Truth is not in the numbers but in the interpretation and understanding of the numbers

From The Sordid History of Forest Service Fire Data by Antiplanner. An excellent example where data trend lines reflect changes in measurement processes, not changes in operational reality. S/He uses this graph as the anchor for the post.

Click to enlarge.

The clear implication is that climate can't have been warming since the 1920s because there was a huge decline in reported wildfire acres between 1928 to a new normal by 1956. But is that really what it shows? Antiplanner provides the backdrop.

The story begins in 1908, when Congress passed the Forest Fires Emergency Funds Act, authorizing the Forest Service to use whatever funds were available from any part of its budget to put out wildfires, with the promise that Congress would reimburse those funds. As far as I know, this is the only time any democratically elected government has given a blank check to any government agency; even in wartime, the Defense Department has to live within a budget set by Congress.

This law was tested just two years later with the Big Burn of 1910, which killed 87 people as it burned 3 million acres in the northern Rocky Mountains. Congress reimbursed the funds the Forest Service spent trying (with little success) to put out the fires, but — more important — a whole generation of Forest Service leaders learned from this fire that all forest fires were bad.

In 1924, Congress passed the Clarke-McNary Act, which allowed the Forest Service with (i.e., provide funds to) “appropriate officials of the various states or other suitable agencies” in developing “systems of forest fire prevention and suppression.” The Forest Service used its financial muscle to encourage states to form fire protection districts.

This led to a conflict over the science of fire that is well documented in a 1962 book titled Fire and Water: Scientific Heresy in the Forest Service. Owners of southern pine forests believed that they needed to burn the underbrush in their forests every few years or the brush would build up, creating the fuels for uncontrollable wildfires. But the mulish Forest Service insisted that all fires were bad, so it refused to fund fire protection districts in any state that allowed prescribed burning.

The Forest Service’s stubborn attitude may have come about because most national forests were in the West, where fuel build-up was slower and in many forests didn’t lead to serious wildfire problems. But it was also a public relations problem: after convincing Congress that fire was so threatening that it deserved a blank check, the Forest Service didn’t want to dilute the message by setting fires itself.

When a state refused to ban prescribed fire, the Forest Service responded by counting all fires in that state, prescribed or wild, as wildfires. Many southern landowners believed they needed to burn their forests every four or five years, so perhaps 20 percent of forests would be burned each year, compared with less than 1 percent of forests burned through actual wildfires. Thus, counting the prescribed fires greatly inflated the total number of acres burned.

The Forest Service reluctantly and with little publicity began to reverse its anti-prescribed-fire policy in the late 1930s. After the war, the agency publicly agreed to provide fire funding to states that allowed prescribed burning. As southern states joined the cooperative program one by one, the Forest Service stopped counting prescribed burns in those states as wildfires. This explains the steady decline in acres burned from about 1946 to 1956.

So the transition from 1928-1956 reflects changes in the human systems of definition and measurement rather than any change in climate, number of fires or acres burned.