Climate Denial Crock of the Week

Above, massive snows in California mountains have created dire situations for many towns.
Meanwhile, an atmospheric river is bearing down, that could create even more havoc.
What’s going on?

Jeff Masters in Yale Climate Connections:

So what’s up with the weather? Because weather is naturally extreme, could the extraordinary weather events in recent years be caused mostly by natural variability, with the expansion of the internet and media hype altering our perception of the weather? Undoubtedly, increased awareness of extreme weather can play a role in the perception that the weather is getting more extreme.

But all weather is now occurring in an atmosphere fundamentally altered by global warming. Heat is energy. More heat in the atmosphere means that there is more energy to power extreme weather events. Moreover, the extra heat energy from human-caused global warming has fundamentally disrupted atmospheric circulation patterns. The combination of more heat energy and a disrupted atmospheric circulation has made extreme weather events more common and more intense, a phenomenon climate scientist Katharine Hayhoe calls “global weirding.” The resulting weather disasters are severely stressing a society constructed for the old, somewhat calmer climate of the 20^thcentury.

Since the preindustrial times of the mid-1800s, Earth’s climate has warmed by about 1.2 degree Celsius (2.2°F). That may seem like a trifling amount until one considers the difference in global temperature today compared to the last Ice Age, when mammoths roamed the Earth and sea levels were 300 feet lower. 

The average global temperature difference between then and now is about 6 degrees Celsius (11°F), or what we can call one “ice age unit.” By that definition, people have already warmed the Earth by 20% of an Ice Age unit. Troublingly, current policies have us on track to warm the planet by about 2.7 degrees Celsius — nearly half an Ice Age unit — by the end of this century, as climate scientist Andrew Dessler explains in the Tweets above.

Consider climate change in terms of ice age units

Since the preindustrial times of the mid-1800s, Earth’s climate has warmed by about 1.2 degree Celsius (2.2°F). That may seem like a trifling amount until one considers the difference in global temperature today compared to the last Ice Age, when mammoths roamed the Earth and sea levels were 300 feet lower. 

The average global temperature difference between then and now is about 6 degrees Celsius (11°F), or what we can call one “ice age unit.” By that definition, people have already warmed the Earth by 20% of an Ice Age unit. Troublingly, current policies have us on track to warm the planet by about 2.7 degrees Celsius — nearly half an Ice Age unit — by the end of this century, as climate scientist Andrew Dessler explains in the Tweets above.

Thus, 1.2°C of warming is very significant, particularly considering that over land areas — where people live — the warming has been greater, about 1.7 degree Celsius (3.1°F). And over Northern Hemisphere land areas, the warming has been even higher, about 1.9 degree Celsius (3.4°F).

More heat means more energy to power heat waves, droughts, and wildfires

When weather patterns favor a dry pattern, global warming will cause the heat waves that occur during those dry periods to be more intense. And since warmer air can hold more water vapor, soil and plants will lose more moisture to the air, causing increased drying, more frequent and more intense droughts and higher wildfire risk. A large volume of research now connects human-caused climate change to increased heat, drought, and wildfires, leading to impacts already beyond what was anticipated even 20 years ago.

The cumulative forest area burned by #wildfires greatly increased between 1984-2015, with analyses estimating that the area burned by wildfire across the western U.S. over that period was twice what would have burned had #climatechange not occurred. #NCA4 https://t.co/H6HVtlnexY pic.twitter.com/EptnYxGzXp

— U.S. Global Change Research Program (@usgcrp) December 15, 2021

When weather patterns favor storms, global warming increases the heat energy available to storms. This extra heat energy can be converted to the kinetic energy of their winds, driving more wind and storm surge damage. 

Moreover, heat-charged storms will also be able to dump more precipitation, since a warmer atmosphere can hold more water vapor. Each degree Celsius the atmosphere warms increases the amount of water vapor that can be present by 7%, leading to more intense heavy precipitation events. And when that extra water vapor condenses inside a storm, the “latent” heat required to evaporate the water is released, invigorating the storm, allowing it to grow larger and stronger and pull in even more moisture. 

Globally, atmospheric water vapor has increased 5-20% since the 1960s, and this is a primary factor in the increase in heavy precipitation events in most regions of the world in recent decades.