Extreme weather

The effects of extreme weather events are economic costs, loss of human lives, droughts, floods, landslides.

[5] Some human activities can exacerbate the effects, for example poor urban planning, wetland destruction, and building homes along floodplains.

Definitions of 'rare' vary, but an extreme weather event would normally be as rare as or rarer than the 10th or 90th percentile of a probability density function estimated from observations.

Power outages can also occur within areas experiencing heat waves due to the increased demand for electricity (i.e. air conditioning use).

Specifically, as used by the U.S. National Weather Service, a cold wave is a rapid fall in temperature within a 24-hour period requiring substantially increased protection for agriculture, industry, commerce, and social activities.

[9] Human populations can be inflicted with frostbite when exposed for extended periods of time to cold and may result in the loss of limbs or damage to internal organs.

[9] Cold waves that bring unexpected freezes and frosts during the growing season in mid-latitude zones can kill plants during the early and most vulnerable stages of growth.

Cold waves can also cause soil particles to harden and freeze, making it harder for plants and vegetation to grow within these areas.

"[22] A tropical cyclone is a rapidly rotating storm system with a low-pressure area, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain and squalls.

In modern times, on average around 80 to 90 named tropical cyclones form each year around the world, over half of which develop hurricane-force winds of 65 kn (120 km/h; 75 mph) or more.

[7] As more research is done in this area, scientists have begun to investigate the connection between climate change and extreme weather events and what future impacts may arise.

Climate models provide important predictions about the future characteristics of the atmosphere, oceans, and Earth using data collected in the modern day.

[24] Aspects of our climate system have a certain level of natural variability, and extreme weather events can occur for several reasons beyond human impact, including changes in pressure or the movement of air.

The atmosphere is a complex and dynamic system, influenced by several factors such as the natural tilt and orbit of the Earth, the absorption or reflection of solar radiation, the movement of air masses, and the water cycle.

[4] The record-breaking extreme weather events that have been catalogued throughout the past two hundred years most likely arise when climate patterns like ENSO or NAO work "in the same direction as human‐induced warming.

"[4] Some studies assert a connection between rapidly warming arctic temperatures and thus a vanishing cryosphere to extreme weather in mid-latitudes.

[30] Other models have shown that modern temperature rise and the subsequent addition of meltwater to the ocean could lead to a disruption of the thermohaline circulation, which is responsible for the movement of seawater and distribution of heat around the globe.

[31] A collapse of this circulation in the northern hemisphere could lead to an increase in extreme temperatures in Europe, as well as more frequent storms by throwing off natural climate variability and conditions.

[32] While there is evidence that a changing global climate, such as an increase in temperature, has impacted the frequency of extreme weather events, the most significant effects are likely to arise in the future.

This is where climate models are useful, for they can provide simulations of how the atmosphere may behave over time and what steps need to be taken in the present day to mitigate any negative changes.

[32] Current evidence and climate models show that an increasing global temperature will intensify extreme weather events around the globe, thereby amplifying human loss, damages and economic costs, and ecosystem destruction.

First, increasing the amount of impervious surfaces, such as sidewalks, roads, and roofs, means that less of the water from incoming storms is absorbed by the land.

[45] The destruction of wetlands, which act as a natural reservoir by absorbing water, can intensify the impact of floods and extreme precipitation.

However, wetland destruction along the coast can mean decreasing an area's natural 'cushion,' thus allowing storm surges and flood waters to reach farther inland during hurricanes or cyclones.

[47] Building homes below sea level or along a floodplain puts residents at increased risk of destruction or injury in an extreme precipitation event.

Tall structures can alter the way that wind moves throughout an urban area, pushing warmer air upwards and inducing convection, creating thunderstorms.

[45] Impervious surfaces also absorb energy from the sun and warm the atmosphere, causing drastic increases in temperatures in urban areas.

[65] Storms such as hurricanes or tropical cyclones may experience greater rainfall, causing major flooding events or landslides by saturating soil.