The complex picture of climate change in Alabama
by Sydney Cromwell
Editor’s note: This is the first in a two-part series about how climate change will affect Alabama. To read the second part of the series, click here.
If you want to talk about climate change in Alabama, it’s not as simple as saying, “it’s getting hotter.”
Alabama has not experienced the levels of rapid warming measured in many other parts of the world so far — but that doesn’t mean the state will be immune. Climate researchers are already seeing increasing temperatures in the Southeast, with rising sea levels, unpredictable weather and other disruptors of daily life in tow.
Without drastic changes in the amount of manmade emissions we produce, that trend is expected to continue.
“Climate change is not something off in the future. It’s something we’re dealing with right now. Whatever choices society makes in terms of how much fossil fuels we continue to burn and put in the atmosphere will, you know, have consequences for decades and decades and centuries to come,” said Adam Terando, a U.S. Geological Survey research ecologist at the Southeast Climate Adaptation Science Center.
So, what does climate change look like in Alabama now — and what might the future hold?
AN INTERNATIONAL CRISIS
First, let’s take a look at the big picture: Based on land and ocean surface temperature measurements, Earth is about 1.8°F warmer now than it was around 1900, according to a report released by the International Panel on Climate Change in August.
“Each of the last four decades has been successively warmer than any decade that preceded it since 1850,” the IPCC report said.
Average temperature records have been broken again and again in recent decades. July 2021 was the hottest month ever recorded, according to the National Oceanic and Atmospheric Administration.
“We’re 100% confident the world is warming up,” said Charles Konrad, director of the Southeast Regional Climate Center, based in North Carolina.
The planet’s temperature has always gone through cycles of heating and cooling, but the warming we are currently experiencing is more rapid thanks to the manmade carbon dioxide emissions released by industry, transportation, power production and other daily human activity.
A 1.8° increase in average temperature sounds small, but it means big environmental changes. The unprecedented speed of this change makes it harder for all life forms — plants, animals and humans — to adjust.
As land, air and sea get hotter, they change patterns of currents and air flow, which in turn can make rainfall and weather events like droughts, floods, wildfires, hurricanes and typhoons more frequent and more intense. Weather- and climate-related disasters are five times more frequent now than in 1970, according to the United Nations Framework Convention on Climate Change.
Ocean levels have risen due to the melting of glaciers and sea ice, and the water has also become more acidic and less oxygenated.
“With every additional increment of global warming, changes in extremes continue to become larger,” the IPCC report says.
Again and again, the IPCC and other international researchers have found that these changes are partly or almost entirely driven by human behaviors.
Climate researchers across the world tend to agree that the global temperature should not rise more than 3.6°F (2°C) above pre-1900 levels, in order to protect people and ecosystems. Beyond that point, the effects of climate change on severe weather, sea level rise, species extinction and human health are only expected to get more severe.
Scot Duncan, a biology professor at Birmingham-Southern College and researcher on conservation, said the current rate of climate change is causing the planet to rapidly approach “tipping points” that can cause irreversible harm in places like the Amazon rainforest and arctic sea ice.
“You hit those tipping points and not only is there no going back in any reasonable human time frame, but they also trigger other tipping points,” Duncan said.
Looking back at Alabama’s temperature record from the late 1800s to the present, the state doesn’t show a strong warming trend.
The 1920s and 1930s generally saw the highest average annual temperatures for the state, including the hottest day on record (1925), then things cooled off for a few decades.
Alabama has been warming up again since the 1970s, Konrad said, but it has yet to surpass the highs experienced nearly a century ago.
“The Southeast has seen some really warm temperatures in the past,” Konrad said.
According to the 2018 National Climate Assessment (NCA), “the southeastern United States is one of the few regions in the world that has experienced little overall warming of daily maximum temperatures since 1900.” Extreme heat days (above 95°) were more common prior to 1960 than in the decades since.
Partly, our region has the benefit of latitude: global temperature increases have been more pronounced at high latitudes, not near the tropics.
Terando, who was the federal coordinating lead author for the NCA’s chapter on the Southeast, said the reasons aren’t entirely clear for why Alabama has seen less warming.
He said some research has suggested that the state has been protected by its forests and their ability to provide shade and absorb carbon. Another possibility is that molecules put into the atmosphere by coal-powered plants, though certainly not environmentally friendly, have provided a layer of protection from the sun.
NOAA’s Climate Summary for Alabama includes cloud cover, rainfall levels, agricultural irrigation and sea surface temperatures as other potential cooling influences.
It’s also possible that Alabama’s lack of warming has happened by chance.
“The climate system is nonlinear, it’s complex,” Terando said. “… There’s also still random little wiggles and things like that.”
While these factors may have protected Alabama from rising heat so far, Terando said it’s not expected to stay that way.
“It’s not something that’s a permanent, protective layer,” he said. “… We are putting so much, such a large amount of greenhouse gasses into the atmosphere that that warming is sort of inexorable.”
The Southeast has matched the rest of the United States in warming rates since the early 1960s.
Birmingham is one of only five large cities in the U.S. whose heat wave trends have exceeded the national average for intensity, frequency and duration, the NCA reported. Two of the other four cities are also in the Southeast.
“Sixty-one percent of major Southeast cities are exhibiting some aspects of worsening heat waves, which is a higher percentage than any other region of the country,” the NCA states.
Based on current fossil fuel consumption, the NCA is projecting that daily high temperatures above 95° will become the “summer norm” for Alabama by the middle of this century, and days above 100° will not be rare.
“Even if Alabama isn’t quite as hot as, say, the hottest parts of the 1920s, it’s very likely that soon Alabama will experience the warmest temperatures that it’s seen in a long time,” Terando said.
WHEN IT RAINS, IT POURS
Along with new summer highs, climate change is also shifting weather patterns.
It’s hard to measure exactly how much climate change is the driving force behind any single weather event, because weather is variable and influenced by many factors. But in general, scientists are expecting droughts to get drier, storms to get wetter and natural disasters like wildfires and hurricanes to get more intense.
Terando said the effect is not necessarily that a severe storm, drought or other weather event is going to happen more frequently, but that it’s more likely to be extreme when it does happen.
“[A] well-founded effect of climate change globally is that a warmer atmosphere will contain more water vapor,” he said. “… That means that when it does rain, you have a higher chance of it being really intense rainstorms.”
The 2018 National Climate Assessment reported that 70% of its rainfall measuring stations in the Southeast have seen an upward trend in extreme events (3 inches or more of rain in a day) since 1950. The assessment said the past three decades have had “historically high” numbers of extreme rainfall events for this region.
“Increasing both the temperature and the humidity is kind of a double whammy,” Konrad said.
Conversely, during dry spells, heat-driven evaporation will pull more moisture from soil and water sources, leading to drought conditions.
Warmer ocean surface temperatures create friendly conditions for strong hurricanes. The IPCC’s September report includes the expectation that as warming continues, a greater percentage of hurricanes and cyclones will reach Category 4 and 5 levels.
“As sea surface temperatures warm, that’s just like you’re turning up the temperature on an oven. … The warmer that oceans are, the more energy there is to rev up that hurricane,” Terando said.
Hotter oceans also mean melting arctic ice, and a global rise in sea levels. This conjures the mental image of polar bears on disappearing glaciers, but it’s also a problem for people who live and work on Dauphin Island, Mobile Bay and other low-lying coastal areas of the state.
Sea levels along the Alabama coast have risen 1.5 inches per decade, according to NOAA, which is “faster than the global rate.”
New areas of the coast are being exposed to regular flooding and erosion as the ocean creeps farther inland. Even if emissions of greenhouse gases are drastically lowered, NOAA anticipates Alabama will see at least one foot of sea level rise by 2050.
In addition to measurements of temperature, rainfall and other climate indicators, researchers tend to use models to try to predict what we might see next.
These models are built on data about emissions levels and our understanding of the atmosphere, oceans and global weather patterns. Scientists create formulas to incorporate possible future emission levels and other human or natural influences on climate, and then see what the outcome is. Terando said these models are much like the ones used to create weather forecasts.
There is always a level of uncertainty to future modeling. Human behaviors change, and weather patterns don’t always behave as expected.
For example, Konrad said many temperature recording stations have been gradually surrounded by the growth of cities, and that “urban heat island” effect can lead to artificially high temperature readings. He said researchers have to do “a lot of painstaking work” to correct for these influences in the data.
The inherent uncertainty of modeling, as well as the variability in Alabama’s temperature and rainfall records over the last century, are important talking points for climate change skeptics like John Christy.
Christy, Alabama’s state climatologist, is part of a small subset of researchers who believe that climate change is less drastic — and less influenced by manmade emissions — than the majority of climate scientists.
The “natural variability of climate is what dominates,” not human influence, he said.
While he concedes that emissions like carbon dioxide in the atmosphere can cause some warming effects, Christy believes that effect is more than cancelled out by other natural weather patterns, or explained away by the growth of urban infrastructure around temperature stations.
Christy’s viewpoints are far outweighed by the body of research by thousands of climate researchers across decades and across countries, some of which have corrected his own findings. Despite this, he has been invited to speak to Congress in 2016 and 2017 about the so-called “warming bias” of mainstream research, and he also served on the Environmental Protection Agency’s Science Advisory Board, at the invitation of President Donald Trump.
One of Christy’s arguments is that models are inherently a flawed source of knowledge about the planet’s climate future. As he puts it: “I use real data and they use models.” He says he “wouldn’t want to put too much confidence” in climate modeling.
However, this ignores that “real data” is the root of those models. Terando said climate models are built off of collected measurements and math, not out of thin air.
“We tend to make scenarios that we think are useful and helpful. We don’t just make random scenarios,” he said.
Models are not perfect or infallible; in fact, scientists are continually updating and revising them to reflect changing circumstances and better understandings of weather and climate patterns.
“The climate models, they still have their issues. They’re getting better over time,” Konrad said. “… It’s a very complex system and you have to be very careful when you assign causality to the warming.”
“We improve our models all the time,” Terando said.
He said the IPCC had to revise one of its recent models because they weren’t properly accounting for cloud cover, making the planet’s warming seem more severe than it actually is.
But that process of catching errors and refining algorithms is part of the nature of research, Terando said. He firmly believes that the models used by mainstream climate science are trustworthy and useful to understanding the future.
“That’s why we do this, and that’s why we have the whole IPCC process,” he said.
In part, that is because these models have been used to successfully “predict” the past, Terando said. These climate models are tested through historical simulations called “hind-casting,” where the models are fed past years’ data to see if they can then predict changes that have already occurred.
If these hind-cast projections consistently match real-life results, Terando said, then their future predictions are likely to be reliable as well.
A 2019 study at University of California Berkeley tested whether 17 climate models could accurately predict global temperature changes through 2017. They found that 14 of the 17 produced accurate results, even though some of the models had been built as far back as the 1970s.
The IPCC’s report from August also included a comparison between simulated and real-life temperature change. It found that the models that included greenhouse gas emissions matched real observed temperatures. The models that included only “natural” factors did not — yet another sign that the changes we’re seeing in the world can’t be separated from human behaviors.
WHAT THE FUTURE WILL HOLD
The global future of climate change is hard to predict, even with the best models, because it will depend on whether countries and corporations choose to change their emissions policies, and by how much.
“We don’t know which pathway humans are going to choose,” Terando said.
The UN said earlier this month, however, that current plans to reduce emissions won’t be enough to stop the planet from crossing that 3.6°F “tipping point” for annual average temperature increase.
“Things will keep getting warmer. That’s going to happen, it’s just a matter of how much. Even if we stopped emitting all greenhouse gases tomorrow, there would still be some warming because of inertia,” Terando said.
In Alabama, NOAA predicts temperatures will at least match historical highs and could get as much as 4°F hotter than the state’s hottest year on record, depending on emissions levels.
What does that mean for Alabamians’ lives and livelihoods? Read on to the second part of our climate series.
Want to know more about the international climate crisis? The International Panel on Climate Change and National Climate Assessment are both expected to release more reports on global climate measurements and future trends in 2022.
Main article image courtesy of Jorge Barrios, Wikimedia Commons.