The Northern Hemisphere is feeling the heat this week.
Temperatures are spiking in parts of Europe, Asia and North America, all while the world’s oceans have hit record-high sea surface temperatures. The return of an El Niño climate pattern, which occurs naturally and often increases global temperatures, is also raising fears about what to expect in the coming weeks as much of the planet heads into the hottest months of the year.
An early season heat wave is hammering the U.S. South and Mexico with high heat and humidity, with dangerously hot conditions and triple-digit temperatures forecast across the region through the weekend. Summer officially starts on June 21, the summer solstice.
“Record high temperatures possible across portions of central to southern Texas and across portions of eastern Louisiana,” the National Weather Service said Friday in its short-range forecast.
Authorities in Mexico said the current heat wave is expected to persist for up to 15 more days, according to Reuters, which reported that the country has already registered six heat-related deaths this year.
Earlier this week, the United Kingdom sweltered under hotter-than-normal conditions for this time in June, with several areas including Wales and Scotland recording temperatures over 86 degrees Fahrenheit (30 degrees Celsius).
Last weekend, at least three British guardsmen fainted during a royal military parade in central London as temperatures topped 86 degrees F, according to Sky News.
Climate change is expected to make heat waves both more likely and more intense, increasing the risk of wildfires, droughts and heat-related illnesses and deaths around the world.
In South Asia, a prolonged heat wave in Bangladesh triggered a power crisis, as temperatures exceeded 104 F (40 C) over multiple days.
Meanwhile, the world’s oceans are not faring much better.
Sea surface temperatures around the globe have been at record or near-record highs over the past three months. The surge in global ocean temperatures — particularly over such a short period of time — is unprecedented, said Glen Gawarkiewicz, an associate scientist in physical oceanography at the Woods Hole Oceanographic Institution in Massachusetts.
“The rapid warming in the spring was on such a massive scale,” he said, adding that it will take some time for scientists to understand what is driving the spike in temperatures. “It’s very tough because we just haven’t seen a jump of that magnitude over such a large area before.”
Scientists closely monitor sea surface temperatures because warmer oceans can accelerate sea-level rise and intensify storms and extreme weather. But even small changes can have wide-ranging consequences for marine ecosystems.
Gawarkiewicz’s own research focuses on the Gulf of Maine, a region that is particularly sensitive to changes in temperature, salinity and other effects of climate change.
“I work very closely with the commercial fishing industry in the Northeast, and it is is very distressing to hear about, for example, the seasonal movements of fish being very strongly affected,” he said.
Elsewhere around the world, warmer sea surface temperatures can supercharge tropical cyclones, wreak havoc on marine environments and cause polar ice to melt at an accelerated pace.
With the return of El Niño, a naturally occurring climate pattern, there is no end in sight to the warming trend.
El Niño occurs when changes in the strength or direction of trade winds cause waters in the central and eastern tropical Pacific Ocean to become warmer than usual. These shifts have a strong influence on global temperatures, rainfall, hurricanes and other severe storm systems.
Gawarkiewicz said that could mean more heat waves and droughts around the world, along with the potential for “major disruptions” to marine ecosystems, such as coral bleaching events.
“I think that the consequences may very well be severe,” he said.