Climate variability includes all the variations in the climate that last longer than individual weather events, whereas the term climate change only refers to those variations that persist for a longer period of time, typically decades or more. Climate change may refer to any time in Earth's history, but the term is now commonly used to describe contemporary climate change, often popularly referred to as global warming. Since the Industrial Revolution, the climate has increasingly been affected by human activities.
There is a nearly unanimous scientific consensus that the Earth has been consistently warming since the start of the Industrial Revolution, that the rate of recent warming is largely unprecedented, and that this warming is mainly the result of a rapid increase in atmospheric carbon dioxide (CO2) caused by human activities. The human activities causing this warming include fossil fuel combustion, cement production, and land use changes such as deforestation, with a significant supporting role from the other greenhouse gases such as methane and nitrous oxide. This human role in climate change is considered "unequivocal" and "incontrovertible".
An ocean current is a continuous, directed movement of seawater generated by a number of forces acting upon the water, including wind, the Coriolis effect, breaking waves, cabbeling, and temperature and salinity differences. Depth contours, shoreline configurations, and interactions with other currents influence a current's direction and strength. Ocean currents move both horizontally, on scales that can span entire oceans, as well as vertically, with vertical currents playing an important role in the movement of nutrients and gases, such as carbon dioxide, between the surface and the deep ocean.
Climate commitment describes the fact that Earth's climate reacts with a delay to influencing factors such as the growth and the greater presence of greenhouse gases. Climate commitment studies attempt to assess the amount of future global warming that is "committed" under the assumption of some constant or some evolving level of forcing. The constant level often used for illustrative purposes is that due to CO2 doubling or quadrupling relative to the pre-industrial level; or the present level of forcing.
Effects of climate change are well documented and growing for Earth's natural environment and human societies. Changes to the climate system include an overall warming trend, changes to precipitation patterns, and more extreme weather. As the climate changes it impacts the natural environment with effects such as more intense forest fires, thawing permafrost, and desertification. These changes impact ecosystems and societies, and can become irreversible once tipping points are crossed. Climate activists are engaged in a range of activities around the world that seek to ameliorate these issues or prevent them from happening.
The Atlantic Multidecadal Oscillation (AMO), also known as Atlantic Multidecadal Variability (AMV), is the theorized variability of the sea surface temperature (SST) of the North Atlantic Ocean on the timescale of several decades.
Climate stabilization wedges are used to describe possible climate change mitigation scenarios and their impact, through the grouping of different types of interventions into "wedges" representing potential decreases in CO2 emissions. When stacked on top of each other, wedges form a "stabilization triangle" that represents the estimated amount of carbon that needs to be removed from the atmosphere to flatten carbon emissions and prevent atmospheric carbon from doubling. This framework is used to organize complex information about mitigation strategies for presentation to policy makers and the public, with the goal of stimulating both technological change and policy actions to deploy precommercial and existing technologies.
Due to climate change in the Arctic, this polar region is expected to become "profoundly different" by 2050. The speed of change is "among the highest in the world", with the rate of warming being 3-4 times faster than the global average. This warming has already resulted in the profound Arctic sea ice decline, the accelerating melting of the Greenland ice sheet and the thawing of the permafrost landscape. These ongoing transformations are expected to be irreversible for centuries or even millennia.
Polar amplification is the phenomenon that any change in the net radiation balance tends to produce a larger change in temperature near the poles than in the planetary average. This is commonly referred to as the ratio of polar warming to tropical warming. On a planet with an atmosphere that can restrict emission of longwave radiation to space, surface temperatures will be warmer than a simple planetary equilibrium temperature calculation would predict. Where the atmosphere or an extensive ocean is able to transport heat polewards, the poles will be warmer and equatorial regions cooler than their local net radiation balances would predict. The poles will experience the most cooling when the global-mean temperature is lower relative to a reference climate; alternatively, the poles will experience the greatest warming when the global-mean temperature is higher.
Warren Morton Washington was an American atmospheric scientist, a chair of the National Science Board, and a Distinguished Scholar at the National Center for Atmospheric Research (NCAR) in Boulder, Colorado. His research was part of the United Nations Intergovernmental Panel on Climate Change that shared the 2007 Nobel Peace Prize with Al Gore. In 2019, he was awarded the Tyler Prize for Environmental Achievement.
Gerald Allen "Jerry" Meehl is a climate scientist who has been a senior scientist at the National Center for Atmospheric Research since 2001.
A global warming hiatus, also sometimes referred to as a global warming pause or a global warming slowdown, is a period of relatively little change in globally averaged surface temperatures. In the current episode of global warming many such 15-year periods appear in the surface temperature record, along with robust evidence of the long-term warming trend. Such a "hiatus" is shorter than the 30-year periods that climate is classically averaged over.
Julie Michelle Arblaster is an Australian scientist. She is a Professor in the School of Earth, Atmosphere and Environment at Monash University. She was a contributing author on reports for which the Intergovernmental Panel on Climate Change (IPCC) was a co-recipient of the 2007 Nobel Peace Prize. Arblaster was a lead author on Chapter 12 of the IPCC Working Group I contribution to the IPCC Fifth Assessment Report in 2013. She has received the 2014 Anton Hales Medal for research in earth sciences from the Australian Academy of Science, and the 2017 Priestley Medal from the Australian Meteorological and Oceanographic Society. She has been ranked as one of the Top Influential Earth Scientists of 2010-2020, based on citations and discussion of her work.
Climate change caused by greenhouse gas emissions from human activities occurs everywhere on Earth, and while Antarctica is less vulnerable to it than any other continent, climate change in Antarctica has been observed. Since 1959, there has been an average temperature increase of >0.05 °C/decade since 1957 across the continent, although it had been uneven. West Antarctica warmed by over 0.1 °C/decade from the 1950s to the 2000s, and the exposed Antarctic Peninsula has warmed by 3 °C (5.4 °F) since the mid-20th century. The colder, stabler East Antarctica had been experiencing cooling until the 2000s. Around Antarctica, the Southern Ocean has absorbed more oceanic heat than any other ocean, and has seen strong warming at depths below 2,000 m (6,600 ft). Around the West Antarctic, the ocean has warmed by 1 °C (1.8 °F) since 1955.
The transient climate response to cumulative emissions of carbon dioxide (TCRE) is the ratio of the globally averaged surface temperature change per unit carbon dioxide (CO2) emitted.
Climate change in Senegal will have wide reaching impacts on many aspects of life in Senegal. Climate change will cause an increase in average temperatures over west Africa by between 1.5 and 4 °C by mid-century, relative to 1986–2005. Projections of rainfall indicate an overall decrease in rainfall and an increase in intense mega-storm events over the Sahel. The sea level is expected to rise faster in West Africa than the global average. Although Senegal is currently not a major contributor to global greenhouse gas emissions, it is one of the countries most vulnerable to climate change.
A marine heatwave is a period of abnormally high sea surface temperatures compared to the typical temperatures in the past for a particular season and region. Marine heatwaves are caused by a variety of drivers. These include shorter term weather events such as fronts, intraseasonal events, annual, and decadal (10-year) modes like El Niño events, and human-caused climate change. Marine heatwaves affect ecosystems in the oceans. For example, marine heatwaves can lead to severe biodiversity changes such as coral bleaching, sea star wasting disease, harmful algal blooms, and mass mortality of benthic communities. Unlike heatwaves on land, marine heatwaves can extend over vast areas, persist for weeks to months or even years, and occur at subsurface levels.
Natalie Mahowald is an American Earth scientist who is the Irving Porter Church Professor of Engineering at Cornell University. Her research considers atmospheric transport of biogeochemically-relevant species, and the impact of humans on their environments.
Bette Otto-Bliesner is an earth scientist known for her modeling of Earth's past climate and its changes over different geological eras.
Rong Zhang is a Chinese-American physicist and climate scientist at the National Oceanic and Atmospheric Administration. Her research considers the impact of Atlantic meridional overturning circulation on climate phenomena. She was elected Fellow of the American Meteorological Society in 2018 and appointed their Bernhard Haurwitz Memorial Lecturer in 2020.
