WASHINGTON – 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 Tuesday 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.
For a long time, we have perceived climate change as an issue that’s distant, affecting just polar bears or something that matters to our kids, said Katharine Hayhoe, a Texas Tech University professor and a co-author of the report. This shows it’s not just in the future; it matters today. Many people are feeling the effects.
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.
But the report ran immediately into conservative critics who called it a political document, aimed at giving President Barack Obama a leg up on regulating major polluters such as power plants.
In their view, regulation costs jobs. Obama, who is increasingly focusing on climate change, spent part of the day talking about the report with television meteorologists from across the country.
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 human activity.
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 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.
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 impacts sound alarming, but there are reasons to be optimistic that they can be mitigated, said David Wolfe of Cornell University, a lead co-author of the report’s chapter on change in the Northeast.
Business leaders are looking more toward investments in renewable energy, he said. This report, unlike the first two, has a website with interactive tools that show Americans how to reduce climate impacts.
It will be a living document, a resource for people, he said. It’s a place to start.
Wolfe’s optimism wasn’t universally shared, even among some co-authors who said the document is a consensus meant to reflect the diverse views of the more than 300 scientists who compiled it.
It’s important to understand that this is a very, very, very conservative document, a consensus document, said Drew Harvell, a Cornell University professor and a co-author of the marine resources chapter of the assessment. The truth is more dire, she said.
But Cato Institute researchers Paul Chip Knappenberger and Patrick Michaels issued a statement calling the assessment biased toward pessimism. As a resource, it is meant to justify federal regulation aimed toward mitigating greenhouse gas emissions.
Sen. Jim Inhofe, R-Okla., joined other conservatives in describing the report as part of a political agenda. He said it seemed timed to coincide with a Senate debate about the Keystone XL oil sands pipeline from Canada.
Increased heat doesn’t affect just humans. In warmer and more acidic oceans, particularly the Pacific, the effects of climate change are deadly, Harvell said.
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.