How Centuries-Old Caribbean Sponges Challenge Our Understanding of Climate Change
A groundbreaking study involving centuries-old sponges from the deep Caribbean is challenging existing perceptions of human-caused climate change. The research, published in Nature Climate Change, suggests that the world may have surpassed the internationally approved target of limiting global warming to 1.5 degrees Celsius since pre-industrial times, hitting 1.7 degrees as of 2020. This revelation could reshape our understanding of the urgency and severity of climate change impacts.
The research utilized measurements obtained from a rare species of small, hard-shelled sponges to construct a temperature record for the 1800s, presenting a stark deviation from the scientifically accepted versions endorsed by the United Nations’ Intergovernmental Panel on Climate Change (IPCC). Contrary to previous beliefs, the study contends that the mid-1800s were approximately half a degree Celsius cooler than indicated by the IPCC, with the onset of warming attributed to heat-trapping gases occurring roughly 80 years earlier than the IPCC's timeline, which shows warming commencing just after 1900.
The assertion that warming began earlier aligns with the emergence of the Industrial Revolution in the mid-1800s, a period marked by the significant release of carbon dioxide into the atmosphere through industrial activities. Carbon dioxide and other gases emitted from fossil fuel combustion are established causes of climate change, as acknowledged by the scientific community.
Researchers Amos Winter and Malcolm McCulloch emphasized the unique qualities of the rusty orange, long-lived sponges employed in the study, with one specimen exceeding 320 years in age. These sponges, according to Winter and McCulloch, serve as an ideal measuring tool, surpassing the efficacy of methods employed in the mid- to late 1800s.
Describing the sponges as "cathedrals of history" capturing essential environmental data, Winter highlighted their ability to record carbon dioxide levels in the atmosphere, water temperature, and water pH. Despite their significance, locating these sponges presents a challenge, requiring a specialized team of divers, as they inhabit depths ranging from 100 to 300 feet in the dark ocean depths.
While the IPCC and most scientists rely on temperature data from the mid-1800s obtained from ships using wooden buckets to collect water, the study argues that such measurements may be susceptible to inaccuracies, such as proximity to warm steamship engines. In contrast, the sponges offer heightened accuracy due to the tracking of consistent deposits of calcium and strontium on their skeletons. The ratio of strontium to calcium deposits reflects water temperature, with warmer water yielding more strontium compared to calcium and cooler water exhibiting higher proportions of calcium to strontium, providing a reliable indicator of historical temperature variations.
Here are some key findings that are especially relevant to journalists covering environmental issues.
In Regard to Sponge Analysis and Temperature Records:
Scientists analyzed six long-lived sponges to understand changes in water temperature, acidity, and carbon dioxide levels.
Sponges, acting as natural recorders, provided insights into environmental conditions dating back centuries, offering a unique perspective compared to traditional proxies like coral, tree rings, and ice cores.
In Regard to the Potential Early Onset of Warming:
The study challenges established timelines, suggesting that warming, caused by heat-trapping gases, began around 80 years earlier than previously believed.
The mid-1800s were approximately half a degree Celsius cooler than previously estimated, indicating an earlier onset of warming linked to the Industrial Revolution.
What The Study Tells Us About Climate Change Acceleration:
Researchers argue that if the sponge calculations are accurate, it supports the theory that climate change is accelerating, as proposed by former NASA top scientist James Hansen.
The findings have potential repercussions, indicating that extreme weather events experienced in recent years may be attributed to more significant warming than initially calculated.
On the Use of Sponges as Accurate Climate Proxies:
The study defends the use of sponges as precise climate proxies due to their unique ability to record changes in water conditions, offering a more accurate representation than historical temperature measurements taken from ships.
On the Need to Reduce Emissions:
The research emphasizes the urgency of reducing emissions to address the accelerated rate of climate change.
Despite skepticism from some scientists, the study authors argue that the rate of change is faster than anticipated, posing high-risk scenarios for the future.
