Is the earth’s climate getting hotter, changing? Is man responsible?

The Intergovernment Panel on Climate Change, in a report Sept. 27, says that man’s activities are at least half to blame for rising global temperatures. But it seems the Southeast doesn’t follow this global warming trend as closely, according to Florida’s climatologist David Zierden.

First, quick background on the IPCC and its reports: The IPCC is sponsored by the United Nations and includes hundreds of leading climate authorities from around the world. Since 1988, the group has issued reports, or assessments, every five to six years. “These reports are widely considered to be the most comprehensive and authoritative summary of current climate science,” Zierden says in a statement about the IPCC most-recent report.

IPCC believes it is extremely likely that human activity and greenhouse gases are responsible for more than half of the observed rise in global temperatures. What does “extremely likely” mean? It means the group has a confidence of 95 percent certainty on this, which is up from its 90 percent certainty from its 2007 report.

On average, the earth’s surface has warmed 1.5 degrees F since 1880. IPCC predicts global temps will rise much higher by 2100 if current human activity and greenhouse gases remain unchecked.

Southeast and Florida not much warmer

But the Southeast, including northern and central Florida, is one region that hasn’t experienced much warming due to greenhouse gases, Zierden says.

“Our historic data records show that the climate of the Southeast was characterized by relatively warm decades in the 1920s, 1930s and 1950s and cooler decades in the 1960s through 1980s. In northern Alabama and northern Georgia, some of the hottest years on record and many daily heat records occurred in the 1930s,” he says.

In Florida, man has impacted the climate, but mostly by changing the land, he says. Temperatures have risen along the southeast Florida coast by more than a 1 degree F in the last 40 years.        

“Much of this can be attributed to urban development, where cities built of concrete and asphalt now absorb and hold more heat than the natural environment they replaced. Similar trends are observed in other urbanized areas like Jacksonville, Tampa, Orlando and the I-4 corridor.

Other changes to the land surface have also impacted the local climate, like the draining of vast wetlands and their conversion to sugar cane fields around Belle Glade on the south shore of Lake Okeechobee,” he says.

To see local historical temperature and precipitation patterns in Florida, click here.

Will the Southeast continue to lag behind global warming trend? Probably.

“While global climate models have some skill at predicting changes to the global average temperature, they have much harder time predicting regional or local changes. Our geography and being surrounded by the Gulf of Mexico and Atlantic Ocean would suggest that temperature changes will be less here in Florida,” he says.

Florida and the Southeast might feel the changes predicted for other parts of the world in the future, or the region may not.

“However, that does not mean that we can sit back without taking action. With a nearly tropical climate, a small increase in temperature or changes in rainfall patterns could have a profound influence on natural and man-made systems. South Florida is already struggling with the reality of sea level rise. Human health and disease is and will be affected,” he says.

IPCC report has weaknesses

IPCC reports are the authoritative opinion on climate science, he says, but the report and the process used to develop the report has some weaknesses.

“First, it is a cumbersome process to compile the thousands of publications and experiments into a coherent document, and newer research and findings can be left out. In some ways, the report is outdated before it is published,” he says.

It seems, too, that over the last 15 years, global warming has stopped since a record warm year in 1998, which was caused by a strong El Niño.  The IPCC says this is "due to natural variability, trends based on short records are very sensitive to the beginning and end dates and do not in general reflect long-term climate trends."

“This statement is true and most scientists believe that the recent slowdown in warming is just a temporary speed bump. However, the climate models used in the 2007 assessment all failed to predict this slowdown in warming. At best that means the models are failing to reproduce internal variability at important time scales, at worst that the models are not properly representing an important physical process,” Zierden says.

Florida experiences climate-related risks, like drought, extreme temperature, heavy rainfall and hurricanes. It has for centuries. It’s part of the Southeast climate. Even so, “Decision makers need the highest quality, accurate, and scientifically sound climate information to help prepare for and anticipate climate risks and opportunities to build a more climate resilient society,” he said.

To read, Zierden’s full statement, and you’re encouraged to do it, click here.

brad.haire@penton.com