Extreme Weather and Climate Change, EarthNow

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Here’s the latest from EarthNow… Three out of four adults in America say that global warming is affecting weather in the United States. After Super Typhoon Haiyan made landfall in the Philippines, seen here by water vapor satellite imagery over sea surface temperatures, delegates at the United Nations Convention on Climate Change also made strong connections between climate change and extreme weather. But, what does the science say? Is global warming changing weather patterns and weather extremes? First, let’s consider some basic facts about weather and climate. Earth is a water planet. Oceans and lakes cover three quarters of the Earth’s surface, as depicted in this pie chart. Water is the only substance on Earth that exists naturally as a solid, liquid, and gas. The gas phase of water is referred to as water vapor. Did you know that water vapor is the most abundant greenhouse gas in Earth’s atmosphere? While we can’t see water vapor in the atmosphere, instruments on satellites can. This animation shows atmospheric water vapor detected by satellites, with moisture-rich air shown as white.

Watch as storms in the mid-latitudes draw the warm moisture from the tropics. Weather patterns help redistribute heat and moisture around the planet. This means that the availability of water vapor fuels or limits all atmospheric processes. Let’s take a closer look at how water vapor fuels tropical cyclones, also called hurricanes and typhoons. Rising air over warm ocean waters carries water vapor upward into colder air. As this happens, warm moist air near the surface rushes in to take its place, creating the strong winds associated with hurricanes. As the warm air rises, the water vapor cools and condenses into clouds, releasing heat. The added heat accelerates this process. The rotating Earth causes the storm to begin spinning. Once a storm moves over land, it weakens rapidly largely because the storm lacks the moisture and heat the ocean provided. Looking at typhoons and hurricanes over time, researchers see a trend. In a warming world with warmer oceans, there is more evaporation and fuel for storms, leading to more powerful storms.

The warmer air can also hold more moisture, meaning heavier rainfall. Finally, rising sea levels mean higher storm surges and more flooding. Basic science points to bigger storms, changing weather patterns, and more extremes. What does this mean for you? If you live near the coast, like a lot of people, there is an increased vulnerability to storms due to rising sea levels. Here, we can see Hurricane Sandy making landfall in the highly populated Northeastern United States. Sandy caused an estimated $70 billion in damage in the U.S. But even if you don’t live near the coastline, research shows that Earth’s changing climate is altering the frequency, intensity, extent, and duration of other extreme weather events around the world. Wherever you live, it’s important to understand the type of hazardous weather that might affect you and your family..

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