Climate change refers to a range of changes in Earth’s weather and environment caused by humans, particularly our use of fossil fuels. These include warming, shrinking ice sheets and glaciers, changes in wind patterns, ocean acidification and biodiversity loss.
Climate changes are happening at a rate that is unprecedented in millennia. The evidence is everywhere—from global temperature rise to thinning polar ice caps to rising sea levels. Scientists agree that the primary cause is human activities, specifically our emissions of greenhouse gases.
Greenhouse gases trap escaping infrared energy, warming Earth’s atmosphere and water. Carbon dioxide is the main greenhouse gas, and it’s released when we burn fossil fuels (like coal and oil) to produce electricity or heat buildings and cars. Other gases like methane and nitrous oxide are also produced from farming, land clearing and other activities.
As temperatures warm, more and more regions will become suitable habitats for mosquitoes, ticks, and other parasites that spread diseases (like dengue fever, Zika virus, malaria and Lyme disease). In addition, the warmer air holds more moisture, increasing the frequency of severe tropical cyclones.
Climate change is affecting all parts of the world, but poorer countries are often hit hardest. This is because they have lower incomes and may lack the resources to adapt. At the same time, wealthy nations are responsible for the lion’s share of historic greenhouse gas emissions and are currently emitting more CO2 than they need to. This creates an unsustainable imbalance that could cross critical “tipping points” that would lead to irreversible, catastrophic climate change.
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