-11-03)
Evidence (2024-01-01): Yes. Wildfires release carbon dioxide (CO2) emissions and other greenhouse gases (GHG) that contribute to climate change. It is challenging to determine how much wildfire emissions alter the GHG concentrations in the atmosphere and contribute to anthropogenic climate change because wildfire emissions are part of the terrestrial carbon cycle. [...] Earth’s terrestrial carbon cycle transfers carbon between the land, ocean, and atmosphere. As part of the terrestrial carbon cycle, fire, plant respiration and decomposition are balanced by plant growth and other processes that take place over decades or centuries. When in balance, these biogenic CO2 emissions from fire and other sources are offset by biogenic CO2 sequestration, resulting in relatively minimal change in the total concentration of atmospheric CO2 that drives climate change. Emissions from fossil-fuel combustion are contributing to putting this cycle out of balance. They are also contributing to a negative feedback loop for California’s forests and lands: as CO2 emission accumulate in the atmosphere and California experiences more warming, extreme heat events, droughts, and invasive species, the risk and intensity of fires also increases, which in turn push the terrestrial carbon cycle further out of balance. [...] In 2018, the Intergovernmental Panel on Climate Change (IPCC) issued a Special Report that made it clear that limiting climate change to 1.5 degrees Celsius would require global carbon neutrality by 2045, and that carbon neutrality must include the sources and sinks from emissions from all sectors, including natural and working lands.
Claim: We do not know if CO2 is the cause of global warming (Holman W. Jenkins Jr., 2023-11-03)
Evidence (2016-09-01): Many greenhouse gases stay in the atmosphere for long periods of time. As a result, even if emissions stopped increasing, atmospheric greenhouse gas concentrations would continue to increase and remain elevated for hundreds of years. Moreover, if we stabilized concentrations and the composition of today's atmosphere remained steady (which would require a dramatic reduction in current greenhouse gas emissions), surface air temperatures would continue to warm. This is because the oceans, which store heat, take many decades to fully respond to higher greenhouse gas concentrations. The ocean's response to higher greenhouse gas concentrations and higher temperatures will continue to impact climate over the next several decades to hundreds of years.[2] [...] Because it is difficult to project far-off future emissions and other human factors that influence climate, scientists use a range of scenarios using various assumptions about future economic, social, technological, and environmental conditions. We have already observed global warming over the last several decades. Future temperatures are expected to change further. Climate models project the following key temperature-related changes.