We've all seen the impact that heat waves have on land. The infamous European heat wave of 2003 was responsible for 30,000 deaths caused by high temperatures that soared 20-30 percent above average. Heat waves like the one in Europe and the one in China in 2013 were not only killers, but also caused forest fires and wreaked economic havoc through higher energy costs and agricultural losses.
Warm blobs of water
In a new paper, environmental physicist Thomas Froelicher from ETH Zurich in Switzerland lays out the case that heat waves in the ocean can be just as deadly, but not as apparent, to those of us stuck on land. NASA has been studying cyclical events like the El Nino phenomenon of the Central Pacific for years. While not a classical heat wave, an El Nino happens when weak trade winds allow warm water to collect in the tropical regions of the Pacific. When this happens, the worldwide effects, according to NASA, are profound: the warm waters are nutrient poor and can devastate fish stocks, the change also causes drought in Indonesia and Australia.
Froelicher examined the effects of a similar but unexpected 'blob' of warm water that appeared in the northeastern Pacific Ocean in 2013, and stayed there until 2015. The bubble of warm water was about 3 degrees Celsius above the average and grew to an astonishing 1,600 kilometers in diameter. The results of the warm water were similar to what happens in an El Nino. Fish and zooplankton looking for food began to desert the region in droves, and by 2015 according to NASA, "...record numbers of starving sea lions and fur seals were found stranded on California’s beaches." The blob has since dissipated, but climate scientists continue to keep a close eye on the Northern Pacific.
A similar blob of warm water heated up Australia's west coast in the winter of 2010, when temperatures soared as high as 6 degrees Celsius above normal. The effects of that heat wave are still being felt in the region. A 1,000 square kilometer region of kelp forests was destroyed by the high temperatures. The forests still haven't returned and in fact a new ecosystem has taken root in the region that once was dominated by the kelp forests.
Is this just natural change?
An occasional heat wave is certainly part of nature's plan, and heat waves like the one that made the U.S. depression worse in the 1930s have always been a part of life on planet earth. But one of the demonstrable effects of human impacted climate change is that extreme events like heat waves will become more common and more extreme. For the first time in July, scientists firmly linked the 2003 European heat wave to climate change.
Just like on land, Froelicher points out, "marine heatwaves are likely to become more frequent and intense." Put all of this together and Froelicher's paper sounds a warning that extreme heat waves, along with increasing ocean acidification and loss of oxygen, are putting "additional stress on marine organisms and ecosystems."
And with this week's announcement from NASA that August and July were the two hottest months ever recorded, that means that we can expect more heat, more extreme events, and more potentially devastating terrestrial and oceanic heat waves.