Results for “Paris Agreement”

Climate Change Overview

** Climate change is the long‑term alteration of temperature, precipitation, and atmospheric composition driven largely by human activities, reshaping ecosystems, economies, and societies worldwide. **CONTENT:** ## Overview Climate change refers to the persistent shift in Earth’s climate system, encompassing rising global average temperatures, altered precipitation patterns, and increasing frequency of extreme weather events. While the planet has experienced natural climate fluctuations over geological time, the current warming trend is unprecedented in its speed and magnitude, primarily due to the **anthropogenic** release of greenhouse gases (GHGs) such as carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O). These gases trap infrared radiation, creating a **greenhouse effect** that thickens the atmospheric “blanket,” warming the surface and oceans. The consequences of this warming ripple through every corner of the biosphere. Glaciers and polar ice sheets are retreating, sea levels are rising, and ocean acidification is threatening coral reefs and shell‑forming organisms. Terrestrial ecosystems are shifting poleward and upward in elevation, forcing species to migrate, adapt, or face extinction. Human communities experience heightened risks from heatwaves, droughts, floods, and the spread of vector‑borne diseases, underscoring the intertwined fate of nature and society. ## History/Background The scientific recognition of climate change began in the late 19th century when **Svante Arrhenius** quantified how CO₂ could influence Earth’s temperature. In the 1930s, **Guy Stewart Callendar** linked rising CO₂ from fossil‑fuel combustion to observed temperature increases, coining the “Callendar effect.” The post‑World War II industrial boom accelerated GHG emissions, prompting the first **CO₂ measurements** at Mauna Loa Observatory in 1958, which revealed a steady upward trajectory now known as the “Keeling Curve.” Key milestones include the **1979** first Earth‑system model simulations, the **1988** establishment of the Intergovernmental Panel on Climate Change (IPCC), and the **1992** United Nations Framework Convention on Climate Change (UNFCCC). The **1997** Kyoto Protocol set the first binding emission‑reduction targets for developed nations, while the **2015** Paris Agreement marked a global pledge to limit warming to well below 2 °C above pre‑industrial levels, aiming for 1.5 °C. Each successive IPCC assessment report has sharpened the scientific consensus, culminating in the **2021** Sixth Assessment Report, which declares that human influence is “unequivocal” and that immediate, deep emissions cuts are essential. ## Key Information - **Greenhouse gases:** CO₂ accounts for ~76 % of total anthropogenic GHG emissions, followed by CH₄ (~16 %) and N₂O (~6 %). - **Temperature rise:** Global mean surface temperature has increased by ~1.2 °C since the pre‑industrial era (1850‑1900). - **Sea‑level rise:** Oceans have risen ~210 mm since 1900, with an accelerating rate of ~3.6 mm yr⁻¹ in the past decade. - **Extreme events:** The frequency of heatwaves, heavy precipitation, and Category 4‑5 hurricanes has risen markedly, linked to higher atmospheric moisture and ocean heat content. - **Ecological impacts:** Approximately 23 % of terrestrial species are projected to lose >50 % of their suitable habitat by 2050 if warming exceeds 2 °C. - **Mitigation pathways:** The IPCC outlines **net‑zero** emissions by mid‑century as the threshold to stay within 1.5 °C, requiring rapid decarbonization of energy, transport, industry, and agriculture. - **Adaptation strategies:** Coastal defenses, climate‑resilient agriculture, and ecosystem‑based approaches (e.g., mangrove restoration) are critical to buffer communities against unavoidable impacts. ## Significance Climate change matters because it is the most pervasive environmental challenge of the 21st century, threatening biodiversity, food security, water availability, and human health. Its **intergenerational equity** dimension forces current societies to consider the rights of future generations to a livable planet. Economically, unchecked warming could erode global GDP by up to 10 % by 2100, while proactive mitigation offers co‑benefits such as cleaner air, reduced health costs, and new green‑technology jobs. Moreover, climate change acts as a **stress multiplier**, amplifying conflicts over resources, prompting migration, and destabilizing fragile states. Understanding its mechanisms, history, and pathways for action is essential for policymakers, scientists, and citizens alike to steer humanity toward a sustainable, resilient future. **INFOBOX:** - Name: Climate Change - Type: Global Environmental Phenomenon - Date: Accelerated since the Industrial Revolution (c. 1750 – present) - Location: Planet Earth (global) - Known For: Rapid warming, sea‑level rise, extreme weather, biodiversity loss, and driving international climate policy **TAGS:** climate change, greenhouse gases, global warming, IPCC, Paris Agreement, sea‑level rise, biodiversity, sustainability