Climate change is an overall shift in the Earth’s weather patterns that can affect our daily lives. It includes increases in temperature, changes in the frequency and severity of extreme weather events, and more.
Temperature is determined by the way the Earth absorbs and radiates solar energy. The atmosphere, oceans, land surfaces and ice sheets absorb and re-radiate this energy in different ways. Greenhouse gases (especially carbon dioxide) trap the sun’s rays in the atmosphere, preventing them from escaping. This process is called the greenhouse effect.
Human activities such as the burning of fossil fuels, deforestation and agriculture increase greenhouse gas concentrations in the atmosphere. This extra heat is then absorbed by the planet’s surface and re-radiated in a warming effect that makes temperatures rise.
This can cause changes in the global air and ocean temperatures, sea level rise, evaporation of water and snowmelt, increased rainfall, and more intense droughts. These changes can cause severe effects on our daily lives, including deteriorating water supplies, increasing pollution levels, and more frequent and intense storms and floods.
Our global climate is also changing through feedback processes that amplify or dampen disturbances caused by human emissions of greenhouse gases. The feedbacks are caused by the interaction of several climate components, including temperature, atmospheric water vapour, the extent of polar ice sheets and the concentration of long-lived greenhouse gases.
The rate at which the world warms depends on many factors, including emissions of greenhouse gases, feedback processes that dampen or reinforce disturbances to the climate system and unpredictable natural influences such as volcanic eruptions. This means that we can’t be sure how fast the world will warm until we know more about how our emissions will influence future climate.
As human emissions of greenhouse gases have increased, the rate at which our planet’s average temperature has increased has accelerated. This means that the risk of extreme and irreversible consequences for our world is greater than ever before, unless we take action to mitigate global warming.
Over the past century, global annual average surface air temperatures have risen about 1.98degF (1.1degC) and are expected to continue to rise under all plausible future climate scenarios. This rate is largely caused by the increase in atmospheric carbon dioxide and other greenhouse gases from fossil fuels, deforestation and agricultural practices.
Our changing climate is affecting the amount of precipitation in many parts of the world, including New York. Over the past century, total annual precipitation has increased by 0.10 inches per decade globally and in the U.S.
Rising temperatures are causing an increase in atmospheric water vapor. Water vapor is a key component of the greenhouse effect and accounts for half the global warming observed over the last century.
The water vapor feedback, which is approximately double the sensitivity of global average climate to increases in human emissions of greenhouse gases, is one of the most important impacts of climate change. It is a complex but essential feedback that is critical to our understanding of the climate and of how it is responding to human emissions.