The third National Climate Assessment was finalized and released Tuesday. Its main point is climate change has already affected every region of the United States. But while its findings are ominous, what is most striking is its conclusions are not new. What is happening is what climate change science has said would happen.
The assessment – www.globalchange.gov – is the result of the Global Change Research Act of 1990. That law mandated a full climate assessment every four years, but the administrations of both Bill Clinton and George W. Bush dragged their feet, with the result that this is just the third one done. It was overseen by a large committee whose members represent a cross section of society, including representatives of the oil industry.
What it said is climate change is clearly happening, with impacts to every part of the country and only expected to grow. In general, the wet parts of the country are getting wetter, the dry parts drier, and all parts can expect more extreme weather events.
In particular, the country can look forward to torrential rains, persistent droughts, recurring heat waves – but not all the time, not everywhere and not occurring in any linear or steady way. And none of that precludes sometimes tragic anomalies. Droughts can be punctuated by floods and long, hot summers by colder than usual winters in parts of the country.
One striking finding is the proportion of total rainfall that comes in heavy-rain events has increased over the last half century, by as much as 71 percent in the Northeast, 37 percent in the Midwest and 27 percent in the South. In 2010, parts of Tennessee got 20 inches of rain in two days. Just two months ago, heavy rain in Washington state led to a landslide that killed more than 40 people.
For this region, the future is potentially grim. The report says the Southwest is “the hottest and driest region in the U.S. ... Climate changes pose challenges for an already parched region that is expected to get hotter and, in its southern half, significantly drier.”
The effects of climate change are already reflected in the explosion of bark beetles and the emergence of “fire season” as a regular and expected time of year. Anyone driving over Wolf Creek Pass can see the beetles’ handiwork, while throughout the West, record-breaking fires have become a regular occurrence.
At risk, too, is the Southwest’s already over-allocated water supply. Parts of seven states depend on the Colorado River and its tributaries and reduced snowpack, as seen in recent years, threatens that entire population – a population the White House expects to top 94 million by 2050. Also at risk would be “more than half of the nation’s high-value specialty crops.”
There has been much debate over climate change and any potential political or societal response. It should be clear, however, any open questions at this point are in the margins or concern exactly how to respond. What is happening may not be understood to an absolute certainty or with perfect precision – few things are – but science has explained the basic process, and things have now progressed to where laymen can see some of the results.
The questions worth debating now turn more on what can be done. That combating, resisting or adapting to climate change will be costly is self-evident and irrelevant. As is becoming clear, doing nothing would be even more expensive.
