DISCUSSION: Recently, the internet has been abuzz with the question of whether we can blame climate change for catastrophes like Harvey and Irma.
The short answer is yes and no – and here’s why.
Climate and weather are two very different things. Climate is the long-term pattern of atmospheric conditions, while weather changes day to day. Hurricanes are weather phenomena. They are caused by waves in air circulation patterns off the west coast of Africa, and gain strength travelling over warm water. So, no, climate change did not directly result in the formation of dangerous hurricanes like the ones we've seen recently.
However, we can say that the effects of anthropogenic climate change made the impacts of these storms worse for two reasons:
1: Warmer air and sea surface temperatures
Air/water temperature is really a measure of the energy of the molecules of the air/water. Warmer temperatures mean more molecular motion which means more energy - the energy that hurricanes feed off of. As a hurricane travels through an area of warmer air and water temperatures, its wind speeds increase. Also, because the air is warmer, it can hold more water vapor – which means more rainfall. The observed increase in both air and ocean temperatures in recent years means that conditions have become increasingly favorable for strong tropical cyclones like Harvey and Irma to form.
2: Sea Level Rise
It's harder for flooding to happen if the level of the ocean starts out at a lower point. This is especially evident in cities like Miami, which already experiences a number of flood days throughout the year, regardless of whether it's a sunny day or a strong hurricane is coming through. This is due to rising sea level. With Miami flooding already from sea level rise, storm surge and rain just make it worse. This is also true for small island countries in the Caribbean that don't have the infrastructure to deal with rising sea levels.
Currently, there isn't enough data to conclusively say how climate change will affect hurricane development. However, we do have enough evidence based on the basic principles of how these storms work to say that climate change will "load the dice" in favor of stronger, more severe, more dangerous hurricanes. We can also say that climate change made the storms of fall 2017 warmer and wetter than they would have been without climate change.
To learn more about other tropical cyclone-related events and issues from around the world, be sure to click here!
©2018 Meteorologist Margaret Orr