The government’s newest national assessment of climate change declares that increased global warming is affecting every part of the United States.
The report released recently cites wide and severe impacts: more sea-level rise, flooding, storm surges, precipitation and heat waves in the Northeast; frequent water shortages and hurricanes in the Southeast and the Caribbean; and more drought and wildfires in the Southwest.
The federal climate assessment — the third since 2000 — brought together hundreds of experts in academia and government to guide U.S. policy based on the best available climate science.
The authors of the more-than-800-page report said it aims to present “actionable science” and a road map for local leaders and average citizens to mitigate carbon and other gas emissions that warm the planet.
Echoing the findings of a recent global report by climate scientists at the Intergovernmental Panel on Climate Change, U.S. scientists said that the climate is changing in the United States and that the warming of the past 50 years was primarily caused by emissions of heat-trapping gases released by humans.
Burning coal for electricity, using gasoline to fuel vehicles, clear-cutting forests and engaging in certain agricultural practices that remove carbon-trapping vegetation contribute to the problem, the assessment said.
By the end of the century, temperatures could be up to 5 degrees higher, even if the nation acts aggressively to reduce greenhouse gas emissions. It could be up to 10 degrees hotter if emissions are high.
The higher the temperature, the more dire the impact. Extreme weather in the United States caused by climate change has increased in recent decades, the report said.
The decade starting in 2000 was the hottest on record, and 2012, the year Hurricane Sandy followed an epic summer drought, was the hottest ever recorded in the nation’s history, the report said. U.S. temperatures are 1.3 degrees to 1.9 degrees Fahrenheit higher now than they were in 1895, and most of that increase — 80 percent — occurred over the past 44 years, the assessment says.
Extreme heat causes more deaths than other weather events, and that is expected to continue. Such fatalities have decreased in recent years, but the assessment attributed that to better weather forecasting.
Alaska warmed twice as fast as the rest of the country in the past 60 years, leading to permafrost thaw that is causing highways and even airport runways to sink.
The climate experts worked for several years, holding 70 workshops nationwide and revising the final drafts to reflect thousands of public comments. They were guided by a 60-member panel called the National Climate Assessment and Development Advisory Committee.
Thirty percent of carbon released into the atmosphere ends up in the ocean, leading to acidification that’s killing coral and shell life. Coral protects young fish from predators, and tiny shellfish, at the bottom of the food chain, help feed entire ecosystems.
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