What is Global Warming? Definition, Facts, Causes and Effects of Global Warming.


Global warming is the long-term rise in the average temperature of the Earth's climate system. It is a serious side of current temperature change and has been demonstrated by direct temperature measurements and by measurements of various effects of the warming. The term unremarkably refers to the mainly human-caused increase in global surface temperatures and its projected continuation. In this context, the terms global warming and climate change are often used interchangeably, but climate change includes both global warming and its effects, like changes in precipitation and impacts that differ by region. There were prehistoric periods of worldwide warming, but observed changes since the mid-20th century are much bigger than those seen in previous records covering decades to thousands of years.

The Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report concluded, "It is very seemingly that human influence has been the dominant reason behind the observed warming since the mid-20th century.” The largest human influence has been the emission of greenhouse gases like CO2, methane, and nitrous oxide. Climate model projections summarized in the report indicated that in the twenty-first century the global surface temperature is probably going to rise a further 0.3 to 1.7 °C (0.5 to 3.1 °F) in a moderate scenario, or as much as 2.6 to 4.8 °C (4.7 to 8.6 °F) in an extreme scenario, depending on the rate of future greenhouse emission and on climate feedback effects. These findings are recognized by the national science academies of the major industrialized nations and are not disputed by any scientific body of national or international standing.

The effects of global warming include rising sea levels, regional changes in precipitation, more frequent extreme weather events such as heatwaves, and expansion of deserts. Surface temperature increases are greatest in the Arctic, which has contributed to the retreat of glaciers, permafrost, and ocean ice. Overall, higher temperatures bring additional rain and snowfall, except for some regions droughts and wildfires increase instead. Climate change threatens to diminish crop yields, harming food security, and rising ocean levels could flood coastal infrastructure and force the abandonment of many coastal cities.

Environmental impacts include the extinction or relocation of many species as their ecosystems change, most immediately the environments of coral reefs, mountains, and the Arctic. Due to the persistence of co2 in the atmosphere and the inertia of the climate system, climatic changes and their effects will continue for millennia even though carbon emissions are stopped. Possible social responses to global warming include mitigation by emissions reduction, adaptation to its effects, and perhaps climate engineering. Countries work together on climate change under the umbrella of the United Nations Framework Convention on Climate Change (UNFCCC), which has near-universal membership.

The ultimate goal of the convention is to "prevent dangerous evolution interference with the climate system”. Although the parties to the UNFCCC have agreed that deep cuts in emissions are required and that global warming ought to be restricted to well below 2 °C (3.6 °F) in the Paris Agreement, the Earth's average surface temperature has already increased by about half this threshold and current pledges by countries to chop emissions are inadequate to limit future warming. Some scientists question the feasibility, in higher emissions scenarios, of climate adaptation.