US climate report points to heightened risk of future threats
Global warming is now affecting the United States more than ever, and the risks of future disasters – from flooding along the coasts to crop failures in the Midwest – could pose a profound threat to Americans’ well-being.
That’s the gist of Volume Two of the latest National Climate Assessment, a 1,656-page report issued Friday that explores both the current and future impacts of climate change. The scientific report, which comes out every four years as mandated by Congress, was produced by 13 federal agencies.
This year’s report contains many of the same findings cited in the previous National Climate Assessment, published in 2014. Temperatures are still going up, and the odds of dangers such as wildfires in the West continue to increase. But reflecting some of the impacts that have been felt across the country in the past four years, some of the report’s emphasis has changed.
Predicted effects: More and more predicted impacts of global warming are now becoming a reality.
For instance, the 2014 assessment forecast that coastal cities would see more flooding in the coming years as sea levels rose. Scientists have now documented a record number of “nuisance flooding” events during high tides in cities like Miami and Charleston, S.C.
“High tide flooding is now posing daily risks to businesses, neighborhoods, infrastructure, transportation, and ecosystems in the Southeast,” the report says. As the oceans have warmed, disruptions in U.S. fisheries are underway.
Tied together: The report suggests a different approach to assessing the effects of climate change, by considering how various impacts – on food supplies, water and electricity generation, for example – interact with each other.
“It is not possible to fully understand the implications of climate change on the United States without considering the interactions among sectors and their consequences,” the report says.
It gives several examples, including recent droughts in California and elsewhere that, in combination with population changes, affect demand for water and energy.
Beyond borders: The U.S. military has long taken climate change seriously, both for its potential impacts on troops and infrastructure around the world and for its potential to cause political instability in other countries.
The report cites these international concerns, but goes far beyond the military. Climate change is affecting U.S. companies’ overseas operations and supply chains, it says, and as these impacts worsen it will take a toll on trade and the economy.
Adaptation: Since 2014, detailed economic research has estimated that climate change could cause hundreds of billions of dollars in annual damage, as heat waves, coastal flooding and an increase in extreme weather take their toll. To limit harm, communities will need to take steps to prepare.
The previous assessment warned that few states and cities were taking steps to adapt to the impacts of climate change. That’s slowly changing, the new report finds.
Air quality: The report puts a renewed emphasis on the impacts of other atmospheric pollutants such as ozone and smoke, which can cause respiratory problems and lead to premature death. The report notes with “high confidence” that climate change will increase ozone levels.
A volunteer guides a rescue boat down a flooded street in September in Wilmington, N.C. A report issued Friday explores current and future impacts of climate change.