Climate change is affecting the United States more than ever, and the impacts on people and the economy are expected to increase, a draft section of the National Climate Assessment says.
The same, only worse.
Global warming is affecting the United States more than ever, and the impacts — on communities, regions, infrastructure and sectors of the economy — are expected to increase.
That’s the gist of Volume II of the National Climate Assessment, a draft report made public on Friday that focuses on the current and future impacts of climate change. The draft will eventually accompany a report on the science of climate change that was unveiled by 13 federal agencies in its final form on the same day.
In addition to comments by members of the public, Volume II is being reviewed by an expert committee of the National Academies of Sciences, Engineering, and Medicine. After revisions by the agencies involved it is expected to be published in December 2018.
Like the scientific report, the draft of Volume II contains many of the same findings cited in the previous National Climate Assessment, published in 2014. But reflecting some of the impacts that have been felt across the country in the past three years, some of the emphasis has changed.
Here’s a look at some of what’s new in the draft assessment.
More and more of the 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. That’s no longer theoretical: Scientists have now documented a record number of “nuisance flooding” events during high tides. In 2014, nearly half of residents in Hampton Roads, Va., could not get out of their neighborhoods at least once because of tidal flooding.
Meanwhile, as the oceans have warmed, disruptions in United States fisheries, long predicted, are now underway. In 2012, record ocean temperatures caused lobster catches in Maine to peak a month earlier than usual — and the distribution chain was unprepared.
While much of the discussion of climate change looks at the role of carbon dioxide and other greenhouse gases in warming the planet, the draft report puts a renewed emphasis on the impacts of other atmospheric p ollutants like ozone and smoke, which can cause respiratory problems and lead to premature death.
The draft notes with “high confidence” that climate change will increase ozone levels, as rising temperatures and changes in atmospheric circulation affect local weather conditions. But the increases will not be uniform; by near the end of the century the worst ozone levels will be found across a wide expanse of the Midwest and Northern Great Plains, while levels are expected to improve, at least somewhat, in parts of the Southeast.
The report reiterates what residents of the West have learned from hard experience: that warmer springs, longer dry seasons in the summer and other impacts are lengthening the fire season. The smoke from fires affects not only health, the report says, but visibility.
Since 2014, more detailed economic research has estimated that climate change could cause hundreds of billions of dollars in annual damage, as deadly heat waves, coastal flooding, and an increase in extreme weather take their toll. Unless, that is, communities take steps to prepare beforehand.
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 draft finds. More and more communities are taking measures such as preserving wetlands along the coasts to act as buffers against storms.
But outside of a few places in Louisiana and Alaska, few coastal communities are rethinking their development patterns in order to avoid the impacts from rising seas and severe weather that the report says are surely coming.
The United States 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 draft report cites these international concerns, but goes far beyond the military. Climate change is already affecting American companies’ overseas operations and supply chains, it says, and as these impacts worsen it will take a toll on trade and the economy.
Global warming and natural disasters are also affecting development in less affluent countries. That, the draft says, puts additional burdens on the United States for humanitarian assistance and disaster aid.
The draft 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 understand the full extent of climate-related impacts in the United States without considering these interactions,” the report says.
It gives several examples, including recent droughts in California and elsewhere that, in combination with population changes, affects demand for water and energy. The draft also cites Hurricane Sandy, five years ago, which caused cascading impacts on interconnected systems in the New York area, some of which had not been anticipated. Flooding of subway and highway tunnels, for example, made it more difficult to repair the electrical system, which suffered widespread damage.
