Factcheck: How #globalwarming has increased US wildfires — Carbon Brief #ActOnClimate #KeepItInTheGround

From Carbon Brief (Zeke Hausfather):

Recently, some commentators have tried to dismiss recent increases in the areas burnt by fires in the US, claiming that fires were much worse in the early part of the century. To do this, they are ignoring clear guidance by scientists that the data should not be used to make comparisons with earlier periods.

The US National Interagency Fire Center (NIFC), which maintains the database in question, tells Carbon Brief that people should not “put any stock” in numbers prior to 1960 and that comparing the modern fire area to earlier estimates is “not accurate or appropriate”.

Here, Carbon Brief takes a look at the links between climate change and wildfires, both in the US and across the globe. As with any environmental issue, there are many different contributing factors, but it is clear that in the western US climate change has made – and will continue to make – fires larger and more destructive…

More area burned

Many areas of the western US are currently being ravaged by record-setting wildfires for the second year in a row. The Mendocino Complex fire in California is now the largest on record in the state, with firefighters expect the fires to keep burning for at least the rest of the month.

In California, 14 of the 20 largest wildfires on record have occurred over the past 15 years. At the same time, the western US has experienced some of its warmest temperatures on record, with 10 of the past 15 years among the 15 warmest years on record, based on temperature records from the US National Oceanic and Atmospheric Administration (NOAA).

According to data from the NIFC, there has been a clear trend in increased area burned by wildfires in the US since the 1980s, when reliable US-wide estimates based on fire situation reports from federal and state agencies became available.

Today, wildfires are burning more than twice the area than in the 1980s and 1990s. These figures include all wildland fires in both forested and non-forested areas. Most of the area burned today is in the western US, where dryer conditions tend to allow for large, quickly-spreading wildfires.

The black bars in the top panel of the figure below show the annual area burned (in acres) by wildfires since 1983 when reliable data became available. The blue line shows the linear trend in fires over the same period. The bottom panel shows all of the data in their database, including pre-1983 values where the data is of poorer quality.

The NIFC explicitly warns users on its website: “Prior to 1983, sources of these figures are not known, or cannot be confirmed, and were not derived from the current situation reporting process. As a result, the figures prior to 1983 should not be compared to later data.”

Annual wildland acres burned since reliable data was available in 1983 (top panel) and area burned since 1923 (bottom panel) showing periods when quality of data was poor and incomparable. Blue line in top panel shows linear trend. Data from the US National Interagency Fire Center; Chart by Carbon Brief using Highcharts.

Leave a Reply