Climate change

Climate change includes both the global warming driven by human emissions of greenhouse gases, and the resulting large-scale shifts in weather patterns. Since the mid-20th century the rate of human impact on Earth’s climate system and its global scale have been unprecedented. The World Health Organization has declared climate change the greatest threat to global health in the 21st century. Even if efforts to minimize future warming are successful, some effects will continue for centuries.

About Climate change in brief

Summary Climate changeClimate change includes both the global warming driven by human emissions of greenhouse gases, and the resulting large-scale shifts in weather patterns. Since the mid-20th century the rate of human impact on Earth’s climate system and its global scale have been unprecedented. The World Health Organization has declared climate change the greatest threat to global health in the 21st century. 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. The Intergovernmental Panel on Climate Change has issued a series of reports that project significant increases in these impacts as warming continues to 1. 5°C and beyond. Under the Paris Agreement, nations agreed to keep warming under 2. 0°C by reducing greenhouse gas emissions. However, under those pledges, global warming would reach about 2. 8 °C by the end of the century, and current policies will result in about 3. 0 C of warming. Limiting warming to 1 5°C would require halving emissions by 2030, then reaching near-zero levels by 2050. Mitigation efforts include the development and deployment of low-carbon energy technologies, enhanced energy efficiency, phase-out of coal, reforestation, and forest preservation. Societies are also working to adapt to current and future global-warming effects through improved coastline protection, better disaster management and the development of more resistant crops. There have been prehistorical episodes of global warming, such as the Paleocene–Eocene Thermal Maximum. Since 1950, the number of cold days and nights has decreased, while warm days has increased.

However there have been abrupt geophysical events that took place in a limited set of regions, like the Medieval Ice Age, but may have been not as synchronous across regions as current warming, but have reached temperatures as high as those of the late 20th century in a few regions. The current global warming has been so rapid that even abrupt events like the Little Ice Age took place so quickly that it may have limited the effects of geophysical change. It has been observed that the climate system is warming, with the 2009 decade being 93 ± 07 C warmer than the pre-industrial baseline. Currently, surface temperatures are rising by about 0.2°C per decade, and since 1950, since 1950,. surface temperatures have risen by 0. 2 C per week. 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. Sparser rainfall leads to desertification that harms agriculture and can displace populations. The Great Barrier Reef and threatens reefs worldwide. Many arctic animals rely on sea ice, which has been disappearing in a warming Arctic. Sea-level rise increases flooding in low-lying coastal regions. Mild winters allow more pine beetles to survive to kill large swaths of forest.