Climate is the long-term pattern of weather in an area, typically averaged over a period of 30 years. More rigorously, it is the mean and variability of meteorological variables over a time spanning from months to millions of years. Some of the meteorological variables that are commonly measured are temperature, humidity, atmospheric pressure, wind, and precipitation. In a broader sense, climate is the state of the components of the climate system, which includes the ocean, land, and ice on Earth. The climate of a location is affected by its latitude/longitude, terrain, and altitude, as well as nearby water bodies and their currents.
Climatology or climate science is the scientific study of Earth's climate, typically defined as weather conditions averaged over a period of at least 30 years. This modern field of study is regarded as a branch of the atmospheric sciences and a subfield of physical geography, which is one of the Earth sciences. Climatology now includes aspects of oceanography and biogeochemistry.
There is a strong scientific consensus that the Earth is warming and that this warming is mainly caused by human activities. This consensus is supported by various studies of scientists' opinions and by position statements of scientific organizations, many of which explicitly agree with the Intergovernmental Panel on Climate Change (IPCC) synthesis reports.
Michael Evan Mann is an American climatologist and geophysicist. He is the director of the Earth System Science Center at Pennsylvania State University. Mann has contributed to the scientific understanding of historic climate change based on the temperature record of the past thousand years. He has pioneered techniques to find patterns in past climate change and to isolate climate signals from noisy data.
In glaciology, an ice sheet, also known as a continental glacier, is a mass of glacial ice that covers surrounding terrain and is greater than 50,000 km2 (19,000 sq mi). The only current ice sheets are in Antarctica and Greenland; during the last glacial period at Last Glacial Maximum (LGM) the Laurentide Ice Sheet covered much of North America, the Weichselian ice sheet covered northern Europe and the Patagonian Ice Sheet covered southern South America.
John Raymond Christy is a climate scientist at the University of Alabama in Huntsville (UAH) whose chief interests are satellite remote sensing of global climate and global climate change. He is best known, jointly with Roy Spencer, for the first successful development of a satellite temperature record.
Kevin Edward Trenberth is part of the Climate Analysis Section at the US NCAR National Center for Atmospheric Research. He was a lead author of the 2001 and 2007 IPCC Scientific Assessment of Climate Change and serves on the Scientific Steering Group for the Climate Variability and Predictability (CLIVAR) program. He chaired the WCRP Observation and Assimilation Panel from 2004 to 2010 and chaired the Global Energy and Water Exchanges (GEWEX) scientific steering group from 2010 to 2013. In addition, he served on the Joint Scientific Committee of the World Climate Research Programme, and has made significant contributions to research into El Niño-Southern Oscillation.
Professor Sir Brian John Hoskins, CBE FRS, is a British dynamical meteorologist and climatologist based at the Imperial College London and the University of Reading. A mathematician by training, his research has focused on understanding atmospheric motion from the scale of fronts to that of the Earth, using a range of theoretical and numerical models. He is perhaps best known for his work on the mathematical theory of extratropical cyclones and frontogenesis, particularly through the use of potential vorticity. He has also produced research across many areas of meteorology, including the Indian monsoon and global warming, recently contributing to the Stern review and the IPCC Fourth Assessment Report.
Roger A. Pielke Sr. is an American meteorologist with interests in climate variability and climate change, environmental vulnerability, numerical modeling, atmospheric dynamics, land/ocean – atmosphere interactions, and large eddy/turbulent boundary layer modeling. He particularly focuses on mesoscale weather and climate processes but also investigates on the global, regional, and microscale. Pielke is an ISI Highly Cited Researcher.
Climate Change 2007, the Fourth Assessment Report (AR4) of the United Nations Intergovernmental Panel on Climate Change (IPCC) was published in 2007 and is the fourth in a series of reports intended to assess scientific, technical and socio-economic information concerning climate change, its potential effects, and options for adaptation and mitigation. The report is the largest and most detailed summary of the climate change situation ever undertaken, produced by thousands of authors, editors, and reviewers from dozens of countries, citing over 6,000 peer-reviewed scientific studies. People from over 130 countries contributed to the IPCC Fourth Assessment Report, which took 6 years to produce. Contributors to AR4 included more than 2500 scientific expert reviewers, more than 800 contributing authors, and more than 450 lead authors.
Natural catastrophe in India, many of them related to the climate of India, cause massive losses of life and property. Droughts, flash floods, cyclones, avalanches, landslides brought by torrential rains, and snowstorms pose the greatest threats. A natural disaster might be caused by earthquakes, flooding, volcanic eruption, landslides, hurricanes etc. In order to be classified as a disaster, it will need to have a profound environmental effect and/or human loss and frequently incurs a financial loss. Other dangers include frequent summer dust storms, which usually track from north to south; they cause extensive property damage in North India and deposit large amounts of dust and dirt from arid regions. Hail is also common in parts of India, causing severe damage to standing crops such as rice and wheat and many more crops.
The IPCC Fourth Assessment Report (AR4) is a report on climate change created with the help of a large number of contributors, both scientists and governmental representatives. There has been considerable political controversy over a small number of errors found in the report, and there have been calls for review of the process used to formulate the report. The overwhelming majority view of scientists with expertise in climate change is that errors, when found, are corrected, and the issues as identified do not undermine the conclusions of the report that the climate system is warming in response to increased levels of greenhouse gases, largely due to human activities.
Willard Anthony Watts is an American blogger who runs Watts Up With That?, a popular climate change denial blog that opposes the scientific consensus on climate change. A former television meteorologist and current radio meteorologist, he is also founder of the Surface Stations project, a volunteer initiative to document the condition of U.S. weather stations. The Heartland Institute helped fund some of Watts' projects, including publishing a report on the Surface Stations project, and has invited him to be a paid speaker at its International Conference on Climate Change from 2008 to 2014.
David Arfon Jones is a senior climatologist at the Australian Bureau of Meteorology.
Climate change causes a variety of physical impacts on the climate system. The physical impacts of climate change foremost include globally rising temperatures of the lower atmosphere, the land, and oceans. Temperature rise is not uniform, with land masses and the Arctic region warming faster than the global average. Effects on weather encompass increased heavy precipitation, reduced amounts of cold days, increase in heat waves and various effects on tropical cyclones. The enhanced greenhouse effect causes the higher part of the atmosphere, the stratosphere, to cool. Geochemical cycles are also impacted, with absorption of CO2 causing ocean acidification, and rising ocean water decreasing the ocean's ability to absorb further carbon dioxide. Annual snow cover has decreased, sea ice is declining and widespread melting of glaciers is underway. Thermal expansion and glacial retreat cause sea levels to increase. Retreat of ice mass may impact various geological processes as well, such as volcanism and earthquakes. Increased temperatures and other human interference with the climate system can lead to tipping points to be crossed such as the collapse of the thermohaline circulation or the Amazon rainforest. Some of these physical impacts also affect social and economic systems.
J. Murray Mitchell Jr. was an American climatologist. As a United States Air Force weather officer in Alaska from 1952 to 1955, he investigated and named the Arctic haze. He served with the United States Weather Bureau and successor agencies from 1955 until his retirement in 1986, and was a prominent member of the National Academy of Sciences and the National Science Foundation. The Mitchell Glacier was named after him.
Prashant Goswami is an Indian computational geoscientist, climatologist and the director of the National Institute of Science, Technology and Development Studies, New Delhi. He is a former scientist at the Fourth Paradigm Institute and is known for his studies on the tropical atmospheric variability across the time scales. The Council of Scientific and Industrial Research, the apex agency of the Government of India for scientific research, awarded him the Shanti Swarup Bhatnagar Prize for Science and Technology, one of the highest Indian science awards for his contributions to Earth, Atmosphere, Ocean and Planetary Sciences in 2001.
Guðfinna 'Tollý' Aðalgeirsdóttir is professor in Geophysics at the Faculty of Earth Sciences, University of Iceland.
William Ka Ming Lau is a senior scientist at the Earth System Science Interdisciplinary Center, a research center at the University of Maryland and an Adjunct Professor of the Department of Atmospheric and Oceanic Sciences at the University of Maryland. A physicist by training, his research spans over 4 decades covering a wide range of topics in climate dynamics, tropical meteorology, ocean-atmosphere coupling, aerosol-water cycle interactions, and climate variability and change. Lau conducted pioneering research on atmospheric teleconnection, and the global monsoon climate system. He discovered the aerosol-monsoon regional feedback mechanism, i.e., the Elevated Heat Pump (EHP) effect that strongly modulate climate change in Asian monsoon regions. He was the senior author of a popular research reference book, “Intraseasonal Variability in the Atmosphere-Ocean Climate System”. As of November 2020, he has coauthored 297 refereed papers, with total citation = 33,932, h-index=101.
John Nielsen-Gammon, 2006