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Portal:Climate change

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The Climate Change Portal

Surface air temperature change over the past 50 years.[1]

Present-day climate change includes both global warming—the ongoing increase in global average temperature—and its wider effects on Earth's climate. Climate change in a broader sense also includes previous long-term changes to Earth's climate. The current rise in global temperatures is driven by human activities, especially fossil fuel burning since the Industrial Revolution. Fossil fuel use, deforestation, and some agricultural and industrial practices release greenhouse gases. These gases absorb some of the heat that the Earth radiates after it warms from sunlight, warming the lower atmosphere. Carbon dioxide, the primary greenhouse gas driving global warming, has grown by about 50% and is at levels not seen for millions of years.

Climate change has an increasingly large impact on the environment. Deserts are expanding, while heat waves and wildfires are becoming more common. Amplified warming in the Arctic has contributed to thawing permafrost, retreat of glaciers and sea ice decline. Higher temperatures are also causing more intense storms, droughts, and other weather extremes. Rapid environmental change in mountains, coral reefs, and the Arctic is forcing many species to relocate or become extinct. Even if efforts to minimize future warming are successful, some effects will continue for centuries. These include ocean heating, ocean acidification and sea level rise.

Climate change threatens people with increased flooding, extreme heat, increased food and water scarcity, more disease, and economic loss. Human migration and conflict can also be a result. The World Health Organization calls climate change one of the biggest threats to global health in the 21st century. Societies and ecosystems will experience more severe risks without action to limit warming. Adapting to climate change through efforts like flood control measures or drought-resistant crops partially reduces climate change risks, although some limits to adaptation have already been reached. Poorer communities are responsible for a small share of global emissions, yet have the least ability to adapt and are most vulnerable to climate change.

Many climate change impacts have been felt in recent years, with 2023 the warmest on record at +1.48 °C (2.66 °F) since regular tracking began in 1850. Additional warming will increase these impacts and can trigger tipping points, such as melting all of the Greenland ice sheet. Under the 2015 Paris Agreement, nations collectively agreed to keep warming "well under 2 °C". 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. Limiting warming to 1.5 °C would require halving emissions by 2030 and achieving net-zero emissions by 2050.

Fossil fuel use can be phased out by conserving energy and switching to energy sources that do not produce significant carbon pollution. These energy sources include wind, solar, hydro, and nuclear power. Cleanly generated electricity can replace fossil fuels for powering transportation, heating buildings, and running industrial processes. Carbon can also be removed from the atmosphere, for instance by increasing forest cover and farming with methods that capture carbon in soil. (Full article...)

Greenhouse gases trap some of the heat that results when sunlight heats the Earth's surface. Three important greenhouse gases are shown symbolically in this image: carbon dioxide, water vapor, and methane.

Greenhouse gases (GHGs) are the gases in the atmosphere that raise the surface temperature of planets such as the Earth. What distinguishes them from other gases is that they absorb the wavelengths of radiation that a planet emits, resulting in the greenhouse effect. The Earth is warmed by sunlight, causing its surface to radiate heat, which is then mostly absorbed by greenhouse gases. Without greenhouse gases in the atmosphere, the average temperature of Earth's surface would be about −18 °C (0 °F), rather than the present average of 15 °C (59 °F).

The five most abundant greenhouse gases in Earth's atmosphere, listed in decreasing order of average global mole fraction, are: water vapor, carbon dioxide, methane, nitrous oxide, ozone. Other greenhouse gases of concern include chlorofluorocarbons (CFCs and HCFCs), hydrofluorocarbons (HFCs), perfluorocarbons, SF
6
, and NF
3
. Water vapor causes about half of the greenhouse effect, acting in response to other gases as a climate change feedback.

Human activities since the beginning of the Industrial Revolution (around 1750) have increased carbon dioxide by over 50%, and methane levels by 150%. Carbon dioxide emissions are causing about three-quarters of global warming, while methane emissions cause most of the rest. The vast majority of carbon dioxide emissions by humans come from the burning of fossil fuels, with remaining contributions from agriculture and industry. Methane emissions originate from agriculture, fossil fuel production, waste, and other sources. The carbon cycle takes thousands of years to fully absorb CO2 from the atmosphere, while methane lasts in the atmosphere for an average of only 12 years. (Full article...)

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Credit: NASA
The collapse of Larsen B Ice Shelf, showing the diminishing extent of the shelf from 1998 to 2002

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Patricia Espinosa Cantellano (born October 21, 1958) is a Mexican diplomat who served as the executive secretary of the United Nations Framework Convention on Climate Change from 2016 to 2022. She was Secretary of Foreign Affairs in the cabinet of President Felipe Calderón; and served as Mexican Ambassador to Austria, Germany, Slovenia and Slovakia. Because of her diplomatic career, she was appointed Ambassador Emeritus of Mexico in 2012. (Full article...)

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The following are images from various climate-related articles on Wikipedia.

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Seagrass meadows are major carbon sinks and highly productive nurseries for many marine species
... that seagrass meadows hold twice as much carbon dioxide as rain forests per hectare?
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Plant Productivity in a Warming World: The past decade is the warmest on record since instrumental measurements began in the 1880s. Previous research suggested that in the '80s and '90s, warmer global temperatures and higher levels of precipitation—factors associated with climate change—were generally good for plant productivity. An updated analysis published this week in Science indicates that as temperatures have continued to rise, the benefits to plants are now overwhelmed by longer and more frequent droughts. High-resolution data from the Moderate-Resolution Imaging Spectroradiometer, or MODIS, indicate a net decrease in net primary production (NPP) from 2000-2009, as compared to the previous two decades. This narrated video gives an overview of NPP and the carbon cycle.

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References

  1. ^ "GISS Surface Temperature Analysis (v4)". NASA. Retrieved 12 January 2024.
  2. ^ Bhargav, Vishal (2021-10-11). "Climate Change Is Making India's Monsoon More Erratic". www.indiaspend.com. Retrieved 2021-10-11.
  3. ^ Tiwari, Dr Pushp Raj; Conversation, The. "Nobel prize: Why climate modellers deserved the physics award – they've been proved right again and again". phys.org. Retrieved 2021-10-11.
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