ISLAND ESTATES — Some people want to break the “hockey stick,” a graphic that climate scientists say illustrates the planet’s abrupt temperature rise, said Donny Smoak, professor of environmental science at the University of South Florida.
In his Aug. 15 presentation “Climate Change and Blue Carbon” at Clearwater Marine Aquarium, he illustrated some of the many sources that he said offer evidence of global temperature rise, exceptional in later decades and contrary to the opinions of disparagers.
“Climate change is not simple,” he said.
The “hockey stick” is a graph in the shape of a hockey stick and blade that reconstructs Northern Hemisphere temperatures over the past 1,000 years. The scientists who published it in 1999 say it shows that temperatures had been fairly flat, but slightly cooling, over the past millennium until the 20th century, when there was rapid global warming. The “hockey stick” model has become a prime target of skeptics.
Smoak outlined some tenets of basic science: greenhouse gases have a warming effect; warming has been observed; and human activities contribute to that escalation.
Then there’s the matter of energy balance. The amount of energy incoming to Earth is equal to the amount outgoing, he said. Otherwise, the temperature would heat up without end.
However, based upon scientific calculations using the temperature of the sun and its distance from Earth, this planet should be much cooler than it is, he said. So why isn’t it?
The professor explained that the greenhouse effect — the idea that the Earth’s atmosphere serves as an insulator — first was identified by French physicist Joseph Fourier in 1827. It was viewed as a positive thing, in part because warmer weather would extend growing seasons.
But by using data from ice core samples, tree rings, marine coral and other sources, a reconstruction of past climates has revealed that global temperatures are now at the highest value ever recorded, except for an El Nino year in 1998, and that carbon dioxide is likely at the highest level in the past 20 million years, Smoak said.
With the rise of greenhouse gases including water vapor, methane, nitrous oxide, ozone and carbon dioxide, the temperature warms. Smoak detailed some of the consequences: Glaciers are retreating and arctic ice is thinning and declining; seas are heating up and water vapors and sea levels are rising; and vegetation is dying.
Of the carbon dioxide emissions, primarily from fossil fuels, half enter the atmosphere and the rest go into vegetation or into the ocean, with the resulting acidification causing coral reefs to suffer, he said.
The professor said the amount of biological carbon buried annually in coastal wetlands, known as blue carbon, is multiple times greater than that stored in terrestrial forests. Now recognized as important carbon storehouses, mangroves, salt marshes and seagrasses long have played critical roles as fish nurseries and served as protective barriers against violent storms.
Soil samples collected around the world are used to measure carbon dioxide content as well as the level of buildup in coastal areas, as Smoak currently is studying in the Everglades. So far, he said, that soil accretion is keeping up with sea level rise, and “Florida is a pretty good place to be.”
But as levels of greenhouse gases rise, so does the temperature.
“The uncertainty isn’t if it’s going up, but how much,” Smoak said.
Joe Malo, who is in charge of video productions at Clearwater Marine Aquarium, wanted to know what people can do to slow that down.
The professor said that isn’t his area of research but suggested, “Lots of little things, like using the correct tire pressure and green energy, solar and wind.”