Climate change includes both global warming driven by human emissions of greenhouse gases, and the resulting large-scale shifts in weather patterns

Climate change includes both global warming driven by human emissions of greenhouse gases, and the resulting large-scale shifts in weather patterns. Though there have been previous periods of climatic change, since the mid-20th century, humans have had unprecedented impact on Earth's climate system and caused change on a global scale.[2] The largest driver of warming is the emission of greenhouse gases, of which more than 90% are carbon dioxide (CO 2) and methane.[3] Fossil fuel burning (coal, oil, and natural gas) for energy consumption is the main source of these emissions, with additional contributions from agriculture, deforestation, and manufacturing.[4] The human cause of climate change is not disputed by any scientific body of national or international standing.[5] Temperature rise is accelerated or tempered by climate feedbacks, such as loss of sunlight-reflecting snow and ice cover, increased water vapour (a greenhouse gas itself), and changes to land and ocean carbon sinks. Temperature rise on land is about twice the global average increase, leading to desert expansion and more common heat waves and wildfires.[6] Increasing rates of evaporation cause more intense storms and weather extremes.[7] Temperature rise is amplified in the Arctic, where it has contributed to melting permafrost, glacial retreat and sea ice loss.[8] Additional warming also increases the risk of triggering critical thresholds called tipping points.[9] Impacts on ecosystems include the relocation or extinction of many species as their environment changes, most immediately in coral reefs, mountains, and the Arctic.[10] Climate change threatens food security and access to water, leads to economic losses, and is projected to increase displacement of people. It further magnifies risks of flooding, infectious diseases and extreme heat, with the World Health Organization calling climate change the greatest threat to global health in the 21st century.[11] Even if efforts to minimize future warming are successful, some effects will continue for centuries, including rising sea levels, rising ocean temperatures, and ocean acidification.[12] Some impacts of climate change Underwater photograph of branching coral that is bleached white Ecological collapse. Bleaching has damaged the Great Barrier Reef and threatens reefs worldwide. Many of these impacts are already felt at the current level of warming, which is about 1.2 °C (2.2 °F).[14] The Intergovernmental Panel on Climate Change (IPCC) has issued a series of reports that project significant increases in these impacts as warming continues to 1.5 °C (2.7 °F) and beyond.[15] Responding to climate change involves mitigation and adaptation.[16] Mitigation – limiting climate change – consists of reducing greenhouse gas emissions, and removing them from the atmosphere;[16] methods include the development and deployment of low-carbon energy sources such as wind and solar, a phase-out of coal, enhanced energy efficiency, reforestation, and forest preservation. Adaptation consists of adjusting to actual or expected climate,[16] such as through improved coastline protection, better disaster management, assisted colonization and the development of more resistant crops. Adaptation alone cannot avert the risk of "severe, widespread and irreversible" impacts.[17] Under the Paris Agreement, nations collectively agreed to keep warming "well under 2.0 °C (3.6 °F)" through mitigation efforts. However, with pledges made under the Agreement, global warming would still reach about 2.8 °C (5.0 °F) by the end of the century.[18] Limiting warming to 1.5 °C (2.7 °F) would require halving emissions by 2030 and achieving near-zero emissions by 2050.[19] Contents 1    Terminology 2    Observed temperature rise 3    Drivers of recent temperature rise 3.1    Greenhouse gases 3.2    Aerosols and clouds 3.3    Changes on land surface 3.4    Solar and volcanic activity 3.5    Climate change feedback 4    Future warming and the carbon budget 5    Impacts 5.1    Physical environment 5.2    Nature and wildlife 5.3    Humans 6    Responses: mitigation and adaptation 6.1    Mitigation 6.2    Adaptation 7    Policies and politics 7.1    Policy options 7.2    International climate agreements 7.3    National responses 8    Scientific consensus and society 8.1    Scientific consensus 8.2    The public 9    Discovery 10    See also 11    References 11.1    Notes 11.2    Sources 12    External links Terminology Before the 1980s, when it was unclear whether warming by greenhouse gases would dominate aerosol-induced cooling, scientists often used the term inadvertent climate modification to refer to humankind's impact on the climate. In the 1980s, the terms global warming and climate change were introduced, the former referring only to increased surface warming, while the latter describes the full effect of greenhouse gases on the climate.[20] Global warming became the most popular term after NASA climate scientist James Hansen used it in his 1988 testimony in the U.S. Senate.[21] In the 2000s, the term climate change increased in popularity.[22] Global warming usually refers to human-induced warming of the Earth system, whereas climate change can refer to natural as well as anthropogenic change.[23] The two terms are often used interchangeably.[24] Various scientists, politicians and media figures have adopted the terms climate crisis or climate emergency to talk about climate change, while using global heating instead of global warming.[25] The policy editor-in-chief of The Guardian explained that they included this language in their editorial guidelines "to ensure that we are being scientifically precise, while also communicating clearly with readers on this very important issue".[26] Oxford Dictionary chose climate emergency as its word of the year in 2019 and defines the term as "a situation in which urgent action is required to reduce or halt climate change and avoid potentially irreversible environmental damage resulting from it".[27] Observed temperature rise Main articles: Temperature record of the last 2,000 years and Instrumental temperature record Global surface temperature reconstruction over the last 2000 years using proxy data from tree rings, corals, and ice cores in blue.[28] Directly observational data is in red.[29] NASA data[29] shows that land surface temperatures have increased faster than ocean temperatures. Multiple independently produced instrumental datasets show that the climate system is warming,[30] with the 2009–2018 decade being 0.93 ± 0.07 °C (1.67 ± 0.13 °F) warmer than the pre-industrial baseline (1850–1900).[31] Currently, surface temperatures are rising by about 0.2 °C (0.36 °F) per decade,[32] with 2020 reaching a temperature of 1.2 °C (2.2 °F) above pre-industrial.[14] Since 1950, the number of cold days and nights has decreased, and the number of warm days and nights has increased.[33] Historical patterns of warming and cooling, like the Medieval Climate Anomaly and the Little Ice Age, did not occur at the same time across different regions, but temperatures may have reached as high as those of the late-20th century in a limited set of regions.[34] There have been prehistorical episodes of global warming, such as the Paleocene–Eocene Thermal Maximum.[35] However, the modern observed rise in temperature and CO 2 concentrations has been so rapid that even abrupt geophysical events that took place in Earth's history do not approach current rates.[36] There was little net warming between the 18th century and the mid-19th century. Climate proxies, sources of climate information from natural archives such as trees and ice cores, show that natural variations offset the early effects of the Industrial Revolution.[37] The Intergovernmental Panel on Climate Change (IPCC) has adopted the baseline reference period 1850–1900 as an approximation of pre-industrial global mean surface temperature,[37] when thermometer records began to provide global coverage.[38] Evidence of warming from air temperature measurements are reinforced with a wide range of other observations.[39] There has been an increase in the frequency and intensity of heavy precipitation, melting of snow and land ice, and increased atmospheric humidity.[40] Flora and fauna are also behaving in a manner consistent with warming; for instance, plants are flowering earlier in spring.[41] Another key indicator is the cooling of the upper atmosphere, which demonstrates that greenhouse gases are trapping heat near the Earth's surface and preventing it from radiating into space.[42] Patterns of warming are independent of where greenhouse gases are emitted, because the gases persist long enough to diffuse across the planet; however, localized black carbon deposits on snow and ice do contribute to Arctic warming.[43] Since the pre-industrial period, global average land temperatures have increased almost twice as fast as global average surface temperatures.[44] This is because of the larger heat capacity of oceans, and because oceans lose more heat by evaporation.[45] Over 90% of the additional energy in the climate system over the last 50 years has been stored in the ocean, warming it.[46] The remainder of the additional energy has melted ice and warmed the continents and the atmosphere.[47] The Northern Hemisphere and North Pole have warmed much faster than the South Pole and Southern Hemisphere. The Northern Hemisphere not only has much more land, but also more snow area and sea ice, because of how the land masses are arranged around the Arctic Ocean. As these surfaces flip from reflecting a lot of light to being dark after the ice has melted, they start absorbing more heat. The Southern Hemisphere already had little sea ice in summer before it started warming.[48] Arctic temperatures have increased and are predicted to continue to increase during this century at over twice the rate of the rest of the world.[49] Melting of glaciers and ice sheets in the Arctic disrupts ocean circulation, including a weakened Gulf Stream, causing increased warming in some areas.[50] Drivers of recent temperature rise Main article: Attribution of recent climate change Contributors to climate change in 2011, as reported in the fifth IPCC assessment report The climate system experiences various cycles on its own which can last for years (such as the El Niño–Southern Oscillation), decades or even centuries.[51] Other changes are caused by an imbalance of energy that is "external" to the climate system, but not always external to the Earth.[52] Examples of external forcings include changes in the composition of the atmosphere (e.g. increased concentrations of greenhouse gases), solar luminosity, volcanic eruptions, and variations in the Earth's orbit around the Sun.[53] The attribution of climate change is the effort to scientifically show which mechanisms are responsible for observed changes in Earth's climate. To determine the human contribution, known internal climate variability and natural external forcings need to be ruled out. A key approach is to use computer modelling of the climate system to determine unique "fingerprints" for all potential causes. By comparing these fingerprints with observed patterns and evolution of climate change, and the observed history of the forcings, the causes of the changes can be determined.[54] For example, solar forcing can be ruled out as major cause because its fingerprint is warming in the entire atmosphere, and only the lower atmosphere has warmed, as expected from greenhouse gases (which trap heat energy radiating from the surface).[55] Attribution of recent climate change shows that the primary driver is elevated greenhouse gases, but that aerosols also have a strong effect https://karantina.pertanian.go.id/question2answer/index.php?qa