Marine Atlas: Maximizing Benefits for Vanuatu

Normal conditions

El Niño conditions

Westerly Winds

Strong Trade Winds

Weaker Trade Winds

Water Heated by the Sun

Weak Upwelling

Strong Upwelling

WarmWater

WarmWater

Thermocline

Thermocline

Deep Cold Water

Deep Cold Water

120°E

140°E

160°E

180°

160°W

140°W

120°W

100°W

80°W

120°E

140°E

160°E

180°

160°W

140°W

120°W

100°W

80°W

Darwin, Australia

Vanuatu

Lima, Peru

Darwin, Australia

Lima, Peru

Vanuatu

Firstly, matter such as solids, dissolved substanc- es and gases are carried by the currents, includ- ing salt, larvae (see also chapter “Travellers or homebodies”), plastics and oil (see also chapters “Plastic oceans” and “Full speed ahead”). Sec- ondly, currents transport energy in the form of heat. Currents therefore have a significant impact on the global climate. El Niño is an example of the big impact that re- gional climate variability related to ocean currents has on Vanuatu (see graphs and chapter “Hot- ter and higher”). Normally, strong trade winds blow from east to west across the Pacific Ocean around the equator. As the winds push warm sur- face water from South America west towards Asia and Australia, cold water wells up from below in the east to take its place along the west coast of South America. This creates a temperature disparity across the Pacific, which also keeps the trade winds blowing. The accumulation of warm water in the west heats the air, causing it to rise and create unstable weather, making the western Pacific region warm and rainy. Cool, drier air is usually found on the eastern side of the Pacific. In an El Niño year, the trade winds weaken or break down. The warm water that is normally pushed towards the western Pacific washes back across, piling up on the east side of the Pacific from California to Chile, causing rain and storms and increasing the risk of cyclone formation over the tropical Pacific Ocean (Climate Prediction Center, 2005) (see also chapter “Stormy times”). On the other side, the western Pacific experienc- es particularly dry conditions. The periods 1997– 1998 and 2014–2016 witnessed some of the most extreme events on record in the region. Between 2015 and 2017, Vanuatu experienced its worst and most sustained drought in decades. Many of the worst affected areas were also those severely hit by Cyclone Pam, itself one of the worst natural disasters in the history of Vanuatu. Throughout this period, a food security crisis loomed that saw many communities struggle to survive, with young children the most acutely affected. More- over, El Niño contributes to an increase in global temperatures. In the particularly hot year of 2015, El Niño was responsible for about 10 per cent of the temperature rise. In turn, rising global and ocean temperatures may intensify El Niño (Cai et al., 2014).

In summary, sea currents driven by wind, heat and salinity influence not only Vanuatu’s marine biodiversity, but also its rainfall patterns and tem- perature on land.

SEA SURFACE CURRENTS Direction and velocity (m/s)

0.09

0.05

0.03

0.01

15°S

20°S

165°E

Vanuatu Provisional EEZ Boundary Boundary as deposited at UN Archipelagic Baseline

100 50

200 km

25°S

Sources : Becker et al, 2009; Claus et al, 2016; ESR, 2009; Smith and Sandwell, 1997. Copyright © MACBIO Map produced by GRID-Arendal

170°E

MAXIMIZING BENEFITS FOR VANUATU

SUPPORTING VALUES

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