Climate change

The current era of climate change is characterized by a significant increase in global average temperatures, a phenomenon known as global warming, alongside its broader impacts on the Earth's climate system. This warming trend is overwhelmingly driven by human activities, primarily the combustion of fossil fuels-coal, oil, and natural gas-which began on a large scale during the Industrial Revolution.

These activities, along with deforestation and certain agricultural and industrial practices, release substantial quantities of greenhouse gases (GHGs) into the atmosphere. GHGs, such as carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O), absorb and re-emit infrared radiation that the Earth radiates after being warmed by sunlight. This process traps heat in the lower atmosphere, leading to a net warming of the planet.

CO2, the principal driver of current warming, has seen its atmospheric concentration rise by approximately 50% from pre-industrial levels, reaching concentrations not observed for millions of years, fundamentally altering Earth's energy balance.

The amplified warming, particularly pronounced in the Arctic, triggers a cascade of environmental changes. This includes the thawing of permafrost, which releases further GHGs, creating a positive feedback loop. Glaciers and ice sheets are retreating at accelerated rates, contributing to sea level rise.

The decline in sea ice extent and thickness in the Arctic has profound implications for polar ecosystems and global weather patterns. Beyond the cryosphere, higher temperatures intensify the hydrological cycle, leading to more frequent and severe extreme weather events, including heat waves, droughts, intense storms, and heavy precipitation. These rapid environmental shifts place immense pressure on ecosystems, forcing species to relocate or face extinction. Mountain regions, coral reefs, and polar environments are particularly vulnerable.

Even if future warming is significantly limited, the inertia of the climate system means that certain impacts, such as ocean heating, ocean acidification (due to increased CO2 absorption), and continued sea level rise, will persist for centuries.

Climate change poses substantial threats to human societies, exacerbating existing vulnerabilities and creating new challenges. Increased frequency of extreme weather events leads to greater risks of flooding, water scarcity, and food insecurity. Public health is also significantly impacted, with rising temperatures contributing to heat-related illnesses and the spread of vector-borne diseases, leading the World Health Organization to identify climate change as one of the greatest threats to global health.

Economically, climate change can result in significant losses through damage to infrastructure, reduced agricultural yields, and disruptions to supply chains. In some regions, these impacts can contribute to human migration and increased potential for conflict. While adaptation measures, such as flood defenses and drought-resistant crops, can help reduce some risks, there are limits to adaptation, and many vulnerable communities, often those least responsible for emissions, bear the brunt of the impacts with the least capacity to cope.

The scientific consensus on climate change is robust, and there is widespread global support for climate action. The 2015 Paris Agreement aims to limit global warming to well below 2 degrees Celsius above pre-industrial levels, with an aspiration to limit it to 1.5 degrees Celsius. However, current national pledges suggest warming could reach around 2.8 degrees Celsius by the end of the century.

To achieve the Paris Agreement goals, a rapid transition away from fossil fuels is essential. This involves phasing out subsidies for fossil fuels, enhancing energy conservation, and significantly scaling up the deployment of low-carbon energy sources, including wind, solar, hydro, and nuclear power. Cleanly generated electricity can power transportation, heating, and industrial processes, displacing fossil fuel use.

Furthermore, strategies for carbon dioxide removal from the atmosphere, such as increasing forest cover (afforestation and reforestation) and employing agricultural practices that enhance soil carbon sequestration, are also crucial components of a comprehensive climate strategy.