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Past and future rainfall in the Horn of Africa

fomented drought and famine, threatening food security in an already vulnerable region. Some attribute this decline to anthropogenic forcing, whereas others maintain that it is a feature of internal climate variability. We show that the rate of drying in the Horn of Africa during the 20th century is unusual in the context of the last 2000 years, is synchronous with recent global and regional warming, and therefore may have an anthropogenic component. In contrast to 20th century drying, climate models predict that the Horn of Africa will become wetter as global temperatures rise. The projected increase in rainfall mainly occurs during the September–November “short rains” season, in response to large-scale weakening of the Walker circulation. Most of the models overestimate short rains precipitation while underestimating long rains precipitation, causing the Walker circulation response to unrealistically dominate the annual mean. Our results highlight the need for accurate simulation of the seasonal cycle and an improved understanding of the dynamics of the long rains season to predict future rainfall in the Horn of Africa.

UNI: 
Publication type: 
Author: 
Jessica E. Tierney
Caroline C. Ummenhofer
Peter B. deMenocal
Subjects: 
Paleoclimatology
Rain and rainfall
Rain and rainfall--Forecasting
Drought forecasting
Climatic changes
Title string: 
Past and future rainfall in the Horn of Africa
GUID update: 
https://academiccommons.columbia.edu/catalog/ac:2jm63xsj4j

Pliocene oceanic seaways and global climate

Tectonically induced changes in oceanic seaways had profound effects on global and regional climate during the Late Neogene. The constriction of the Central American Seaway reached a critical threshold during the early Pliocene ~4.8–4 million years (Ma) ago. Model simulations indicate the strengthening of the Atlantic Meridional Overturning Circulation (AMOC) with a signature warming response in the Northern Hemisphere and cooling in the Southern Hemisphere. Subsequently, between ~4–3 Ma, the constriction of the Indonesian Seaway impacted regional climate and might have accelerated the Northern Hemisphere Glaciation. We here present Pliocene Atlantic interhemispheric sea surface temperature and salinity gradients (deduced from foraminiferal Mg/Ca and stable oxygen isotopes, δ18O) in combination with a recently published benthic stable carbon isotope (δ13C) record from the southernmost extent of North Atlantic Deep Water to reconstruct gateway-related changes in the AMOC mode. After an early reduction of the AMOC at ~5.3 Ma, we show in agreement with model simulations of the impacts of Central American Seaway closure a strengthened AMOC with a global climate signature. During ~3.8–3 Ma, we suggest a weakening of the AMOC in line with the global cooling trend, with possible contributions from the constriction of the Indonesian Seaway.

UNI: 
Publication type: 
Author: 
Cyrus Karas
Dirk Nurnberg
Andre Bahr
Jeroen Groeneveld
Jens O. Herrle
Ralf Tiedemann
Peter B. deMenocal
Subjects: 
Paleoceanography
Paleoclimatology
Climatic changes
Ocean-atmosphere interaction
Title string: 
Pliocene oceanic seaways and global climate
GUID update: 
https://academiccommons.columbia.edu/catalog/ac:s4mw6m9083

The Effect of Botulinum Toxin on Network Connectivity in Cervical Dystonia: Lessons from Magnetoencephalography

Background: Pharmacological management of cervical dystonia (CD) is considered to be symptomatic in effect, rather than targeting the underlying pathophysiology of the disease. Magnetoencephalography (MEG), a direct measure of neuronal activity, while accepted as a modality for pre-surgical mapping in epilepsy, has never been used to explore the effect of pharmacotherapy in movement disorders.

Methods: Resting state MEG data were collected from patients with CD, pre- and post-botulinum toxin injections. All of these patients exhibited good clinical benefit with botulinum toxin. Resting state MEG data from four age- and gender-matched healthy controls with no neurological disorders were also collected.

Results: Our exploratory study reveals a difference in coherence between controls and patients in the following regions: fronto-striatal, occipito-striatal, parieto-striatal, and striato-temporal networks. In these regions there is an increase after botulinum toxin. Specifically, increased coherence in the left putamen and right superior parietal gyrus was noticeable. Both intrahemispheric and interhemispheric networks were affected.

Discussion: This is the first attempt to directly assess changes in functional connectivity with pharmacotherapy using MEG. Botulinum toxin might affect sensorimotor integration, leading to clinical benefit. The presence of increased interhemispheric coherence and intrahemispheric coherence points to the importance of global and local networks in the pathophysiology of dystonia.

Publication type: 
Author: 
Abhimanyu Mahajan
Abdullah Alshammaa
Andrew Zillgitt
Susan M. Bowyer
Peter LeWitt
Patricia Kaminski
Christos Sidiropoulos
Subjects: 
Magnetoencephalography
Dystonia
Botulinum toxin--Therapeutic use
Sensorimotor integration
Neurosciences
Title string: 
The Effect of Botulinum Toxin on Network Connectivity in Cervical Dystonia: Lessons from Magnetoencephalography
GUID update: 
https://academiccommons.columbia.edu/catalog/ac:3tx95x69px

The Inter-rater Variability of Clinical Assessment in Post-anoxic Myoclonus

Background: Acute post-anoxic myoclonus (PAM) can be divided into an unfavorable (generalized/subcortical) and more favorable ((multi)focal/cortical) outcome group that could support prognostication in post-anoxic encephalopathy; however, the inter-rater variability of clinically assessing these PAM subtypes is unknown.

Methods: We prospectively examined PAM patients using a standardized video protocol. Videos were rated by three neurologists who classified PAM phenotype (generalized/(multi)focal), stimulus sensitivity, localization (proximal/distal/both), and severity (Clinical Global Impression-Severity Scale (CGI-S) and Unified Myoclonus Rating Scale (UMRS)).

Results: Poor inter-rater agreement was found for phenotype and stimulus sensitivity (κ = –0.05), moderate agreement for localization (κ = 0.46). Substantial agreement was obtained for the CGI-S (intraclass correlation coefficient (ICC) = 0.64) and almost perfect agreement for the UMRS (ICC = 0.82).

Discussion: Clinical assessment of PAM is not reproducible between physicians, and should therefore not be used for prognostication. PAM severity measured by the UMRS appears to be reliable; however, the relation between PAM severity and outcome is unknown.

Topic: 
Publication type: 
Author: 
van Jonathan C. Zijl
Martijn Beudel
Jan Elting-Willem J.
de Bauke M. Jong
van der Joukje Naalt
van den Walter M. Bergh
Andrea O. Rossetti
Marina A. J. Tijssen
Janneke Horn
Subjects: 
Neurology
Myoclonus
Prognosis
Title string: 
The Inter-rater Variability of Clinical Assessment in Post-anoxic Myoclonus
GUID update: 
https://academiccommons.columbia.edu/catalog/ac:7sqv9s4mxh

Life cycles of agriculturally relevant ENSO teleconnections in North and South America

The characteristic evolution of El Niño Southern Oscillation (ENSO) on timescales of months to years means that risks to agriculture have structure between seasons and years. The potential for consecutive ENSO-induced yield anomalies is of particular interest in major food producing areas, where modest changes in yield have significant effects on global markets. In this study, we analyse how multi-year El Niño and La Niña life cycles relate to climate sensitive portions of major crop-growing seasons in North and South America.

We analyse the dynamics underlying these life cycles to illustrate which aspects of the system are most important for agriculture. In North America, the same-season teleconnections affecting soybean and maize have been well studied, but we demonstrate the importance of lagged soil moisture teleconnections for wheat in the southern Great Plains. In South America, peak ENSO sea surface temperature (SST) teleconnections are concurrent with, and therefore critical for, wheat and maize growing seasons while soil moisture memory in Argentina plays an important role during the soybean growing season.

Finally, we show that ENSO teleconnection life cycles are consistent with historical yield anomalies. Both El Niño and La Niña life cycles tend to force consecutive seasons of either above or below expected yields. While the magnitude of the yield anomalies forced by ENSO is often modest, they occur in major crop-producing regions.

Publication type: 
Author: 
Weston Buckley Anderson
Richard Seager
Walter E. Baethgen
Mark A. Cane
Subjects: 
Southern oscillation
Teleconnections (Climatology)
Crops and climate
Title string: 
Life cycles of agriculturally relevant ENSO teleconnections in North and South America
GUID update: 
https://academiccommons.columbia.edu/catalog/ac:2z34tmpg5b

Precipitation, Temperature, and Teleconnection Signals across the Combined North American, Monsoon Asia, and Old World Drought Atlases

The tree-ring-based North American Drought Atlas (NADA), Monsoon Asia Drought Atlas (MADA), and Old World Drought Atlas (OWDA) collectively yield a near-hemispheric gridded reconstruction of hydroclimate variability over the last millennium. To test the robustness of the large-scale representation of hydroclimate variability across the drought atlases, the joint expression of seasonal climate variability and teleconnections in the NADA, MADA, and OWDA are compared against two global, observation-based PDSI products. Predominantly positive (negative) correlations are determined between seasonal precipitation (surface air temperature) and collocated tree-ring-based PDSI, with average Pearson’s correlation coefficients increasing in magnitude from boreal winter to summer. For precipitation, these correlations tend to be stronger in the boreal winter and summer when calculated for the observed PDSI record, while remaining similar for temperature. Notwithstanding these differences, the drought atlases robustly express teleconnection patterns associated with El Niño–Southern Oscillation (ENSO), the North Atlantic Oscillation (NAO), the Pacific decadal oscillation (PDO), and the Atlantic multidecadal oscillation (AMO). These expressions exist in the drought atlas estimates of boreal summer PDSI despite the fact that these modes of climate variability are dominant in boreal winter, with the exception of the AMO. ENSO and NAO teleconnection patterns in the drought atlases are particularly consistent with their well-known dominant expressions in boreal winter and over the OWDA domain, respectively. Collectively, the findings herein confirm that the joint Northern Hemisphere drought atlases robustly reflect large-scale patterns of hydroclimate variability on seasonal to multidecadal time scales over the twentieth century and are likely to provide similarly robust estimates of hydroclimate variability prior to the existence of widespread instrumental data.

Topic: 
Publication type: 
Author: 
Seung Hun Baek
Jason E. Smerdon
Sloan Coats
A. Park Williams
Benjamin I. Cook
Edward R. Cook
Richard Seager
Subjects: 
Climatic changes
Climatic changes--Models
Hydrologic models--Evaluation
Title string: 
Precipitation, Temperature, and Teleconnection Signals across the Combined North American, Monsoon Asia, and Old World Drought Atlases
GUID update: 
https://academiccommons.columbia.edu/catalog/ac:7m0cfxpnx1

Crop production variability in North and South America forced by life-cycles of the El Niño Southern Oscillation

In this analysis we show how globally coherent teleconnections from life-cycles of the El Niño Southern Oscillation (ENSO) lead to correlated crop production anomalies in North and South America. We estimate the magnitude of ENSO-induced Pan-American production anomalies and discuss how increasing crop harvesting frequency may affect Pan-American production variability.

We find that ENSO accounts for ∼72%, 30% and 57% of Pan-American maize, soybean and wheat production variability, respectively. ENSO-induced production anomalies are greatest for maize, with median anomalies of ∼5% of Pan-American production. ENSO-induced yield anomalies for maize and soybeans tend to be of the same sign in North America and southeast South America but of an opposite sign in northeast Brazil. Teleconnections for wheat are more complicated because ENSO affects wheat yields via lagged soil moisture teleconnections in the US and an increased probability of disease in South America, but anomalies tend to be of the same sign in North America and southeast South America.

After broadly characterizing ENSO-induced production anomalies, we demonstrate that they are not static in time. Increasing crop harvesting frequency has affected the correlated risks posed by ENSO. We use a soil water balance to show that in Brazil changing to a safrinha cropping cycle increases both the mean water stress and the ENSO-induced soil water content anomalies during flowering in both the maize and soybean seasons, which is a result of increasing evaporative demand during times of lower precipitation and moving the flowering seasons into months with strong ENSO teleconnections. Increasing crop harvesting frequency in Brazil has therefore increased ENSO-induced production variability of soybeans and maize.

Publication type: 
Author: 
Weston Buckley Anderson
Richard Seager
Walter E. Baethgen
Mark A. Cane
Subjects: 
Southern oscillation
Teleconnections (Climatology)
Crops and climate
Title string: 
Crop production variability in North and South America forced by life-cycles of the El Niño Southern Oscillation
GUID update: 
https://academiccommons.columbia.edu/catalog/ac:xpnvx0k6gx

No Access Are Glacials Dry? Consequences for Paleoclimatology and for Greenhouse Warming

Past cold climates are often thought to have been drier than today on land, which appears to conflict with certain recent studies projecting widespread terrestrial drying with near-future warming. However, other work has found that, over large portions of the continents, the conclusion of future drying versus wetting strongly depends on the physical property of interest. Here, it is shown that this also holds in simulations of the Last Glacial Maximum (LGM): the continents have generally wetter topsoils and higher values of common climate wetness metrics than in the preindustrial, as well as generally lower precipitation and ubiquitously lower photosynthesis (likely driven by the low CO2), with streamflow responses falling in between. Using a large existing global pollen and plant fossil compilation, it is also confirmed that LGM grasslands and open woodlands grew at many sites of present-day forest, seasonal forests at many sites of present-day rain forest, and so forth (116–144 sites out of 302), while changes in the opposite sense were very few (9–17 sites out of 302) and spatially confined. These vegetation changes resemble the model photosynthesis responses but not the hydroclimate responses, while published lake-level changes resemble the latter but not the former. Thus, confidence in both the model hydrologic and photosynthesis projections is increased, and there is no significant conflict. Instead, paleo- and modern climate researchers must carefully define “wetting” and “drying” and, in particular, should not assume hydrologic drying on the basis of vegetation decline alone or assume vegetation stress on the basis of declines in hydroclimatic indicators.

Topic: 
Publication type: 
Author: 
Jacob S. Scheff
Richard Seager
Haibo Liu
Sloan Coats
Subjects: 
Climatic changes
Hydrologic cycle
Paleoclimatology
Glacial climates
Atmospheric circulation--Models
Title string: 
No Access Are Glacials Dry? Consequences for Paleoclimatology and for Greenhouse Warming
GUID update: 
https://academiccommons.columbia.edu/catalog/ac:hhmgqnk9bd

Minimum Global Effective Corporate Tax Rate as General Anti-Avoidance Rule

In this article, I propose to add a new provision to the U.S. Internal Revenue Code that adopts a minimum global effective corporate tax rate that will serve as a general anti-avoidance rule and is targeted toward international corporate tax avoidance. According to this proposed new section, if the global effective corporate tax rate of any American Multi-National Corporation (MNC) is below 15%, the MNC will then be required to close the gap and pay the U.S. Treasury up to the minimum.[28] For purposes of my proposal, the global effective corporate tax rate will be calculated according to the ratio between the global corporate tax paid and the global earnings and profits (E&P) in the financial statements of the MNC.[29] The tax imposed according to my proposed rule is an interim liability that serves to limit tax avoidance schemes on international transactions.

I argue that this rule is expected to reduce the incentives for international tax avoidance because all MNCs will be liable for the minimum global effective corporate tax rate no matter which tax-planning scheme is used. In my opinion, this regime improves the fairness and efficiency of the U.S. international corporate tax regime while protecting and maintaining the competitive position of American MNCs in the global digital economy. I contend that my proposal is politically feasible in the U.S. because the U.S. must act in order to protect its base and its multinationals in the new international environment. Without U.S. response, other unilateral or international responses are likely to negatively affect U.S. interests as the State Aid Cases of Apple and other U.S. multinationals reveal. My proposal is feasible since it is consistent with the ideology and interests of both Democrats and Republicans. Furthermore, the Obama Administration has already proposed a similar minimum tax, and the similarities between my proposal and that of the Administration outweigh the differences.[30] I use Former President Obama’s minimum taxation proposal to support the political feasibility of my minimum taxation proposal, but at the same time, I argue that my proposal is distinct and more appropriate than Former President Obama’s proposal and other proposals of minimum taxation such as the Shay, Fleming and Peroni interim minimum tax[31] and the Grubert, Altshuler minimum tax versions.[32] If the United States adopts this proposed rule, it will substantially contribute, through “constructive unilateralism”, to international tax reform that will better equip the global community to meet the challenges of a twenty-first century digital economy. [33]

This article contributes to a timely issue of international taxation. It brings a fresh perspective on the debate about international corporate tax avoidance. My proposal is innovative and distinct from current discourse and other proposals. Little attention has been given by scholars of international corporate tax avoidance to the extensive literature and comparative experience available that addresses: (i) the impact of corporate tax avoidance at the national level and (ii) the government’s attempts to limit such behavior, particularly through regulatory reform.[34] My proposal deviates from the current puzzling situation in that it utilizes the significant insights that this literature provides in order to improve reform efforts at the international level. Therefore, rather than proposing an entirely new scheme that addresses the challenges presented by international corporate tax avoidance in an isolated manner, my proposal uses relevant experiences at the domestic level in the United States and in other countries as a foundation.

Following this introduction, Part II describes the current U.S. rules of international taxation on outbound and inbound transactions as well as the interaction between these rules and (i) the bilateral rules provided by the U.S. treaty network and (ii) the international norms such as the OECD norms. Furthermore, Part II analyzes the challenges faced by the U.S. and the global tax regime as a result of international corporate tax avoidance. Data is provided to illustrate the impact. Part III explores the current American responses to this challenge. Part IV briefly describes the OECD international response through the BEPS project and examines the interactions between the American responses and the OECD responses. In Part V, I present my proposal in detail, as well as the philosophy and justifications behind it. I compare my proposal to other proposals of minimum taxation, and I respond to counterarguments. I end my article with a brief conclusion.

Topic: 
Publication type: 
Author: 
Rifat Azam
Subjects: 
Law
Corporations--Taxation--Law and legislation
Tax evasion--Prevention
Taxation--International cooperation
Title string: 
Minimum Global Effective Corporate Tax Rate as General Anti-Avoidance Rule
GUID update: 
https://academiccommons.columbia.edu/catalog/ac:5qfttdz09h

The Status Quo of Racial Discrimination in Japan and the Republic of Korea and the Need to Provide for Anti-Discrimination Laws

Japan and the Republic of Korea, two neighboring nations situated in East Asia, have homogenous demographics. Both societies face large influxes of foreigners—from immigration and tourism alike—due to various factors ranging from rapidly aging populations, low birth rates, and globalization. Despite this, neither country has sufficient legal means of halting racially discriminatory practices that occur within them. This Note illustrates the rampant nature of racial discrimination in Japan and the Republic of Korea, analyzes the current state of their anti-discrimination laws, argues that the existing legal protections for foreigners against racial discrimination are inadequate at best, and finally, urges that the two governments adopt available means to improve upon the situation.

Topic: 
Publication type: 
Author: 
Yujin Yi
Subjects: 
Race discrimination--Law and legislation
Race relations--Law and legislation
Law
Title string: 
The Status Quo of Racial Discrimination in Japan and the Republic of Korea and the Need to Provide for Anti-Discrimination Laws
GUID update: 
https://academiccommons.columbia.edu/catalog/ac:j0zpc866vx

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