Portal:Climate change

The Climate Change Portal

Average global temperatures from 2010 to 2019 compared to a baseline average from 1951 to 1978. Source: NASA.

Climate change includes both the global warming driven by human emissions of greenhouse gases, and the resulting large-scale shifts in weather patterns. Though there have been previous periods of climatic change, since the mid-20th century the rate of human impact on Earth's climate system and its global scale have been unprecedented.

That human activity has caused climate change is not disputed by any scientific body of national or international standing. The largest driver has been the emission of greenhouse gases, of which more than 90% are carbon dioxide (CO
2
) and methane. Fossil fuel burning for energy consumption is the main source of these emissions, with additional contributions from agriculture, deforestation, and industrial processes. Temperature rise is accelerated or tempered by climate feedbacks, such as loss of sunlight-reflecting snow and ice cover, increased water vapour (a greenhouse gas itself), and changes to land and ocean carbon sinks.

Because land surfaces heat faster than ocean surfaces, deserts are expanding and heat waves and wildfires are more common. Surface temperature rise is greatest in the Arctic, where it has contributed to melting permafrost, the retreat of glaciers and sea ice. Increasing atmospheric energy and rates of evaporation cause more intense storms and weather extremes, which damage infrastructure and agriculture. Rising temperatures are limiting ocean productivity and harming fish stocks in most parts of the globe. Current and anticipated effects from undernutrition, heat stress and disease have led the World Health Organization to declare climate change the greatest threat to global health in the 21st century. Environmental effects include the extinction or relocation of many species as their ecosystems change, most immediately in coral reefs, mountains, and the Arctic. Even if efforts to minimize future warming are successful, some effects will continue for centuries, including rising sea levels, rising ocean temperatures, and ocean acidification.

Many of these effects are already observed at the current level of warming, which is about 1.1 °C (2.0 °F). The Intergovernmental Panel on Climate Change (IPCC) has issued a series of reports that project significant increases in these impacts as warming continues to 1.5 °C (2.7 °F) and beyond. Under the Paris Agreement, nations agreed to keep warming "well under 2.0 °C (3.6 °F)" by reducing greenhouse gas emissions. However, under those pledges, global warming would reach about 2.8 °C (5.0 °F) by the end of the century, and current policies will result in about 3.0 °C (5.4 °F) of warming. Limiting warming to 1.5 °C (2.7 °F) would require halving emissions by 2030, then reaching near-zero levels by 2050. (Full article...)

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A runaway greenhouse effect occurs when a planet's atmosphere contains greenhouse gas in an amount sufficient to block thermal radiation from the planet, preventing the planet from cooling and from having liquid water on its surface. A runaway version of the greenhouse effect can be defined by a limit on a planet's outgoing longwave radiation which is asymptotically reached due to higher surface temperatures boiling a condensable species (often water vapor) into the atmosphere, increasing its optical depth. This positive feedback means the planet cannot cool down through longwave radiation (via the Stefan–Boltzmann law) and continues to heat up until it can radiate outside of the absorption bands of the condensable species.

The runaway greenhouse effect is often formulated with water vapor as the condensable species. In this case the water vapor reaches the stratosphere and escapes into space via hydrodynamic escape, resulting in a desiccated planet. This may have happened in the early history of Venus. (Full article...)
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Global vegetation – Food, fuel and shelter. Vegetation is one of the most important requirements for human populations around the world. Satellites monitor how "green" different parts of the planet are and how that greenness changes over time. These observations help scientists understand the influence of natural cycles, such as drought and pest outbreaks, on vegetation, as well as human influences, such as land-clearing and global warming.

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The atmospheric CO2 concentration
Roger Randall Dougan Revelle (March 7, 1909 – July 15, 1991) was a scientist and scholar who was instrumental in the formative years of the University of California San Diego and was among the early scientists to study anthropogenic global warming, as well as the movement of Earth's tectonic plates. UC San Diego's first college is named Revelle College in his honor. (Full article...)

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

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Contamination pathways large.jpg
... Arctic haze contributes to global warming, raising temperatures by up to 5.4°F (3°C) during the arctic winter? A major distinguishing factor of Arctic haze is the ability of its chemical ingredients to persist in the atmosphere for an extended period of time compared to other pollutants.
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Sand Mountain Little Sahara Utah.jpg
Credit: Mike Scalora
A view of Sand Mountain campground from the side of Sand Mountain at Little Sahara Recreation Area in Utah. The Little Sahara sand dunes are remnants of a large river delta formed by the Sevier River from about 12,500 to 20,000 years ago. The river emptied into ancient Lake Bonneville near the present day mouth of Leamington Canyon. After Lake Bonneville receded, winds transported the sand from the river delta to the current location. The dunes are still moving 5 to 9 feet (1.5 to 3 m) per year. The area is home to typical Great Basin desert wildlife including mule deer, pronghorn antelope, snakes, lizards and birds of prey. Great horned owls make their home among juniper trees in the Rockwell Natural Area.

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References

  1. ^ McCurry, Justin (2020-10-26). "Japan will become carbon neutral by 2050, PM pledges". The Guardian. ISSN 0261-3077. Retrieved 2020-10-26.
  2. ^ Carrington, Damian (2020-03-05). "This winter in Europe was hottest on record by far, say scientists". The Guardian. ISSN 0261-3077. Retrieved 2020-03-08.

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