Climate report: Louisiana, Southeast at exceptional risk through end of century
By Mark Schleifstein | Posted November 27, 2018 at 05:11 PM | Updated November 30, 2018 at 02:22 PM
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Cars plow down Orleans Avenue at as the streets flood during an extreme rainfall event in New Orleans on Saturday, August 5, 2017. While major problems with Sewerage & Water Board pump stations and power supply exacerbated the flooding, the thunderstorm dumped between 6 and 9 inches of rain on a small area of the city in only three hours. Researchers say it was fed in part by climate-related warming that allowed the atmosphere to hold more moisture over the city. (Photo by Michael DeMocker, NOLA.com | The Times-Picayune archives)
Louisiana is at exceptional risk from climate change effects through the remainder of the 21st century, including the effects of between 1 and 4 feet of sea level rise, a greater number of intense rainfall days, increasingly warmer temperatures, and exposure to mosquito-borne diseases, according to a new federal National Climate Assessment report.
The impacts to both infrastructure and human health already are especially high and will continue to be so for New Orleans and other major cities in southeastern states, according to the report released Friday (Nov. 23).
"The vibrancy and viability of these metropolitan areas, including the people and critical regional resources located in them, are increasingly at risk due to heat, flooding, and vector-borne disease brought about by a changing climate," said the report.
The figure shows the percent of land area in the contiguous 48 states experiencing extreme one-day precipitation events between 1910 and 2017. These extreme events pose erosion and water quality risks that have increased in recent decades. The bars represent individual years, and the orange line is a nine-year weighted average. (U.S. Global Change Research Program)
That's in part because the region's coastal plain and inland low-lying areas are home to a rapidly-growing population and features industries critical to the nation, to cultural resources and to a major tourism economy, all of which are becoming increasingly vulnerable to climate change impacts.
"The combined effects of changing extreme rainfall events and sea level rise are already increasing flood frequencies, which impacts property values and infrastructure viability, particularly in coastal cities," said the report's chapter on the southeast region. That included coastal and inland states from Louisiana and Arkansas to Virginia and Kentucky.
"After the 1,000-year rain event of 2016 in my city, I have been paying close attention to credible projections for future events," said Sharon Weston Broome, mayor-president of Baton Rouge, in a news release distributed by the Mississippi River Cities and Towns Initiative on Tuesday. "The NCA released (Friday) states the combined impacts of sea level rise and storm surge in the southeast have the potential to cost up to $60 billion each year in 2050 and up to $99 billion in 2090; that level of impact cannot be dismissed or put off for the next generation to deal with."
The left graph shows observed and projected changes in fossil fuel and industrial emissions of carbon dioxide (CO2) from human activities. The right graph shows projections of direct damage to the current U.S. economy for six impact sectors (agriculture, crime, coasts, energy, heat mortality, and labor) as a function of global average temperature change (represented as average for 2080-2099 compared to 1980-2010). Compared to RCP8.5 (high greenhouse gas scenario), lower temperatures due to mitigation under either of the lower scenarios (RCP2.6 or RCP4.5) substantially reduce median damages (dots) to the U.S. economy while also narrowing the uncertainty in potential adverse impacts. The gray shaded area represents the 90% confidence interval in the fit (black line) to the damage estimates. Damage estimates only capture adaptation to the extent that populations employed them in the historical period. (U.S. Global Change Research Program)
Estimates of Direct Economic Damage from Temperature Change
Also threatened, the report said, is the Southeast's diverse natural ecosystems, which will be "transformed by climate change."
"Changing winter temperature extremes, wildfire patterns, sea levels, hurricanes, floods, droughts, and warming ocean temperatures are expected to redistribute species and greatly modify ecosystems," said the report's region chapter. "As a result, the ecological resources that people depend on for livelihood, protection, and well-being are increasingly at risk, and future generations can expect to experience and interact with natural systems that are much different than those that we see today."
The congressionally mandated report was written by more than 300 federal scientists under the direction of 13 federal agencies. The 1,600-page document consists of 12 high-level chapters explaining the national effects of climate change, 10 regional chapters, and two chapters outlining alternatives for reducing risk by reducing greenhouse gases, or by accommodating climate change's effects.
"Observations of global average temperature provide clear and compelling evidence that global average temperature is much higher and is rising more rapidly than anything modern civilization has experienced," said David Easterling, director of the Technical Support Unit at the NOAA National Centers for Environmental Information, during a news teleconference in Washington announcing the report's release Friday. "And, this warming trend can only be explained by human activities, especially the emission of greenhouse gases into the atmosphere."
Easterling insisted that there was no external interference in the report's development, in response to questions about why it was released on Black Friday, a day when many Americans were unlikely to be focusing on the report's dire conclusions.
President Donald Trump issued a series of comments over the weekend discounting the report's results and blaming its findings on what he said were scientists interested in money to support their research.
"I don’t believe it," Trump said about the report's warning that climate change would cost the U.S. hundreds of billions of dollars a year.
A statement released by White House deputy press secretary Lindsay Walters stressed that this fourth four-year assessment was begun under the Obama administration and that the next report would show that its alarm was overstated.
"The report is largely based on the most extreme scenario, which contradicts long-established trends by assuming that, despite strong economic growth that would increase greenhouse gas emissions, there would be limited technology and innovation, and a rapidly expanding population," Walters said.
"To better assess the potential future effects of climate change, we need to focus on improving the transparency and accuracy of our modeling and projections," the statement said. "The Fifth National Climate Assessment gives us the opportunity to provide for a more transparent and data-driven process that includes fuller information on the range of potential scenarios and outcomes."
However, the report's authors point out that the document clearly outlines the results of a number of models that range from minimal to major effects of various climate change indicators, and that it is based on the most recent science available.
The main report summarizes the link between climate change and increased risk in a series of bullet points:
- Observations collected around the world provide significant, clear, and compelling evidence that global average temperature is much higher, and is rising more rapidly, than anything modern civilization has experienced.
- The warming trend observed over the past century can only be explained by the effects that human activities, especially emissions of greenhouse gases, have had on the climate.
- Earth's climate will continue to change over this century and beyond. After mid-century, how much the climate changes will depend primarily on global emissions of greenhouse gases and on the response of Earth's climate system to human-induced warming.
The report also warns that sea level has risen by about 7 to 8 inches globally since 1900, with half the rise occurring since 1993, the result of both ocean water molecules warming and expanding in size and land-based ice melting.
"Relative to the year 2000, sea level is very likely to rise 1 to 4 feet by the end of the century," says a slide accompanying the report. "Emerging science regarding Antarctic ice sheet stability suggests that, for higher scenarios, a rise exceeding 8 feet by 2100 is physically possible, although the probability of such an extreme outcome cannot currently be assessed."
For Louisiana state climatologist Barry Keim, that conclusion is part of the major conundrum facing the state.
"Every year that passes by and this goes on, we become more vulnerable to hurricanes and to flooding," Keim, a professor at Louisiana State University, said. "The reason I say it's a conundrum is we're an oil and gas state and that's part of the economy. Obviously, we want the industry to do well for the jobs and economy in Louisiana, but the longer picture is not good for the state if the climate does change as it's predicted to do by modeling."
The problem is that Louisiana's industry has a key role in producing the greenhouse gases that are linked to rising temperatures. The report ranks Louisiana at the bottom of states that are taking steps to reduce the greenhouse gases that have been linked to the increased climate change rate.
Louisiana is among only five states that have adopted only 4 or less state-wide carbon and greenhouse gas emission reduction efforts, among 30 alternatives reviewed as part of the report. The state does rely heavily on nuclear power for electricity, supplied by Entergy's Waterford 3 plant in Hahnville and River Bend in St. Francisville. The two plants first went into service in 1985 and 1986, respectively, and both are in the midst of relicensing, as they are approaching the end of the 40-year initial licenses.
Entergy's Arkansas subsidiary announced last week that it planned to shut down by 2030 two coal-fired power plants in that state that supply about 35 percent of the electricity used by Entergy Louisiana and Entergy New Orleans. That power would be replaced with more greenhouse gas friendly sources, Entergy officials have said, which could include cleaner-burning natural gas.
According to the World Resources Institute, in 2014 Louisiana was responsible for 3.4 percent of the nation's greenhouse gas emissions, with about half emitted by industrial sources. At the time, it ranked 8th nationwide in greenhouse gas emissions, with Texas, 12.73 percent, and California, 6.62 percent, well ahead.
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