Extreme lake temperatures rise due to climate change

The world’s largest lakes are hit by severe lake heat waves—when water temperatures soar far above normal—six times as frequently as they were about two decades ago, according to a new study. The new research shows that nearly all severe heat waves in the last 20 years were caused by climate changes. It is possible that the number of these heat waves could rise to between three and 25 percent by the end.

A new study has analyzed surface temperature data from the largest lakes in the world over two decades to determine how often they occur. lakeHeat waves can occur and how to model them Anthrogenic climate changeThey are a result of their existence.

Researchers found that severe lake heat wave are twice as likely as they were in pre-industrial conditions. Lake heat waves can alter water conditions, stress aquatic animals and plants, and cause algae blooms and other problems with water quality.

The study was published by the AGU journal Geophysical Research Letters. The study is the only to quantify how human-caused climate change has affected lake heat waves. This provides a critical new perspective on the way that the world’s lakes are responding.

“What really stood out was how much human involvement: Most severe lake heat waves that we looked at had a significant anthropogenic impact,” said R. Iestyn Woolway (climate scientist at Bangor University in Wales), who led the study. He stated that unlike humans who can turn on emergency shade or air conditioning, aquatic organisms cannot escape extreme temperatures.

Luke Grant, a data scientist at Vrije Univ. Brussel, said that “it’s a welcome addition [to the attribution of anthropogenic effects on lakes].” He was not involved in this study. It fills an evidentiary void, looking at the impact of temperature extremes upon lakes. Grant said that the finding that most heat waves are influenced by humans is “striking.”

Anthropogenic contribution

Woolway said that the increase in remotely sensed data has made studies such as this possible. This allows scientists to move beyond single-lake studies and address global-scale changes within similar ecosystems. The researchers used data from the European Space Agency to analyze lake surface temperatures. They used data from 78 lakes large enough to measure temperatures at multiple points. This covered 1995 to 2019.

Woolway and his coauthors searched for lake heat waves with varying intensities. However, their attribution analysis was limited to “severe,” or “extreme”, heat waves.

To determine Heat waveResearchers analyzed surface temperature anomalies to determine how much warmer temperatures are than normal. Extreme heat waves can see lake surface temperatures rise well above the top 10% of all temperatures. Woolway stated that if humans feel the heat, then the lakes will feel it too.

The researchers compared historical temperature data with climate models from Intersectoral Impact Model Intercomparison project, a large community effort that simulates lake responses to climate change. They were able to estimate how much human-caused heat waves have occurred and predict how often they will occur in the future.

Researchers discovered that severe and extreme lake heat wave may be three times more common at 1.5 degrees Celsius global warming, which is the goal set by the Paris Agreement. If global warming is 3 degrees Celsius, which could happen this century, severe heat waves may be 25 times more likely than if there are no reductions in greenhouse gas emissions. This is in comparison to the likelihood of such events in a preindustrial climate. Woolway stated that anthropogenic contributions were also higher at tropical lakes. This is consistent with other studies that show lower-latitude regions are the most affected by climate change.

In hot water

Because the study was limited to large lakes (which can be more resistant against changes and severe heat waves), it may be an inaccurate estimate of how often severe lake heatwaves hit.

Woolway stated, “When we scale up these findings to a worldwide scale, the results can be much worse.”

Many ways can lake heat waves be detrimental to ecosystems Even small temperature fluctuations can have a negative impact on organisms that live within a very narrow temperature range. TemperatureThis can lead to death. Warmer waters also result in more evaporation and less mixing. The lake’s water becomes stratified, with hot water at the top and cooler water below. Both of these effects can result in less oxygen, which can be a problem for lake dwellers who are dependent on oxygen.

Grant stated that as the field of lake-heat waves develops, Grant suggested that better data and studies on heat refuges could help to refine predictions. Lake ecosystems‘ Responses to Heat.

“The only way to combat this is to reduce global heating. Woolway said that if temperatures continue rising, lake heat waves will only get worse.”