Tropical climate and vegetation changes during Heinrich Event 1: a model-data comparison

Abrupt climate changes from 18 to 15 thousand years before present (kyr BP) associated with Heinrich Event 1 (HE1) had a strong impact on vegetation patterns not only at high latitudes of the Northern Hemisphere, but also in the tropical regions around the Atlantic Ocean. To gain a better understanding of the linkage between high and low latitudes, we used the University of Victoria (UVic) Earth System-Climate Model (ESCM) with dynamical vegetation and land surface components to simulate four scenarios of climate-vegetation interaction: the pre-industrial era, the Last Glacial Maximum (LGM), and a Heinrich-like event with two different climate backgrounds (interglacial and glacial). We calculated mega-biomes from the plant-functional types (PFTs) generated by the model to allow for a direct comparison between model results and palynological vegetation reconstructions. <br><br> Our calculated mega-biomes for the pre-industrial period and the LGM corresponded well with biome reconstructions of the modern and LGM time slices, respectively, except that our pre-industrial simulation predicted the dominance of grassland in southern Europe and our LGM simulation resulted in more forest cover in tropical and sub-tropical South America. <br><br> The HE1-like simulation with a glacial climate background produced sea-surface temperature patterns and enhanced inter-hemispheric thermal gradients in accordance with the "bipolar seesaw" hypothesis. We found that the cooling of the Northern Hemisphere caused a southward shift of those PFTs that are indicative of an increased desertification and a retreat of broadleaf forests in West Africa and northern South America. The mega-biomes from our HE1 simulation agreed well with paleovegetation data from tropical Africa and northern South America. Thus, according to our model-data comparison, the reconstructed vegetation changes for the tropical regions around the Atlantic Ocean were physically consistent with the remote effects of a Heinrich event under a glacial climate background

Masked millennial-scale climate variations in South West Africa during the last glaciation

To address the connection between tropical African vegetation development and high-latitude climate change we present a high-resolution pollen record from ODP Site 1078 (off Angola) covering the period 50–10 ka BP. Although several tropical African vegetation and climate reconstructions indicate an impact of Heinrich Stadials (HSs) in Southern Hemisphere Africa, our vegetation record shows no response. Model simulations conducted with an Earth System Model of Intermediate Complexity including a dynamical vegetation component provide one possible explanation. Because both precipitation and evaporation increased during HSs and their effects nearly cancelled each other, there was a negligible change in moisture supply. Consequently, the resulting climatic response to HSs might have been too weak to noticeably affect the vegetation composition in the study area. Our results also show that the response to HSs in southern tropical Africa neither equals nor mirrors the response to abrupt climate change in northern Africa

Kajian Kerentanan Pesisir Terhadap Kenaikan Muka Air Laut di Kabupaten Subang-Jawa Barat

Akresi dan erosi di sepanjang garis pantai merupakan salah satu masalah di pesisir Kabupaten Subang-Jawa Barat. Kondisi tersebut digabungkan dengan kenaikan muka air laut akibat perubahan iklim global mengakibatkan wilayah pesisir tersebut rentan mengalami bencana. Penelitian ini bertujuan menentukan indeks kerentanan wilayah pesisir Kabupaten Subang berdasarkan parameter fisik pesisir, yaitu geomorfologi, rentang pasang surut, rata-rata ketinggian gelombang dan permukaan air laut, jenis batuan geologi, serta perubahan garis pantai (akresi dan erosi). Data-data spasial pesisir diklasifikasikan berdasarkan tingkat kerentanan, dan nilai kerentanan total dihitung dengan rumusan coastal vulnerability index. Hasilnya menunjukkan parameter fisik oseanografi (pasut dan tinggi gelombang) memiliki tingkat kerentanan sangat rendah. Sedangkan, ketinggian permukaan air laut dan jenis batuan geologi di sekitar pantai menunjukkan kerentanan tinggi dan sangat tinggi. Adapun klasifikasi perubahan garis pantai di sepanjang kecamatan bervariasi dan kerentanannya berkorealsi dengan tingkat akresi dan erosinya. Hasil perhitungan indeks kerentanan total CVI di semua kecamatan pesisir di Kabupaten Subang dikategorikan sangat rendah, akan tetapi kajian indeks secara lokal menunjukkan Kecamatan Sukasari dan Blanakan memiliki kerentanan sangat tinggi. Variasi indeks ini menunjukkan perubahan lokal di pesisir Kabupaten Subang berkorelasi dengan perubahan global yang terjadi, dimana kenaikan permukaan air laut lokal merupakan dampak perubahan laut dan iklim secara global

Analisis Efektivitas Bangunan Pelindung Pelabuhan Patimban dan Pantai Sekitar Melalui Tinjauan Hidro-Oseanografi

ABSTRAKPemerintah Indonesia akan membangun pelabuhan baru dengan hierarki Pelabuhan Utama sebagai penopang Pelabuhan Tanjung Priok yang direncanakan akan dibangun di Patimban, Kabupaten Subang. Pembangunan pelabuhan membutuhkan kajian aspek teknis, salah satu di antaranya adalah bangunan pelindung pelabuhan. Penelitian ini bertujuan melakukan tinjauan hidro-oseanografi yang terdiri atas analisis tinggi gelombang, pelayaran, dan sedimentasi di area rencana pembangunan Pelabuhan Patimban sebagai analisis efektivitas bangunan pelindung dermaga Pelabuhan Patimban dan pantai di sekitarnya. Berdasarkan analisis diperoleh bahwa gelombang (yang dapat mencapai tinggi 1,5 meter) dan sedimentasi (berupa akresi dan abrasi) menjadi faktor penting dalam mempertimbangkan pemilihan jenis bangunan pelindung pantai di Perairan Patimban. Struktur pelindung dermaga yang direncanakan dalam Rencana Induk Pelabuhan Patimban cukup efektif melindungi dermaga. Untuk pantai di sekitar pelabuhan direkomendasikan bangunan pelindung berupa jetty bertipe pendek untuk mengantisipasi pembelokan muara sungai yang diakibatkan aktivitas sedimentasi di muara Sungai Cipunagara dan penanaman hutan mangrove di sepanjang Pantai Patimban untuk mengatasi fenomena abrasi.Kata kunci: tinjauan hidro-oseanografi, bangunan pelindung pelabuhan, pelabuhan utamaABSTRACTGovernment of Indonesia plans to construct a new port as International Hub Port hierarchy which support Port of Tanjung Priok at Patimban, Subang District. The port construction needs technical aspects studies, such as coastal protection stuctures. This study aims to analyze the hydrooceanography factors (wave, vessel maneuverability, and sedimentation) on Port of Patimban plan area to find the effectivity of coastal protection stuctures to protect port and its coastal area. Based on analysis it is found that the wave (which can reach 1,5 metres high) and sedimentation (accretion and abrasion) will be the main factors to consider for determining the appropriate coastal protection structures in Patimban Waters. The coastal protection structures planned in the Patimban Port Master Plan are quite effective at protecting the port. For the Port of Patimban coastal area, protective building in the form of short-type jetty is recommended to anticipate the deflection of Cipunagara River estuary caused by sedimentation. Besides that, planting mangroves along Patimban coastline will overcome the abrasion problem.Keywords: hidro-oceanography consideration, coastal protection structures, international hub por

Tropical vegetation response to Heinrich Event 1 as simulated with the UVic ESCM and CCSM3

We investigated changes in tropical climate and vegetation cover associated with abrupt climate change during Heinrich Event 1 (HE1, ca. 17.5 ka BP) using two different global climate models: the University of Victoria Earth System-Climate Model (UVic ESCM) and the Community Climate System Model version 3 (CCSM3). Tropical South American and African pollen records suggest that the cooling of the North Atlantic Ocean during HE1 influenced the tropics through a southward shift of the rain belt. In this study, we simulated the HE1 by applying a freshwater perturbation to the North Atlantic Ocean. The resulting slowdown of the Atlantic Meridional Overturning Circulation was followed by a temperature seesaw between the Northern and Southern Hemispheres, as well as a southward shift of the tropical rain belt. The shift and the response pattern of the tropical vegetation around the Atlantic Ocean were more pronounced in the CCSM3 than in the UVic ESCM simulation. For tropical South America, opposite changes in tree and grass cover were modeled around 10° S in the CCSM3 but not in the UVic ESCM. In tropical Africa, the grass cover increased and the tree cover decreased around 15° N in the UVic ESCM and around 10° N in the CCSM3. In the CCSM3 model, the tree and grass cover in tropical Southeast Asia responded to the abrupt climate change during the HE1, which could not be found in the UVic ESCM. The biome distributions derived from both models corroborate findings from pollen records in southwestern and equatorial western Africa as well as northeastern Brazil

Identifikasi Perubahan Garis Pantai dan Ekosistem Pesisir di Kabupaten Subang

ABSTRAKPenelitian ini adalah kajian awal dari valuasi ekonomi atas manfaat dan jasa ekosistem di pesisir Subang. Faktor-faktor utama dalam valuasi adalah keberadaan ekosistem dan perubahan di pesisir, serta manfaat dan jasa ekosistemnya. Estimasi perubahan garis pantai dihitung berdasarkan tumpang susun data satelit Landsat tahun 1988, 1996, 2003, dan 2016. Estimasi menunjukkan terjadi perubahan garis pantai sebesar 8,17 km sejak tahun 1988-2013. Perubahan tersebut didominasi oleh sedimentasi dan abrasi sepanjang pantai. Sedimentasi tertinggi terjadi di Kecamatan Pusakanagara (869,9 ha) dan Blanakan (725,4 ha), serta abrasi tertinggi terjadi di Kecamatan Legonkulon (885,8 ha). Ekosistem alami yang berubah dan dimanfaatkan secara intensif di pesisir Subang adalah kawasan estuari dan mangrove. Sehingga mengakibatkan penurunan fungsi ekologi pada ekosistem tersebut. Adapun lahan tambak sebagai ekosistem buatan yang menggantikan kawasan mangrove, hanya berfungsi sebagai penyedia kebutuhan pangan. Penelitian ini menunjukkan perlunya valuasi ekonomi atas lahan mangrove versus budidaya tambak di Kecamatan Legonkulon, serta kawasan estuari yang berfungsi sebagai sarana transportasi di Kecamatan Pusakanagara.Kata kunci: garis pantai, ekosistem pesisir, erosi, sedimentasi, SubangABSTRACTThis research is a preliminary study for economic valuation of coastal services and goods in Subang Regency. Main factors in the valuation are ecological existing, changing, services and goods of coastal ecosystem. Coastline changes estimation was based on the overlay of Landsat satellite image at year of 1988, 1996, 2003, and 2016. Estimation shows since year of 1988 to 2013 there is changing of coastline around 8,17 km. The changes are dominantly caused by coastline sedimentation and abrasion. Higher sedimentation occured in Pusakanagara (869,9 ha) and Blanakan (725,4) Subdistrict, while highest abrasion occured in Legonkulon (885,8 ha) Subdistrict. Estuary and mangrove forests are natural ecosystem that had been used intensively and changing very excessively in this region. These changing causes degradation in functions of these ecosystems. Meanwhile, changing of mangrove forest into aquaculture only provides food. This research shows the necessity in economic valution of mangrove forest versus aquaculture in Legonkulon Subdistrict, and also estuary as transportation function in Pusakanagara Subdistrict.Keywords: coastline, coastal ecosystem, erosion, sedimentation, Suban