• Wed. Dec 6th, 2023

Does extreme summer weather signal a new phase of climate change?

Does extreme summer weather signal a new phase of climate change?

Here in New England it’s been a hot summer. Although the current pattern has changed to sunny and dry weather, we have had high humidity, lots of rain and abundant cloud cover in mid-June and mid-July. All over the world, from Texas to Italy, to the East, North, and South, we’ve heard of extreme heat.

All this talk of extreme weather can be unsettling, and when summer is usually hot it’s hard to know what’s hyperbole or clickbait and what we should be paying attention to.

Now, one extreme summer does not make a trend. These new highs and lows may indeed be new records that will stand for several years before being surpassed. Warming, which has continued and accelerated over the past two decades, is likely to further accelerate. Scientists won’t know exactly how to make sense of this summer until we have more years under our belts.

If you look at the global climate models and what they’re predicting, even though the pace is faster this summer, the records we’re seeing are still within the range of predictions.

In fact, there are a lot of disturbing weather and climate numbers around the planet. The Atlantic basin is well above average and, by some measures, warmer than ever recorded.

Sea surface temperature anomaly (°C) for June 2023 compared to the 1991–2020 reference period. Data source: ERA5.

Copernicus Climate Change Service/ECMWF

Streaks of hot temperatures in places like Phoenix have reached new milestones. While climate change certainly plays a role in that example, so does the urban heat island effect. This is the understanding that buildings and other objects radiate heat, especially at night.

Boston suffers from this to a lesser extent, with the valleys at night much warmer than the surrounding suburbs and countryside. This month, Phoenix will likely become the first major US city to average 100 degrees for an entire month!

In some parts of Europe, monthly records and even all-time records have fallen.

In the wintery Antarctic, the ice has not recovered as usual.

Current sea ice extent across Antarctica.

National Snow and Ice Data Center

In Greenland, the summer melt season was one of the most extensive on record.

The extent of Greenland melting this year was extensive.

National Snow and Ice Data Center

Meteorologists are confident that sea ice will continue to melt and global temperatures will continue to rise, but by how much remains a lack of confidence.

A line graph with waves tracking the surface temperature of the North Atlantic Ocean shows a 1.4-degree Celsius rise in 2023, much higher than all lines in previous years.
The figure shows the surface temperature of the North Atlantic Ocean this year compared to previous years.

Leon Simons

This is where this summer comes into play. Just because this one data point is at the high end of predictions doesn’t mean it will continue to be. Some of the individual numbers also require scrutiny.

Figure SPM.6 | Multimodel simulations determine global mean surface temperature change (a) and global mean sea level 10 (b) from 2006 to 2100. All changes are relative to 1986-2005. Time series of projections and degree of uncertainty (shading) are shown for the RCP2.6 (blue) and RCP8.5 (red) scenarios. Means and associated uncertainties over 2081–2100 are given as colored vertical bars to the right of each panel for all RCP scenarios. The number of Coupled Model Intercomparison Project Phase 5 (CMIP5) models used to calculate the multimodel mean is indicated.

IPCC 2015 Synthesis Report

Most experts agree that how much greenhouse gases humans contribute over the next few decades will determine how much the planet warms by the end of the century.

In our daily life, there is not much you can do to make big changes, but it is not hopeless. If you’re feeling anxious or panicked about all the media reports this summer, engaging with various policy organizations around climate is one way to take control. You can also make small changes in your lifestyle that align with your values. Both of these can help alleviate that overwhelming feeling.

Global leaders are expected to agree on some major changes that will lead to meaningful reductions in greenhouse gases.

Emission conditions.jpg
Various emission pathways for the remainder of the century. Climate models use these various scenarios to predict future temperatures.

What we need to do is adapt to a changing climate in the years to come, even if emissions decline decades later.

It can be as simple as changing your schedule to work outside in the mornings and evenings on very hot days. If you have summer travel plans, you may want to look into where you’re going and whether or not the heat will have a disproportionate effect on your vacation. If you’re looking for waterfront property that’s going to be in the family for several generations, you don’t want to be in an area where the shoreline is rapidly disappearing. If you’re buying a ski cottage, I might suggest one that’s not on the southern edge of usable snow, because that line will continue to push northward in the coming decades.

Of course, there are still many individuals and people in power who believe that human-caused climate change is not real. Perhaps they feel like they are trying to be controlled, that something is going to be taken away, or they see others who are like-minded and like to be part of that movement of denial and doubt. Deniers and skeptics often conflate other political causes and movements with climate.

Years ago, many meteorologists, including myself, were somewhat skeptical. But at this point the data becomes almost undeniable. It’s hard to let go of an idea once you’ve embraced it, but that process starts with a willingness to be educated and open to change.

How much sea level will warm and rise by mid- to late-century is, of course, debatable and much more needs to be learned, but the coming climate will be warmer — and the rate of that warming will be almost unprecedented. Yes, our Earth’s climate has been changing for billions of years, but those changes have been slow and natural and have not affected humanity. This is not that historical version of climate change.

The map shows the global average surface temperature in 2022 compared to the 1991-2020 average, with warmer than average locations in red and cooler than average locations in blue. At the bottom of the graphic, the bar graph shows global temperatures for each year from 2022 (right) to 1976 (left) compared to the 20th century average – the last year the world was cooler than average.

NOAA Climate.gov image, based on data from NOAA National Centers for Environmental Information

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