It took the Earth’s climate around 100,000 years or more to recover, showing that a CO2 release of such magnitude may affect the Earth’s climate for that length of time. From 1990 to 2018 there was a 43% increase in total radiative forcing, with CO2 accounting for about 80% of this, according to figures from the NOAA, which is focused on the many sources, sinks and chemical transformations in the atmosphere. Carbon dioxide has a much longer residence time in the atmosphere, until it is either used up in photosynthesis or absorbed in rain or oceans. The oceans have also warmed slightly, affecting the climate. In December 2011 a report from the Global Carbon Project (GCP), a research consortium, pointed out that in 2010 CO2 emissions from fossil fuels and cement production were 33.4 ±1.8 Gt CO2, 41% of which was from coal and 34% from oil. Such estimates depend on the physical behaviour of each kind of molecule and its lifetime in the atmosphere, as well as the gas's concentration. In 2018 it rose 2.3 ppm (0.8%), and about 3 ppm in 2019 – the largest annual increase yet observed. Its remit does not focus on natural causes or trends of climate change. While the increase in carbon dioxide concentrations is remarkable, and the rate of anthropogenic emissions considerable (some 36 billion tonnes per year in 2014), even this is only about four percent of the natural flux between the atmosphere and the land and oceans. Substitution of coal by natural gas however requires consideration of methane leakage, and 3% leakage means that the global warming potential from using gas is the same as burning coal. The Geological Society, Climate Change: evidence from the geological record, A statement from the Geological Society of London (November 2010) For North America, climate change has had a major contribution to impacts on glaciers, snow, ice and/or permafrost and terrestrial ecosystems. * Carbon dioxide is essential to plant life, and needs to be at least 150 ppm to sustain it. It's the sun. Atmospheric concentrations of some of the gases that produce the greenhouse effect are increasing due to human activity and most of the world's climate scientists consider that this is a significant part of the cause of observed climate change. CO2 levels were already high at the time. Relating these atmospheric concentrations to emissions, sources and sinks is a steadily evolving sphere of scientific inquiry. The first two of four headline statements from Climate Change 2014: Synthesis Report (the Synthesis Report of the Fifth Assessment Report) are: Among the Fifth Assessment Report findings on physical science were: In the Fifth Assessment Report, four scenarios for future carbon emissions to 2100 ranged from means of 270 GtC, assuming substantial cuts in emissions and correlated with best-case radiative forcing of 2.5 W/m2, to 1685 GtC correlated with 8.5 W/m2 radiative forcing. (In the Antarctic there has been a slight increase in ice extent.). At the beginning of that cooling (in the early Eocene), the global average temperature was about 6-7 ºC warmer than now. Warming also heats the ocean, causing the water to expand and the sea level to rise. Carbon isotopic data show that this warming event (called by some the Paleocene-Eocene Thermal Maximum, or PETM) was accompanied by a major release of 1500-2000 billion tonnes or more of carbon (5550-7400 billion tonnes or more of CO2) into the ocean and atmosphere. The Fourth Assessment Report in 2007 further reduced uncertainties and led to calls for action. During the last ice age, pulses of freshwater from the ice sheet over North America led to slowing down of this overturning circulation and to widespread changes in climate around the Northern Hemisphere. This effect is enhanced by atmospheric sulfate aerosols and dust, which provide condensation nuclei. A sea level rise most likely to be 47-63 cm, due more to thermal expansion than retreating glaciers and Greenland ice cap. About 55 million years ago, at the end of the Paleocene, there was a sudden warming event in which temperatures rose by about 6 °C globally and by 10-20 °C at the poles. Arctic sea ice is an indicator. However, in many countries there are now programmes to reduce sulfur dioxide emissions from power stations, as these emissions cause acid rain. Scientists have studied plausible pathways to a ‘Hothouse Earth’ scenario, where interacting tipping points could potentially lead to a cascading effect where Earth’s temperature heats up to a catastrophic 4-5 °C. Evidence for climate change is preserved in a wide range of geological settings, including marine and lake sediments, ice sheets, fossil corals, stalagmites and fossil tree rings. Concentrations of some of them have increased steadily during the 20th century and into the 21st, with carbon dioxide (CO2) rising from under 300 parts per million (ppm) to over 400 ppm. Finally, in relating emissions to atmospheric concentrations, there is the question of sinks, or natural processes for breaking down or removing individual gases, particularly carbon dioxide. Widespread changes in extreme temperatures have been observed over the last 50 years. The Geological Society, An Addendum to the Statement on Climate Change: Evidence from the Geological Record, The Geological Society (December 2013), © 2016-2021 World Nuclear Association, registered in England and Wales, number 01215741. This is natural and what keeps the Earth habitable. As well as the band consideration, methane is a stronger greenhouse gas because it has more atoms in the molecule than CO2. Climate scientists use a concept called radiative forcing to quantify the effect of these increased concentrations on climate. The Fifth Assessment Report in 2013-2014 repeated the call for a global agreement to limit carbon emissions, though it did slightly adjust downward the likely effects of increased CO2 levels. The Sixth Assessment Report is anticipated in 2021, but meanwhile there are two other relevant reports (see below). 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