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Planktonic foraminiferal area density as a proxy for carbonate ion concentration: a calibration study using the Cariaco Basin Ocean Time Series

Published 19 June 2013 Science Leave a Comment
Tags: biological response, chemistry, field, morphology, paleo, protists

Biweekly sediment trap samples and concurrent hydrographic measurements collected between March 2005 and October 2008 from the Cariaco Basin, Venezuela are used to assess the relationship between [CO₃^2-] and the area densities (ρ_A) of two species of planktonic foraminifera (Globigerinoides ruber (pink) and Globigerinoides sacculifer). Calcification temperatures were calculated for each sample using species-appropriate oxygen isotope (δ¹⁸O) temperature equations that were then compared to monthly temperature profiles taken at the study site in order to determine calcification depth. Ambient [CO₃^2-] was determined for these calcification depths using alkalinity, pH, temperature, salinity, and nutrient concentration measurements taken during monthly hydrographic cruises. ρ_A, which is representative of calcification efficiency, is determined by dividing individual foraminiferal shell weights (± 0.43 µg) by their associated silhouette areas and taking the sample average. The results of this study show a strong correlation between ρ_A and ambient [CO₃^2-] for both G. ruber and G. sacculifer (R² = 0.89 and 0.86 respectively), confirming that [CO₃^2-] has a pronounced effect on the calcification of these species. Though the ρ_A for both species reveal a highly significant (p < 0.001) relationship with ambient [CO₃^2-], linear regression reveals that the extent to which [CO₃^2-] influences foraminiferal calcification is species-specific. Hierarchical regression analyses indicate that other environmental parameters (temperature and [PO₄^3-]) do not confound the use of G. ruber and G. sacculifer ρ_A as a predictor for [CO₃^2-]. This study suggests that G. ruber and G. sacculifer ρ_A can be used as reliable proxies for past surface ocean [CO₃^2-].

 

Marshall B. J., Thunell R. C., Henehan M. J., Astor Y. & Wejnert K. E., in press. Planktonic foraminiferal area density as a proxy for carbonate ion concentration: a calibration study using the Cariaco Basin Ocean Time Series. Paleoceanography. Article (subscription required).

Wellington battered as storm heads north

Winds gusting up to 140km/h were battering downtown Wellington, lifting roofs from homes and cutting power to about 30,000 customers.

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Author: Reuters

(US Senator Sheldon Whitehouse is a Reuters columnist but his opinions are his own.)

By Senator Sheldon Whitehouse

June 19 (Reuters) – The effects of climate change, driven by carbon pollution, hit Americans harder each year. Extreme weather events like hurricanes, wildfires and droughts are growing ever more frequent and severe.

Beyond our borders, these changes are hitting developing nations.

Since our nation’s founding, America has stood as an example for the world. Now, we owe it to ourselves and to other nations, who look to Washington, to lead the way on climate change by putting a price on carbon pollution and taking other steps to minimize the harm being done to developing nations – and our own.

In many of the world’s poorest regions, the sun scorches drought-stricken farmland and parches freshwater sources. Fierce storms bring ravaging floods. Warming, rapidly acidifying oceans and shifting seasons drive off economically valuable species and foster pests and disease.

This year, the worst flood in a decade killed at least 38 people in Mozambique and left 150,000 homeless. Warmer weather allows malaria-bearing mosquitoes to move into previously unaffected altitudes, infecting cities like Nairobi, which had purposely been built above the “malaria line.” Ten of the 15 largest cities in the developing world, including Shanghai, Mumbai and Cairo, are at risk of flooding from rising sea levels or coastal storm surges. Rising seas are swallowing low-lying land in countries such as Bangladesh and India.

Climate change endangers much of the world economy as well. Economists calculate that a 3.5?F rise in global temperature would reduce global gross domestic product by 1 percent. But loss will be 4 percent in Africa, and 5 percent in India. The United Nations estimates that environmental disasters could drive as many as 3 billion people into extreme poverty by the year 2050.

These regions face a crisis not of their making. Developed countries have churned out two-thirds of all the carbon dioxide pollution since the Industrial Revolution – one-quarter of that from the United States alone.

We have much to gain here at home from efforts to mitigate the effects of climate change: safer coastal communities, healthier farming and fishing industries, and cleaner air to breathe. But the American experiment has always been about more than that.

Indeed, as one of the largest emitters of carbon pollution, the United States has a responsibility to help emerging nations adapt to the stark reality of a changing climate, lest, as Daniel Webster warned, our own example “become an argument against the experiment.”

We are now taking important steps to help poorer nations cope with climate change. Indeed, federal agencies, from the U.S. Agency for International Development and the Environmental Protection Agency, to the Agriculture and Defense Departments, support adaptation strategies in the developing world. We provide financing to support construction and hardening of physical infrastructure. We make available technology to improve weather forecasting and irrigation techniques. While these physical adaptation programs are crucial, the crisis of climate change also requires political and diplomatic adaptation.

This is the mission of the State Department’s Environment, Science and Technology and Health (ESTH) officers. These officers engage on both a bilateral and a regional basis to promote good environmental governance, enable sustainable trade practices, advance resource and wildlife conservation, and improve access to healthcare. Many work closely with our allies around the globe, helping make communities more resilient to the devastating effects of climate change.

This is still a small effort. As of 2011, 260 of the State Department’s more than 13,000 Foreign Service officers handled environment, science, technology and health issues in our embassies. Only 76 were full-time ESTH officers. Theirs is vital work. It is worth replicating on a larger scale.

The United States must also set an example by putting a price on carbon pollution. I’m working with Representative Henry Waxman (D-Calif.) and others to finalize legislation that would do so. Right now, the big polluters pump billions of tons of carbon into our atmosphere, forcing the rest of us to pay the price through higher healthcare costs, higher rebuilding costs after carbon-driven extreme weather events, and more.

Our proposal would put those costs back on the polluters. It would generate billions of dollars in new revenue, which could produce substantial benefits for the U.S. economy. But, just as important, it would improve the global environment by encouraging reduced emissions. It would also send a message that we are ready to lead once more on one of the great issues of our time.

The effects of more than a century of Western pollution bear heavily on less-developed countries. The eyes of the world are on us. Without concerted action, we run the risk of allowing climate change to destabilize entire nations – and their confidence in America’s leadership.

(U.S. Senator Sheldon Whitehouse (D-R.I.) is a member of the Environment and Public Works Committee and co-chairman of the Bicameral Task Force on Climate Change of the US Senate. He also serves on the Budget and Judiciary Committees. (Senator Sheldon Whitehouse)

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