Reconstructing past thermal conditions in beach microclimates

Area of Science:

• Paleoclimatology
• Marine Biology
• Ecology

Background:

• Long-term temperature data for microhabitats like sea turtle nests are scarce.
• Accurate reconstruction of past temperatures is crucial for understanding ecosystem responses to climate change.
• Debate exists on the best large-scale environmental proxies for local temperature reconstruction.

Purpose of the Study:

• To evaluate the accuracy of environmental proxies (sea surface and air temperature) in reconstructing sand temperatures at sea turtle nesting sites.
• To determine if these proxies can be used globally to infer historical sand temperature trends.
• To assess the impact of climate change on sea turtle nesting microhabitats.

Main Methods:

• Collected instrumental air and sea surface temperature data alongside empirical sand temperature observations from five global nesting sites.
• Utilized Granger causality testing to establish the temporal relationship between temperature variables.
• Developed predictive models using different combinations of temperature proxies.

Main Results:

• Strong correlations were found between sea surface temperatures, air temperatures, and sand temperatures across all study sites.
• Variations in sea surface and air temperatures were found to precede changes in sand temperatures.
• Proxies accurately predicted mean monthly sand temperatures within 0.5°C, with reconstructions showing a slight warming trend (max 0.5°C per century).

Conclusions:

• Sea surface and air temperatures are reliable proxies for reconstructing historical sand temperatures at sea turtle nesting sites.
• The established relationship between air and sand temperatures is consistent globally, enabling temperature reconstructions even without direct measurements.
• This approach provides a valuable tool for understanding long-term temperature changes in various microhabitats and their response to climate change.