climatechange.procon.orgIs Human Activity Responsible for Climate Change? 13 Pros and Cons

More IssuesFAQs Teachers’ Corner Climate Change Is Human Activity Primarily Responsible for Global Climate Change? Last updated on: 4/1/2020 | Author: ProCon.org ARCHIVED WEBSITE This topic was archived on June 23, 2023. A reconsideration of the topic is possible in the future. Average surface temperatures on earth have risen more than 2°F over the past 100 years. During this time period, atmospheric levels of greenhouse gases such as carbon dioxide (CO2) and methane (CH4) have notably increased. This site explores the debate on whether climate change is caused by humans (also known as anthropogenic climate change). The pro side argues rising levels of atmospheric greenhouse gases are a direct result of human activities such as burning fossil fuels , and that these increases are causing significant and increasingly severe climate changes including global warming, loss of sea ice, sea level rise, stronger storms, and more droughts. They contend that immediate international action to reduce greenhouse gas emissions is necessary to prevent dire climate changes. The con side argues human-generated greenhouse gas emissions are too small to substantially change the earth’s climate and that the planet is capable of absorbing those increases. They contend that warming over the 20th century resulted primarily from natural processes such as fluctuations in the sun’s heat and ocean currents. They say the theory of human-caused global climate change is based on questionable measurements, faulty climate models, and misleading science. Read more background… Pro & Con Arguments Pro 1 Overwhelming scientific consensus finds human activity primarily responsible for climate change. According to many peer-reviewed studies, over 97% of climate scientists agree that human activity is extremely likely to be the cause of global climate change. [ 7 ] Most scientific organizations also support this view, including the American Medical Association and an international coalition of science academies. [ 7 ] A prominent review of 11,944 peer-reviewed studies on climate change found that only 78 studies (0.7%) explicitly rejected the idea of anthropogenic (resulting from human activity) global warming. [ 1 ] A separate review of 13,950 peer-reviewed studies on climate change found only 24 that rejected human-caused global warming. [ 5 ] An examination of scientific papers that didn’t agree that humans cause climate change found serious flaws and bias in their research. [ 206 ] Read More Pro 2 Rising levels of human-produced gases released into the atmosphere create a greenhouse effect that traps heat and causes global warming. Gases released into the atmosphere trap heat and cause the planet to warm through a process called the greenhouse effect. [ 8 ] When we burn fossil fuels to heat our homes, drive our cars, and run factories, we’re releasing emissions that cause the planet to warm. [ 9 ] Methane, which is increasing in the atmosphere due to agriculture and fossil fuel production, traps 84 times as much heat as CO2 for the first 20 years it is in the atmosphere, [ 11 ] and is responsible for about one-fifth of global warming since 1750. [ 12 ] Nitrous oxide, primarily released through agricultural practices, traps 300 times as much heat as CO2. [ 13 ] Over the 20th century, as the concentrations of CO2, CH4, and NO2 increased in the atmosphere due to human activity, [ 13 ] [ 14 ] the earth warmed by approximately 1.4°F. [ 99 ] Read More Pro 3 The rise in atmospheric CO2 over the last century was clearly caused by human activity, as it occurred at a rate much faster than natural climate changes could produce. Over the past 650,000 years, atmospheric CO2 levels did not rise above 300 ppm until the mid-20th century. [ 100 ] Atmospheric levels of CO2 have risen from about 317 ppm in 1958 to 415 ppm in 2019. [ 10 ] [ 194 ] According to the Scripps Institution of Oceanology, the extreme speed at which carbon dioxide concentrations are increasing is unprecedented. An increase of 10 parts per million might have needed 1,000 years or more to come to pass during ancient climate change events.” [ 17 ] Some climate models predict that by the end of the 21st century an additional 5°F-10°F of warming will occur. [ 16 ] Read More Pro 4 The specific type of CO2 that is increasing in earth’s atmosphere can be directly connected to human activity. We can tell that CO2 produced by humans burning fossil fuels such as oil and coal [ 18 ] is different than naturally occurring CO2 by looking at the specific isotopic ratio. [ 101 ] According to the Intergovernmental Panel on Climate Change (IPCC), 20th century measurements of CO2 isotope ratios in the atmosphere confirm that rising CO2 levels are the result of human activity as opposed to gas coming off the oceans, volcanic activity, or other natural causes. [ 102 ] The US Environmental Protection Agency says that Human activities are responsible for almost all of the increase in greenhouse gases in the atmosphere over the last 150 years.” [ 19 ] Read More Pro 5 Average temperatures on earth have increased at a rate far faster than can be explained by natural climate changes. Average surface temperatures on earth have risen more than 2°F over the past 100 years. [ 205 ] According to NASA, The current warming trend is of particular significance because most of it is extremely likely (greater than 95 percent probability) to be the result of human activity since the mid-20th century and proceeding at a rate that is unprecedented over decades to millennia.” [ 24 ] A 2008 study comparing data from tree rings, ice cores, and corals over the past millennium created the famous hockey stick” graph showing a steady trend in the earth’s temperature over the last 1,700 years followed by a steep jump in the previous decade (forming a shape like a hockey stick). [ 23 ] Berkeley scientists found that the average temperature of the earth’s land increased 2.5°F over 250 years (1750-2000), 1.5°F of which appears likely” to be attributable to humans over the past 50 years. [ 21 ] Read More Pro 6 Natural changes in the sun’s activity cannot explain 20th century global warming. The amount of solar energy received by the earth goes up and down in cycles, but overall there is no net change since the 1950s. There has, however, been a big increase in global temperatures that is too large to attribute to the sun. For this reason, NASA and other scientists say the sun is not responsible for global warming. [ 28 ] The sun has had only a minor effect on the Northern Hemisphere climate over the past 1,000 years, and global warming from human-produced greenhouse gases has been the primary cause of climate change since 1900. [ 26 ] A study found that solar activity could not have contributed to more than 10% of the observed global warming over the 20th century. [ 27 ] Read More Pro 7 Global warming caused by human-produced greenhouse gases is causing the Arctic ice cap to melt at an increasing rate. From 1953–2006, Arctic sea ice declined 7.8% per decade. Between 1979 and 2006, the decline was 9.1% each decade. [ 105 ] By 2019, Arctic sea ice was being lost at a rate of 12.9% per decade. [ 163 ] As the Arctic ice cover continues to decrease, the amount of the sun’s heat reflected by the ice back into space also decreases. This positive-feedback loop amplifies global warming at a rate even faster than previous climate models had predicted. [ 30 ] Some studies predicted the Arctic could become nearly ice free sometime between 2020-2060. [ 164 ] Read More Pro 8 Sea levels are rising at an unprecedented rate due to human activities. Sea levels rise due to thermal expansion of warming ocean waters and melt water from receding glaciers and the polar ice cap. [ 165 ] According to the IPCC, there has been a substantial” human contribution to the global mean sea-level rise since the 1970s. [ 29 ] As much as 87% of the rise in sea levels since 1970 resulted from human activities such as...