Climate change
Climate change is a persistent alteration in the state of the climate, identifiable through changes in average conditions or variability that last for decades or longer. It can arise from natural processes and external forces, but current human-caused climate change is principally driven by greenhouse gas emissions.
In simple terms
Weather describes conditions over hours or days; climate describes patterns over much longer periods. Climate change includes shifts in temperature, rainfall, ice, oceans, extremes, and related systems. The Intergovernmental Panel on Climate Change concludes that human influence has unequivocally warmed the atmosphere, ocean, and land, mainly through greenhouse gas emissions. The effects differ by region and depend on both the amount of warming and the vulnerability of people and ecosystems.
Why it matters
Climate change affects health, food and water security, biodiversity, infrastructure, livelihoods, and economic stability. Carbon accounting helps organizations understand their contribution, while renewable energy and energy efficiency can reduce emissions. Carbon sequestration can remove and store carbon, but it does not remove the need for rapid emission reductions and adaptation to changes already occurring.
Example
For example, a city can observe a long-term rise in average summer temperature alongside more frequent extreme-heat days. It may reduce emissions through efficient buildings and cleaner energy while also expanding shade, cooling access, and heat-health plans to manage impacts that cannot be avoided.