About 34 million years ago, at the end of the Eocene, ice caps coalesced to form a continental ice sheet on Antarctica. World Meteorological Organization, Greenhouse Gas Bulletin #13 (30 October 2017) The third part of each IPCC Assessment Report (Working Group III) deals with the mitigation of climate change, outlining the prospects and options for change, particularly in the energy sector, which accounts for 60% of emissions. Limiting climate change would require substantial and sustained reductions in greenhouse gas emissions which, together with adaptation, can limit climate change risks. Global emissions of energy-related CO2 are projected in several scenarios in the International Energy Agency's (IEA) annual World Energy Outlook reports. Average life-cycle carbon dioxide-equivalent emissions for different electricity generators (Source: IPCC). The Intergovernmental Panel on Climate Change (IPCC) is a scientific body under the auspices of the UN, set up in 1988 to review and assess scientific and other information on human contributions to climate change. This is natural and what keeps the Earth habitable. * Carbon dioxide is essential to plant life, and needs to be at least 150 ppm to sustain it. The following information comes from a 2010 position statement from the Geological Society of London.The Earth’s climate has been gradually cooling for most of the las… During those periods, global temperatures were 2-3 °C higher than now, and sea levels were higher than now by 10-25 metres, implying that global ice volume was much less than today. In 2013 the Geological Society published an addendum to its 2010 position statement, which said that new climate data from the geological record strengthen the 2010 statement’s original conclusion that CO2 is a major modifier of the climate system, and that human activities are responsible for recent warming. It said that the most cost-effective option for restricting the temperature rise to under 3 °C will require an increase in non-carbon electricity generation from 34% (nuclear plus hydro) now to 48-53% by 2030, along with other measures. Then there is the question of residence time in the atmosphere. It also appears that increased levels of carbon dioxide will increase the capture of heat in its main absorption band to some extent, though diminishing as levels increase, while more energy is absorbed in the weaker bands. 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. The rate was faster over 1993 to 2010, about 3.2 mm per year. Climate researchers have designed models to predict the longer-term consequences both in air and ocean circulation patterns. That period is known as the ‘Ice Age’, a series of glacial episodes separated by short warm ‘interglacial’ periods that lasted between 10,000-30,000 years. The current warming trend is of particular significance because most of it is extremely likely (greater than 95% probability) to be the result of human activity since the mid-20 th century and proceeding at a rate that is unprecedented over decades to millennia. However there is now strong evidence that significant global warming is occurring. The remainder of the 'window' coincides with the absorption proclivities of the other radiative gases: methane, (tropospheric) ozone, CFCs and nitrous oxide. European Commission, Joint Research Centre (JRC) Emissions Database for Global Atmospheric Research (EDGAR) 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. Climate Change 2013: The Physical Science Basis The Working Group I contribution to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) provides a comprehensive assessment of the physical science basis of climate change since 2007 when the Fourth Assessment Report (AR4) was released. Recent estimates suggest that at times between 5.2 and 2.6 million years ago (during the Pliocene), the carbon dioxide concentrations in the atmosphere reached between 330 and 400 ppm. However, as warming increases, the possibilities of major abrupt change cannot be ruled out.” However, “the climate system involves many competing processes that could switch the climate into a different state once a threshold has been exceeded. Of this 545 GtC, about 240 GtC (44%) had accumulated in the atmosphere, 155 GtC (28%) had been taken up in the oceans with slight consequent acidification, and 150 GtC (28%) had accumulated in the terrestrial ecosystems. Ice sheets grow when the Earth cools and melt when it warms. The first details the physical scientific basis for climate change. The IPCC prepared a special report on Global Warming of 1.5 °C, and how this might be achieved in the context of sustainable development and efforts to eradicate poverty. Emissions of sulfates are increasingly constrained in most countries. The report projects other non-carbon sources apart from hydro contributing some 12-17% of global electricity generation by 2030. However, the climate is a complex system and other factors influence global temperatures. The present warm period (known as the Holocene) became established only 11,500 years ago, since when our climate has been relatively stable. 15 (25 November 2019). 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. Radiative forcing … Accordingly, it predicted that, based on the range of scenarios, by the end of the 21st century climate change will result in : There remains considerable uncertainty regarding the above effects on the frequency and intensity of hurricanes, tornadoes and to some extent, droughts. The ocean absorbs nearly 25% of the annual emissions of anthropogenic CO, Implementing current unconditional nationally-determined contributions (NDC) to reducing CO. On this course you will explore this science, looking back across 4 billion years of Earth’s history to help you learn the difference between ‘natural’ from ‘human’ induced change; looking to the present to see how the impacts of climate change … It also says: “Results from the best available climate models do not predict abrupt changes in such systems (often referred to as tipping points) in the near future. 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. T he work of the Intergovernmental Panel on Climate Change (IPCC) represents the consensus of the international scientific community on climate change science. The difference is greater considering developing countries' average 25% efficiency. * About 36.6 billion tonnes (9.98 GtC) from fossil fuels and cement production in 2018, plus about 5.5 Gt from land use change and deforestation (WMO Greenhouse Gas Bulletin #15). During parts of the previous interglacial period, when polar temperatures reached 3-5 °C above today’s, global sea levels were higher than today’s by around 4-9 metres. In May 2013 the daily mean concentration of carbon dioxide in the atmosphere of Mauna Loa, Hawaii, the primary global benchmark site, surpassed 400 ppm for the first time since measurements began there in 1958. Relatively rapid global warming has occurred in the past. S.J. It was signed off by over 100 countries which agreed that major changes are required, to adopt low-carbon energy technologies. Both direct and indirect effects due to interaction with other gases and radicals must be taken into account and some of the latter remain uncertain. A large part of the increase in all greenhouse gases is attributed to human sources, i.e. The combined radiative forcing due to increases in carbon dioxide, methane, nitrous oxide and halocarbons is +2.83 W/m. 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. This perspective is important as a reminder that only a very small change to natural processes is required to compensate for (or exacerbate) anthropogenic emissions. Continued emission of greenhouse gases will cause further warming and long-lasting changes in all components of the climate system, increasing the likelihood of severe, pervasive and irreversible impacts for people and ecosystems. However, there is doubt about whether in practice this occurs to the extent previously thought. There are clear benefits to keeping warming to 1.5 °C compared with 2 °C or higher. Although water vapour has a major influence on absorbing long-wave thermal radiation, its GWP is not calculated since its concentration in the atmosphere varies widely and mainly depends on air temperature. More bonds = more vibrations = more IR absorption. Climate Change poses an increasing threat to the stability of Earth’s systems. The second part of each IPCC Assessment Report (Working Group II) deals with impacts, adaptation and vulnerabilities. Global Monitoring Division (GMD) of the National Oceanic and Atmospheric Administration's Earth System Research Laboratory, Trends in Atmospheric Carbon Dioxide Over the last decades, global warming has led to widespread shrinking of the cryosphere, with mass loss from ice sheets and glaciers (, Global mean sea level (GMSL) is rising, with acceleration in recent decades due to increasing rates of ice loss from the Greenland and Antarctic ice sheets (, Ecosystems in high mountain and polar regions and also marine ecosystems have changed (. Climate change has inexorably stacked the deck in favor of bigger and more intense fires across the American West over the past few decades, science … 1 Relating these atmospheric concentrations to emissions, sources and sinks is a steadily evolving sphere of scientific inquiry. Furthermore, slow-acting factors like the decay of large ice sheets and the operation of the full carbon cycle, suggest that this could double the climate sensitivity. As well as the band consideration, methane is a stronger greenhouse gas because it has more atoms in the molecule than CO2. Meeting the Paris Agreement requires immediate and all-inclusive action encompassing deep decarbonization complemented by ambitious policy measures, protection and enhancement of carbon sinks and biodiversity, and effort to remove CO. Hence this balancing factor will diminish and the rate of temperature increase due to greenhouse gases may consequently increase. Hence there is, for the time being, a balancing cooling effect on the Earth's surface. It is based at the WMO in Geneva. Global air temperatures do appear to have risen about 0.6 °C over the last century, though this has been irregular rather than steady, and does not correlate well with the steady increase in greenhouse gas – notably CO2 – concentrations. A number of indicators suggest that atmospheric warming due to increased levels of greenhouse gases is indeed observable since 1970, despite some masking by aerosols (see below). Human influence on the climate system is clear, and recent anthropogenic emissions of greenhouse gases are the highest in history. 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. Electricity generation is one of the major sources of carbon dioxide emissions, providing about one-third of the total and one-half of the increase expected 2005-30. (In the Antarctic there has been a slight increase in ice extent.). If we want to protect our planet from dangerous and unprecedented change, first we must understand the science behind climate change. According to the GCP these ended up 50% in the atmosphere, 26% in biomass and 24% in oceans. Recent studies show that the oceans lose heat to the atmosphere during warm El Niño events, while more heat penetrates to ocean depths in cold La Niñas. The third part identifies options for mitigation of climate change. If all the world's nuclear power were replaced by coal-fired power, electricity's carbon dioxide emissions (now at least 11 billion tonnes per year) would rise by a quarter – about 3 billion tonnes per year. More than 60% of the net energy increase in the climate system was stored in the upper ocean (0-700 m) from 1971 to 2010, and about 30% is stored in the ocean below 700 m. Anthropogenic influences likely contributed to the retreat of glaciers since the 1960s and to the diminution of the Greenland ice sheet since 1993. Thus nuclear power's contribution could increase to perhaps 30% of the global generation mix in 2030. If such a rapid release occurred, then major, fast climate changes would ensue. A Synthesis Report, including a Summary for Policymakers, is also published for all three reports. 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 the atmosphere, some warming of the troposphere is evident since the mid-20th century, though there has been an apparent pause in warming since 1998. When ice sheets were at a maximum during the Pleistocene, world sea level fell to at least 120 metres below where it stands today. Climate change has had a minor contribution to impacts on wildfires. In addition to these well-documented radiative gases there is increasing concern about sulfur hexafluoride (SF6) used in grid switchgear, with about 8000 tonnes emitted annually and increased use envisaged. The 'greenhouse effect' is the term used to describe the retention of heat in the Earth's lower atmosphere (troposphere) due to concentrations of certain trace gases and water vapour in the atmosphere. Estimates of the individual contribution of particular gases to the greenhouse effect – their global warming potential (GWP), are broadly agreed (relative to carbon dioxide = 1). 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. Certain inputs to the atmosphere can be discerned and readily quantified – carbon dioxide from fossil fuel burning* and CFCs from refrigerants for instance. The oceans have also warmed slightly, affecting the climate. The Geological Society, Climate change: evidence from the geological record Master the basics of climate science so you can better understand the news, evaluate scientific evidence, and explain global warming to anyone. * Part of this 'window' (12.5-18 µm) is largely blocked by carbon dioxide absorption, even at the low levels originally existing in the atmosphere. * in developed countries, with average 33% thermal efficiency. The Geological Society, Climate Change: evidence from the geological record, A statement from the Geological Society of London (November 2010) It was released in October 2018 and said: An IPCC report from Working Groups I and II (physical science & impacts/adaptation) was released in September 2019, on The Ocean and Cryosphere in a Changing Climate. The greenhouse effect occurs naturally, providing a habitable climate. Geologists have recently contributed to improved estimates of climate sensitivity (defined as the increase in global mean temperature resulting from a doubling in atmospheric CO2 levels). -2. * World Meteorological Organization, WMO Greenhouse Gas Bulletin No. Smith et al, Anthropogenic sulfur dioxide emissions: 1850-2005, Atmospheric Chemistry and Physics, 11, 1101-1116 (2011) Climate scientists use a concept called radiative forcing to quantify the effect of these increased concentrations on climate. Warming also heats the ocean, causing the water to expand and the sea level to rise. This course will give you the knowledge you need, and practice communicating about climate change. There is a positive feedback in summer since ice is reflective and open water absorbs heat. Arctic sea ice is an indicator. Fletcher's 1st edition of "Climate Change: What the Science Tells Us" places strong emphasis on the peer-reviewed literature in reporting the impacts of climate change on the ocean, terrestrial ecosystems, the water cycle, human communities, dangerous weather patterns, and potential future Earth systems. it is anthropogenic, hence the term ‘anthropogenic global warming’ (AGW). These projected figures are estimates, and it is evident that if renewables fail to grow as much as hoped, which is likely, due to system costs, it means that other non-carbon sources will need to play a larger role. Its GWP is 23,900. Each IPCC Assessment Report report is published in three parts. This removes about one-quarter of anthropogenic emissions and is responsible for much of the increase in photosynthesis worldwide since about 1900. However, in many countries there are now programmes to reduce sulfur dioxide emissions from power stations, as these emissions cause acid rain. More than half of the observed increase in globally averaged temperatures since the mid-20th century is, Greenhouse gases contributed a global mean surface warming. “Such high-risk changes are considered unlikely in this century, but are by definition hard to predict.”, The WMO 2019 United in Science report said: “With continued warming, systems can reach tipping points where they rapidly collapse or a major, largely unstoppable transformation is initiated. Science Moms says part of the problem trying to solve climate change is too few of us are talking about it. The National Oceanic and Atmospheric Administration (NOAA) Annual Greenhouse Gas Index (AGGI) in 2017 showed that from 1990 to 2016, radiative forcing by long-lived greenhouse gases increased by 40%, with CO2 accounting for about 80% of this increase. * Increased concentrations of CO2 and other radiative gases here mean that less heat is lost to space from the Earth's lower atmosphere, and temperatures at the Earth's surface are therefore likely to increase. It is virtually certain that there will be more frequent hot and fewer cold temperature extremes over most land areas on daily and seasonal timescales as global mean temperatures increase. Since then, the pause in tropospheric warming may be due to the timing of long Pacific and Atlantic ocean cycles. The Earth’s climate has been gradually cooling for most of the last 50 million years. 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. Over the past 2.6 million years (the Pleistocene and Holocene), the Earth’s climate has been on average cooler than today, and often much colder. The Foundation for Science and Technology, summary of debate on What is the right level of response to anthropogenic induced climate change?, held at The Royal Society on 16 June 2014 The average global temperature for 2015-2019 is on track to be the warmest of any equivalent period on record. Though Science Moms is nonpartisan and doesn't plan on backing political candidates, it does support policies like re-joining the Paris Agreement on Climate Change. 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