Climate change: Quick Facts

Climate change refers to long-term shifts in temperatures and weather patterns. While these shifts can occur naturally, human activities, primarily the burning of fossil fuels like coal, oil, and gas, have been the main driver since the 1800s. This human-caused change encompasses global warming, which is the increase in average air temperatures, but also includes broader changes like rising sea levels and melting glaciers. These changes are largely due to increased greenhouse gases in the atmosphere.

Climate change is primarily caused by human activities that increase the concentration of greenhouse gases in the Earth's atmosphere. The combustion of fossil fuels and deforestation are major contributors to the release of carbon dioxide (CO2), a significant greenhouse gas. Other human activities, such as rice cultivation, livestock farming, and industrial processes, release methane (CH4) and fluorinated gases, which also trap heat.

These increased greenhouse gas concentrations enhance the greenhouse effect, leading to a warming trend observed over the past century. Changes in land use, such as converting forests to agriculture, also influence climate by altering the Earth's surface reflectivity and heat exchange with the atmosphere. While natural factors can influence climate, the current warming trend is overwhelmingly attributed to human-induced emissions.

Greenhouse gases are atmospheric gases that absorb and reradiate heat energy emitted from Earth's surface, contributing to the greenhouse effect. This natural process keeps the planet warm enough to support life.

The most significant greenhouse gases include:
* Water vapor: The most potent, its concentration is influenced by air temperature.
* Carbon dioxide (CO₂): A major contributor, increased by human activities like burning fossil fuels and deforestation.
* Methane (CH₄): More potent than CO₂ but less concentrated, emitted from sources like livestock farming and natural gas leaks.
* Ozone (O₃): Specifically surface-level ozone, resulting from air pollution.
* Nitrous oxides (N₂O) and fluorinated gases: Primarily produced by industrial activities.

Human activities, particularly the combustion of fossil fuels since the Industrial Revolution, have significantly increased the concentrations of these gases, intensifying the greenhouse effect and driving climate change.

Climate change significantly alters weather patterns, making them more extreme and unstable. Global warming leads to shifts in precipitation, with increased rainfall expected in polar and subpolar regions, while middle latitudes may experience decreased precipitation due to poleward shifts in jet streams. Equatorial regions are predicted to see more rainfall, contrasting with a decrease in subtropical areas.

These changes can result in a higher probability of both droughts and floods in various regions. Additionally, rising ocean temperatures associated with global warming may lead to more intense tropical cyclones, such as hurricanes. While the exact impact on the frequency of these storms is still debated, the intensity of those that do form is expected to increase.

Climate change poses significant threats to plants and animals. Rising global temperatures can alter established seasonal patterns, impacting processes like leaf production and migration timing for birds and fish. Species may face increased extinction risks as their natural adaptive capacities are challenged by rapid climatic shifts. Ocean acidification, caused by increased carbon dioxide absorption, reduces carbonate ions essential for shell and skeleton formation in marine life like corals and shellfish. This can lead to smaller organisms, increased vulnerability to predators, and even dissolution of shells. Furthermore, changes in sea ice affect high-latitude predators such as polar bears and walruses. Extreme weather events, intensified by climate change, also cause direct mortality and habitat destruction for various species.

To slow climate change, individuals can reduce their carbon footprint by adopting energy-efficient practices at home, such as improving insulation and using less energy for heating and cooling. They can also opt for renewable energy sources for household electricity and choose more energy-efficient vehicles like electric or hybrid cars, or utilize public transportation. Additionally, making conscious purchasing decisions for more sustainable products and reducing meat consumption can contribute to lowering secondary carbon footprints.

Globally, mitigation policies focus on reducing greenhouse gas emissions by transitioning to less carbon-intensive energy sources like wind, solar, and hydropower, and by improving energy efficiency in transportation and developing technologies such as carbon capture and storage.