climate change

climate change
NASA’s Scientific Visualization Studio, Key and Title by uploader (Eric Fisk) · CC BY-SA 4.0 · source
Name	Climate change
Caption	Global surface temperature anomalies (20th–21st century)
Field	Earth science, Environmental science, Atmospheric science
Causes	Greenhouse gas emissions, Land-use change, Aerosols
Effects	Sea-level rise, Extreme weather, Biodiversity loss, Socioeconomic disruption

climate change

Climate change refers to long-term shifts in global and regional patterns of temperature, precipitation, wind, and other climate variables driven by natural processes and anthropogenic influences. The topic intersects with disciplines such as Meteorology, Oceanography, Glaciology, Ecology, and Paleoclimatology and is a central concern for institutions including the Intergovernmental Panel on Climate Change, the United Nations Framework Convention on Climate Change, and national agencies like the National Aeronautics and Space Administration and the National Oceanic and Atmospheric Administration. Scientific assessment reports, such as those by the Intergovernmental Panel on Climate Change and the National Academies of Sciences, Engineering, and Medicine, synthesize observations, theories, and model projections to inform policy, law, and international agreements.

Overview

Observed changes include rising global average temperatures, altered precipitation patterns, shrinking glaciers, reduced snow cover, Arctic sea-ice decline, ocean warming, and ocean acidification. Key measurement programs and observatories—like Mauna Loa Observatory, the Global Historical Climatology Network, the Copernicus Programme, the Hadley Centre and the Global Climate Observing System—provide datasets used by modeling centers such as the Met Office Hadley Centre, the National Center for Atmospheric Research, and the European Centre for Medium-Range Weather Forecasts. Paleoclimate records from Greenland ice core, Antarctic ice core, Vostok Station and sediment archives place recent changes in the context of natural variability and epochs such as the Holocene.

Causes

Anthropogenic drivers are dominated by emissions of greenhouse gases (GHGs) from fossil-fuel combustion, industrial processes, and land-use change. Major sources include the International Energy Agency-tracked sectors of electricity generation, transport systems such as the Automotive industry and Aviation, and industrial activities including operations by multinational firms and national utilities. Carbon dioxide increases are linked to combustion of coal, oil, and natural gas and to deforestation in regions like the Amazon rainforest and Congo Basin. Methane sources are associated with fossil fuel extraction in regions like the Gulf of Mexico and enteric fermentation in agriculture exemplified by livestock sectors in countries such as Brazil and India. Nitrous oxide and fluorinated gases arise from fertilizer use and industrial chemistry tied to corporations and regulatory frameworks such as the Montreal Protocol and subsequent amendments. Aerosol emissions from industrial centers and volcanic events such as Mount Pinatubo modulate radiative forcing and influence regional patterns measured by satellites like those of the Landsat Program.

Observed Impacts

Physical impacts include accelerating ice-mass loss from the Greenland Ice Sheet and the West Antarctic Ice Sheet, contributing to global sea-level rise that affects coastal megacities including New York City, Mumbai, and Tokyo. Ocean warming and acidification have stressed ecosystems including Great Barrier Reef coral systems and upwelling regions like the California Current. Hydrological shifts influence water resources in basins such as the Colorado River and the Mekong River, affecting agriculture in regions served by institutions like the Food and Agriculture Organization. Biological responses include shifts in species ranges documented for taxa in the Amazon Basin, the Arctic tundra, and the Mediterranean Sea, as well as phenological changes recorded by naturalists following traditions established by figures like Charles Darwin and programs tied to museums such as the Smithsonian Institution. Socioeconomic consequences are evident in disaster events such as Hurricane Katrina and in heatwaves affecting urban populations exemplified by the 2003 European heat wave.

Future Projections and Scenarios

Integrated assessment models, coupled climate models developed by centers like the Max Planck Institute for Meteorology and the Geophysical Fluid Dynamics Laboratory, and scenario frameworks such as the Representative Concentration Pathways and Shared Socioeconomic Pathways provide projections of temperature, precipitation, and sea level under differing emissions trajectories. High-emission scenarios project multi-meter sea-level rise over centuries with increased frequency of extreme events similar to past events cataloged by agencies like the Federal Emergency Management Agency, while low-emission pathways compatible with targets set at the Paris Agreement limit warming to lower thresholds. Regional climate model downscaling for areas such as the Sahel, Southeast Asia, and the Mediterranean Basin informs adaptation planning undertaken by national agencies including the European Environment Agency and development banks like the World Bank.

Mitigation and Adaptation

Mitigation options include decarbonizing energy systems via deployment of renewables such as technologies promoted by the International Renewable Energy Agency and policy measures like carbon pricing exemplified by systems in the European Union Emissions Trading System and national programs in Sweden and Canada. Land-based strategies involve afforestation and sustainable management in landscapes including the Boreal Forest and restoration projects supported by organizations like the Food and Agriculture Organization. Carbon dioxide removal techniques are researched at institutions like the Lawrence Berkeley National Laboratory and debated in forums including the IPCC Special Reports. Adaptation measures range from coastal defenses in cities like Rotterdam to agricultural practices in the Sahel supported by programs from the United Nations Development Programme and social safety nets influenced by policies in countries such as Bangladesh.

Policy, Economics, and International Response

International governance is anchored in the United Nations Framework Convention on Climate Change and agreements such as the Kyoto Protocol and the Paris Agreement, negotiated at Conferences of the Parties hosted in cities like Copenhagen and Glasgow. Economic analyses by entities like the Intergovernmental Panel on Climate Change and the World Bank evaluate costs and co-benefits of mitigation, adaptation, and transition policies, while legal instruments at national levels—such as emissions standards in the United States Environmental Protection Agency mandates and renewable targets in the European Union—shape implementation. Finance mechanisms include the Green Climate Fund and multilateral development banks that support projects in countries from Indonesia to Ethiopia, and public movements mobilized by organizations like Extinction Rebellion and figures such as Greta Thunberg have influenced public discourse and policymaking.

Category:Climate