This Looks Like Earth’s Warmest Month. Hotter Ones Appear to Be in Store.
Weeks of scorching summer heat in North America, Europe, Asia and elsewhere are putting July on track to be Earths warmest month on record, the said on Thursday, the latest milestone in what is emerging as an extraordinary year for global temperatures. Last month, the planet experienced its since records began in 1850. July 6 was its . And the odds are rising that 2023 will end up displacing 2016 as the . At the moment, the on the books are the past eight. The extreme weather which has affected many millions of people in July is unfortunately the harsh reality of climate change and a foretaste of the future, Petteri Taalas, the secretary general of the World Meteorological Organization, said in a statement. The need to reduce greenhouse-gas emissions is more urgent than ever before. The world has entered what forecasters warn could be a multiyear period of exceptional warmth, one in which the warming effects of humankinds continuing emissions of heat-trapping gases are compounded by El Nino, the recurring climate pattern typically associated with hotter conditions in many regions. Even so, when global average temperatures , as they have been doing since early June, it raises questions about whether the climate is also being shaped by other factors, said Karen A. McKinnon, a climate scientist and statistician at the University of California, Los Angeles. These elements might be less-well understood than global warming and El Nino. Do we expect, given those two factors, the record to be broken by this much? Or is this a case where we dont expect it? Dr. McKinnon said. Is there some other factor that were seeing come into play? Many parts of the world are continuing to swelter this week as July enters its final days. In the United States, a dangerous heat wave was taking shape on Thursday in the Northeast and Mid-Atlantic, the National Weather Service said, and high temperatures remained a concern in the Southwest and Central States. Its been scorching in parts of North Africa, Southeastern Europe and Turkey. Wildfires, amplified by heat and dryness, have raged in and around the . Researchers who analyzed this months punishing heat waves in the Southwestern United States, northern Mexico and Southern Europe said this week that the temperatures observed in those regions, over a span of so many days, would have been without the influence of human-driven climate change. Still, scientists will need to investigate further to fully understand the alarming extent to which the entire surface of the planet has, on average, been hotter than usual this summer, said Emily Becker, a climate scientist at the University of Miami. Fossil-fuel emissions, which cause heat to build up near Earths surface, are certainly playing a role. Since the Industrial Revolution, humans have pumped 1.6 trillion tons of carbon dioxide into the atmosphere. This has caused the world to be about 1.2 degrees Celsius, or 2.2 Fahrenheit, warmer than it was in the second half of the 19th century. But the way this extra heat is distributed around the globe is still shaped by a complex brew of factors spanning land, sea and air, plus a certain amount of random chance. Which is why untangling the specific factors behind this summers severe heat will take time, Dr. Becker said. Theres going to need to be quite a lot of research to understand it, and understand if were going to be seeing this again next year or 10 years from now. One factor that probably hasnt been very important so far this summer, at least not in North America, is El Nino, Dr. Becker said. The cyclical phenomenon emerges when the surface of the central tropical Pacific is hotter than normal. Its arrival, which this year occurred in late spring, triggers a cascade of changes to wind patterns and rainfall around the globe. But its most immediate effects are felt in the tropical and far western Pacific, in places like Indonesia. In terms of North America, this El Nino is really just getting started, said Dr. Becker, who contributes to the National Oceanic and Atmospheric Administrations El Nino and La Nina forecasts. Winter is when North America experiences El Ninos most prominent effects, including wetter conditions in the Southern United States. This summers record heat could still affect the way this El Nino plays out later this year and into 2024, Dr. Becker said. Large areas of the planets oceans have been warmer than average. If this continues into fall and winter, it could lead to even stronger storms, with even heavier rain, in places that typically receive more storms during El Nino, Dr. Becker said. When it comes to factors besides global warming that may also be worsening heat waves, scientists have been examining potential changes in the jet streams, the rivers of air that influence weather systems around the planet. In the Northern Hemisphere, the differences in temperature between the Arctic and the Equator keep the subtropical jet stream moving. As humans warm the planet, those temperature differences are narrowing, which could be causing the jet stream to weaken and hot spells to last longer. So far, though, the evidence for this is inconclusive, said Tim Woollings, a professor of physical climate science at the University of Oxford. Its really not clear that the jet has been getting weaker, he said. published in April, Dr. Woollings and four other scientists found that human-caused warming might have shifted the jet streams in both hemispheres toward the poles in recent decades. More research is needed to understand this potential shift, he said. But if it continues, it could make subtropical regions susceptible to greater heat and drought, he said. is a climate reporter. He joined The Times in 2017 and was part of the team that won the 2021 Pulitzer Prize in public service for coverage of the coronavirus pandemic.