“There is an immense asymmetry in the time it takes to consume, alter or destroy natural phenomena compared with the time required to replace, restore or repair them.” — Marcia Bjornerud in her book “Timefulness: How Thinking Like a Geologist Can Help Save the World”
Perhaps the most disturbing conclusion of the latest Intergovernmental Panel on Climate Change report is the permanence of climate impacts. Changes like shrinking ice sheets, rising sea levels and oxygen depletion and acidification of the oceans are deemed “irreversible for centuries to millennia.”
An April 19 article in Carbon Brief, “Climate change could cause ‘irreversible impacts’ to lake ecosystems,” illustrates why sharp emission reductions are needed if the Great Lakes region is to avoid the worst effects of global warming. The article discusses the increased stratification of northern hemisphere lakes as temperatures warm and the harm this will likely produce as fish are deprived of oxygen in cooler, deeper waters. Stratification is the layering of lakes by temperature, which can prevent surface oxygen from mixing with other layers.
According to a study in Nature Communications reviewed in this piece, the Great Lakes are particularly vulnerable and “are already experiencing ‘rapid changes’ in their stratification periods.” Some lake ecosystems could undergo “catastrophic changes” under high emissions scenarios.
To quote lead author Dr. Richard Woolway: “Fish often migrate to deeper waters during the summer to escape warmer conditions at the surface — for example during a lake heatwave. A decrease in oxygen at depth will mean that fish will have no thermal refuge, as they often can’t survive when oxygen concentrations are too low.”
Increased stratification affects smaller, inland lakes as well. Moreover, warming is having similar impacts in the oceans, where deoxygenation has been associated with major extinction events in past eras.
On June 30, 49 U.S. scientific organizations, including the American Association for the Advancement of Science and the American Meteorological Society, sent a letter to Congress expressing the “urgency of boldly addressing climate change.” The letter asserts:
“There is strong evidence that ongoing climate change is having broad negative impacts on society, including the global economy, our shared environment and oceans, and human health. … To reduce the risk of the most severe impacts of climate change, anthropogenic greenhouse gas emissions must be substantially reduced. …Rapid action is necessary to avoid potentially disastrous consequences for health, biodiversity, food security, water availability, and national security.”
A $3.5 trillion reconciliation bill is now being considered in Congress, and it’s likely to contain major climate provisions. Congress may have a narrow window for substantive climate action. Please call your representatives in Washington and urge them to include a price on carbon dioxide emissions in this legislation. According to the IPCC, “Explicit carbon prices remain a necessary condition of ambitious climate policies.” It’s the single most powerful way to reduce emissions.
Terry Hansen is a resident of Hales Corners, Wis.
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