# Arctic Northwest Atlantic 646 Year Coralline Algae Sea Ice Record #----------------------------------------------------------------------- # World Data Center for Paleoclimatology, Boulder # and # NOAA Paleoclimatology Program #----------------------------------------------------------------------- # NOTE: Please cite original publication, online resource and date accessed when using this data. # If there is no publication information, please cite Investigator, title, online resource and date accessed. # # Description/Documentation lines begin with # # Data lines have no # # # Online_Resource: https://www.ncdc.noaa.gov/paleo/study/15454 # # Online_Resource: http://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/halfar2014/halfar2014sic.txt # # Archive: Paleoceanography #--------------------------------------- # Contribution_Date # Date: 2013-11-18 #--------------------------------------- # Title: Arctic Northwest Atlantic 646 Year Coralline Algae Sea Ice Record # #--------------------------------------- # Investigators: Halfar, J.; Adey, W.H.; Kronz, A.; Hetzinger, S.; Edinger, E.; Fitzhugh, W.W. #--------------------------------------- # Description_Notes_and_Keywords # Description: # Description: Samples of Clathromorphum compactum were live collected at Arctic Bay, Nunavut, Canada (73.0174°N; 85.1536°W, Sample AB1, 17m depth, lifespan 1779-2009) and off Kingitok Island, Labrador, Canada (55.3983°N; 59.8467°W, Sample Ki1, 17m depth, lifespan 1851-2011; Sample Ki2, 15m depth, lifespan 1365-2011). Mg/Ca ratios were measured along transects extending over the entire lifespan of each specimen using a JEOL JXA 8900 RL electron microprobe at the University of Göttingen, Germany. Samples were obtained along transect lines oriented perpendicular to the plane of calcite accretion. At each interval the specific subsample location was selected manually by moving the stage no more than 20 µm laterally from the transect line to avoid unsuitable sample locations (i.e., conceptacles= reproductive structures and uncalcified cell interiors). The relative mean standard deviations of multiple standard measurements were found to be no larger than 1.0 % for MgO and 1.2 % for CaO (2-sigma). Counting statistics errors vary between 1.0 relative % and 2.9 relative % for MgO and between 0.40 relative % and 0.62 relative % for CaO (2-sigma). Algal growth-increment widths were calculated from widths of annual Mg/Ca cycles. Reconstructions were standardized to have a mean of zero and unit variance. A combined algal record was calculated by averaging the normalized annual growth rates and annually-averaged Mg/Ca ratios from all three samples. #--------------------------------------- # Publication # Authors: Jochen Halfar, Walter H. Adey, Andreas Kronz, Steffen Hetzinger, Evan Edinger, and William W. Fitzhugh # Published_Date_or_Year: 2013-11-18 # Published_Title: Arctic sea-ice decline archived by multicentury annual-resolution record from crustose coralline algal proxy # Journal_Name: Proceedings National Academy of Sciences # Volume: # Issue: # Pages: # Report Number: # DOI: www.pnas.org/cgi/doi/10.1073/pnas.1313775110 # Abstract: Northern Hemisphere sea ice has been declining sharply over the past decades and 2012 exhibited the lowest Arctic summer sea-ice cover in historic times. Whereas ongoing changes are closely monitored through satellite observations, we have only limited data of past Arctic sea-ice cover derived from short historical records, indirect terrestrial proxies, and low-resolution marine sediment cores. A multicentury time series from extremely long-lived annual increment-forming crustose coralline algal buildups now provides the first high-resolution in situ marine proxy for sea-ice cover. Growth and Mg/Ca ratios of these Arctic-wide occurring calcified algae are sensitive to changes in both temperature and solar radiation. Growth sharply declines with increasing sea-ice blockage of light from the benthic algal habitat. The 646-y multisite record from the Canadian Arctic indicates that during the Little Ice Age, sea ice was extensive but highly variable on subdecadal time scales and coincided with an expansion of ice-dependent Thule/Labrador Inuit sea mammal hunters in the region. The past 150 y instead have been characterized by sea ice exhibiting multidecadal variability with a long-term decline distinctly steeper than at any time since the 14th century. #--------------------------------------- # Funding_Agency # Funding_Agency_Name: Natural Sciences and Engineering Research Council of Canada # Grant: Discovery Grant #--------------------------------------- # Site Information # Site_Name: Arctic Northwest Atlantic # Location: Ocean>Atlantic Ocean>North Atlantic Ocean # Northernmost_Latitude: 73.0174 # Southernmost_Latitude: 55.3983 # Easternmost_Longitude: -59.8467 # Westernmost_Longitude: -85.1536 # Elevation: -17 #--------------------------------------- # Data_Collection # Collection_Name: Halfar2014sic # First_Year: 1365 # Last_Year: 2010 # Time_Unit: AD # Core_Length: # Notes: Average of cores AB1, Ki1 and Ki2 #--------------------------------------- # Chronology: # Chronology established based on annual increment counting and confirmed by radiocarbon (see Table S1, Halfar et al. PNAS) # # Sample # Measured Age (BP) 13C/12C Conventional Age 2 s Calibration Expected* # RC1 140 +/- 30 -2.0 ‰ 520 +/- 30 BP Cal AD 1820 - post 1950 1875-1880 # RC2 240 +/- 30 +0.5 ‰ 660 +/- 30 BP Cal AD 1670 - 1840 1815-1825 # RC3 670 +/- 30 0.0 ‰ 1080 +/- 30 BP Cal AD 1310 - 1440 1435-1445 # # * 'Expected' indicates age determined by age model based on growth increments and Mg/Ca cycles # #--------------------------------------- # Variables # # Data variables follow (have no #) # Data line variables format: Variables list, one per line, shortname-tab-longname-tab-longname components (9 components: what, material, error, units, seasonality, archive, detail, method, C or N for Character or Numeric data) ## age_AD age, , , AD, , , , ,N ## SIC Sea Ice Cover, , , algal proxy anomalies, annual, crustose coralline algae, , ,N #------------------------------------ # Data # Missing Value: NA age_AD SIC 2010 0.65 2009 -0.97 2008 0.42 2007 1.25 2006 0.21 2005 0.83 2004 0.24 2003 0.75 2002 0.71 2001 0.62 2000 0.56 1999 1.06 1998 0.72 1997 0.18 1996 -0.01 1995 -0.13 1994 0.52 1993 -0.05 1992 -0.47 1991 -0.06 1990 0.44 1989 0.07 1988 0.16 1987 0.55 1986 0.67 1985 0.04 1984 -0.20 1983 -0.02 1982 0.33 1981 0.98 1980 0.57 1979 0.79 1978 -0.32 1977 1.33 1976 -0.34 1975 0.72 1974 0.39 1973 0.53 1972 0.04 1971 0.81 1970 0.22 1969 0.81 1968 0.95 1967 0.41 1966 0.83 1965 0.44 1964 0.95 1963 1.22 1962 1.18 1961 1.29 1960 0.57 1959 0.19 1958 0.68 1957 0.73 1956 0.37 1955 0.83 1954 0.49 1953 0.21 1952 -0.05 1951 1.15 1950 0.94 1949 0.59 1948 0.78 1947 1.05 1946 0.33 1945 0.52 1944 -0.05 1943 0.71 1942 1.08 1941 0.81 1940 0.58 1939 0.79 1938 0.99 1937 0.44 1936 0.27 1935 0.43 1934 0.59 1933 0.99 1932 0.78 1931 1.21 1930 0.99 1929 1.00 1928 0.22 1927 -0.16 1926 -0.58 1925 0.15 1924 0.43 1923 0.13 1922 -0.10 1921 0.01 1920 -0.51 1919 -0.18 1918 0.36 1917 -0.07 1916 -0.28 1915 -0.59 1914 0.15 1913 -0.49 1912 -0.23 1911 -0.10 1910 -0.20 1909 0.26 1908 -0.38 1907 -0.31 1906 0.33 1905 -0.07 1904 -0.47 1903 -0.54 1902 -0.54 1901 0.20 1900 -0.07 1899 0.32 1898 0.19 1897 0.15 1896 0.56 1895 0.07 1894 0.64 1893 0.29 1892 0.47 1891 -0.27 1890 0.11 1889 -0.33 1888 -0.01 1887 0.13 1886 -0.13 1885 0.39 1884 -0.19 1883 0.04 1882 0.44 1881 0.15 1880 0.80 1879 -0.33 1878 -0.51 1877 -0.17 1876 0.23 1875 0.50 1874 0.26 1873 -0.58 1872 -0.30 1871 -0.30 1870 0.63 1869 0.38 1868 -0.52 1867 0.04 1866 -0.13 1865 0.47 1864 0.23 1863 0.54 1862 -0.02 1861 0.22 1860 -0.01 1859 0.29 1858 0.13 1857 -0.35 1856 0.06 1855 -0.20 1854 -0.88 1853 -0.03 1852 -0.33 1851 -0.17 1850 -1.01 1849 -0.65 1848 0.73 1847 -0.70 1846 -0.66 1845 0.09 1844 -1.21 1843 -0.08 1842 -0.37 1841 -0.84 1840 -0.58 1839 0.02 1838 -0.78 1837 -0.11 1836 -0.15 1835 0.01 1834 -0.52 1833 0.03 1832 0.25 1831 -0.85 1830 -0.54 1829 0.42 1828 0.67 1827 -0.07 1826 -0.95 1825 0.26 1824 -0.11 1823 0.46 1822 0.20 1821 -0.80 1820 0.39 1819 -0.27 1818 -0.44 1817 -0.61 1816 0.01 1815 0.28 1814 -0.44 1813 -0.97 1812 -1.26 1811 -1.00 1810 -0.18 1809 -0.64 1808 -0.20 1807 -0.90 1806 -0.54 1805 -0.41 1804 -0.26 1803 0.01 1802 -0.36 1801 0.25 1800 -0.73 1799 -0.67 1798 -0.37 1797 0.02 1796 0.68 1795 0.08 1794 -0.09 1793 -0.33 1792 -0.54 1791 0.28 1790 0.19 1789 0.08 1788 -0.17 1787 -0.63 1786 -0.35 1785 0.14 1784 0.04 1783 0.31 1782 0.02 1781 -0.35 1780 -0.97 1779 -0.22 1778 -0.69 1777 -0.93 1776 -0.87 1775 -1.28 1774 0.13 1773 -0.15 1772 -0.26 1771 -0.85 1770 -0.59 1769 0.25 1768 -0.52 1767 -0.84 1766 -0.22 1765 0.30 1764 -0.70 1763 -1.07 1762 0.36 1761 0.38 1760 -0.04 1759 -0.38 1758 0.98 1757 -0.63 1756 -0.47 1755 -0.84 1754 -0.76 1753 -0.66 1752 -0.35 1751 0.70 1750 -0.01 1749 -0.79 1748 -0.49 1747 -0.29 1746 1.28 1745 -0.09 1744 0.36 1743 0.45 1742 0.23 1741 0.48 1740 0.43 1739 0.48 1738 -0.58 1737 -0.17 1736 -0.11 1735 -0.27 1734 -0.18 1733 -0.59 1732 -0.44 1731 -0.27 1730 -0.18 1729 -0.48 1728 -0.18 1727 -0.43 1726 -0.94 1725 -0.85 1724 -1.04 1723 -0.59 1722 -0.41 1721 -0.73 1720 -0.22 1719 0.23 1718 -0.54 1717 -0.19 1716 -0.95 1715 -1.04 1714 -0.77 1713 -0.50 1712 -0.75 1711 -0.51 1710 0.18 1709 0.51 1708 -0.25 1707 -0.12 1706 -0.04 1705 0.07 1704 -0.57 1703 -0.07 1702 1.10 1701 0.07 1700 0.62 1699 0.08 1698 -0.71 1697 -0.12 1696 -0.32 1695 -0.02 1694 0.41 1693 1.08 1692 -0.51 1691 -1.06 1690 -0.34 1689 -0.37 1688 -0.72 1687 -0.44 1686 -0.74 1685 0.47 1684 0.62 1683 0.74 1682 -0.55 1681 0.90 1680 0.59 1679 -0.22 1678 0.38 1677 0.27 1676 -0.23 1675 -0.27 1674 -0.49 1673 0.08 1672 0.13 1671 -0.90 1670 -0.63 1669 -0.24 1668 -0.05 1667 0.09 1666 -0.83 1665 -0.29 1664 -0.12 1663 -0.43 1662 -0.36 1661 -0.19 1660 -0.05 1659 -0.34 1658 -1.18 1657 -0.44 1656 0.20 1655 -0.45 1654 -0.06 1653 -0.58 1652 0.00 1651 0.68 1650 0.83 1649 -0.12 1648 -0.58 1647 -0.68 1646 -0.59 1645 1.31 1644 -0.42 1643 -0.54 1642 0.15 1641 -1.26 1640 -0.57 1639 -0.26 1638 0.08 1637 -0.75 1636 -0.28 1635 -0.44 1634 -0.30 1633 0.63 1632 -0.36 1631 -0.20 1630 -1.10 1629 -0.76 1628 -0.35 1627 -0.05 1626 0.46 1625 -0.22 1624 -1.23 1623 -0.24 1622 -0.49 1621 -1.82 1620 -1.27 1619 -0.45 1618 -1.02 1617 0.10 1616 -0.23 1615 -0.05 1614 -0.87 1613 -1.16 1612 -1.02 1611 -0.03 1610 0.09 1609 0.07 1608 0.50 1607 -0.61 1606 -0.37 1605 0.33 1604 -0.33 1603 -0.74 1602 -0.47 1601 -0.10 1600 -0.25 1599 -0.18 1598 -0.88 1597 -0.97 1596 -0.62 1595 0.22 1594 -0.22 1593 0.03 1592 -0.11 1591 -0.16 1590 -0.67 1589 -0.92 1588 -0.17 1587 0.11 1586 0.13 1585 0.81 1584 0.42 1583 0.23 1582 0.21 1581 -1.13 1580 -0.91 1579 -0.67 1578 0.08 1577 0.53 1576 0.21 1575 -1.10 1574 -0.95 1573 -0.97 1572 -1.02 1571 0.05 1570 -1.16 1569 -0.37 1568 -1.27 1567 -1.93 1566 -0.63 1565 -0.44 1564 -1.05 1563 0.08 1562 -0.15 1561 0.15 1560 -0.72 1559 -1.15 1558 -1.04 1557 -0.60 1556 -1.06 1555 -0.15 1554 -0.54 1553 -0.79 1552 -0.08 1551 -0.14 1550 -0.05 1549 0.17 1548 -0.10 1547 -0.42 1546 0.71 1545 0.25 1544 -0.08 1543 -0.53 1542 -0.91 1541 -1.06 1540 -0.38 1539 -0.72 1538 -0.85 1537 -0.97 1536 0.16 1535 -0.44 1534 -0.62 1533 -0.54 1532 -0.41 1531 0.22 1530 -0.52 1529 0.01 1528 0.77 1527 0.30 1526 0.23 1525 0.51 1524 0.61 1523 -0.17 1522 0.44 1521 0.10 1520 1.20 1519 0.98 1518 0.84 1517 -0.09 1516 -0.35 1515 0.18 1514 0.02 1513 0.01 1512 -0.27 1511 -0.03 1510 0.17 1509 -0.83 1508 -0.43 1507 -0.92 1506 -0.04 1505 -0.22 1504 -0.11 1503 -0.25 1502 0.49 1501 -0.32 1500 0.13 1499 0.06 1498 -0.53 1497 -0.35 1496 -1.35 1495 0.24 1494 0.41 1493 0.54 1492 -0.32 1491 -0.86 1490 -0.57 1489 1.69 1488 -0.16 1487 0.02 1486 0.60 1485 0.92 1484 1.58 1483 1.28 1482 -0.05 1481 -0.44 1480 0.22 1479 0.57 1478 -0.07 1477 0.40 1476 -0.26 1475 1.29 1474 0.45 1473 0.21 1472 0.55 1471 0.38 1470 1.09 1469 0.04 1468 0.35 1467 1.47 1466 0.41 1465 0.10 1464 0.18 1463 -0.68 1462 -1.38 1461 0.57 1460 0.85 1459 0.43 1458 0.76 1457 0.54 1456 -0.25 1455 -0.45 1454 -0.30 1453 0.36 1452 -0.03 1451 -0.35 1450 0.26 1449 -0.28 1448 -0.70 1447 0.20 1446 -0.33 1445 0.15 1444 -0.70 1443 -1.15 1442 -1.24 1441 -0.94 1440 0.45 1439 0.14 1438 0.20 1437 0.16 1436 0.08 1435 0.96 1434 1.56 1433 0.01 1432 0.63 1431 0.62 1430 0.16 1429 -0.75 1428 -1.29 1427 0.36 1426 0.05 1425 -0.17 1424 0.18 1423 0.51 1422 0.67 1421 -0.72 1420 -0.23 1419 -0.94 1418 -0.88 1417 0.05 1416 0.03 1415 -0.57 1414 -0.60 1413 -0.76 1412 -0.82 1411 -1.09 1410 -0.74 1409 -0.51 1408 -0.41 1407 -0.13 1406 -0.40 1405 0.07 1404 -0.50 1403 -0.44 1402 0.38 1401 0.96 1400 0.16 1399 -0.48 1398 0.25 1397 -0.31 1396 -0.15 1395 -0.74 1394 0.85 1393 0.69 1392 -0.16 1391 0.34 1390 0.02 1389 -0.43 1388 -0.20 1387 0.62 1386 -0.83 1385 -1.42 1384 -0.83 1383 -0.78 1382 -1.21 1381 -0.84 1380 -1.44 1379 -1.56 1378 -1.19 1377 -0.18 1376 -0.47 1375 -0.73 1374 -0.92 1373 -0.88 1372 -0.11 1371 0.43 1370 0.57 1369 -0.14 1368 1.06 1367 0.39 1366 0.16 1365 -0.82