Halfar, Jochen
Contact Information
3359 Mississauga Road North
Mississauga , Ontario
L5L 1C6
Research
My research is focused on deciphering paleoclimates on different time scales ranging from the past centuries to the Neogene using geochemical, sedimentological, and oceanographic approaches. In collaboration with biologists and oceanographers I have recently completed a field calibration study of coralline red algae confirming their usefulness as climate archives. I am now utilizing climate information contained in calcified growth bands of long-lived coralline red algae to reconstruct sea surface temperatures of extratropical seas using state-of-the-art microanalytical geochemical techniques.
A further aspect of my research is concerned with quantifying the complex interplay of oceanographic controls such as nutrients and temperatures on modern shallow water carbonate depositional systems in order to facilitate the interpretation of paleoclimates and paleoceanography from fossil carbonates. I have completed a first such study by combining long-term field monitoring of oceanography with sedimentologic investigations in a range of modern carbonate environments located along a latitudinal gradient. Applying this knowledge to the fossil record I could demonstrate that increased nutrient levels in connection with deteriorating temperatures resulted in a global turnover of shallow water carbonate producing biota during the middle Miocene.
Publications
Halfar, J., Eisele, M., Riegl, B., Hetzinger, S., Godinez-Orta, L., in press, Modern rhodolith-dominated carbonates at Punta Chivato, Mexico. Geodiversitas.
Halfar, J., Williams, B, Hetzinger, S., Steneck, R.S., Lebednik, P., Winsborough, C., Omar, A., Chan, P., Wanamaker, A., 2011, 225 years of Bering Sea climate and ecosystem dynamics archived by coralline algae, Geology, v. 39, 6, 579-582, doi:10.1130/G31996.
Chan, P., Halfar, J., Hetzinger, S., Williams, B., Steneck, R.S., Zack, T., Kunz, B., Jacob, D., 2011, Freshening of the Alaska Coastal Current recorded by coralline algal Ba/Ca ratios, Journal of Geophysical Research – Biogeosciences 116, G01032, doi:10.1029/2010JG001548
Wanamaker, A.D. Jr., Hetzinger, S., Halfar, J., 2011, Reconstructing mid- to high-latitude marine climate and ocean variability using bivalves, coralline algae, and marine sediments from the Northern Hemisphere, Palaeogeography, Palaeoclimatology, Palaeoecology, 302, 1-9, doi:10.1016/j.palaeo.2010.12.024
Halfar, J., Hetzinger, S., Zack T., Adey, W., Gamboa, G., Kunz, B., Williams, B., Jacob D., 2011, Coralline red algal growth-increment widths archive North Atlantic climate variability. Palaeogeography, Palaeoclimatology, Palaeoecology, 302, 71-80, doi:10.1016/j.palaeo.2010.04.009
Hetzinger, S., Halfar, J., Zack, T., Jacob, D., Kunz, B., Gamboa, G., Kronz, A., Adey, W., Lebednik, P., Steneck, R., 2011. High-resolution analysis of trace elements from the North Atlantic and North Pacific in encrusting coralline algae by laser ablation ICP-MS. Palaeogeography, Palaeoclimatology, Palaeoecology, 302, 81-94 doi:10.1016/j.palaeo.2010.06.004
Williams, B., Halfar, J., Steneck, R.S., Wortmann, U.G., Hetzinger, S., Adey, W., Lebednik, P., Joachimski, M., 2011, Twentieth century 13C variability in surface water dissolved inorganic carbon recorded by coralline algae in the northern North Pacific Ocean and the Bering Sea, Biogeosciences, 8, 165-174. doi:10.5194/bg-8-165-2011.
Gamboa, G., Halfar, J., Hetzinger, S., Adey, W., Zack, T., Kunz, B., Jacob D.E., 2010, Mg/Ca ratios in coralline algae as proxies for NW Atlantic temperature variations. Journal of Geophysical Research – Oceans, 115, C12044, doi:10.1029/2010JC006262.
Hetzinger, S., Pfeiffer, M., Dullo, W.C., Garbe-Schönberg, D., Halfar, J., 2010, Rapid 20th century warming in the Caribbean and impact of remote forcing on climate in the northern tropical Atlantic as recorded in a Guadeloupe coral. Palaeogeography, Palaeoclimatology, Palaeoecology, 296, 1-2, 111-124.
Westphal, H., Halfar, J., Freiwald, A., 2010, Non-coralgal carbonates in subtropical to tropical settings in the present and in the past. International Journal of Earth Sciences, 99, S153-S169
Hetzinger, S., Halfar, J., Kronz, A., Steneck, R., Adey, W., Lebednik, P., Schöne, B.R., 2009, High-resolution Mg/Ca ratios in a coralline red algae as a proxy for Bering Sea temperature variations. Palaios, v. 24, 406-412.
Halfar, J., Steneck, R., Joachimski, M., Kronz, A., Wanamaker, A.D. Jr., 2008, Coralline red algae as high-resolution climate recorders, Geology, v. 36, 6, 463-466.
Halfar, J., Fujita, R. M., 2007, Danger of deep-sea mining - Plans for deep-sea mining could pose a serious threat to marine ecosystems, Science, 316, 987.
Halfar, J., Steneck, R., Schöne, B., Moore, G. W. K., Joachimski, M., Kronz, A., Fietzke, J., and Estes J., 2007, Coralline alga reveals first marine record of subarctic North Pacific climate change, Geophysical Research Letters, 34, L07702, doi:10.1029/2006GL028811.