Phoenix has hit 110 degrees for 20 days and counting.
Canadian wildfires have choked some of the largest U.S. cities, including Denver, since spring.
June temperatures worldwide set a record, and not in a good way.
Ocean temperatures, a key indicator of both hurricane risk and potential damage to wildlife, are the highest ever measured. Waters off the Florida Keys — the water, mind you — hit 98 degrees.
Rain-caused floods rage from Vermont to Pennsylvania to Spain.
Has the weather news merged once and for all with the climate news? Are we overly focused on “bad” weather during summer doldrums, or is there an accumulation of evidence that climate change is worsening dangerous weather patterns?
We turned to the Colorado-based experts, the National Oceanic and Atmospheric Administration, and research meteorologist Andrew Hoell for a check-in on planet health and our summer psyche.
The following has been edited for clarity and length.
The Colorado Sun: There have been a number of recent events and headlines that may nudge readers toward thinking the impacts of climate change have accelerated. We’d like to help put things in perspective, and sort the real worries from the unhelpful hype.
Can we start with a direct impact on Colorado, and many other states, of the ongoing Canadian wildfires? Is the severity of Canada’s wildfires, which has of course impacted the United States, related to longer-term climate changes that go beyond seasonal drought?
Andrew Hoell: Evidence suggests that conditions that lead to drought and wildfire in many regions are caused by natural variations of the Earth system in addition to effects of climate change. This is why drought and wildfires don’t happen each and every year, but when they do, they tend to be somewhat more intense compared to droughts and wildfires of the past.
Weather and climate variability in North America this spring and summer so far has been rather unusual, leading to low precipitation, heat and wildfires in Canada, and below-average temperatures and above-average precipitation in the Southwest U.S. The weather can lead to unusual situations sometimes. Regarding Canada, high pressure has persisted there, which has led to below-average precipitation and above-average temperatures. The most apparent effect of climate change on drought there would be through temperatures, where warmer temperatures beyond that of natural variability led to a more rapid desiccation of vegetation, which in turn was easier to burn.
Sun: Many in the Southwest and South are experiencing the last of the July heat dome effect that set multiple records. Can we put that event in the context of longer-term climate impacts of global warming, vs. normal seasonal fluctuations of weather extremes?
Hoell: Heat waves and the physical mechanisms that lead to them occur naturally in the climate system. The same goes for periods of below-average temperatures. However, the higher temperatures of our contemporary climate leads to more intense and longer heat waves compared to a climate of the past, assuming that our thresholds for defining heat waves remain the same.
Sun: Did preliminary readings of high world temperatures in June turn out to be true?
Hoell: June 2023 was the warmest June on record. Ocean temperatures were the warmest on record by a wide margin and land temperatures were either warmest or second-warmest on record depending on the source, rivaling 2022 for the top spot.
(Hoell sent this graphic to illustrate how bad things were in June:)
It’s important to note that parts of the U.S. observed below-average temperatures in June 2023. These areas include the Southwest and the Mid-Atlantic. This goes to show that even in the midst of climate change below-average temperatures can be observed regionally for months, seasons or even years.
Sun: News out of the Southeast is that Florida is experiencing intensely high heat and humidity, and that is piling on the woes of people who suffered greatly from last year’s hurrican Ian and still do not have rebuilt homes. There is also news that ocean temperatures are very high and may cause another active hurricane season.
Again, is it fair to talk about these short-term weather events in the larger context of global warming?
Hoell: Yes, we can’t fully understand and forecast heat waves without considering the short-term variations of weather and how they fit into the context of a changing climate.
On hurricanes, several metrics of hurricane activity indicate increases since the 1980s. However, evidence for changes in these metrics over longer time periods is not strong due to data limitations. Concerning physical factors related to hurricanes in recent decades, there is no scientific consensus, though aerosols in the atmosphere and ocean circulations have been considered as possible causes. Greenhouse-gas-caused warming has also been put forth as a possible cause, though confidence is not high because of aerosols or natural variations of the climate system that could mask its effects. As far as projections, fewer tropical storms and hurricanes are indicated, though with possible increases in strong hurricanes, and increases in coastal inundation due to sea level rise, and increased rain rates and wind speeds related to hurricanes.
Sun: Where is the current measure of global warming totals compared to pre-industrial benchmarks? Have we made any progress on slowing the addition of carbon dioxide into the atmosphere? Coloradans have helped make some remarkable progress in retiring coal-fired utilities and promoting clean electrification, is there any global news that might reinforce their efforts with some optimism?
Hoell: There are a few metrics used to benchmark greenhouse gas concentrations in the atmosphere. One of the most common is carbon dioxide concentrations measured at the Mauna Loa Observatory in Hawaii. The concentration in 2022 was 418.56 parts per million, which was 2 ppm greater than the year prior and about 100 ppm greater than 1960.
My interpretation of carbon dioxide concentrations in the atmosphere based on measurements at Mauna Loa Observatory is that the year-over-year increase has been consistent at about 2 ppm since around 2000.
(Hoell sent a link to this graphic of the Mauna Loa measurements:)
From a NOAA web page Hoell linked to: “Since the middle of the 20th century, annual emissions from burning fossil fuels have increased every decade, from close to 11 billion tons of carbon dioxide per year in the 1960s to an estimated 36.6 billion tons in 2022 according to the Global Carbon Budget 2022.”