We’re about to wrap up 2021, another year of climate extremes across the U.S. It’s tempting to look back at the big stories: record cold in Texas, record heat in the Northwest, record rains from Hurricane Ida and December’s heat and deadly weather. But thinking about my climate work over the last year, I was struck by how much of it is about trends. I see six trends that can impact virtually all of us next year.
The first is the big one: carbon dioxide in the atmosphere. We all hoped that maybe the economic slowdown from the COVID-19 pandemic would blunt the rise of carbon dioxide that drives global warming and makes extreme weather more likely. Nope.
Humans around the world still burned tons of fossil fuels — likely adding 36.4 billion tons of carbon dioxide to the atmosphere. Atmospheric CO2 reaches its annual peak in May. Last year, the CO2 monitoring station in Hawaii recorded an all-time weekly high of 418 parts per million (ppm). In 2021, the question is not whether we will beat 418 — we definitely will — but whether we see signs that emissions are slowing. That would mean growing less than 2.4 ppm, so staying below 421 ppm.
The second trend follows the first: rising temperatures. The National Oceanic and Atmospheric Administration (NOAA) and NASA in the U.S. and the UK Met Office will soon release their final calculations of global mean temperature. The year 2021 will likely be the sixth warmest on record. We are currently in a La Nina — a weather pattern triggered by unusually cool water in the equatorial Pacific. La Nina is like having the global air conditioner set on max — it tends to depress global temperatures. But it’s expected to fade in the coming months, so 2022 has a good shot at being warmer than 2021.
With or without La Nina, we can expect to see parts of the country struggle with deadly heat this summer. Something as weird as the 2021 Northwest heatwave may be unlikely, but the climbing global temperatures ratchet up the probability of dangerously high temperatures in the U.S. and around the world.
Rising temperatures also affect hurricanes, some of the costliest and deadliest weather events that we experience. Hurricanes feed off of very warm ocean waters. The amount of ocean area that is warm enough to sustain a hurricane is increasing and warm conditions occur earlier in the spring and extend later in the year.
The biggest trend, though, is the chance of storms rapidly intensifying into major hurricanes. In many ways, Ida was the perfect example of how climate change affects hurricanes. It was a fairly ordinary storm until it passed over the unusually hot waters of the Gulf of Mexico. Then, it exploded into a Category 4 hurricane and crashed into Louisiana — but caused heavy rains and flooding as far north as New York. Even if the number of named storms fluctuates year-to-year, each storm that forms now has a greater chance of growing into a monster like Ida.
Ida points to the fourth big climate trend to watch: more extremes in precipitation. A warmer atmosphere can hold more water vapor. This means that when it rains, there is a greater chance that it will pour. Events like the flash flooding in West Virginia and the catastrophic rains from Ida are becoming more common. Extremes in precipitation also apply to snow. Even though the number of days when it’s cold enough to snow is decreasing across much of the country, the same moist atmosphere that can bring us big rain events can also produce big snow events.
The fifth trend to watch is the drought in the Southwest, which contributes to higher wildfire risk and threatens water supplies. Big parts of the Southwest have experienced drought conditions for more than a year. Because of La Nina, NOAA is predicting that southern California, Arizona and New Mexico will be drier than normal for the next few months. This suggests that drought will continue, although it looks like the Northwest might get some relief. But throughout the West, drier conditions coupled with hotter, windier weather increases the number of ideal days for fires to start and spread.
The final trend to watch is the total cost of all of these climate-influenced events. The human costs of extreme heat, fires, floods and high winds are brutal. But there are also direct economic costs — money that we have to pay to rebuild communities and money that we lose due to droughts and disruption. In dollars, final tallies from these events often reach the billions. And their frequency — and costs — are growing every year: the U. S. now experiences a billion-dollar disaster every 22 days.
One interesting thing about disasters is that we have some control over how bad they are. While we can’t directly control the weather, we do have some say over climate trends. Once we stop putting carbon dioxide into the atmosphere, the rate of climate change will slow and we will be more able to adjust to a new normal.
In the meantime, there are things we can do to make disasters less costly and less deadly. We can recognize the increase in deadly heat and take steps to make our cities cooler and safer for everyone. We can recognize the trend in extreme precipitation and give planners the tools to protect people from flash floods. We can plan and build for stronger storms and higher coastal flood risks. Finally, we can take advantage of improved weather forecasts to keep our communities safe during extreme weather.
The key takeaway from the 2021 climate disasters in our rearview mirror is to keep looking forward, using the trends we’ve seen to anticipate and meet the challenges of the future.
Andrew Pershing is the director of Climate Science at Climate Central. He is an expert on how climate trends and events impact ecosystems and people and recently led the Oceans and Marine Resources chapter of the fourth U.S. National Climate Assessment. Follow him on Twitter: @Sci_Officer